refactor: centralize runtime logic (v0.4)
Extract scheduler responsibilities into a dedicated Runtime component: - src/runtime.rs: New centralized control flow (669 lines) - src/scheduler.rs: Simplified to task queue & preemption management - tests/runtime.rs: Comprehensive runtime test suite - benches/multi_scheduler.rs: Multi-runtime scheduling benchmarks - Improves modularity and enables per-runtime configuration
This commit is contained in:
Claude
@@ -9,7 +9,7 @@ libc = "0.2"
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[dev-dependencies]
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libc = "0.2"
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tokio = { version = "1", features = ["rt", "macros", "sync"] }
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tokio = { version = "1", features = ["rt", "rt-multi-thread", "macros", "sync"] }
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[profile.dev]
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panic = "unwind"
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@@ -22,3 +22,7 @@ codegen-units = 1
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[[bench]]
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name = "primes"
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harness = false
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[[bench]]
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name = "multi_scheduler"
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harness = false
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343
benches/multi_scheduler.rs
Normal file
343
benches/multi_scheduler.rs
Normal file
@@ -0,0 +1,343 @@
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//! Benchmarks for the multi-scheduler runtime.
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//!
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//! Three workloads, three runtimes:
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//! - smarm single-thread (exact = 1)
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//! - smarm multi-thread (exact = available_parallelism)
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//! - tokio current_thread (single-thread baseline)
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//! - tokio multi-thread (the parallel comparison)
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//!
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//! Workloads:
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//! 1. Fan-out / fan-in compute (primes) — CPU-bound, tests parallelism
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//! 2. Ping-pong — message-passing overhead, park/unpark cost
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//! 3. Spawn throughput — cost of spawn + join per actor
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use std::sync::atomic::{AtomicU64, Ordering};
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use std::sync::Arc;
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use std::time::Instant;
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// ---------------------------------------------------------------------------
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// Shared helpers
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// ---------------------------------------------------------------------------
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fn available_threads() -> usize {
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std::thread::available_parallelism()
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.map(|n| n.get())
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.unwrap_or(1)
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}
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fn print_header(title: &str) {
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println!("\n{}", "=".repeat(80));
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println!(" {title}");
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println!("{}", "=".repeat(80));
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println!(
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"{:>22} | {:>12} | {:>10} | {:>10} | {:>10}",
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"runtime", "result", "median µs", "min µs", "max µs"
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);
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println!("{}", "-".repeat(80));
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}
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fn run_n<F: FnMut() -> (u64, u128)>(name: &str, n: u32, mut f: F) {
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let mut times = Vec::new();
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let mut last = 0u64;
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for _ in 0..n {
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let (v, t) = f();
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times.push(t);
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last = v;
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}
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times.sort_unstable();
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let median = times[times.len() / 2];
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let min = *times.iter().min().unwrap();
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let max = *times.iter().max().unwrap();
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println!(
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"{:>22} | {:>12} | {:>10} | {:>10} | {:>10}",
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name, last, median, min, max
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);
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}
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const ITERS: u32 = 7;
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// ---------------------------------------------------------------------------
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// Workload 1: fan-out / fan-in primes
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// ---------------------------------------------------------------------------
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const PRIME_N: u64 = 400_000;
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const WORKERS: u64 = 64;
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fn is_prime(n: u64) -> bool {
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if n < 2 { return false; }
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if n < 4 { return true; }
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if n % 2 == 0 { return false; }
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let mut i = 3u64;
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while i * i <= n { if n % i == 0 { return false; } i += 2; }
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true
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}
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fn count_primes(lo: u64, hi: u64) -> u64 {
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(lo..hi).filter(|&n| is_prime(n)).count() as u64
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}
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fn primes_slice(w: u64) -> (u64, u64) {
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let per = PRIME_N / WORKERS;
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let lo = w * per;
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let hi = if w + 1 == WORKERS { PRIME_N } else { lo + per };
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(lo, hi)
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}
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fn bench_primes_smarm(threads: usize) -> (u64, u128) {
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let total = Arc::new(AtomicU64::new(0));
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let t2 = total.clone();
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let start = Instant::now();
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smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(move || {
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let mut handles = Vec::new();
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for w in 0..WORKERS {
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let (lo, hi) = primes_slice(w);
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let tc = t2.clone();
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handles.push(smarm::spawn(move || {
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tc.fetch_add(count_primes(lo, hi), Ordering::Relaxed);
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}));
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}
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for h in handles { h.join().unwrap(); }
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});
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(total.load(Ordering::Relaxed), start.elapsed().as_micros())
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}
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fn bench_primes_tokio_current() -> (u64, u128) {
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let total = Arc::new(AtomicU64::new(0));
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let t2 = total.clone();
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let rt = tokio::runtime::Builder::new_current_thread().build().unwrap();
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let start = Instant::now();
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let local = tokio::task::LocalSet::new();
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local.block_on(&rt, async move {
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let mut handles = Vec::new();
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for w in 0..WORKERS {
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let (lo, hi) = primes_slice(w);
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let tc = t2.clone();
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handles.push(tokio::task::spawn_local(async move {
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tc.fetch_add(count_primes(lo, hi), Ordering::Relaxed);
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}));
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}
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for h in handles { let _ = h.await; }
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});
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(total.load(Ordering::Relaxed), start.elapsed().as_micros())
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}
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fn bench_primes_tokio_multi() -> (u64, u128) {
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let total = Arc::new(AtomicU64::new(0));
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let t2 = total.clone();
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let rt = tokio::runtime::Builder::new_multi_thread()
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.worker_threads(available_threads())
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.build()
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.unwrap();
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let start = Instant::now();
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rt.block_on(async move {
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let mut handles = Vec::new();
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for w in 0..WORKERS {
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let (lo, hi) = primes_slice(w);
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let tc = t2.clone();
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handles.push(tokio::spawn(async move {
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tc.fetch_add(count_primes(lo, hi), Ordering::Relaxed);
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}));
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}
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for h in handles { let _ = h.await; }
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});
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(total.load(Ordering::Relaxed), start.elapsed().as_micros())
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}
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fn bench_primes_baseline() -> (u64, u128) {
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let start = Instant::now();
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let total: u64 = (0..WORKERS).map(|w| {
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let (lo, hi) = primes_slice(w);
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count_primes(lo, hi)
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}).sum();
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(total, start.elapsed().as_micros())
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}
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// ---------------------------------------------------------------------------
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// Workload 2: channel ping-pong
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// ---------------------------------------------------------------------------
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const PING_ROUNDS: u64 = 10_000;
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fn bench_pingpong_smarm(threads: usize) -> (u64, u128) {
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let start = Instant::now();
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smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(|| {
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let (tx_a, rx_a) = smarm::channel::<u64>();
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let (tx_b, rx_b) = smarm::channel::<u64>();
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let ha = smarm::spawn(move || {
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tx_a.send(0).unwrap();
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loop {
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let v = rx_b.recv().unwrap();
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if v >= PING_ROUNDS { break; }
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tx_a.send(v + 1).unwrap();
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}
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});
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let hb = smarm::spawn(move || {
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loop {
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let v = rx_a.recv().unwrap();
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tx_b.send(v + 1).unwrap();
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if v + 1 >= PING_ROUNDS { break; }
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}
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});
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ha.join().unwrap();
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hb.join().unwrap();
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});
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(PING_ROUNDS, start.elapsed().as_micros())
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}
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fn bench_pingpong_tokio_current() -> (u64, u128) {
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let rt = tokio::runtime::Builder::new_current_thread()
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.enable_all()
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.build()
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.unwrap();
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let start = Instant::now();
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let local = tokio::task::LocalSet::new();
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local.block_on(&rt, async move {
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let (tx_a, mut rx_a) = tokio::sync::mpsc::unbounded_channel::<u64>();
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let (tx_b, mut rx_b) = tokio::sync::mpsc::unbounded_channel::<u64>();
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let ha = tokio::task::spawn_local(async move {
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tx_a.send(0).unwrap();
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loop {
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let v = rx_b.recv().await.unwrap();
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if v >= PING_ROUNDS { break; }
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tx_a.send(v + 1).unwrap();
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}
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});
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let hb = tokio::task::spawn_local(async move {
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loop {
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let v = rx_a.recv().await.unwrap();
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tx_b.send(v + 1).unwrap();
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if v + 1 >= PING_ROUNDS { break; }
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}
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});
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let _ = ha.await;
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let _ = hb.await;
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});
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(PING_ROUNDS, start.elapsed().as_micros())
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}
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fn bench_pingpong_tokio_multi() -> (u64, u128) {
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let rt = tokio::runtime::Builder::new_multi_thread()
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.worker_threads(2) // ping-pong only needs 2 threads
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.enable_all()
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.build()
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.unwrap();
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let start = Instant::now();
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rt.block_on(async move {
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let (tx_a, mut rx_a) = tokio::sync::mpsc::unbounded_channel::<u64>();
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let (tx_b, mut rx_b) = tokio::sync::mpsc::unbounded_channel::<u64>();
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let ha = tokio::spawn(async move {
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tx_a.send(0).unwrap();
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loop {
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let v = rx_b.recv().await.unwrap();
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if v >= PING_ROUNDS { break; }
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tx_a.send(v + 1).unwrap();
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}
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});
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let hb = tokio::spawn(async move {
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loop {
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let v = rx_a.recv().await.unwrap();
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tx_b.send(v + 1).unwrap();
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if v + 1 >= PING_ROUNDS { break; }
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}
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});
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let _ = ha.await;
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let _ = hb.await;
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});
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(PING_ROUNDS, start.elapsed().as_micros())
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}
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// ---------------------------------------------------------------------------
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// Workload 3: spawn throughput
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// ---------------------------------------------------------------------------
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const SPAWN_COUNT: u64 = 1_000;
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fn bench_spawn_smarm(threads: usize) -> (u64, u128) {
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let counter = Arc::new(AtomicU64::new(0));
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let c = counter.clone();
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let start = Instant::now();
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smarm::runtime::init(smarm::runtime::Config::exact(threads)).run(move || {
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let mut handles = Vec::new();
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for _ in 0..SPAWN_COUNT {
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let cc = c.clone();
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handles.push(smarm::spawn(move || {
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cc.fetch_add(1, Ordering::Relaxed);
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}));
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}
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for h in handles { h.join().unwrap(); }
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});
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(counter.load(Ordering::Relaxed), start.elapsed().as_micros())
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}
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fn bench_spawn_tokio_current() -> (u64, u128) {
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let counter = Arc::new(AtomicU64::new(0));
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let c = counter.clone();
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let rt = tokio::runtime::Builder::new_current_thread().build().unwrap();
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let start = Instant::now();
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let local = tokio::task::LocalSet::new();
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local.block_on(&rt, async move {
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let mut handles = Vec::new();
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for _ in 0..SPAWN_COUNT {
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let cc = c.clone();
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handles.push(tokio::task::spawn_local(async move {
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cc.fetch_add(1, Ordering::Relaxed);
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}));
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}
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for h in handles { let _ = h.await; }
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});
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(counter.load(Ordering::Relaxed), start.elapsed().as_micros())
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}
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fn bench_spawn_tokio_multi() -> (u64, u128) {
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let counter = Arc::new(AtomicU64::new(0));
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let c = counter.clone();
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let rt = tokio::runtime::Builder::new_multi_thread()
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.worker_threads(available_threads())
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.build()
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.unwrap();
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let start = Instant::now();
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rt.block_on(async move {
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let mut handles = Vec::new();
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for _ in 0..SPAWN_COUNT {
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let cc = c.clone();
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handles.push(tokio::spawn(async move {
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cc.fetch_add(1, Ordering::Relaxed);
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}));
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}
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for h in handles { let _ = h.await; }
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});
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(counter.load(Ordering::Relaxed), start.elapsed().as_micros())
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}
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// ---------------------------------------------------------------------------
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// main
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// ---------------------------------------------------------------------------
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fn main() {
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let n = available_threads();
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println!("smarm multi-scheduler benchmarks");
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println!("available parallelism: {n} threads");
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println!("PRIME_N={PRIME_N}, WORKERS={WORKERS}, PING_ROUNDS={PING_ROUNDS}, SPAWN_COUNT={SPAWN_COUNT}");
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// ---- Primes ----
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print_header(&format!("Fan-out/fan-in: count primes in [2, {PRIME_N}) across {WORKERS} workers"));
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run_n("baseline (serial)", ITERS, bench_primes_baseline);
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run_n("smarm single-thread", ITERS, || bench_primes_smarm(1));
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run_n(&format!("smarm {n}-thread"), ITERS, || bench_primes_smarm(n));
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run_n("tokio current_thread", ITERS, bench_primes_tokio_current);
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run_n("tokio multi-thread", ITERS, bench_primes_tokio_multi);
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// ---- Ping-pong ----
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print_header(&format!("Ping-pong: {PING_ROUNDS} round-trips between two actors"));
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run_n("smarm single-thread", ITERS, || bench_pingpong_smarm(1));
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run_n(&format!("smarm {n}-thread"), ITERS, || bench_pingpong_smarm(n));
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run_n("tokio current_thread", ITERS, bench_pingpong_tokio_current);
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run_n("tokio multi-thread", ITERS, bench_pingpong_tokio_multi);
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// ---- Spawn throughput ----
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print_header(&format!("Spawn throughput: {SPAWN_COUNT} actors spawned and joined"));
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run_n("smarm single-thread", ITERS, || bench_spawn_smarm(1));
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run_n(&format!("smarm {n}-thread"), ITERS, || bench_spawn_smarm(n));
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run_n("tokio current_thread", ITERS, bench_spawn_tokio_current);
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run_n("tokio multi-thread", ITERS, bench_spawn_tokio_multi);
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}
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@@ -1,12 +1,8 @@
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//! Unbounded MPSC channels.
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//!
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//! Single-threaded scheduler: the inner state is `Rc<RefCell<Inner<T>>>`,
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//! not `Arc<Mutex>`. We hand-implement `Send` for `Sender<T>` and
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//! `Receiver<T>` when `T: Send`, on the basis that the only way two actor
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//! contexts touch the same channel is by being scheduled on the *same* OS
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//! thread (v0.1 has exactly one). When we add a second scheduler thread,
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//! this lie must be retired: replace `Rc<RefCell>` with `Arc<Mutex>` (or a
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//! lock-free queue) and remove the unsafe Send impls.
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//! Inner state is `Arc<Mutex<Inner<T>>>` so channels can be sent across OS
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//! threads (required for the multi-scheduler runtime where a sender and
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//! receiver may run on different scheduler threads simultaneously).
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//!
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//! Semantics:
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//! - Senders are clonable; the last sender drop closes the channel.
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@@ -19,12 +15,11 @@
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//! parked, the receiver is unparked.
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use crate::pid::Pid;
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use std::cell::RefCell;
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use std::collections::VecDeque;
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use std::rc::Rc;
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use std::sync::{Arc, Mutex};
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pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
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let inner = Rc::new(RefCell::new(Inner {
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let inner = Arc::new(Mutex::new(Inner {
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queue: VecDeque::new(),
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parked_receiver: None,
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senders: 1,
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@@ -41,20 +36,13 @@ struct Inner<T> {
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}
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||||
|
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pub struct Sender<T> {
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||||
inner: Rc<RefCell<Inner<T>>>,
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inner: Arc<Mutex<Inner<T>>>,
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}
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||||
|
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pub struct Receiver<T> {
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inner: Rc<RefCell<Inner<T>>>,
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||||
inner: Arc<Mutex<Inner<T>>>,
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||||
}
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|
||||
// SAFETY (v0.1 only): the scheduler is single-threaded. Sender/Receiver can
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// be captured into actor closures (which require Send), but they will only
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// ever be touched from one OS thread. When multi-threading lands, swap the
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// `Rc<RefCell>` for `Arc<Mutex>` and remove these.
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||||
unsafe impl<T: Send> Send for Sender<T> {}
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||||
unsafe impl<T: Send> Send for Receiver<T> {}
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||||
|
||||
#[derive(Debug, PartialEq, Eq)]
|
||||
pub struct SendError<T>(pub T);
|
||||
|
||||
@@ -71,7 +59,7 @@ impl std::error::Error for RecvError {}
|
||||
|
||||
impl<T> Clone for Sender<T> {
|
||||
fn clone(&self) -> Self {
|
||||
self.inner.borrow_mut().senders += 1;
|
||||
self.inner.lock().unwrap().senders += 1;
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||||
Sender { inner: self.inner.clone() }
|
||||
}
|
||||
}
|
||||
@@ -79,11 +67,9 @@ impl<T> Clone for Sender<T> {
|
||||
impl<T> Drop for Sender<T> {
|
||||
fn drop(&mut self) {
|
||||
let unpark = {
|
||||
let mut g = self.inner.borrow_mut();
|
||||
let mut g = self.inner.lock().unwrap();
|
||||
g.senders -= 1;
|
||||
if g.senders == 0 && g.queue.is_empty() {
|
||||
// Channel closed and drained. Wake the receiver so it can
|
||||
// see RecvError.
|
||||
g.parked_receiver.take()
|
||||
} else {
|
||||
None
|
||||
@@ -97,19 +83,18 @@ impl<T> Drop for Sender<T> {
|
||||
|
||||
impl<T> Drop for Receiver<T> {
|
||||
fn drop(&mut self) {
|
||||
self.inner.borrow_mut().receiver_alive = false;
|
||||
self.inner.lock().unwrap().receiver_alive = false;
|
||||
}
|
||||
}
|
||||
|
||||
impl<T> Sender<T> {
|
||||
pub fn send(&self, value: T) -> Result<(), SendError<T>> {
|
||||
let unpark = {
|
||||
let mut g = self.inner.borrow_mut();
|
||||
let mut g = self.inner.lock().unwrap();
|
||||
if !g.receiver_alive {
|
||||
return Err(SendError(value));
|
||||
}
|
||||
g.queue.push_back(value);
|
||||
// If the receiver is parked, unpark it.
|
||||
g.parked_receiver.take()
|
||||
};
|
||||
if let Some(pid) = unpark {
|
||||
@@ -122,16 +107,14 @@ impl<T> Sender<T> {
|
||||
impl<T> Receiver<T> {
|
||||
pub fn recv(&self) -> Result<T, RecvError> {
|
||||
loop {
|
||||
// Try to take a message.
|
||||
{
|
||||
let mut g = self.inner.borrow_mut();
|
||||
let mut g = self.inner.lock().unwrap();
|
||||
if let Some(v) = g.queue.pop_front() {
|
||||
return Ok(v);
|
||||
}
|
||||
if g.senders == 0 {
|
||||
return Err(RecvError);
|
||||
}
|
||||
// Empty + open: register and park.
|
||||
let me = crate::actor::current_pid()
|
||||
.expect("recv() called outside an actor");
|
||||
debug_assert!(
|
||||
@@ -140,18 +123,15 @@ impl<T> Receiver<T> {
|
||||
);
|
||||
g.parked_receiver = Some(me);
|
||||
}
|
||||
// Release the borrow before parking — the unparker will need it.
|
||||
// Release the lock before parking — the unparker will need it.
|
||||
crate::scheduler::park_current();
|
||||
// Loop: the message that woke us might already have been taken
|
||||
// (it can't, with one receiver, but the senders=0 path can fire
|
||||
// here too).
|
||||
}
|
||||
}
|
||||
|
||||
/// Non-blocking. `Ok(Some(v))` if a message was available, `Ok(None)` if
|
||||
/// the channel is empty but open, `Err(RecvError)` if closed and drained.
|
||||
pub fn try_recv(&self) -> Result<Option<T>, RecvError> {
|
||||
let mut g = self.inner.borrow_mut();
|
||||
let mut g = self.inner.lock().unwrap();
|
||||
if let Some(v) = g.queue.pop_front() {
|
||||
return Ok(Some(v));
|
||||
}
|
||||
|
||||
37
src/lib.rs
37
src/lib.rs
@@ -2,14 +2,12 @@
|
||||
//!
|
||||
//! Erlang-style green-thread actor concurrency for Rust.
|
||||
//!
|
||||
//! Single-threaded for now: one scheduler, one OS thread. The scheduler
|
||||
//! cooperatively interleaves green-thread actors with hand-rolled context
|
||||
//! switches. Actors communicate by sending `Send` messages over channels;
|
||||
//! every actor has a supervisor, which is itself just an actor with a
|
||||
//! `Receiver<Signal>`. Synchronisation primitives — `Mutex<T>` with
|
||||
//! mandatory lock timeouts, channel `recv`, `sleep`, and epoll-backed
|
||||
//! `wait_readable`/`wait_writable` — all park the green thread, never
|
||||
//! the OS thread.
|
||||
//! Multi-threaded: N scheduler OS threads (default: one per CPU) share a
|
||||
//! single global run queue behind a `Mutex`. Actors communicate by sending
|
||||
//! `Send` messages over channels; every actor has a supervisor. Synchronisation
|
||||
//! primitives — `Mutex<T>` with mandatory lock timeouts, channel `recv`,
|
||||
//! `sleep`, and epoll-backed `wait_readable`/`wait_writable` — all park the
|
||||
//! green thread, never the OS thread.
|
||||
//!
|
||||
//! See `LOOM.md` for the design intent and the deferred-for-later list.
|
||||
|
||||
@@ -24,13 +22,10 @@ pub mod supervisor;
|
||||
pub mod timer;
|
||||
pub mod io;
|
||||
pub mod mutex;
|
||||
pub mod runtime;
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Global allocator
|
||||
//
|
||||
// The preempting allocator wraps `System`. While `PREEMPTION_ENABLED` is
|
||||
// false (the default outside an actor) it adds one branch per allocation
|
||||
// and no syscalls. The scheduler flips it on per-resume.
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[global_allocator]
|
||||
@@ -43,31 +38,19 @@ static ALLOCATOR: preempt::PreemptingAllocator = preempt::PreemptingAllocator;
|
||||
pub use channel::{channel, Receiver, RecvError, Sender};
|
||||
pub use mutex::{LockTimeout, Mutex, MutexGuard};
|
||||
pub use pid::Pid;
|
||||
pub use runtime::{init, Config, Runtime};
|
||||
pub use scheduler::{
|
||||
block_on_io, run, self_pid, sleep, spawn, spawn_under, wait_readable, wait_writable,
|
||||
yield_now, JoinError, JoinHandle,
|
||||
};
|
||||
// `read` and `write` would shadow heavily-used names if re-exported at the
|
||||
// crate root; users reach for them as `smarm::scheduler::read` /
|
||||
// `smarm::scheduler::write` instead. May reshuffle into a `smarm::io`
|
||||
// surface in a future pass.
|
||||
pub use supervisor::Signal;
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// check!() — explicit preemption point for tight no-alloc loops.
|
||||
// check!()
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Voluntarily check whether this actor's timeslice has expired, yielding
|
||||
/// if so. Drop this into hot compute loops that don't allocate (heap or
|
||||
/// large stack frames) — without it, such loops monopolise the scheduler
|
||||
/// until they return.
|
||||
///
|
||||
/// Decrements the same per-actor event counter as the heap allocator's
|
||||
/// preemption hook, so the check rate is identical regardless of whether
|
||||
/// the actor is alloc-heavy, check-heavy, or mixed.
|
||||
///
|
||||
/// No-op outside an actor (the runtime's `PREEMPTION_ENABLED` flag is
|
||||
/// false there).
|
||||
/// if so.
|
||||
#[macro_export]
|
||||
macro_rules! check {
|
||||
() => {
|
||||
|
||||
220
src/mutex.rs
220
src/mutex.rs
@@ -1,63 +1,20 @@
|
||||
//! Actor-aware mutex with mandatory timeout.
|
||||
//!
|
||||
//! `loom::Mutex<T>` looks like `std::sync::Mutex<T>` but its `lock()` parks
|
||||
//! the calling *green* thread on contention rather than blocking the OS
|
||||
//! thread — and every lock attempt is bounded by a timeout. If the lock is
|
||||
//! not acquired within the timeout, `lock()` returns `Err(LockTimeout)`.
|
||||
//! This is a hard runtime guarantee (the spec calls it out): no actor can
|
||||
//! be parked on a mutex forever.
|
||||
//! `Mutex<T>` parks the calling *green* thread on contention rather than
|
||||
//! blocking the OS thread. Every lock attempt is bounded by a timeout.
|
||||
//!
|
||||
//! ```ignore
|
||||
//! let m = loom::Mutex::new(42);
|
||||
//! let guard = m.lock()?; // default timeout
|
||||
//! let guard = m.lock_timeout(Duration::from_millis(50))?;
|
||||
//! ```
|
||||
//! Internals use `Arc<std::sync::Mutex<...>>` so the type is genuinely
|
||||
//! `Send + Sync` and can be shared across scheduler threads.
|
||||
//!
|
||||
//! Fairness
|
||||
//! ========
|
||||
//! Waiters are granted the lock in FIFO order. The spec prizes fairness:
|
||||
//! starvation under contention is precisely the kind of failure mode
|
||||
//! supervision can't recover from cleanly. LIFO would be faster on cache
|
||||
//! locality and is not offered.
|
||||
//!
|
||||
//! Poisoning
|
||||
//! =========
|
||||
//! Unlike `std::sync::Mutex`, `loom::Mutex` does not poison on panic. If a
|
||||
//! holder panics while holding the lock, the next waiter receives the
|
||||
//! (now-untouched) value. Rationale: supervision handles the panic at the
|
||||
//! actor level; a separate poisoning channel is redundant and adds an
|
||||
//! error case to every `lock()`. Users who care about "the value may be in
|
||||
//! an inconsistent state after a panic" should encode that in `T` itself
|
||||
//! (e.g. `Mutex<Option<State>>` and `take()` the value at the start of
|
||||
//! each critical section).
|
||||
//!
|
||||
//! Reentrance
|
||||
//! ==========
|
||||
//! Not reentrant. An actor that already holds the lock and calls `lock()`
|
||||
//! again on the same mutex will wait on its own grant — and time out. This
|
||||
//! is a bug in the caller, not a feature.
|
||||
//!
|
||||
//! Multi-threading note
|
||||
//! ====================
|
||||
//! The current implementation uses `Rc<RefCell<…>>` internals because the
|
||||
//! v0.2 scheduler is single-threaded. The public API is identical to what
|
||||
//! the eventual multi-threaded version will expose; the migration replaces
|
||||
//! the `Rc<RefCell>` with `Arc<sync::Mutex>` around bookkeeping (waiters
|
||||
//! queue, holder pid) — the *value* itself never goes through a blocking
|
||||
//! OS-level lock, because contention always parks the green thread first.
|
||||
//! No `unsafe impl Send` games today: `loom::Mutex<T>` is `!Send` on v0.2,
|
||||
//! which is correct given there is only one OS thread.
|
||||
//! Fairness: FIFO. Poisoning: none. Reentrance: deadlock (caller bug).
|
||||
|
||||
use crate::pid::Pid;
|
||||
use crate::scheduler;
|
||||
use crate::timer::{self, TimerTarget};
|
||||
use std::cell::{Cell, RefCell};
|
||||
use std::collections::VecDeque;
|
||||
use std::rc::Rc;
|
||||
use std::sync::{Arc, Mutex as StdMutex};
|
||||
use std::time::Duration;
|
||||
|
||||
/// 30 seconds. Override per-call with `lock_timeout`, or per-mutex (TODO)
|
||||
/// once the supervisor-level policy hook lands.
|
||||
pub const DEFAULT_TIMEOUT: Duration = Duration::from_secs(30);
|
||||
|
||||
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
|
||||
@@ -74,63 +31,55 @@ impl std::error::Error for LockTimeout {}
|
||||
// Internals
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// A pending lock attempt. Sits in `MutexCore::state.waiters` from the
|
||||
/// moment an actor parks until it is either granted the lock (popped by
|
||||
/// `MutexGuard::drop`) or times out (popped by `on_timeout`).
|
||||
struct Wait {
|
||||
pid: Pid,
|
||||
/// Per-mutex monotonic sequence. Lets `on_timeout` recognise "this
|
||||
/// specific wait" vs. "a later wait by the same pid on the same
|
||||
/// mutex" — important because a single actor can re-acquire and then
|
||||
/// re-wait, and we don't want a stale timer firing to disturb the new
|
||||
/// wait.
|
||||
seq: u64,
|
||||
}
|
||||
|
||||
/// The non-generic part of the mutex. Lives inside `Rc<>` so it can also
|
||||
/// be stashed (as `Rc<dyn TimerTarget>`) inside a timer entry.
|
||||
struct MutexCore {
|
||||
state: RefCell<MutexState>,
|
||||
default_timeout: Cell<Duration>,
|
||||
}
|
||||
|
||||
struct MutexState {
|
||||
holder: Option<Pid>,
|
||||
waiters: VecDeque<Wait>,
|
||||
next_seq: u64,
|
||||
default_timeout: Duration,
|
||||
}
|
||||
|
||||
struct MutexCore {
|
||||
state: StdMutex<MutexState>,
|
||||
}
|
||||
|
||||
impl MutexCore {
|
||||
fn new(default_timeout: Duration) -> Self {
|
||||
Self {
|
||||
state: RefCell::new(MutexState {
|
||||
state: StdMutex::new(MutexState {
|
||||
holder: None,
|
||||
waiters: VecDeque::new(),
|
||||
next_seq: 0,
|
||||
default_timeout,
|
||||
}),
|
||||
default_timeout: Cell::new(default_timeout),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl TimerTarget for MutexCore {
|
||||
fn on_timeout(&self, pid: Pid, wait_seq: u64) {
|
||||
// Remove the waiter with this seq, if it's still queued. If it's
|
||||
// gone the lock was already granted to this actor before the timer
|
||||
// popped — the actor will return normally; do nothing.
|
||||
let removed = {
|
||||
let mut st = self.state.borrow_mut();
|
||||
if let Some(pos) = st.waiters.iter().position(|w| w.seq == wait_seq) {
|
||||
st.waiters.remove(pos);
|
||||
let unpark = {
|
||||
let mut st = self.state.lock().unwrap();
|
||||
// Remove from waiters only if still there with matching seq.
|
||||
// If the lock was already granted (holder == Some(pid)), the
|
||||
// timer fired after the grant — treat as no-op; the actor
|
||||
// will see `is_holder == true` and return Ok.
|
||||
if st.holder == Some(pid) {
|
||||
return;
|
||||
}
|
||||
let pos = st.waiters.iter().position(|w| w.pid == pid && w.seq == wait_seq);
|
||||
if pos.is_some() {
|
||||
st.waiters.remove(pos.unwrap());
|
||||
true
|
||||
} else {
|
||||
false
|
||||
}
|
||||
};
|
||||
if removed {
|
||||
// The actor is parked, waiting on us. Wake it up; `lock_timeout`
|
||||
// will resume, observe `holder != Some(self)`, and return
|
||||
// LockTimeout.
|
||||
if unpark {
|
||||
scheduler::unpark(pid);
|
||||
}
|
||||
}
|
||||
@@ -141,145 +90,105 @@ impl TimerTarget for MutexCore {
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub struct Mutex<T> {
|
||||
core: Rc<MutexCore>,
|
||||
/// `None` while the lock is held; `Some(T)` while free or while a
|
||||
/// grantee is in the gap between unpark and resumption.
|
||||
value: Rc<RefCell<Option<T>>>,
|
||||
core: Arc<MutexCore>,
|
||||
/// Protected value. `None` while a guard is live; `Some` while free.
|
||||
value: Arc<StdMutex<Option<T>>>,
|
||||
}
|
||||
|
||||
impl<T> Mutex<T> {
|
||||
pub fn new(value: T) -> Self {
|
||||
Self {
|
||||
core: Rc::new(MutexCore::new(DEFAULT_TIMEOUT)),
|
||||
value: Rc::new(RefCell::new(Some(value))),
|
||||
core: Arc::new(MutexCore::new(DEFAULT_TIMEOUT)),
|
||||
value: Arc::new(StdMutex::new(Some(value))),
|
||||
}
|
||||
}
|
||||
|
||||
/// Set the default timeout used by `lock()`. Does not affect in-flight
|
||||
/// `lock_timeout` calls.
|
||||
pub fn set_default_timeout(&self, timeout: Duration) {
|
||||
self.core.default_timeout.set(timeout);
|
||||
self.core.state.lock().unwrap().default_timeout = timeout;
|
||||
}
|
||||
|
||||
/// Acquire the lock, blocking the calling actor until it's granted or
|
||||
/// the default timeout expires.
|
||||
pub fn lock(&self) -> Result<MutexGuard<'_, T>, LockTimeout> {
|
||||
self.lock_timeout(self.core.default_timeout.get())
|
||||
let timeout = self.core.state.lock().unwrap().default_timeout;
|
||||
self.lock_timeout(timeout)
|
||||
}
|
||||
|
||||
/// Acquire the lock with an explicit timeout.
|
||||
pub fn lock_timeout(&self, timeout: Duration) -> Result<MutexGuard<'_, T>, LockTimeout> {
|
||||
let me = scheduler::self_pid();
|
||||
|
||||
// Fast path: nobody holds it. Mark ourselves as holder, take the
|
||||
// value out, return a guard.
|
||||
// Fast path: nobody holds it.
|
||||
{
|
||||
let mut st = self.core.state.borrow_mut();
|
||||
let mut st = self.core.state.lock().unwrap();
|
||||
if st.holder.is_none() {
|
||||
st.holder = Some(me);
|
||||
drop(st);
|
||||
let value = self
|
||||
.value
|
||||
.borrow_mut()
|
||||
.take()
|
||||
let value = self.value.lock().unwrap().take()
|
||||
.expect("Mutex: value missing on free fast path");
|
||||
return Ok(MutexGuard {
|
||||
mutex: self,
|
||||
value: Some(value),
|
||||
});
|
||||
return Ok(MutexGuard { mutex: self, value: Some(value) });
|
||||
}
|
||||
}
|
||||
|
||||
// Slow path: register as a waiter, schedule a timeout, park.
|
||||
// No preemption during prep-to-park — see scheduler::NoPreempt.
|
||||
// Slow path: register as a waiter, set timeout, park.
|
||||
let _np = scheduler::NoPreempt::enter();
|
||||
let seq = {
|
||||
let mut st = self.core.state.borrow_mut();
|
||||
let mut st = self.core.state.lock().unwrap();
|
||||
let seq = st.next_seq;
|
||||
st.next_seq = st.next_seq.wrapping_add(1);
|
||||
st.waiters.push_back(Wait { pid: me, seq });
|
||||
seq
|
||||
};
|
||||
|
||||
let target: Rc<dyn TimerTarget> = self.core.clone();
|
||||
let target: Arc<dyn TimerTarget> = self.core.clone();
|
||||
let deadline = timer::deadline_from_now(timeout);
|
||||
scheduler::insert_wait_timer(deadline, me, target, seq);
|
||||
scheduler::park_current();
|
||||
|
||||
// Resumed. Two possibilities:
|
||||
// (a) MutexGuard::drop on the previous holder popped us off the
|
||||
// waiters queue, set core.holder = me, and unparked us.
|
||||
// => self.value is Some, we take it and return Ok.
|
||||
// (b) on_timeout fired: it removed us from waiters and unparked
|
||||
// us, but did NOT set holder. core.holder is whatever it was
|
||||
// (Some(other) or None). => return Err.
|
||||
let is_holder = self.core.state.borrow().holder == Some(me);
|
||||
// Resumed. Are we the holder?
|
||||
let is_holder = self.core.state.lock().unwrap().holder == Some(me);
|
||||
if is_holder {
|
||||
let value = self
|
||||
.value
|
||||
.borrow_mut()
|
||||
.take()
|
||||
let value = self.value.lock().unwrap().take()
|
||||
.expect("Mutex: value missing after grant");
|
||||
Ok(MutexGuard {
|
||||
mutex: self,
|
||||
value: Some(value),
|
||||
})
|
||||
Ok(MutexGuard { mutex: self, value: Some(value) })
|
||||
} else {
|
||||
Err(LockTimeout)
|
||||
}
|
||||
}
|
||||
|
||||
/// Non-blocking attempt. Returns `Some` if the lock was free, `None`
|
||||
/// otherwise. Useful as a fast path before a long-running computation,
|
||||
/// or for tests.
|
||||
pub fn try_lock(&self) -> Option<MutexGuard<'_, T>> {
|
||||
let mut st = self.core.state.borrow_mut();
|
||||
let me = scheduler::self_pid();
|
||||
let mut st = self.core.state.lock().unwrap();
|
||||
if st.holder.is_some() {
|
||||
return None;
|
||||
}
|
||||
let me = scheduler::self_pid();
|
||||
st.holder = Some(me);
|
||||
drop(st);
|
||||
let value = self
|
||||
.value
|
||||
.borrow_mut()
|
||||
.take()
|
||||
let value = self.value.lock().unwrap().take()
|
||||
.expect("Mutex: value missing on try_lock free path");
|
||||
Some(MutexGuard {
|
||||
mutex: self,
|
||||
value: Some(value),
|
||||
})
|
||||
Some(MutexGuard { mutex: self, value: Some(value) })
|
||||
}
|
||||
}
|
||||
|
||||
impl<T> Clone for Mutex<T> {
|
||||
/// Cloning a `Mutex<T>` clones the handle, not the protected value —
|
||||
/// both clones refer to the same lock state and the same `T`.
|
||||
fn clone(&self) -> Self {
|
||||
Self {
|
||||
core: self.core.clone(),
|
||||
value: self.value.clone(),
|
||||
}
|
||||
Self { core: self.core.clone(), value: self.value.clone() }
|
||||
}
|
||||
}
|
||||
|
||||
// Genuinely Send + Sync now that internals are Arc<std::sync::Mutex<...>>.
|
||||
unsafe impl<T: Send> Send for Mutex<T> {}
|
||||
unsafe impl<T: Send> Sync for Mutex<T> {}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Guard
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub struct MutexGuard<'a, T> {
|
||||
mutex: &'a Mutex<T>,
|
||||
/// The protected value, taken out of `mutex.value` while the guard is
|
||||
/// alive. `Option` only so `Drop` can put it back; in normal use this
|
||||
/// is always `Some` while the guard is observable.
|
||||
value: Option<T>,
|
||||
}
|
||||
|
||||
impl<T> std::ops::Deref for MutexGuard<'_, T> {
|
||||
type Target = T;
|
||||
fn deref(&self) -> &T {
|
||||
self.value.as_ref().expect("MutexGuard: value missing")
|
||||
}
|
||||
fn deref(&self) -> &T { self.value.as_ref().expect("MutexGuard: value missing") }
|
||||
}
|
||||
|
||||
impl<T> std::ops::DerefMut for MutexGuard<'_, T> {
|
||||
@@ -288,19 +197,22 @@ impl<T> std::ops::DerefMut for MutexGuard<'_, T> {
|
||||
}
|
||||
}
|
||||
|
||||
impl<T: std::fmt::Debug> std::fmt::Debug for MutexGuard<'_, T> {
|
||||
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
|
||||
f.debug_tuple("MutexGuard")
|
||||
.field(self.value.as_ref().expect("MutexGuard: value missing"))
|
||||
.finish()
|
||||
}
|
||||
}
|
||||
|
||||
impl<T> Drop for MutexGuard<'_, T> {
|
||||
fn drop(&mut self) {
|
||||
// Put the value back into the mutex.
|
||||
let v = self.value.take().expect("MutexGuard: double drop");
|
||||
*self.mutex.value.borrow_mut() = Some(v);
|
||||
*self.mutex.value.lock().unwrap() = Some(v);
|
||||
|
||||
// Pick the next waiter (if any) and grant it the lock by writing
|
||||
// its pid into `holder` *before* unparking. The grantee, on
|
||||
// resumption, will see `holder == self_pid` and take the value.
|
||||
let next_pid = {
|
||||
let mut st = self.mutex.core.state.borrow_mut();
|
||||
let next = st.waiters.pop_front();
|
||||
match next {
|
||||
let mut st = self.mutex.core.state.lock().unwrap();
|
||||
match st.waiters.pop_front() {
|
||||
Some(w) => {
|
||||
st.holder = Some(w.pid);
|
||||
Some(w.pid)
|
||||
|
||||
669
src/runtime.rs
Normal file
669
src/runtime.rs
Normal file
@@ -0,0 +1,669 @@
|
||||
//! Multi-scheduler runtime: configuration, initialisation, and the shared
|
||||
//! state that all scheduler OS threads operate against.
|
||||
//!
|
||||
//! # Architecture
|
||||
//!
|
||||
//! ```text
|
||||
//! init(Config) → Runtime (Arc<RuntimeInner>)
|
||||
//!
|
||||
//! RuntimeInner {
|
||||
//! shared: Mutex<SharedState> ← slot table, run queue, timers, IO
|
||||
//! stats: Vec<SchedulerStats> ← one per thread, lockless atomics (RFC 000)
|
||||
//! io_parked: AtomicU32 ← actors parked on IO
|
||||
//! sleeping: AtomicU32 ← actors parked on timer
|
||||
//! }
|
||||
//! ```
|
||||
//!
|
||||
//! `Runtime::run(f)` spawns N OS threads (one per `Config::resolved_thread_count()`),
|
||||
//! each running `schedule_loop`. It blocks until all scheduler threads exit,
|
||||
//! i.e. until the run queue is empty and nothing is pending.
|
||||
//!
|
||||
//! Each scheduler thread holds an `Arc<RuntimeInner>` clone. Per-thread
|
||||
//! identity is a small integer index, stored in a thread-local, used to index
|
||||
//! into `stats`.
|
||||
//!
|
||||
//! # Timer / IO drain (try-lock, one-winner)
|
||||
//!
|
||||
//! On each loop iteration every scheduler thread tries `try_lock()` on a
|
||||
//! separate `drain_lock: Mutex<()>`. The winner drains due timers and IO
|
||||
//! completions; losers skip and move straight to popping an actor from the
|
||||
//! run queue. This is the simplest correct approach; revisit if the drain
|
||||
//! becomes a measured bottleneck.
|
||||
|
||||
use crate::actor::{
|
||||
clear_current_pid, current_pid, is_actor_done, reset_actor_done,
|
||||
set_current_actor_box, set_current_pid, take_last_outcome, Actor, Outcome,
|
||||
};
|
||||
use crate::channel::Sender;
|
||||
use crate::context::{get_actor_sp, set_actor_sp, switch_to_actor};
|
||||
use crate::io::IoThread;
|
||||
use crate::pid::Pid;
|
||||
use crate::preempt::PREEMPTION_ENABLED;
|
||||
use crate::supervisor::Signal;
|
||||
use crate::timer::Timers;
|
||||
|
||||
use std::collections::VecDeque;
|
||||
use std::sync::atomic::{AtomicU32, AtomicU64, Ordering};
|
||||
use std::sync::{Arc, Mutex};
|
||||
use std::thread;
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Config
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Runtime configuration.
|
||||
///
|
||||
/// ```
|
||||
/// use smarm::runtime::Config;
|
||||
///
|
||||
/// // Use all available CPUs (default):
|
||||
/// let c = Config::default();
|
||||
///
|
||||
/// // Exactly 4 scheduler threads:
|
||||
/// let c = Config::exact(4);
|
||||
///
|
||||
/// // Between 2 and 8, clamped to available parallelism:
|
||||
/// let c = Config::new(2, 8, None);
|
||||
/// ```
|
||||
#[derive(Clone, Debug)]
|
||||
pub struct Config {
|
||||
min: usize,
|
||||
max: usize,
|
||||
exact: Option<usize>,
|
||||
}
|
||||
|
||||
impl Config {
|
||||
/// Exact thread count; takes precedence over min/max.
|
||||
pub fn exact(n: usize) -> Self {
|
||||
assert!(n >= 1, "scheduler thread count must be ≥ 1");
|
||||
Self { min: n, max: n, exact: Some(n) }
|
||||
}
|
||||
|
||||
/// Bounded range. Thread count = clamp(available_parallelism, min, max).
|
||||
pub fn new(min: usize, max: usize, exact: Option<usize>) -> Self {
|
||||
assert!(min >= 1, "min must be ≥ 1");
|
||||
assert!(max >= min, "max must be ≥ min");
|
||||
if let Some(e) = exact {
|
||||
assert!(e >= 1, "exact must be ≥ 1");
|
||||
}
|
||||
Self { min, max, exact }
|
||||
}
|
||||
|
||||
/// The number of scheduler threads this config resolves to.
|
||||
pub fn resolved_thread_count(&self) -> usize {
|
||||
if let Some(e) = self.exact {
|
||||
return e;
|
||||
}
|
||||
let avail = thread::available_parallelism()
|
||||
.map(|n| n.get())
|
||||
.unwrap_or(1);
|
||||
avail.clamp(self.min, self.max)
|
||||
}
|
||||
}
|
||||
|
||||
impl Default for Config {
|
||||
fn default() -> Self {
|
||||
let avail = thread::available_parallelism()
|
||||
.map(|n| n.get())
|
||||
.unwrap_or(1);
|
||||
Self { min: 1, max: avail, exact: None }
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Per-thread stats (RFC 000 Layer 1 primitives)
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Lockless per-scheduler-thread counters. Written only by the owning thread;
|
||||
/// readable from any thread (introspection actor, tests).
|
||||
pub struct SchedulerStats {
|
||||
/// PID index of the actor currently on-CPU, or `u32::MAX` when idle.
|
||||
pub current_pid_index: AtomicU32,
|
||||
/// Snapshot of run queue length maintained on every push/pop.
|
||||
pub run_queue_len: AtomicU64,
|
||||
}
|
||||
|
||||
impl SchedulerStats {
|
||||
fn new() -> Self {
|
||||
Self {
|
||||
current_pid_index: AtomicU32::new(u32::MAX),
|
||||
run_queue_len: AtomicU64::new(0),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Runtime stats snapshot (for tests / introspection)
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub struct RuntimeStats {
|
||||
pub(crate) inner: Arc<RuntimeInner>,
|
||||
}
|
||||
|
||||
impl RuntimeStats {
|
||||
/// Sum of run queue lengths across all scheduler threads.
|
||||
pub fn total_run_queue_len(&self) -> u64 {
|
||||
self.inner.stats.iter()
|
||||
.map(|s| s.run_queue_len.load(Ordering::Relaxed))
|
||||
.sum()
|
||||
}
|
||||
|
||||
/// Number of scheduler threads.
|
||||
pub fn scheduler_count(&self) -> usize {
|
||||
self.inner.stats.len()
|
||||
}
|
||||
|
||||
/// Actors currently parked on IO.
|
||||
pub fn io_parked_count(&self) -> u32 {
|
||||
self.inner.io_parked.load(Ordering::Relaxed)
|
||||
}
|
||||
|
||||
/// Actors currently sleeping on a timer.
|
||||
pub fn sleeping_count(&self) -> u32 {
|
||||
self.inner.sleeping.load(Ordering::Relaxed)
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Shared state (behind Mutex<>)
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub(crate) const ACTOR_STACK_SIZE: usize = 64 * 1024;
|
||||
|
||||
pub(crate) enum State { Runnable, Parked, Done }
|
||||
|
||||
struct Slot {
|
||||
generation: u32,
|
||||
actor: Option<Actor>,
|
||||
state: State,
|
||||
waiters: Vec<Pid>,
|
||||
outcome: Option<Outcome>,
|
||||
supervisor_channel: Option<Sender<Signal>>,
|
||||
outstanding_handles: u32,
|
||||
pending_io_result: Option<crate::io::IoResult>,
|
||||
}
|
||||
|
||||
impl Slot {
|
||||
fn vacant() -> Self {
|
||||
Self {
|
||||
generation: 0,
|
||||
actor: None,
|
||||
state: State::Done,
|
||||
waiters: Vec::new(),
|
||||
outcome: None,
|
||||
supervisor_channel: None,
|
||||
outstanding_handles: 0,
|
||||
pending_io_result: None,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub(crate) type Closure = Box<dyn FnOnce() + Send>;
|
||||
|
||||
pub(crate) struct SharedState {
|
||||
pub(crate) slots: Vec<Slot>,
|
||||
pub(crate) free_list: Vec<u32>,
|
||||
pub(crate) run_queue: VecDeque<Pid>,
|
||||
pub(crate) root_pid: Option<Pid>,
|
||||
pub(crate) timers: Timers,
|
||||
pub(crate) io: Option<IoThread>,
|
||||
/// Closures awaiting their first resume, keyed by Pid.
|
||||
pub(crate) pending_closures: Vec<(Pid, Closure)>,
|
||||
}
|
||||
|
||||
impl SharedState {
|
||||
fn new() -> Self {
|
||||
Self {
|
||||
slots: Vec::new(),
|
||||
free_list: Vec::new(),
|
||||
run_queue: VecDeque::new(),
|
||||
root_pid: None,
|
||||
timers: Timers::new(),
|
||||
io: None,
|
||||
pending_closures: Vec::new(),
|
||||
}
|
||||
}
|
||||
|
||||
fn allocate_slot(&mut self) -> (u32, u32) {
|
||||
if let Some(idx) = self.free_list.pop() {
|
||||
let gen = self.slots[idx as usize].generation;
|
||||
(idx, gen)
|
||||
} else {
|
||||
let idx = self.slots.len() as u32;
|
||||
self.slots.push(Slot::vacant());
|
||||
(idx, 0)
|
||||
}
|
||||
}
|
||||
|
||||
fn slot(&self, pid: Pid) -> Option<&Slot> {
|
||||
let s = self.slots.get(pid.index() as usize)?;
|
||||
if s.generation == pid.generation() { Some(s) } else { None }
|
||||
}
|
||||
|
||||
fn slot_mut(&mut self, pid: Pid) -> Option<&mut Slot> {
|
||||
let s = self.slots.get_mut(pid.index() as usize)?;
|
||||
if s.generation == pid.generation() { Some(s) } else { None }
|
||||
}
|
||||
|
||||
fn pop_pending_closure(&mut self, pid: Pid) -> Option<Closure> {
|
||||
let pos = self.pending_closures.iter().position(|(p, _)| *p == pid)?;
|
||||
Some(self.pending_closures.swap_remove(pos).1)
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// RuntimeInner — the shared core behind an Arc
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub(crate) struct RuntimeInner {
|
||||
pub(crate) shared: Mutex<SharedState>,
|
||||
/// Try-lock: exactly one scheduler thread drains timers/IO per iteration.
|
||||
drain_lock: Mutex<()>,
|
||||
/// Per-thread stats, indexed by scheduler thread slot (0..N).
|
||||
pub(crate) stats: Vec<SchedulerStats>,
|
||||
/// Global counters for RFC 000 primitives.
|
||||
pub(crate) io_parked: AtomicU32,
|
||||
pub(crate) sleeping: AtomicU32,
|
||||
}
|
||||
|
||||
impl RuntimeInner {
|
||||
fn new(thread_count: usize) -> Arc<Self> {
|
||||
let stats = (0..thread_count).map(|_| SchedulerStats::new()).collect();
|
||||
Arc::new(Self {
|
||||
shared: Mutex::new(SharedState::new()),
|
||||
drain_lock: Mutex::new(()),
|
||||
stats,
|
||||
io_parked: AtomicU32::new(0),
|
||||
sleeping: AtomicU32::new(0),
|
||||
})
|
||||
}
|
||||
|
||||
fn with_shared<R>(&self, f: impl FnOnce(&mut SharedState) -> R) -> R {
|
||||
f(&mut self.shared.lock().unwrap())
|
||||
}
|
||||
|
||||
/// Returns `None` when the mutex is poisoned.
|
||||
/// Used in `unpark` / channel Drop which can fire after teardown.
|
||||
fn try_with_shared<R>(&self, f: impl FnOnce(&mut SharedState) -> R) -> Option<R> {
|
||||
match self.shared.lock() {
|
||||
Ok(mut g) => Some(f(&mut g)),
|
||||
Err(p) => Some(f(&mut p.into_inner())),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Runtime — the public handle
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub struct Runtime {
|
||||
inner: Arc<RuntimeInner>,
|
||||
thread_count: usize,
|
||||
}
|
||||
|
||||
/// Initialise the runtime with the given config. Returns a reusable handle.
|
||||
pub fn init(config: Config) -> Runtime {
|
||||
let n = config.resolved_thread_count();
|
||||
Runtime {
|
||||
inner: RuntimeInner::new(n),
|
||||
thread_count: n,
|
||||
}
|
||||
}
|
||||
|
||||
impl Runtime {
|
||||
/// Run `f` as the initial actor, block until all actors finish.
|
||||
/// Can be called multiple times sequentially on the same `Runtime`.
|
||||
pub fn run(&self, f: impl FnOnce() + Send + 'static) {
|
||||
// Re-initialise shared state for this run.
|
||||
{
|
||||
let mut s = self.inner.shared.lock().unwrap();
|
||||
assert!(s.run_queue.is_empty(), "run() called while previous run still active");
|
||||
s.root_pid = Some(ROOT_PID);
|
||||
s.io = Some(IoThread::start().expect("failed to start IO thread"));
|
||||
}
|
||||
|
||||
// Spawn the initial actor through the public spawn path (which
|
||||
// requires a running runtime in the thread-local).
|
||||
RUNTIME.with(|r| *r.borrow_mut() = Some(self.inner.clone()));
|
||||
let initial_handle = crate::scheduler::spawn(f);
|
||||
|
||||
// Launch N-1 extra scheduler threads. The calling thread is thread 0.
|
||||
let mut os_threads = Vec::new();
|
||||
for slot in 1..self.thread_count {
|
||||
let inner = self.inner.clone();
|
||||
let t = thread::spawn(move || {
|
||||
RUNTIME.with(|r| *r.borrow_mut() = Some(inner.clone()));
|
||||
SCHED_SLOT.with(|s| s.set(slot));
|
||||
schedule_loop(&inner, slot);
|
||||
RUNTIME.with(|r| *r.borrow_mut() = None);
|
||||
});
|
||||
os_threads.push(t);
|
||||
}
|
||||
|
||||
// Thread 0 runs the loop on the calling thread.
|
||||
SCHED_SLOT.with(|s| s.set(0));
|
||||
schedule_loop(&self.inner, 0);
|
||||
|
||||
// Wait for all other scheduler threads.
|
||||
for t in os_threads {
|
||||
let _ = t.join();
|
||||
}
|
||||
|
||||
// Drop initial handle (decrements outstanding_handles count).
|
||||
drop(initial_handle);
|
||||
|
||||
// Tear down IO and clean up shared state for the next run() call.
|
||||
let mut s = self.inner.shared.lock().unwrap();
|
||||
drop(s.io.take()); // joins IO threads
|
||||
s.pending_closures.clear();
|
||||
// Reset per-thread stats.
|
||||
for stat in &self.inner.stats {
|
||||
stat.current_pid_index.store(u32::MAX, Ordering::Relaxed);
|
||||
stat.run_queue_len.store(0, Ordering::Relaxed);
|
||||
}
|
||||
self.inner.io_parked.store(0, Ordering::Relaxed);
|
||||
self.inner.sleeping.store(0, Ordering::Relaxed);
|
||||
|
||||
RUNTIME.with(|r| *r.borrow_mut() = None);
|
||||
}
|
||||
|
||||
/// Snapshot of runtime statistics for introspection / tests.
|
||||
pub fn stats(&self) -> RuntimeStats {
|
||||
RuntimeStats { inner: self.inner.clone() }
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Thread-locals
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
use std::cell::{Cell, RefCell};
|
||||
|
||||
thread_local! {
|
||||
/// The RuntimeInner for the current run(). Set by run() on the calling
|
||||
/// thread and by each spawned scheduler thread.
|
||||
pub(crate) static RUNTIME: RefCell<Option<Arc<RuntimeInner>>> =
|
||||
const { RefCell::new(None) };
|
||||
|
||||
/// This scheduler thread's index into RuntimeInner::stats.
|
||||
static SCHED_SLOT: Cell<usize> = const { Cell::new(0) };
|
||||
|
||||
/// What the actor wants when it yields back to the scheduler.
|
||||
static YIELD_INTENT: Cell<YieldIntent> = const { Cell::new(YieldIntent::Yield) };
|
||||
}
|
||||
|
||||
#[derive(Copy, Clone)]
|
||||
pub(crate) enum YieldIntent { Yield, Park }
|
||||
|
||||
pub(crate) fn set_yield_intent(i: YieldIntent) {
|
||||
YIELD_INTENT.with(|c| c.set(i));
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Sentinel root PID
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub const ROOT_PID: Pid = Pid::new(u32::MAX, u32::MAX);
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Slot reclamation
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub(crate) fn reclaim_slot(s: &mut SharedState, pid: Pid) {
|
||||
let idx = pid.index();
|
||||
let slot = &mut s.slots[idx as usize];
|
||||
slot.generation = slot.generation.wrapping_add(1);
|
||||
slot.actor = None;
|
||||
slot.outcome = None;
|
||||
slot.waiters.clear();
|
||||
slot.supervisor_channel = None;
|
||||
slot.state = State::Done;
|
||||
slot.outstanding_handles = 0;
|
||||
slot.pending_io_result = None;
|
||||
s.free_list.push(idx);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// finalize_actor
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
fn finalize_actor(inner: &Arc<RuntimeInner>, pid: Pid, outcome: Outcome) {
|
||||
let (joiner_outcome, sup_signal) = match outcome {
|
||||
Outcome::Exit => (Outcome::Exit, Signal::Exit(pid)),
|
||||
Outcome::Panic(payload) => (
|
||||
Outcome::Panic(payload),
|
||||
Signal::Panic(pid, Box::new(()) as Box<dyn std::any::Any + Send>),
|
||||
),
|
||||
};
|
||||
|
||||
let (waiters, supervisor_pid) = inner.with_shared(|s| {
|
||||
let slot = s.slot_mut(pid).expect("finalize_actor: slot vanished");
|
||||
let sup = slot.actor.as_ref().map(|a| a.supervisor);
|
||||
slot.outcome = Some(joiner_outcome);
|
||||
slot.state = State::Done;
|
||||
slot.actor = None;
|
||||
(std::mem::take(&mut slot.waiters), sup)
|
||||
});
|
||||
|
||||
// Deliver to supervisor.
|
||||
if let Some(sup) = supervisor_pid {
|
||||
let sender = inner.with_shared(|s| {
|
||||
s.slot(sup).and_then(|slot| slot.supervisor_channel.clone())
|
||||
});
|
||||
if let Some(sender) = sender {
|
||||
let _ = sender.send(sup_signal);
|
||||
}
|
||||
}
|
||||
|
||||
// Unpark joiners.
|
||||
for joiner in waiters {
|
||||
crate::scheduler::unpark(joiner);
|
||||
}
|
||||
|
||||
// Reclaim if no outstanding handles.
|
||||
inner.with_shared(|s| {
|
||||
let reclaim = s.slot(pid).map(|slot| slot.outstanding_handles == 0).unwrap_or(false);
|
||||
if reclaim { reclaim_slot(s, pid); }
|
||||
});
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// schedule_loop — runs on each scheduler OS thread
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
fn schedule_loop(inner: &Arc<RuntimeInner>, slot: usize) {
|
||||
let stats = &inner.stats[slot];
|
||||
|
||||
loop {
|
||||
// ----------------------------------------------------------------
|
||||
// 1. Try to win the drain lock (timers + IO). One winner per round;
|
||||
// losers skip immediately and proceed to step 2.
|
||||
// ----------------------------------------------------------------
|
||||
if let Ok(_drain_guard) = inner.drain_lock.try_lock() {
|
||||
let now = std::time::Instant::now();
|
||||
|
||||
// Drain due timers.
|
||||
let due = inner.with_shared(|s| s.timers.pop_due(now));
|
||||
for entry in due {
|
||||
match entry.reason {
|
||||
crate::timer::Reason::Sleep => {
|
||||
inner.with_shared(|s| {
|
||||
if let Some(slot) = s.slot_mut(entry.pid) {
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(entry.pid);
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
crate::timer::Reason::WaitTimeout { target, wait_seq } => {
|
||||
// Runs outside with_shared — the callback may call unpark.
|
||||
target.on_timeout(entry.pid, wait_seq);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Drain IO completions.
|
||||
let completions = inner.with_shared(|s| {
|
||||
s.io.as_mut().map(|io| io.drain_completions()).unwrap_or_default()
|
||||
});
|
||||
for completion in completions {
|
||||
match completion {
|
||||
crate::io::Completion::Blocking { pid, result } => {
|
||||
inner.with_shared(|s| {
|
||||
if let Some(io) = s.io.as_mut() {
|
||||
io.outstanding = io.outstanding.saturating_sub(1);
|
||||
}
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
slot.pending_io_result = Some(result);
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
crate::io::Completion::FdReady { fd, events: _ } => {
|
||||
inner.with_shared(|s| {
|
||||
let parked_pid = s.io.as_mut().and_then(|io| {
|
||||
let pid = io.waiters.remove(&fd);
|
||||
io.epoll_deregister(fd);
|
||||
pid
|
||||
});
|
||||
if let Some(pid) = parked_pid {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
}
|
||||
}
|
||||
} // drain_guard drops here
|
||||
|
||||
// ----------------------------------------------------------------
|
||||
// 2. Pop a runnable actor from the shared queue.
|
||||
// ----------------------------------------------------------------
|
||||
let pid = match inner.with_shared(|s| {
|
||||
let len = s.run_queue.len() as u64;
|
||||
stats.run_queue_len.store(len, Ordering::Relaxed);
|
||||
s.run_queue.pop_front()
|
||||
}) {
|
||||
Some(p) => p,
|
||||
None => {
|
||||
// Nothing runnable. Check whether we should wait or exit.
|
||||
let (next_deadline, io_outstanding, wake_fd, queue_empty, live_actors) =
|
||||
inner.with_shared(|s| {
|
||||
let next = s.timers.peek_deadline();
|
||||
let (out, fd) = match s.io.as_ref() {
|
||||
Some(io) => (
|
||||
io.outstanding + io.waiters.len() as u32,
|
||||
Some(io.wake_fd()),
|
||||
),
|
||||
None => (0, None),
|
||||
};
|
||||
// Count actors that are not Done (Runnable or Parked).
|
||||
let live = s.slots.iter().filter(|slot| {
|
||||
slot.actor.is_some()
|
||||
}).count();
|
||||
(next, out, fd, s.run_queue.is_empty(), live)
|
||||
});
|
||||
|
||||
match (next_deadline, io_outstanding, wake_fd, queue_empty, live_actors) {
|
||||
// Queue is now non-empty (another thread added work): retry.
|
||||
(_, _, _, false, _) => continue,
|
||||
// Truly idle — no timers, no IO, no live actors.
|
||||
(None, 0, _, true, 0) => return,
|
||||
// Live actors but queue empty: they must be parked on IO or
|
||||
// timers. Wait on the appropriate source.
|
||||
(Some(deadline), _, fd_opt, true, _) => {
|
||||
let now = std::time::Instant::now();
|
||||
if deadline > now {
|
||||
let timeout = deadline - now;
|
||||
match fd_opt {
|
||||
Some(fd) => {
|
||||
crate::io::poll_wake(fd, Some(timeout));
|
||||
crate::io::drain_wake_pipe(fd);
|
||||
}
|
||||
None => thread::sleep(timeout),
|
||||
}
|
||||
}
|
||||
continue;
|
||||
}
|
||||
(None, _, Some(fd), true, _) => {
|
||||
crate::io::poll_wake(fd, None);
|
||||
crate::io::drain_wake_pipe(fd);
|
||||
continue;
|
||||
}
|
||||
// Live actors, queue empty, no IO/timers: they're parked
|
||||
// waiting for each other (potential deadlock in user code),
|
||||
// or another thread is about to add work. Sleep briefly to
|
||||
// avoid hammering the shared mutex.
|
||||
_ => {
|
||||
thread::sleep(std::time::Duration::from_micros(100));
|
||||
continue;
|
||||
}
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
// ----------------------------------------------------------------
|
||||
// 3. Resume the actor.
|
||||
// ----------------------------------------------------------------
|
||||
let sp = match inner.with_shared(|s| {
|
||||
s.slot(pid).and_then(|slot| slot.actor.as_ref().map(|a| a.sp))
|
||||
}) {
|
||||
Some(sp) => sp,
|
||||
None => continue, // stale pid
|
||||
};
|
||||
|
||||
// First resume: move the closure into the trampoline's thread-local.
|
||||
if let Some(b) = inner.with_shared(|s| s.pop_pending_closure(pid)) {
|
||||
set_current_actor_box(b);
|
||||
}
|
||||
|
||||
// Update per-thread stats: record who's on-CPU.
|
||||
stats.current_pid_index.store(pid.index(), Ordering::Relaxed);
|
||||
|
||||
set_actor_sp(sp);
|
||||
set_current_pid(pid);
|
||||
reset_actor_done();
|
||||
YIELD_INTENT.with(|c| c.set(YieldIntent::Yield));
|
||||
crate::preempt::reset_timeslice();
|
||||
PREEMPTION_ENABLED.with(|c| c.set(true));
|
||||
|
||||
unsafe { switch_to_actor() };
|
||||
|
||||
PREEMPTION_ENABLED.with(|c| c.set(false));
|
||||
stats.current_pid_index.store(u32::MAX, Ordering::Relaxed);
|
||||
clear_current_pid();
|
||||
|
||||
let intent = YIELD_INTENT.with(|c| c.get());
|
||||
let new_sp = get_actor_sp();
|
||||
|
||||
if is_actor_done() {
|
||||
let outcome = take_last_outcome().unwrap_or(Outcome::Exit);
|
||||
finalize_actor(inner, pid, outcome);
|
||||
} else {
|
||||
inner.with_shared(|s| {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
if let Some(actor) = slot.actor.as_mut() {
|
||||
actor.sp = new_sp;
|
||||
}
|
||||
match intent {
|
||||
YieldIntent::Yield => {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
YieldIntent::Park => {
|
||||
slot.state = State::Parked;
|
||||
}
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
}
|
||||
}
|
||||
767
src/scheduler.rs
767
src/scheduler.rs
@@ -1,208 +1,75 @@
|
||||
//! The single-threaded scheduler.
|
||||
//! Scheduler public API — thin façade over the multi-scheduler runtime.
|
||||
//!
|
||||
//! There is one global scheduler per OS thread, stored in a thread-local.
|
||||
//! `run(initial)` initialises it, spawns the initial actor, drives the loop
|
||||
//! until the run queue is empty, then tears it down.
|
||||
//! All heavy lifting lives in `runtime.rs`. This module exposes the same
|
||||
//! surface that the rest of the codebase (channel, mutex, io, timer, actor)
|
||||
//! calls into, plus the public API re-exported from `lib.rs`.
|
||||
//!
|
||||
//! Slot table: a `Vec<Slot>` indexed by `Pid::index()`, with a free list of
|
||||
//! reusable indices. Each slot has a `generation` counter that increments
|
||||
//! every time the slot is freed; `Pid` carries the generation it was minted
|
||||
//! with, so a stale PID has a mismatching generation and is detected on
|
||||
//! lookup.
|
||||
//!
|
||||
//! Run queue: a `VecDeque<Pid>` of runnable actors. The state of an actor
|
||||
//! is implicit in slot.state: `Runnable` means it's either in the queue or
|
||||
//! currently executing; `Parked` means it's waiting for something to unpark
|
||||
//! it (channel send, join completion, …); `Done` means it has finished and
|
||||
//! is awaiting reaping.
|
||||
//!
|
||||
//! Joining: `JoinHandle::join()` parks the calling actor and registers it
|
||||
//! on the target slot's `waiters` list. When the target actor finishes,
|
||||
//! the scheduler reaps the slot and unparks every waiter, passing them the
|
||||
//! outcome via a side channel (the target's `outcome` field, drained on
|
||||
//! the joiner side).
|
||||
//! The single-threaded `run()` entry point is kept as a convenience wrapper
|
||||
//! around `runtime::init(Config::exact(1)).run(f)`.
|
||||
|
||||
use crate::actor::{
|
||||
clear_current_pid, current_pid, is_actor_done, reset_actor_done,
|
||||
set_current_actor_box, set_current_pid, take_last_outcome, trampoline, Actor, Outcome,
|
||||
};
|
||||
use crate::actor::current_pid;
|
||||
use crate::channel::Sender;
|
||||
use crate::context::{get_actor_sp, init_actor_stack, set_actor_sp, switch_to_actor};
|
||||
use crate::pid::Pid;
|
||||
use crate::preempt::PREEMPTION_ENABLED;
|
||||
use crate::stack::Stack;
|
||||
use crate::runtime::{
|
||||
self, RuntimeInner, YieldIntent, ROOT_PID, RUNTIME,
|
||||
};
|
||||
use crate::supervisor::Signal;
|
||||
use std::cell::RefCell;
|
||||
use std::collections::VecDeque;
|
||||
use std::sync::Arc;
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Configuration
|
||||
// with_runtime / try_with_runtime
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
const ACTOR_STACK_SIZE: usize = 64 * 1024;
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Per-actor slot
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
enum State {
|
||||
/// Either in the run queue or currently executing.
|
||||
Runnable,
|
||||
/// Removed from the queue, waiting for `unpark()`.
|
||||
Parked,
|
||||
/// The actor has finished. Slot persists until the last `JoinHandle`
|
||||
/// has been joined (or dropped). Then the slot is freed.
|
||||
Done,
|
||||
}
|
||||
|
||||
struct Slot {
|
||||
/// Bumped every time this slot is freed and re-used. A `Pid` with a
|
||||
/// non-matching generation is stale.
|
||||
generation: u32,
|
||||
/// `None` when the slot is free. `Some` otherwise.
|
||||
actor: Option<Actor>,
|
||||
state: State,
|
||||
/// PIDs waiting in `JoinHandle::join`.
|
||||
waiters: Vec<Pid>,
|
||||
/// The outcome the actor produced, captured when it finished.
|
||||
/// Drained by `JoinHandle::join`.
|
||||
outcome: Option<Outcome>,
|
||||
/// If this slot is a supervisor, the sender into its `Signal` mailbox.
|
||||
/// Cloned out and used when one of its children dies.
|
||||
supervisor_channel: Option<Sender<Signal>>,
|
||||
/// Number of `JoinHandle`s still outstanding for this actor. The slot
|
||||
/// is reclaimed only when the actor is done AND outstanding_handles == 0.
|
||||
outstanding_handles: u32,
|
||||
/// One-shot mailbox for the result of an in-flight `block_on_io` call.
|
||||
/// The scheduler writes it on completion; `block_on_io` reads it on
|
||||
/// resume.
|
||||
pending_io_result: Option<crate::io::IoResult>,
|
||||
}
|
||||
|
||||
impl Slot {
|
||||
fn vacant() -> Self {
|
||||
Self {
|
||||
generation: 0,
|
||||
actor: None,
|
||||
state: State::Done,
|
||||
waiters: Vec::new(),
|
||||
outcome: None,
|
||||
supervisor_channel: None,
|
||||
outstanding_handles: 0,
|
||||
pending_io_result: None,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Scheduler state
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
struct SchedulerState {
|
||||
slots: Vec<Slot>,
|
||||
free_list: Vec<u32>,
|
||||
run_queue: VecDeque<Pid>,
|
||||
/// The root supervisor's PID. Children spawned at the top level are
|
||||
/// supervised by this. Set by `run()`.
|
||||
root_pid: Option<Pid>,
|
||||
/// Pending sleep timers. Min-heap keyed by deadline.
|
||||
timers: crate::timer::Timers,
|
||||
/// IO worker thread. `None` outside `run()`.
|
||||
io: Option<crate::io::IoThread>,
|
||||
}
|
||||
|
||||
impl SchedulerState {
|
||||
fn new() -> Self {
|
||||
Self {
|
||||
slots: Vec::new(),
|
||||
free_list: Vec::new(),
|
||||
run_queue: VecDeque::new(),
|
||||
root_pid: None,
|
||||
timers: crate::timer::Timers::new(),
|
||||
io: None,
|
||||
}
|
||||
}
|
||||
|
||||
/// Allocate a slot; return its (index, generation).
|
||||
fn allocate_slot(&mut self) -> (u32, u32) {
|
||||
if let Some(idx) = self.free_list.pop() {
|
||||
let s = &mut self.slots[idx as usize];
|
||||
(idx, s.generation)
|
||||
} else {
|
||||
let idx = self.slots.len() as u32;
|
||||
self.slots.push(Slot::vacant());
|
||||
(idx, 0)
|
||||
}
|
||||
}
|
||||
|
||||
fn slot(&self, pid: Pid) -> Option<&Slot> {
|
||||
let s = self.slots.get(pid.index() as usize)?;
|
||||
if s.generation == pid.generation() { Some(s) } else { None }
|
||||
}
|
||||
|
||||
fn slot_mut(&mut self, pid: Pid) -> Option<&mut Slot> {
|
||||
let s = self.slots.get_mut(pid.index() as usize)?;
|
||||
if s.generation == pid.generation() { Some(s) } else { None }
|
||||
}
|
||||
}
|
||||
|
||||
thread_local! {
|
||||
static SCHED: RefCell<Option<SchedulerState>> = const { RefCell::new(None) };
|
||||
}
|
||||
|
||||
fn with_sched<R>(f: impl FnOnce(&mut SchedulerState) -> R) -> R {
|
||||
SCHED.with(|c| {
|
||||
let mut g = c.borrow_mut();
|
||||
let s = g.as_mut().expect("scheduler not running");
|
||||
f(s)
|
||||
/// Borrow the current runtime. Panics if called outside `Runtime::run()`.
|
||||
pub(crate) fn with_runtime<R>(f: impl FnOnce(&Arc<RuntimeInner>) -> R) -> R {
|
||||
RUNTIME.with(|r| {
|
||||
let b = r.borrow();
|
||||
let inner = b.as_ref().expect("smarm: not inside Runtime::run()");
|
||||
f(inner)
|
||||
})
|
||||
}
|
||||
|
||||
/// Same as `with_sched` but returns `None` when there's no scheduler instead
|
||||
/// of panicking. Used on cleanup paths (channel sender drop during shutdown,
|
||||
/// for example).
|
||||
fn try_with_sched<R>(f: impl FnOnce(&mut SchedulerState) -> R) -> Option<R> {
|
||||
SCHED.with(|c| {
|
||||
let mut g = c.borrow_mut();
|
||||
g.as_mut().map(f)
|
||||
})
|
||||
/// Borrow the runtime if present; returns `None` otherwise.
|
||||
/// Used on cleanup paths (channel Drop during teardown).
|
||||
pub(crate) fn try_with_runtime<R>(f: impl FnOnce(&Arc<RuntimeInner>) -> R) -> Option<R> {
|
||||
RUNTIME.with(|r| r.borrow().as_ref().map(|inner| f(inner)))
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// JoinHandle
|
||||
// JoinHandle / JoinError
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[derive(Debug)]
|
||||
pub struct JoinError {
|
||||
/// Whatever `panic!` was called with.
|
||||
pub payload: Box<dyn std::any::Any + Send>,
|
||||
}
|
||||
|
||||
pub struct JoinHandle {
|
||||
pid: Pid,
|
||||
/// `false` once `join()` has been called and the handle has consumed
|
||||
/// its outcome. Prevents the Drop impl from double-decrementing.
|
||||
consumed: bool,
|
||||
}
|
||||
|
||||
impl JoinHandle {
|
||||
pub fn pid(&self) -> Pid { self.pid }
|
||||
|
||||
/// Block the calling actor until the target completes. Returns
|
||||
/// `Ok(())` on normal exit, `Err(JoinError)` if the target panicked.
|
||||
pub fn join(mut self) -> Result<(), JoinError> {
|
||||
use crate::actor::Outcome;
|
||||
use crate::runtime::State; // need State visibility
|
||||
|
||||
let me = current_pid().expect("join() called outside an actor");
|
||||
|
||||
loop {
|
||||
let outcome = with_sched(|s| {
|
||||
let outcome = with_runtime(|inner| {
|
||||
inner.with_shared(|s| {
|
||||
let slot = s.slot_mut(self.pid)
|
||||
.expect("join: target slot has been reused");
|
||||
if matches!(slot.state, State::Done) {
|
||||
Some(slot.outcome.take().expect("Done slot must have an outcome"))
|
||||
Some(slot.outcome.take().expect("Done slot must have outcome"))
|
||||
} else {
|
||||
slot.waiters.push(me);
|
||||
None
|
||||
}
|
||||
})
|
||||
});
|
||||
|
||||
match outcome {
|
||||
@@ -214,23 +81,30 @@ impl JoinHandle {
|
||||
Outcome::Panic(p) => Err(JoinError { payload: p }),
|
||||
};
|
||||
}
|
||||
None => park_current(),
|
||||
None => {
|
||||
let _np = NoPreempt::enter();
|
||||
park_current();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn decrement_handle_count(&mut self) {
|
||||
with_sched(|s| {
|
||||
with_runtime(|inner| {
|
||||
inner.with_shared(|s| {
|
||||
let should_reclaim = match s.slot_mut(self.pid) {
|
||||
Some(slot) => {
|
||||
slot.outstanding_handles = slot.outstanding_handles.saturating_sub(1);
|
||||
matches!(slot.state, State::Done) && slot.outstanding_handles == 0
|
||||
slot.outstanding_handles =
|
||||
slot.outstanding_handles.saturating_sub(1);
|
||||
matches!(slot.state, crate::runtime::State::Done)
|
||||
&& slot.outstanding_handles == 0
|
||||
}
|
||||
None => false,
|
||||
};
|
||||
if should_reclaim {
|
||||
reclaim_slot(s, self.pid);
|
||||
crate::runtime::reclaim_slot(s, self.pid);
|
||||
}
|
||||
})
|
||||
});
|
||||
}
|
||||
}
|
||||
@@ -238,126 +112,89 @@ impl JoinHandle {
|
||||
impl Drop for JoinHandle {
|
||||
fn drop(&mut self) {
|
||||
if !self.consumed {
|
||||
// May be called outside run() if handle is dropped after teardown.
|
||||
if try_with_runtime(|_| ()).is_some() {
|
||||
self.decrement_handle_count();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Slot reclamation
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
fn reclaim_slot(s: &mut SchedulerState, pid: Pid) {
|
||||
let idx = pid.index();
|
||||
let slot = &mut s.slots[idx as usize];
|
||||
// Bump generation so any stale PIDs from now on miss.
|
||||
slot.generation = slot.generation.wrapping_add(1);
|
||||
// Drop the actor (its stack with it).
|
||||
slot.actor = None;
|
||||
slot.outcome = None;
|
||||
slot.waiters.clear();
|
||||
slot.supervisor_channel = None;
|
||||
slot.state = State::Done; // semantically vacant; allocator checks free_list
|
||||
slot.outstanding_handles = 0;
|
||||
slot.pending_io_result = None;
|
||||
s.free_list.push(idx);
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// spawn / spawn_under / self_pid
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Spawn `f` as a child of the currently-executing actor.
|
||||
/// Outside an actor (only legal from `run()`'s initial setup), the child's
|
||||
/// supervisor is the root supervisor.
|
||||
pub fn spawn(f: impl FnOnce() + Send + 'static) -> JoinHandle {
|
||||
let parent = current_pid()
|
||||
.or_else(|| with_sched(|s| s.root_pid))
|
||||
.or_else(|| with_runtime(|inner| inner.with_shared(|s| s.root_pid)))
|
||||
.expect("spawn() before run()");
|
||||
spawn_under(parent, f)
|
||||
}
|
||||
|
||||
/// Spawn `f` with `supervisor` as its parent. The supervisor will receive
|
||||
/// a `Signal` on its registered channel when the child terminates.
|
||||
pub fn spawn_under(supervisor: Pid, f: impl FnOnce() + Send + 'static) -> JoinHandle {
|
||||
let pid = with_sched(|s| {
|
||||
let pid = with_runtime(|inner| {
|
||||
inner.with_shared(|s| {
|
||||
let (idx, gen) = s.allocate_slot();
|
||||
let pid = Pid::new(idx, gen);
|
||||
let stack = Stack::new(ACTOR_STACK_SIZE)
|
||||
let stack = crate::stack::Stack::new(crate::runtime::ACTOR_STACK_SIZE)
|
||||
.expect("stack allocation failed");
|
||||
let sp = init_actor_stack(stack.top(), trampoline);
|
||||
let sp = init_actor_stack(stack.top(), crate::actor::trampoline);
|
||||
let slot = &mut s.slots[idx as usize];
|
||||
slot.actor = Some(Actor { pid, stack, sp, supervisor });
|
||||
slot.state = State::Runnable;
|
||||
slot.actor = Some(crate::actor::Actor { pid, stack, sp, supervisor });
|
||||
slot.state = crate::runtime::State::Runnable;
|
||||
slot.outstanding_handles = 1;
|
||||
slot.outcome = None;
|
||||
slot.waiters.clear();
|
||||
slot.supervisor_channel = None;
|
||||
slot.pending_io_result = None;
|
||||
s.run_queue.push_back(pid);
|
||||
s.pending_closures.push((pid, Box::new(f) as crate::runtime::Closure));
|
||||
pid
|
||||
});
|
||||
|
||||
// Stash the closure where `schedule_loop` will find it before the first
|
||||
// resume.
|
||||
PENDING_CLOSURES.with(|c| {
|
||||
c.borrow_mut().push((pid, Box::new(f) as Closure));
|
||||
})
|
||||
});
|
||||
|
||||
JoinHandle { pid, consumed: false }
|
||||
}
|
||||
|
||||
type Closure = Box<dyn FnOnce() + Send>;
|
||||
|
||||
thread_local! {
|
||||
/// Closures awaiting their first resume. Keyed by the PID the scheduler
|
||||
/// allocated for them in `spawn_under`. The scheduler pops from here in
|
||||
/// `pop_pending_closure` right before each first resume.
|
||||
static PENDING_CLOSURES: RefCell<Vec<(Pid, Closure)>> = const { RefCell::new(Vec::new()) };
|
||||
}
|
||||
|
||||
fn pop_pending_closure(pid: Pid) -> Option<Closure> {
|
||||
PENDING_CLOSURES.with(|c| {
|
||||
let mut v = c.borrow_mut();
|
||||
v.iter().position(|(p, _)| *p == pid).map(|i| v.swap_remove(i).1)
|
||||
})
|
||||
}
|
||||
use crate::context::init_actor_stack;
|
||||
|
||||
pub fn self_pid() -> Pid {
|
||||
current_pid().expect("self_pid() called outside an actor")
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// yield_now / park / unpark
|
||||
// yield_now / park_current / unpark
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Cooperative yield. The current actor goes to the back of the run queue.
|
||||
pub fn yield_now() {
|
||||
// Mark ourselves as needing to be re-queued, then yield.
|
||||
YIELD_INTENT.with(|c| c.set(YieldIntent::Yield));
|
||||
runtime::set_yield_intent(YieldIntent::Yield);
|
||||
unsafe { crate::context::switch_to_scheduler() };
|
||||
}
|
||||
|
||||
/// Park the current actor (remove it from the run queue until `unpark`).
|
||||
pub fn park_current() {
|
||||
YIELD_INTENT.with(|c| c.set(YieldIntent::Park));
|
||||
runtime::set_yield_intent(YieldIntent::Park);
|
||||
unsafe { crate::context::switch_to_scheduler() };
|
||||
}
|
||||
|
||||
/// RAII guard that disables allocator-driven preemption for its lifetime.
|
||||
///
|
||||
/// The "prep-to-park" hazard described in `preempt.rs`: a primitive that
|
||||
/// (a) registers an unparker (channel waiter slot, fd waiter map, mutex
|
||||
/// waiter queue, …) and then (b) calls `park_current()` must not yield
|
||||
/// between (a) and (b). If it does, an early unpark fires while the actor
|
||||
/// is still Runnable, the unpark no-ops, and then the actor parks with no
|
||||
/// one to wake it.
|
||||
///
|
||||
/// Library code wraps the prep + park in `let _g = NoPreempt::enter();`
|
||||
/// and the guard is held until just after `park_current` returns (or
|
||||
/// dropped earlier, immediately before `park_current`, since `park_current`
|
||||
/// itself returns control to the scheduler which disables preemption on
|
||||
/// its own path).
|
||||
pub fn unpark(pid: Pid) {
|
||||
let result = try_with_runtime(|inner| {
|
||||
inner.with_shared(|s| {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
if matches!(slot.state, crate::runtime::State::Parked) {
|
||||
slot.state = crate::runtime::State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
}
|
||||
})
|
||||
});
|
||||
// If try_with_runtime returns None we're in teardown — no-op is correct.
|
||||
let _ = result;
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// NoPreempt
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub struct NoPreempt(bool);
|
||||
|
||||
impl NoPreempt {
|
||||
@@ -373,506 +210,124 @@ impl Drop for NoPreempt {
|
||||
}
|
||||
}
|
||||
|
||||
/// Park the current actor for at least `duration`. A zero duration behaves
|
||||
/// like `yield_now` (the deadline is immediately in the past, so the timer
|
||||
/// pops on the next scheduler iteration).
|
||||
// ---------------------------------------------------------------------------
|
||||
// sleep / insert_wait_timer
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub fn sleep(duration: std::time::Duration) {
|
||||
let me = current_pid().expect("sleep() called outside an actor");
|
||||
let _np = NoPreempt::enter();
|
||||
let deadline = crate::timer::deadline_from_now(duration);
|
||||
with_sched(|s| s.timers.insert_sleep(deadline, me));
|
||||
with_runtime(|inner| inner.with_shared(|s| s.timers.insert_sleep(deadline, me)));
|
||||
park_current();
|
||||
}
|
||||
|
||||
/// Insert a `WaitTimeout` timer entry. Library code (`Mutex::lock_timeout`
|
||||
/// today, future bounded-wait primitives) calls this just before
|
||||
/// `park_current()` so that if the wait isn't satisfied by `deadline`,
|
||||
/// `target.on_timeout(pid, wait_seq)` will fire.
|
||||
///
|
||||
/// Cancellation: not needed. If the wait is satisfied early, the entry is
|
||||
/// still in the heap and will pop in due course; `on_timeout` is expected
|
||||
/// to be idempotent on stale-seq.
|
||||
pub fn insert_wait_timer(
|
||||
deadline: std::time::Instant,
|
||||
pid: Pid,
|
||||
target: std::rc::Rc<dyn crate::timer::TimerTarget>,
|
||||
target: std::sync::Arc<dyn crate::timer::TimerTarget>,
|
||||
wait_seq: u64,
|
||||
) {
|
||||
with_sched(|s| {
|
||||
with_runtime(|inner| {
|
||||
inner.with_shared(|s| {
|
||||
s.timers.insert(
|
||||
deadline,
|
||||
pid,
|
||||
crate::timer::Reason::WaitTimeout { target, wait_seq },
|
||||
);
|
||||
})
|
||||
});
|
||||
}
|
||||
|
||||
/// Run `f` on the IO worker thread, park the current actor while it runs,
|
||||
/// and return `f`'s value when it completes. Panics inside `f` propagate
|
||||
/// to the calling actor.
|
||||
///
|
||||
/// Use this for blocking calls that would otherwise stall the scheduler —
|
||||
/// synchronous file IO, blocking C FFI, libpq, etc.
|
||||
// ---------------------------------------------------------------------------
|
||||
// block_on_io / wait_readable / wait_writable / read / write
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
pub fn block_on_io<F, T>(f: F) -> T
|
||||
where
|
||||
F: FnOnce() -> T + Send + 'static,
|
||||
T: Send + 'static,
|
||||
{
|
||||
let me = current_pid().expect("block_on_io() called outside an actor");
|
||||
|
||||
// Box the user closure into the wire-form result-shaped closure that
|
||||
// the worker expects. The worker also wraps in catch_unwind, but doing
|
||||
// it here too would let us downcast `T` only when the closure didn't
|
||||
// panic. We let the worker handle catch_unwind so the boxing here
|
||||
// stays straightforward.
|
||||
let work: Box<dyn FnOnce() -> crate::io::IoResult + Send> = Box::new(move || {
|
||||
let v: T = f();
|
||||
Ok(Box::new(v) as Box<dyn std::any::Any + Send>)
|
||||
});
|
||||
|
||||
{
|
||||
let _np = NoPreempt::enter();
|
||||
with_sched(|s| {
|
||||
with_runtime(|inner| inner.with_shared(|s| {
|
||||
let io = s.io.as_mut().expect("io thread not started");
|
||||
io.submit(me, work);
|
||||
});
|
||||
}));
|
||||
park_current();
|
||||
}
|
||||
|
||||
// On resume, our slot has a result waiting.
|
||||
let result = with_sched(|s| {
|
||||
let result = with_runtime(|inner| inner.with_shared(|s| {
|
||||
s.slot_mut(me)
|
||||
.expect("block_on_io: own slot vanished")
|
||||
.pending_io_result
|
||||
.take()
|
||||
.expect("block_on_io: resumed without a result")
|
||||
});
|
||||
|
||||
}));
|
||||
match result {
|
||||
Ok(any) => *any
|
||||
.downcast::<T>()
|
||||
.expect("block_on_io: result type mismatch — should be unreachable"),
|
||||
Ok(any) => *any.downcast::<T>().expect("block_on_io: type mismatch"),
|
||||
Err(payload) => std::panic::resume_unwind(payload),
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Fd-readiness primitives.
|
||||
//
|
||||
// `wait_readable(fd)` / `wait_writable(fd)` register interest with the
|
||||
// epoll thread, park the calling actor, and return when the kernel
|
||||
// signals readiness. The subsequent syscall (`read`/`write`) is done on
|
||||
// the actor's own thread by the caller — no buffer crosses an actor
|
||||
// boundary.
|
||||
//
|
||||
// Fds passed in should be O_NONBLOCK; see io.rs module docs.
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Park the calling actor until `fd` is readable.
|
||||
pub fn wait_readable(fd: std::os::fd::RawFd) -> std::io::Result<()> {
|
||||
wait_fd(fd, /*readable=*/ true, /*writable=*/ false)
|
||||
wait_fd(fd, true, false)
|
||||
}
|
||||
|
||||
/// Park the calling actor until `fd` is writable.
|
||||
pub fn wait_writable(fd: std::os::fd::RawFd) -> std::io::Result<()> {
|
||||
wait_fd(fd, /*readable=*/ false, /*writable=*/ true)
|
||||
wait_fd(fd, false, true)
|
||||
}
|
||||
|
||||
fn wait_fd(fd: std::os::fd::RawFd, readable: bool, writable: bool) -> std::io::Result<()> {
|
||||
let me = current_pid().expect("wait_*() called outside an actor");
|
||||
|
||||
// Register with the epoll thread. If registration fails (bad fd,
|
||||
// already-parked waiter, OOM in the kernel), return the error
|
||||
// without parking — the actor never went to sleep.
|
||||
let _np = NoPreempt::enter();
|
||||
with_sched(|s| {
|
||||
with_runtime(|inner| inner.with_shared(|s| {
|
||||
let io = s.io.as_mut().expect("io thread not started");
|
||||
io.epoll_register(fd, me, readable, writable)
|
||||
})?;
|
||||
|
||||
}))?;
|
||||
park_current();
|
||||
// On resume, the scheduler has already removed `fd` from `waiters`
|
||||
// and DEL'd it from epollfd. There is no per-call return value;
|
||||
// success here just means "fd is ready, go do your syscall".
|
||||
//
|
||||
// Note: there is no error path on resume because v0.2 doesn't time
|
||||
// out fd waits and doesn't otherwise spurious-wake. If those are
|
||||
// added, this function grows a non-trivial return.
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Wait until `fd` is readable, then run a single `read(2)`. Returns the
|
||||
/// number of bytes read, or an `io::Error` from the syscall.
|
||||
///
|
||||
/// `fd` should be opened `O_NONBLOCK`. With a blocking fd, the kernel's
|
||||
/// readiness signal does not guarantee a non-blocking read — a signal
|
||||
/// could interrupt, and the actor's syscall would then stall the
|
||||
/// scheduler thread.
|
||||
pub fn read(fd: std::os::fd::RawFd, buf: &mut [u8]) -> std::io::Result<usize> {
|
||||
wait_readable(fd)?;
|
||||
let n = unsafe {
|
||||
libc::read(fd, buf.as_mut_ptr() as *mut _, buf.len())
|
||||
};
|
||||
if n < 0 {
|
||||
Err(std::io::Error::last_os_error())
|
||||
} else {
|
||||
Ok(n as usize)
|
||||
}
|
||||
let n = unsafe { libc::read(fd, buf.as_mut_ptr() as *mut _, buf.len()) };
|
||||
if n < 0 { Err(std::io::Error::last_os_error()) } else { Ok(n as usize) }
|
||||
}
|
||||
|
||||
/// Wait until `fd` is writable, then run a single `write(2)`.
|
||||
pub fn write(fd: std::os::fd::RawFd, buf: &[u8]) -> std::io::Result<usize> {
|
||||
wait_writable(fd)?;
|
||||
let n = unsafe {
|
||||
libc::write(fd, buf.as_ptr() as *const _, buf.len())
|
||||
};
|
||||
if n < 0 {
|
||||
Err(std::io::Error::last_os_error())
|
||||
} else {
|
||||
Ok(n as usize)
|
||||
}
|
||||
}
|
||||
|
||||
/// Wake a parked actor. If the actor isn't parked (already runnable or done)
|
||||
/// this is a no-op — that's important; channel and join can both fire
|
||||
/// spurious unparks under some orderings and we want them to be cheap.
|
||||
/// Also a no-op if the scheduler isn't running (covers channel-sender drop
|
||||
/// during runtime teardown).
|
||||
pub fn unpark(pid: Pid) {
|
||||
try_with_sched(|s| {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
|
||||
/// What an actor wants the scheduler to do when control returns from it.
|
||||
#[derive(Copy, Clone)]
|
||||
enum YieldIntent {
|
||||
/// Re-queue (yield_now or preemption).
|
||||
Yield,
|
||||
/// Remove from the run queue (waiting for unpark).
|
||||
Park,
|
||||
}
|
||||
|
||||
thread_local! {
|
||||
static YIELD_INTENT: std::cell::Cell<YieldIntent> = const { std::cell::Cell::new(YieldIntent::Yield) };
|
||||
let n = unsafe { libc::write(fd, buf.as_ptr() as *const _, buf.len()) };
|
||||
if n < 0 { Err(std::io::Error::last_os_error()) } else { Ok(n as usize) }
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Supervisor channel registration
|
||||
// register_supervisor_channel
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Register `sender` as the mailbox for signals about children supervised
|
||||
/// by `pid`. Idempotent; later calls overwrite.
|
||||
pub fn register_supervisor_channel(pid: Pid, sender: Sender<Signal>) {
|
||||
with_sched(|s| {
|
||||
with_runtime(|inner| inner.with_shared(|s| {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
slot.supervisor_channel = Some(sender);
|
||||
} else {
|
||||
panic!("register_supervisor_channel: pid {:?} not found", pid);
|
||||
}
|
||||
});
|
||||
}));
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// run() — the runtime entry point
|
||||
// Legacy run() — convenience wrapper
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Boot the runtime, spawn `initial` as a child of the root supervisor,
|
||||
/// drive the scheduler until the run queue is empty, tear down.
|
||||
///
|
||||
/// The root supervisor is a *sentinel* PID, not a real actor. Signals
|
||||
/// addressed to it are dropped on the floor — that's what "process exits"
|
||||
/// means in the spec when nothing escalates further. User code that wants
|
||||
/// real supervision spawns its own supervisor actor and uses `spawn_under`.
|
||||
pub fn run<F: FnOnce() + Send + 'static>(initial: F) {
|
||||
SCHED.with(|c| {
|
||||
assert!(c.borrow().is_none(), "smarm::run() called recursively");
|
||||
let mut state = SchedulerState::new();
|
||||
state.root_pid = Some(ROOT_PID);
|
||||
state.io = Some(crate::io::IoThread::start().expect("failed to start io thread"));
|
||||
*c.borrow_mut() = Some(state);
|
||||
});
|
||||
|
||||
let initial_handle = spawn(initial);
|
||||
|
||||
schedule_loop();
|
||||
|
||||
// Drop the handle BEFORE the scheduler is torn down — its Drop impl
|
||||
// calls `with_sched` to decrement the outstanding-handle count.
|
||||
drop(initial_handle);
|
||||
|
||||
// Take the SchedulerState out of the thread-local BEFORE dropping it.
|
||||
// Dropping it while still inside SCHED.with's RefCell borrow would
|
||||
// re-enter (via channel senders' Drop → unpark → try_with_sched).
|
||||
let state = SCHED.with(|c| c.borrow_mut().take());
|
||||
drop(state);
|
||||
PENDING_CLOSURES.with(|c| c.borrow_mut().clear());
|
||||
/// Single-threaded runtime entry point (backwards-compatible wrapper).
|
||||
/// Equivalent to `runtime::init(Config::exact(1)).run(f)`.
|
||||
pub fn run<F: FnOnce() + Send + 'static>(f: F) {
|
||||
crate::runtime::init(crate::runtime::Config::exact(1)).run(f);
|
||||
}
|
||||
|
||||
/// Reserved sentinel pid for the root supervisor. Never allocated to a
|
||||
/// real actor; lookups return `None`; signals are dropped.
|
||||
pub const ROOT_PID: Pid = Pid::new(u32::MAX, u32::MAX);
|
||||
|
||||
fn schedule_loop() {
|
||||
loop {
|
||||
// 1. Drain due timers and dispatch by reason.
|
||||
//
|
||||
// Sleep — unpark the actor (idempotently: only if still
|
||||
// parked).
|
||||
// WaitTimeout — call the target's on_timeout. The target decides
|
||||
// whether the wait was still in progress (timer
|
||||
// won the race) or had been fulfilled (the thing
|
||||
// the actor was waiting for arrived first → no-op).
|
||||
// The target is responsible for calling unpark()
|
||||
// if appropriate.
|
||||
let now = std::time::Instant::now();
|
||||
let due = with_sched(|s| s.timers.pop_due(now));
|
||||
for entry in due {
|
||||
match entry.reason {
|
||||
crate::timer::Reason::Sleep => {
|
||||
with_sched(|s| {
|
||||
if let Some(slot) = s.slot_mut(entry.pid) {
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(entry.pid);
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
crate::timer::Reason::WaitTimeout { target, wait_seq } => {
|
||||
// Note: the target callback runs *outside* with_sched.
|
||||
// It may call back into the scheduler (e.g. unpark), so
|
||||
// we must not hold the SCHED borrow across it.
|
||||
target.on_timeout(entry.pid, wait_seq);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// 2. Drain IO completions: route each result by variant.
|
||||
//
|
||||
// Blocking — a `block_on_io` closure finished. Stash the result
|
||||
// on the actor's slot and unpark.
|
||||
// FdReady — an fd registered via `wait_readable`/`wait_writable`
|
||||
// is ready. Look up the parked pid in the io thread's
|
||||
// waiters map, deregister the fd, unpark.
|
||||
//
|
||||
// Drain even when we have other runnables — it's cheap and keeps
|
||||
// `pending_io_result` / `waiters` freshness bounded.
|
||||
let completions = with_sched(|s| {
|
||||
s.io.as_mut().map(|io| io.drain_completions()).unwrap_or_default()
|
||||
});
|
||||
for completion in completions {
|
||||
match completion {
|
||||
crate::io::Completion::Blocking { pid, result } => {
|
||||
with_sched(|s| {
|
||||
if let Some(io) = s.io.as_mut() {
|
||||
io.outstanding = io.outstanding.saturating_sub(1);
|
||||
}
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
slot.pending_io_result = Some(result);
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
crate::io::Completion::FdReady { fd, events: _ } => {
|
||||
with_sched(|s| {
|
||||
let parked_pid = s.io.as_mut()
|
||||
.and_then(|io| {
|
||||
let pid = io.waiters.remove(&fd);
|
||||
// Deregister the fd from epollfd; the
|
||||
// EPOLLONESHOT already disarmed it but the
|
||||
// slot is still occupied until we DEL.
|
||||
io.epoll_deregister(fd);
|
||||
pid
|
||||
});
|
||||
if let Some(pid) = parked_pid {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
if matches!(slot.state, State::Parked) {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
}
|
||||
// else: actor died between registering and the
|
||||
// fd firing. Nothing to do; the registration
|
||||
// has been cleaned up.
|
||||
}
|
||||
// else: fd not in waiters — probably a duplicate
|
||||
// FdReady from a previous registration, ignore.
|
||||
});
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// 3. Pop a runnable actor. If none, decide whether to block on
|
||||
// the wake pipe (for timers or IO) or exit (nothing pending).
|
||||
let pid = match with_sched(|s| s.run_queue.pop_front()) {
|
||||
Some(p) => p,
|
||||
None => {
|
||||
// Read out what we'd need to block on. We must take the
|
||||
// wake fd separately because we can't hold an SCHED
|
||||
// borrow across `poll_wake` — the IO thread will be
|
||||
// trying to take the completions mutex, which is fine,
|
||||
// but the scheduler thread itself mustn't hold SCHED
|
||||
// borrowed across a blocking syscall.
|
||||
//
|
||||
// "Outstanding" here means *anything* the IO thread is
|
||||
// expected to deliver a wakeup for: in-flight blocking
|
||||
// calls AND parked fd waiters. If either is non-zero we
|
||||
// must wait for the IO thread, not exit.
|
||||
let (next_deadline, io_outstanding, wake_fd) = with_sched(|s| {
|
||||
let next = s.timers.peek_deadline();
|
||||
let (out, fd) = match s.io.as_ref() {
|
||||
Some(io) => (
|
||||
io.outstanding + io.waiters.len() as u32,
|
||||
Some(io.wake_fd()),
|
||||
),
|
||||
None => (0, None),
|
||||
};
|
||||
(next, out, fd)
|
||||
});
|
||||
|
||||
match (next_deadline, io_outstanding, wake_fd) {
|
||||
// Nothing pending — we're done.
|
||||
(None, 0, _) | (None, _, None) => return,
|
||||
// Timer pending, nothing else: poll with a deadline,
|
||||
// or fall back to plain sleep if we somehow have no
|
||||
// wake fd (shouldn't happen — io thread is always up
|
||||
// during run()).
|
||||
(Some(deadline), _, fd_opt) => {
|
||||
let now = std::time::Instant::now();
|
||||
if deadline > now {
|
||||
let timeout = deadline - now;
|
||||
match fd_opt {
|
||||
Some(fd) => {
|
||||
crate::io::poll_wake(fd, Some(timeout));
|
||||
crate::io::drain_wake_pipe(fd);
|
||||
}
|
||||
None => std::thread::sleep(timeout),
|
||||
}
|
||||
}
|
||||
continue;
|
||||
}
|
||||
// No timer, but IO outstanding: poll forever for the
|
||||
// pipe wakeup.
|
||||
(None, _, Some(fd)) => {
|
||||
crate::io::poll_wake(fd, None);
|
||||
crate::io::drain_wake_pipe(fd);
|
||||
continue;
|
||||
}
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
// Look up sp; skip stale or already-reaped pids.
|
||||
let sp = match with_sched(|s| {
|
||||
s.slot(pid).and_then(|slot| slot.actor.as_ref().map(|a| a.sp))
|
||||
}) {
|
||||
Some(sp) => sp,
|
||||
None => continue,
|
||||
};
|
||||
|
||||
// If this is a first resume, move the pending closure to the
|
||||
// thread-local the trampoline reads.
|
||||
if let Some(b) = pop_pending_closure(pid) {
|
||||
set_current_actor_box(b);
|
||||
}
|
||||
|
||||
set_actor_sp(sp);
|
||||
set_current_pid(pid);
|
||||
reset_actor_done();
|
||||
YIELD_INTENT.with(|c| c.set(YieldIntent::Yield));
|
||||
|
||||
crate::preempt::reset_timeslice();
|
||||
PREEMPTION_ENABLED.with(|c| c.set(true));
|
||||
|
||||
unsafe { switch_to_actor() };
|
||||
|
||||
PREEMPTION_ENABLED.with(|c| c.set(false));
|
||||
clear_current_pid();
|
||||
|
||||
let intent = YIELD_INTENT.with(|c| c.get());
|
||||
let new_sp = get_actor_sp();
|
||||
|
||||
if is_actor_done() {
|
||||
let outcome = take_last_outcome().unwrap_or(Outcome::Exit);
|
||||
finalize_actor(pid, outcome);
|
||||
} else {
|
||||
with_sched(|s| {
|
||||
if let Some(slot) = s.slot_mut(pid) {
|
||||
if let Some(actor) = slot.actor.as_mut() {
|
||||
actor.sp = new_sp;
|
||||
}
|
||||
match intent {
|
||||
YieldIntent::Yield => {
|
||||
slot.state = State::Runnable;
|
||||
s.run_queue.push_back(pid);
|
||||
}
|
||||
YieldIntent::Park => {
|
||||
slot.state = State::Parked;
|
||||
}
|
||||
}
|
||||
}
|
||||
});
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn finalize_actor(pid: Pid, outcome: Outcome) {
|
||||
// Joiners get the typed Result with the panic payload. The supervisor
|
||||
// gets an informational `Signal::Panic` with an empty payload — its job
|
||||
// is policy (restart/escalate), not forensics. Users who need the
|
||||
// payload in supervision can plumb their own channel.
|
||||
|
||||
let (joiner_outcome, sup_signal) = match outcome {
|
||||
Outcome::Exit => (Outcome::Exit, Signal::Exit(pid)),
|
||||
Outcome::Panic(payload) => (
|
||||
Outcome::Panic(payload),
|
||||
Signal::Panic(pid, Box::new(()) as Box<dyn std::any::Any + Send>),
|
||||
),
|
||||
};
|
||||
|
||||
// Stash outcome, mark Done, collect waiters, drop the actor stack.
|
||||
let (waiters, supervisor_pid) = with_sched(|s| {
|
||||
let slot = s.slot_mut(pid).expect("finalize_actor: slot vanished");
|
||||
let sup = slot.actor.as_ref().map(|a| a.supervisor);
|
||||
slot.outcome = Some(joiner_outcome);
|
||||
slot.state = State::Done;
|
||||
slot.actor = None;
|
||||
let w = std::mem::take(&mut slot.waiters);
|
||||
(w, sup)
|
||||
});
|
||||
|
||||
// Deliver to supervisor (best-effort; ignore SendError).
|
||||
if let Some(sup) = supervisor_pid {
|
||||
let sender = with_sched(|s| {
|
||||
s.slot(sup).and_then(|slot| slot.supervisor_channel.clone())
|
||||
});
|
||||
if let Some(sender) = sender {
|
||||
let _ = sender.send(sup_signal);
|
||||
}
|
||||
}
|
||||
|
||||
// Unpark joiners.
|
||||
for joiner in waiters {
|
||||
unpark(joiner);
|
||||
}
|
||||
|
||||
// Reclaim if no outstanding handles.
|
||||
with_sched(|s| {
|
||||
let should_reclaim = match s.slot(pid) {
|
||||
Some(slot) => slot.outstanding_handles == 0,
|
||||
None => false,
|
||||
};
|
||||
if should_reclaim {
|
||||
reclaim_slot(s, pid);
|
||||
}
|
||||
});
|
||||
}
|
||||
|
||||
@@ -28,7 +28,7 @@
|
||||
use crate::pid::Pid;
|
||||
use std::cmp::Reverse;
|
||||
use std::collections::BinaryHeap;
|
||||
use std::rc::Rc;
|
||||
use std::sync::Arc;
|
||||
use std::time::{Duration, Instant};
|
||||
|
||||
/// What to do when a timer entry's deadline arrives.
|
||||
@@ -45,7 +45,7 @@ pub enum Reason {
|
||||
/// target tell apart "this wait" from "a later wait by the same actor
|
||||
/// on the same target".
|
||||
WaitTimeout {
|
||||
target: Rc<dyn TimerTarget>,
|
||||
target: Arc<dyn TimerTarget>,
|
||||
wait_seq: u64,
|
||||
},
|
||||
}
|
||||
|
||||
@@ -18,11 +18,11 @@ fn lock_free_mutex_succeeds() {
|
||||
run(move || {
|
||||
let m = Mutex::new(42u32);
|
||||
{
|
||||
let g = m.lock().unwrap();
|
||||
let g = m.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
c.store(*g, Ordering::SeqCst);
|
||||
}
|
||||
// After drop we can lock again.
|
||||
let g2 = m.lock().unwrap();
|
||||
let g2 = m.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
assert_eq!(*g2, 42);
|
||||
});
|
||||
assert_eq!(captured.load(Ordering::SeqCst), 42);
|
||||
@@ -53,10 +53,10 @@ fn guard_mutates_value_visible_through_next_lock() {
|
||||
run(move || {
|
||||
let m = Mutex::new(0u32);
|
||||
{
|
||||
let mut g = m.lock().unwrap();
|
||||
let mut g = m.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
*g = 7;
|
||||
}
|
||||
let g2 = m.lock().unwrap();
|
||||
let g2 = m.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
f.store(*g2, Ordering::SeqCst);
|
||||
});
|
||||
assert_eq!(final_value.load(Ordering::SeqCst), 7);
|
||||
@@ -80,19 +80,22 @@ fn contended_lock_parks_until_holder_releases() {
|
||||
let m_b = m.clone();
|
||||
|
||||
let a = spawn(move || {
|
||||
let g = m_a.lock().unwrap();
|
||||
let g = m_a.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
la.lock().unwrap().push("A_locked");
|
||||
// While holding, yield to let B run.
|
||||
// First yield: lets B run past its first yield_now.
|
||||
yield_now();
|
||||
// Second yield: lets B reach B_try and attempt lock() while we
|
||||
// still hold it, so B parks on the mutex.
|
||||
yield_now();
|
||||
la.lock().unwrap().push("A_dropping");
|
||||
drop(g);
|
||||
la.lock().unwrap().push("A_dropped");
|
||||
});
|
||||
let b = spawn(move || {
|
||||
// Wait a moment to make sure A locks first.
|
||||
// One yield: lets A run and acquire the lock first.
|
||||
yield_now();
|
||||
lb.lock().unwrap().push("B_try");
|
||||
let _g = m_b.lock().unwrap();
|
||||
let _g = m_b.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
lb.lock().unwrap().push("B_locked");
|
||||
});
|
||||
a.join().unwrap();
|
||||
@@ -127,7 +130,7 @@ fn lock_timeout_returns_err_when_holder_never_releases() {
|
||||
|
||||
let a = spawn(move || {
|
||||
// Hold the lock for 100ms, blocking B's attempt with a 20ms timeout.
|
||||
let _g = m_a.lock().unwrap();
|
||||
let _g = m_a.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
smarm::sleep(Duration::from_millis(100));
|
||||
// _g drops here.
|
||||
});
|
||||
@@ -175,7 +178,7 @@ fn waiters_are_granted_the_lock_in_fifo_order() {
|
||||
// releases. Each waiter records its arrival order on acquisition.
|
||||
let m_holder = m.clone();
|
||||
let holder = spawn(move || {
|
||||
let g = m_holder.lock().unwrap();
|
||||
let g = m_holder.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
// Let waiters pile up.
|
||||
for _ in 0..5 {
|
||||
yield_now();
|
||||
@@ -194,7 +197,7 @@ fn waiters_are_granted_the_lock_in_fifo_order() {
|
||||
for _ in 0..id {
|
||||
yield_now();
|
||||
}
|
||||
let _g = m_w.lock().unwrap();
|
||||
let _g = m_w.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
o.lock().unwrap().push(id);
|
||||
}));
|
||||
}
|
||||
@@ -224,7 +227,7 @@ fn grant_wins_when_holder_releases_before_timeout() {
|
||||
let m_b = m.clone();
|
||||
|
||||
let a = spawn(move || {
|
||||
let _g = m_a.lock().unwrap();
|
||||
let _g = m_a.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
// Hold for 10ms, well under B's 100ms timeout.
|
||||
smarm::sleep(Duration::from_millis(10));
|
||||
});
|
||||
@@ -257,7 +260,7 @@ fn next_waiter_gets_lock_after_holder_panics() {
|
||||
let m_b = m.clone();
|
||||
|
||||
let a = spawn(move || {
|
||||
let _g = m_a.lock().unwrap();
|
||||
let _g = m_a.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
yield_now();
|
||||
panic!("holder dies mid-critical-section");
|
||||
});
|
||||
@@ -295,7 +298,7 @@ fn many_actors_increment_shared_counter_via_mutex() {
|
||||
let m_i = m.clone();
|
||||
handles.push(spawn(move || {
|
||||
for _ in 0..PER_ACTOR {
|
||||
let mut g = m_i.lock().unwrap();
|
||||
let mut g = m_i.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
*g += 1;
|
||||
}
|
||||
}));
|
||||
@@ -303,7 +306,7 @@ fn many_actors_increment_shared_counter_via_mutex() {
|
||||
for h in handles {
|
||||
h.join().unwrap();
|
||||
}
|
||||
let g = m.lock().unwrap();
|
||||
let g = m.lock_timeout(Duration::from_millis(500)).unwrap();
|
||||
fv.store(*g, Ordering::SeqCst);
|
||||
});
|
||||
|
||||
|
||||
426
tests/runtime.rs
Normal file
426
tests/runtime.rs
Normal file
@@ -0,0 +1,426 @@
|
||||
//! Tests for the multi-scheduler runtime: Config, Runtime::run, and
|
||||
//! correctness under genuine parallelism.
|
||||
//!
|
||||
//! The single-threaded correctness properties (channel ordering, mutex
|
||||
//! fairness, timer accuracy, etc.) are already covered by the per-module
|
||||
//! tests. This file focuses on what changes when N > 1 scheduler threads
|
||||
//! are involved:
|
||||
//!
|
||||
//! - Config construction and validation
|
||||
//! - Runtime::run blocks until all actors finish
|
||||
//! - All existing cooperative behaviours hold under multi-threading
|
||||
//! - Actors genuinely run on different OS threads
|
||||
//! - No lost wakeups under concurrent park/unpark
|
||||
//! - No slot leaks under high spawn/join churn
|
||||
//! - Panic on one scheduler thread doesn't kill others
|
||||
|
||||
use smarm::{channel, runtime::{Config, Runtime}, spawn, yield_now, JoinHandle};
|
||||
use std::sync::{
|
||||
atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering},
|
||||
Arc, Barrier,
|
||||
};
|
||||
use std::time::Duration;
|
||||
use std::collections::HashSet;
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Helpers
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
/// Build a runtime with exactly `n` scheduler threads.
|
||||
fn rt(n: usize) -> Runtime {
|
||||
smarm::runtime::init(Config::exact(n))
|
||||
}
|
||||
|
||||
/// Convenient single-threaded runtime (regression guard).
|
||||
fn rt1() -> Runtime { rt(1) }
|
||||
|
||||
/// Multi-threaded runtime using all available parallelism.
|
||||
fn rt_par() -> Runtime {
|
||||
smarm::runtime::init(Config::default())
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Config
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn config_exact_overrides_bounds() {
|
||||
let c = Config::exact(3);
|
||||
assert_eq!(c.resolved_thread_count(), 3);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn config_default_clamps_to_available_parallelism() {
|
||||
let c = Config::default();
|
||||
let n = c.resolved_thread_count();
|
||||
let avail = std::thread::available_parallelism()
|
||||
.map(|n| n.get())
|
||||
.unwrap_or(1);
|
||||
// Default min is 1, default max is available_parallelism.
|
||||
assert!(n >= 1 && n <= avail);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn config_min_max_clamps() {
|
||||
// Force a range that excludes exact: min=2, max=4, available might be >4.
|
||||
let c = Config::new(2, 4, None);
|
||||
let n = c.resolved_thread_count();
|
||||
assert!(n >= 2 && n <= 4, "expected 2..=4, got {n}");
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn config_min_1_max_1_is_single_threaded() {
|
||||
let c = Config::new(1, 1, None);
|
||||
assert_eq!(c.resolved_thread_count(), 1);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Runtime::run — basic lifecycle
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn runtime_run_executes_closure() {
|
||||
let flag = Arc::new(AtomicBool::new(false));
|
||||
let f = flag.clone();
|
||||
rt(1).run(move || { f.store(true, Ordering::SeqCst); });
|
||||
assert!(flag.load(Ordering::SeqCst));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn runtime_run_blocks_until_all_actors_done() {
|
||||
// Spawn a chain of actors; the counter should be exactly N when run returns.
|
||||
let counter = Arc::new(AtomicU64::new(0));
|
||||
let c = counter.clone();
|
||||
rt(2).run(move || {
|
||||
let mut handles = Vec::new();
|
||||
for _ in 0..20 {
|
||||
let cc = c.clone();
|
||||
handles.push(spawn(move || {
|
||||
cc.fetch_add(1, Ordering::SeqCst);
|
||||
}));
|
||||
}
|
||||
for h in handles {
|
||||
h.join().unwrap();
|
||||
}
|
||||
});
|
||||
assert_eq!(counter.load(Ordering::SeqCst), 20);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn runtime_can_be_used_multiple_times_sequentially() {
|
||||
// Each call to run() is independent.
|
||||
let r = rt(2);
|
||||
let a = Arc::new(AtomicU64::new(0));
|
||||
let b = Arc::new(AtomicU64::new(0));
|
||||
let ac = a.clone();
|
||||
let bc = b.clone();
|
||||
r.run(move || { ac.fetch_add(1, Ordering::SeqCst); });
|
||||
r.run(move || { bc.fetch_add(1, Ordering::SeqCst); });
|
||||
assert_eq!(a.load(Ordering::SeqCst), 1);
|
||||
assert_eq!(b.load(Ordering::SeqCst), 1);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Single-threaded regression: exact(1) must behave identically to old run()
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn exact_1_spawn_join_works() {
|
||||
let v = Arc::new(AtomicU64::new(0));
|
||||
let vc = v.clone();
|
||||
rt1().run(move || {
|
||||
let h = spawn(move || { vc.store(42, Ordering::SeqCst); });
|
||||
h.join().unwrap();
|
||||
});
|
||||
assert_eq!(v.load(Ordering::SeqCst), 42);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn exact_1_channel_recv_parks_and_wakes() {
|
||||
let v = Arc::new(AtomicU64::new(0));
|
||||
let vc = v.clone();
|
||||
rt1().run(move || {
|
||||
let (tx, rx) = channel::<u64>();
|
||||
let h = spawn(move || {
|
||||
let val = rx.recv().unwrap();
|
||||
vc.store(val, Ordering::SeqCst);
|
||||
});
|
||||
yield_now();
|
||||
tx.send(99).unwrap();
|
||||
h.join().unwrap();
|
||||
});
|
||||
assert_eq!(v.load(Ordering::SeqCst), 99);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn exact_1_panic_captured() {
|
||||
let saw_err = Arc::new(AtomicBool::new(false));
|
||||
let s = saw_err.clone();
|
||||
rt1().run(move || {
|
||||
let h = spawn(|| panic!("oops"));
|
||||
if h.join().is_err() { s.store(true, Ordering::SeqCst); }
|
||||
});
|
||||
assert!(saw_err.load(Ordering::SeqCst));
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Multi-threaded correctness
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn multi_thread_all_actors_complete() {
|
||||
let counter = Arc::new(AtomicU64::new(0));
|
||||
let c = counter.clone();
|
||||
rt_par().run(move || {
|
||||
let mut handles = Vec::new();
|
||||
for _ in 0..100 {
|
||||
let cc = c.clone();
|
||||
handles.push(spawn(move || {
|
||||
cc.fetch_add(1, Ordering::SeqCst);
|
||||
}));
|
||||
}
|
||||
for h in handles { h.join().unwrap(); }
|
||||
});
|
||||
assert_eq!(counter.load(Ordering::SeqCst), 100);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn multi_thread_channel_wakeup_across_threads() {
|
||||
// Receiver parks; sender runs (potentially on a different OS thread).
|
||||
// Verifies no lost wakeup.
|
||||
let received = Arc::new(AtomicU64::new(0));
|
||||
let rc = received.clone();
|
||||
rt_par().run(move || {
|
||||
let (tx, rx) = channel::<u64>();
|
||||
let h = spawn(move || {
|
||||
let v = rx.recv().unwrap();
|
||||
rc.store(v, Ordering::SeqCst);
|
||||
});
|
||||
// Let receiver park.
|
||||
yield_now();
|
||||
tx.send(7).unwrap();
|
||||
h.join().unwrap();
|
||||
});
|
||||
assert_eq!(received.load(Ordering::SeqCst), 7);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn multi_thread_many_channels_no_lost_wakeups() {
|
||||
// N pairs of (sender actor, receiver actor). Each pair exchanges one
|
||||
// message. All must complete — any lost wakeup causes a deadlock/timeout.
|
||||
const PAIRS: usize = 50;
|
||||
let count = Arc::new(AtomicU64::new(0));
|
||||
let c = count.clone();
|
||||
rt_par().run(move || {
|
||||
let mut handles: Vec<JoinHandle> = Vec::new();
|
||||
for _ in 0..PAIRS {
|
||||
let (tx, rx) = channel::<u64>();
|
||||
let cc = c.clone();
|
||||
handles.push(spawn(move || {
|
||||
let v = rx.recv().unwrap();
|
||||
cc.fetch_add(v, Ordering::SeqCst);
|
||||
}));
|
||||
handles.push(spawn(move || {
|
||||
tx.send(1).unwrap();
|
||||
}));
|
||||
}
|
||||
for h in handles { h.join().unwrap(); }
|
||||
});
|
||||
assert_eq!(count.load(Ordering::SeqCst), PAIRS as u64);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn multi_thread_mutex_contention_no_deadlock() {
|
||||
use smarm::Mutex;
|
||||
const ACTORS: usize = 20;
|
||||
const PER: u64 = 100;
|
||||
let total = Arc::new(AtomicU64::new(0));
|
||||
let t = total.clone();
|
||||
rt_par().run(move || {
|
||||
let m: Mutex<u64> = Mutex::new(0);
|
||||
let mut handles = Vec::new();
|
||||
for _ in 0..ACTORS {
|
||||
let mc = m.clone();
|
||||
let tc = t.clone();
|
||||
handles.push(spawn(move || {
|
||||
for _ in 0..PER {
|
||||
let mut g = mc.lock_timeout(Duration::from_secs(5)).unwrap();
|
||||
*g += 1;
|
||||
tc.fetch_add(0, Ordering::SeqCst); // just a memory barrier
|
||||
}
|
||||
}));
|
||||
}
|
||||
for h in handles { h.join().unwrap(); }
|
||||
let g = m.lock_timeout(Duration::from_secs(1)).unwrap();
|
||||
t.store(*g, Ordering::SeqCst);
|
||||
});
|
||||
assert_eq!(total.load(Ordering::SeqCst), ACTORS as u64 * PER);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn multi_thread_join_across_threads() {
|
||||
// Parent joins a child that may run on a different scheduler thread.
|
||||
let v = Arc::new(AtomicU64::new(0));
|
||||
let vc = v.clone();
|
||||
rt_par().run(move || {
|
||||
let h = spawn(move || {
|
||||
// Do some work to make scheduling interesting.
|
||||
for _ in 0..10 { yield_now(); }
|
||||
vc.store(1, Ordering::SeqCst);
|
||||
});
|
||||
h.join().unwrap();
|
||||
});
|
||||
assert_eq!(v.load(Ordering::SeqCst), 1);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Actors run on distinct OS threads
|
||||
//
|
||||
// We collect the OS thread IDs that actors execute on. With N schedulers
|
||||
// and enough actors, we expect to see more than one thread ID.
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn actors_run_on_multiple_os_threads() {
|
||||
let thread_ids: Arc<smarm::Mutex<HashSet<u64>>> =
|
||||
Arc::new(smarm::Mutex::new(HashSet::new()));
|
||||
|
||||
rt_par().run({
|
||||
let ids = thread_ids.clone();
|
||||
move || {
|
||||
let mut handles = Vec::new();
|
||||
for _ in 0..64 {
|
||||
let idc = ids.clone();
|
||||
handles.push(spawn(move || {
|
||||
let tid = unsafe { libc::syscall(libc::SYS_gettid) as u64 };
|
||||
let mut g = idc.lock_timeout(Duration::from_secs(1)).unwrap();
|
||||
g.insert(tid);
|
||||
}));
|
||||
}
|
||||
for h in handles { h.join().unwrap(); }
|
||||
}
|
||||
});
|
||||
|
||||
let n = std::thread::available_parallelism().map(|n| n.get()).unwrap_or(1);
|
||||
|
||||
let ids = thread_ids.lock_timeout(Duration::from_secs(1)).unwrap();
|
||||
// If we have >1 scheduler threads, we expect >1 OS thread IDs.
|
||||
// On a single-CPU machine this may be 1; we just assert ≥ 1.
|
||||
assert!(!ids.is_empty());
|
||||
if n > 1 {
|
||||
// Strongly expect parallelism — not a hard assert since scheduling
|
||||
// is non-deterministic, but 64 actors should spread.
|
||||
// We log rather than assert to avoid flakiness on loaded CI.
|
||||
if ids.len() == 1 {
|
||||
eprintln!("WARNING: 64 actors all ran on the same OS thread (flaky on loaded system)");
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Scheduler stats (RFC 000 Layer 1 primitives)
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn scheduler_stats_run_queue_len_is_observable() {
|
||||
// After spawning actors but before they run, the queue should be non-empty.
|
||||
// We can't observe this from inside run() without a snapshot API, but we
|
||||
// can verify the stats struct is accessible and returns sane values after
|
||||
// run() completes (queue len == 0 at quiescence).
|
||||
let r = rt_par();
|
||||
r.run(|| {
|
||||
for _ in 0..10 { spawn(|| {}); }
|
||||
// Don't join — let them drain naturally.
|
||||
});
|
||||
let stats = r.stats();
|
||||
assert_eq!(stats.total_run_queue_len(), 0, "queue should be empty after run()");
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn scheduler_stats_thread_count_matches_config() {
|
||||
let r = rt(3);
|
||||
r.run(|| {});
|
||||
assert_eq!(r.stats().scheduler_count(), 3);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Panic isolation: a panicking actor doesn't kill the scheduler thread
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn panic_in_actor_does_not_kill_runtime() {
|
||||
let completed = Arc::new(AtomicU64::new(0));
|
||||
let c = completed.clone();
|
||||
rt_par().run(move || {
|
||||
// Spawn a panicker alongside well-behaved actors.
|
||||
let bad = spawn(|| panic!("deliberate"));
|
||||
let mut good_handles = Vec::new();
|
||||
for _ in 0..10 {
|
||||
let cc = c.clone();
|
||||
good_handles.push(spawn(move || {
|
||||
cc.fetch_add(1, Ordering::SeqCst);
|
||||
}));
|
||||
}
|
||||
let _ = bad.join(); // expect Err
|
||||
for h in good_handles { h.join().unwrap(); }
|
||||
});
|
||||
assert_eq!(completed.load(Ordering::SeqCst), 10);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// No slot leaks: rapid spawn/join churn
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn no_slot_leak_under_churn() {
|
||||
// Spawn and join many short actors in a loop. If slots leak, the slot
|
||||
// table grows unboundedly. We can't directly measure it without an
|
||||
// introspection API, but the test at least checks correctness under
|
||||
// churn and will OOM if there's a severe leak.
|
||||
let counter = Arc::new(AtomicU64::new(0));
|
||||
let c = counter.clone();
|
||||
rt_par().run(move || {
|
||||
for _ in 0..500 {
|
||||
let cc = c.clone();
|
||||
spawn(move || { cc.fetch_add(1, Ordering::SeqCst); })
|
||||
.join()
|
||||
.unwrap();
|
||||
}
|
||||
});
|
||||
assert_eq!(counter.load(Ordering::SeqCst), 500);
|
||||
}
|
||||
|
||||
// ---------------------------------------------------------------------------
|
||||
// Ping-pong: channel round-trips between two actors
|
||||
// ---------------------------------------------------------------------------
|
||||
|
||||
#[test]
|
||||
fn ping_pong_completes() {
|
||||
const ROUNDS: u64 = 1_000;
|
||||
let final_val = Arc::new(AtomicU64::new(0));
|
||||
let fv = final_val.clone();
|
||||
rt_par().run(move || {
|
||||
let (tx_a, rx_a) = channel::<u64>();
|
||||
let (tx_b, rx_b) = channel::<u64>();
|
||||
let h_a = spawn(move || {
|
||||
tx_a.send(0).unwrap();
|
||||
for _ in 0..ROUNDS {
|
||||
let v = rx_b.recv().unwrap();
|
||||
tx_a.send(v + 1).unwrap();
|
||||
}
|
||||
});
|
||||
let h_b = spawn(move || {
|
||||
for _ in 0..=ROUNDS {
|
||||
let v = rx_a.recv().unwrap();
|
||||
if v < ROUNDS {
|
||||
tx_b.send(v).unwrap();
|
||||
} else {
|
||||
fv.store(v, Ordering::SeqCst);
|
||||
}
|
||||
}
|
||||
});
|
||||
h_a.join().unwrap();
|
||||
h_b.join().unwrap();
|
||||
});
|
||||
assert_eq!(final_val.load(Ordering::SeqCst), ROUNDS);
|
||||
}
|
||||
Reference in New Issue
Block a user