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bodged refactor

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Markk116
2026-03-08 20:10:15 +01:00
parent 71e63e4410
commit b10326b242
12 changed files with 801 additions and 339 deletions
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Cargo.lock
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+136
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@@ -8,6 +8,15 @@ version = "0.2.21"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923" checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
[[package]]
name = "android_system_properties"
version = "0.1.5"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "819e7219dbd41043ac279b19830f2efc897156490d7fd6ea916720117ee66311"
dependencies = [
"libc",
]
[[package]] [[package]]
name = "anyhow" name = "anyhow"
version = "1.0.102" version = "1.0.102"
@@ -177,6 +186,19 @@ version = "1.0.4"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801" checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
[[package]]
name = "chrono"
version = "0.4.44"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "c673075a2e0e5f4a1dde27ce9dee1ea4558c7ffe648f576438a20ca1d2acc4b0"
dependencies = [
"iana-time-zone",
"js-sys",
"num-traits",
"wasm-bindgen",
"windows-link",
]
[[package]] [[package]]
name = "concurrent-queue" name = "concurrent-queue"
version = "2.5.0" version = "2.5.0"
@@ -192,6 +214,12 @@ version = "0.9.6"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8" checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"
[[package]]
name = "core-foundation-sys"
version = "0.8.7"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
[[package]] [[package]]
name = "cpufeatures" name = "cpufeatures"
version = "0.2.17" version = "0.2.17"
@@ -374,6 +402,21 @@ dependencies = [
"percent-encoding", "percent-encoding",
] ]
[[package]]
name = "futures"
version = "0.3.32"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "8b147ee9d1f6d097cef9ce628cd2ee62288d963e16fb287bd9286455b241382d"
dependencies = [
"futures-channel",
"futures-core",
"futures-executor",
"futures-io",
"futures-sink",
"futures-task",
"futures-util",
]
[[package]] [[package]]
name = "futures-channel" name = "futures-channel"
version = "0.3.32" version = "0.3.32"
@@ -418,6 +461,17 @@ version = "0.3.32"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "cecba35d7ad927e23624b22ad55235f2239cfa44fd10428eecbeba6d6a717718" checksum = "cecba35d7ad927e23624b22ad55235f2239cfa44fd10428eecbeba6d6a717718"
[[package]]
name = "futures-macro"
version = "0.3.32"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e835b70203e41293343137df5c0664546da5745f82ec9b84d40be8336958447b"
dependencies = [
"proc-macro2",
"quote",
"syn",
]
[[package]] [[package]]
name = "futures-sink" name = "futures-sink"
version = "0.3.32" version = "0.3.32"
@@ -436,8 +490,10 @@ version = "0.3.32"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "389ca41296e6190b48053de0321d02a77f32f8a5d2461dd38762c0593805c6d6" checksum = "389ca41296e6190b48053de0321d02a77f32f8a5d2461dd38762c0593805c6d6"
dependencies = [ dependencies = [
"futures-channel",
"futures-core", "futures-core",
"futures-io", "futures-io",
"futures-macro",
"futures-sink", "futures-sink",
"futures-task", "futures-task",
"memchr", "memchr",
@@ -631,6 +687,30 @@ dependencies = [
"tower-service", "tower-service",
] ]
[[package]]
name = "iana-time-zone"
version = "0.1.65"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e31bc9ad994ba00e440a8aa5c9ef0ec67d5cb5e5cb0cc7f8b744a35b389cc470"
dependencies = [
"android_system_properties",
"core-foundation-sys",
"iana-time-zone-haiku",
"js-sys",
"log",
"wasm-bindgen",
"windows-core",
]
[[package]]
name = "iana-time-zone-haiku"
version = "0.1.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
dependencies = [
"cc",
]
[[package]] [[package]]
name = "icu_collections" name = "icu_collections"
version = "2.1.1" version = "2.1.1"
@@ -829,13 +909,16 @@ version = "0.1.0"
dependencies = [ dependencies = [
"anyhow", "anyhow",
"axum", "axum",
"chrono",
"dashmap", "dashmap",
"futures",
"maud", "maud",
"serde", "serde",
"serde_json", "serde_json",
"sqlx", "sqlx",
"tokio", "tokio",
"tokio-stream", "tokio-stream",
"tracing",
"uuid", "uuid",
] ]
@@ -1966,12 +2049,65 @@ dependencies = [
"wasite", "wasite",
] ]
[[package]]
name = "windows-core"
version = "0.62.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "b8e83a14d34d0623b51dce9581199302a221863196a1dde71a7663a4c2be9deb"
dependencies = [
"windows-implement",
"windows-interface",
"windows-link",
"windows-result",
"windows-strings",
]
[[package]]
name = "windows-implement"
version = "0.60.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "053e2e040ab57b9dc951b72c264860db7eb3b0200ba345b4e4c3b14f67855ddf"
dependencies = [
"proc-macro2",
"quote",
"syn",
]
[[package]]
name = "windows-interface"
version = "0.59.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "3f316c4a2570ba26bbec722032c4099d8c8bc095efccdc15688708623367e358"
dependencies = [
"proc-macro2",
"quote",
"syn",
]
[[package]] [[package]]
name = "windows-link" name = "windows-link"
version = "0.2.1" version = "0.2.1"
source = "registry+https://github.com/rust-lang/crates.io-index" source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5" checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
[[package]]
name = "windows-result"
version = "0.4.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "7781fa89eaf60850ac3d2da7af8e5242a5ea78d1a11c49bf2910bb5a73853eb5"
dependencies = [
"windows-link",
]
[[package]]
name = "windows-strings"
version = "0.5.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "7837d08f69c77cf6b07689544538e017c1bfcf57e34b4c0ff58e6c2cd3b37091"
dependencies = [
"windows-link",
]
[[package]] [[package]]
name = "windows-sys" name = "windows-sys"
version = "0.48.0" version = "0.48.0"
Cargo.toml
+6
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@@ -16,3 +16,9 @@ uuid = { version = "1", features = ["v4", "serde"] }
dashmap = "6" dashmap = "6"
anyhow = "1" anyhow = "1"
tokio-stream = "0.1" tokio-stream = "0.1"
tracing = "0.1.44"
futures = "0.3.32"
[dev-dependencies]
chrono = { version = "0.4", features = ["clock"] }
examples/todo/about.rs
+7 -14
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@@ -1,14 +1,6 @@
use livevue_rs::RenderContext; use livevue_rs::RenderContext;
use maud::{html, Markup}; use maud::{html, Markup};
/// Second page component: a simple "About" page.
///
/// This exists specifically to exercise:
/// - The `tree` signal page routing (resolve_root match arm)
/// - SPA-like navigation via tree signal mutation
/// - Round-trip: TodoList → About → TodoList without full page reload
///
/// In a real app this might show user info, settings, etc.
pub async fn about(_cx: &mut RenderContext) -> anyhow::Result<Markup> { pub async fn about(_cx: &mut RenderContext) -> anyhow::Result<Markup> {
Ok(html! { Ok(html! {
div.about-page { div.about-page {
@@ -16,7 +8,7 @@ pub async fn about(_cx: &mut RenderContext) -> anyhow::Result<Markup> {
nav { nav {
button.nav-link button.nav-link
data-on:click="$tree = {page: 'TodoList'}; @post('/render')" { data-on:click="$tree = {page: 'TodoList'}" {
"Todos" "Todos"
} }
" | " " | "
@@ -34,12 +26,13 @@ pub async fn about(_cx: &mut RenderContext) -> anyhow::Result<Markup> {
strong { "full rerender is cheap" } strong { "full rerender is cheap" }
", so skip diffing, skip partial updates, skip client-side state management." ", so skip diffing, skip partial updates, skip client-side state management."
} }
h2 { "v0 Status" } h2 { "Architecture" }
ul { ul {
li { "Single process, single node" } li { "Actions post signals → 202, no response body" }
li { "SQLite for storage" } li { "Rerenders come down the SSE pipe from the fanout task" }
li { "Subscription keys collected (Phase 2 seam)" } li { "KV store writes auto-publish broadcast invalidation events" }
li { "No cache, no auth, no WAL consumer" } li { "SubscriptionRegistry maps CacheKeys → connections" }
li { "Clock ticks via " code { "store.kv.set(\"clock\", ...)" } " every second" }
} }
} }
} }
examples/todo/app.rs
+49 -157
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@@ -1,6 +1,6 @@
use livevue_rs::{ use livevue_rs::{
AppState, CacheKey, ComponentTree, RenderContext, SharedState, SignalStore, AppState, CacheKey, ComponentTree, RenderContext, SharedState, SignalStore,
format_patch_elements, sse_handler, ingest_signals, sse_handler,
}; };
use axum::extract::{Query as AxumQuery, State}; use axum::extract::{Query as AxumQuery, State};
@@ -19,7 +19,6 @@ pub fn router(state: SharedState) -> Router {
.route("/", get(initial_page_load)) .route("/", get(initial_page_load))
.route("/about", get(initial_about_load)) .route("/about", get(initial_about_load))
.route("/sse", get(sse_handler)) .route("/sse", get(sse_handler))
.route("/render", post(render_handler))
.route("/action/add_todo", post(action_add_todo)) .route("/action/add_todo", post(action_add_todo))
.route("/action/toggle_todo", post(action_toggle_todo)) .route("/action/toggle_todo", post(action_toggle_todo))
.route("/action/delete_todo", post(action_delete_todo)) .route("/action/delete_todo", post(action_delete_todo))
@@ -30,14 +29,7 @@ pub fn router(state: SharedState) -> Router {
// Document shell // Document shell
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// Full HTML document for initial page load. fn document_shell(conn_id: Uuid) -> String {
///
/// DataStar v1 contract:
/// - `data-signals` — initialize signals (JS object literal syntax)
/// - `data-on-signal-patch__debounce.300ms` — fires when any signal is patched,
/// debounced 300ms, posts all non-_ signals as JSON body to /render
/// - `data-init` — fires when element enters DOM, opens long-lived SSE pipe
fn document_shell(conn_id: Uuid, initial_signals: &str, inner_html: &str) -> String {
format!( format!(
r#"<!DOCTYPE html> r#"<!DOCTYPE html>
<html lang="en"> <html lang="en">
@@ -45,47 +37,42 @@ fn document_shell(conn_id: Uuid, initial_signals: &str, inner_html: &str) -> Str
<meta charset="utf-8"> <meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="viewport" content="width=device-width, initial-scale=1">
<title>LiveVue.rs — Todo</title> <title>LiveVue.rs — Todo</title>
<script type="module" src="https://cdn.jsdelivr.net/gh/starfederation/datastar@v1.0.0-RC.8/bundles/datastar.js"></script> <script type="module" src="https://cdn.jsdelivr.net/gh/starfederation/datastar@1.0.0-RC.8/bundles/datastar.js"></script>
<style> <style>
{css} {css}
</style> </style>
</head> </head>
<body> <body
{app} data-init="@get('/sse?conn={conn}')">
<div id="app">
<div/>
</body> </body>
</html>"#, </html>"#,
css = INLINE_CSS, css = INLINE_CSS,
app = app_wrapper(conn_id, initial_signals, inner_html), conn = conn_id,
) )
} }
/// The `<div id="app">` wrapper with DataStar bindings. /// Used by the fanout task to wrap rendered inner HTML for morphing.
/// pub fn app_wrapper(conn_id: Uuid, signals: &str, inner_html: &str) -> String {
/// Extracted separately so `/render` can return just this element as
/// `text/html` — DataStar morphs it into the existing DOM by id.
fn app_wrapper(conn_id: Uuid, signals: &str, inner_html: &str) -> String {
format!( format!(
r#"<div id="app" r#"<div id="app"
data-signals='{signals}' data-signals='{signals}'>
data-on-signal-patch="@post('/render')"
data-on-init="@get('/sse?conn={conn}')">
{inner} {inner}
<pre data-json-signals></pre> <pre data-json-signals></pre>
</div>"#, </div>"#,
// Could __debounce.300ms on the signal patch
signals = signals, signals = signals,
conn = conn_id,
inner = inner_html, inner = inner_html,
) )
} }
/// Minimal CSS for the todo app.
const INLINE_CSS: &str = r#" const INLINE_CSS: &str = r#"
body { font-family: system-ui, sans-serif; max-width: 600px; margin: 2rem auto; padding: 0 1rem; background: #fafafa; color: #333; } body { font-family: system-ui, sans-serif; max-width: 600px; margin: 2rem auto; padding: 0 1rem; background: #fafafa; color: #333; }
h1 { color: #2563eb; } h1 { color: #2563eb; }
nav { margin-bottom: 1.5rem; } nav { margin-bottom: 1.5rem; }
.nav-link { background: none; border: none; color: #2563eb; cursor: pointer; text-decoration: underline; font-size: inherit; padding: 0; } .nav-link { background: none; border: none; color: #2563eb; cursor: pointer; text-decoration: underline; font-size: inherit; padding: 0; }
.nav-current { font-weight: bold; } .nav-current { font-weight: bold; }
.clock { font-variant-numeric: tabular-nums; color: #555; font-size: 0.95rem; margin-bottom: 1rem; }
.add-form { display: flex; gap: 0.5rem; margin-bottom: 1rem; } .add-form { display: flex; gap: 0.5rem; margin-bottom: 1rem; }
.add-form input { flex: 1; padding: 0.5rem; border: 1px solid #ccc; border-radius: 4px; } .add-form input { flex: 1; padding: 0.5rem; border: 1px solid #ccc; border-radius: 4px; }
.add-form button { padding: 0.5rem 1rem; background: #2563eb; color: white; border: none; border-radius: 4px; cursor: pointer; } .add-form button { padding: 0.5rem 1rem; background: #2563eb; color: white; border: none; border-radius: 4px; cursor: pointer; }
@@ -101,42 +88,18 @@ const INLINE_CSS: &str = r#"
"#; "#;
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Page resolution // Page resolution + render pipeline
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
async fn resolve_and_render(cx: &mut RenderContext) -> anyhow::Result<String> { pub async fn resolve_and_render(cx: &mut RenderContext) -> anyhow::Result<String> {
let markup = match cx.tree.page.as_str() { let markup = match cx.tree.page.as_str() {
"TodoList" => crate::todo_list::todo_list(cx).await?, "TodoList" => crate::todo_list::todo_list(cx).await?,
"About" => crate::about::about(cx).await?, "About" => crate::about::about(cx).await?,
other => maud::html! { other => crate::todo_list::todo_list(cx).await?
div {
h1 { "404 — Unknown page" }
p { "No component registered for: " (other) }
button.nav-link
data-on-click="$tree = {page: 'TodoList'}; @post('/render')" {
"Go to Todos"
}
}
},
}; };
Ok(markup.into_string()) Ok(markup.into_string())
} }
/// Shared render pipeline. Returns `(rendered_inner_html, subscription_keys, signals_json)`.
async fn render_page(
db: &sqlx::SqlitePool,
conn_id: Uuid,
signals: SignalStore,
tree: ComponentTree,
) -> anyhow::Result<(String, Vec<CacheKey>, String)> {
let signals_json = signals.to_json_string();
let mut cx = RenderContext::new(conn_id, signals, tree, db.clone());
let html = resolve_and_render(&mut cx).await?;
let keys = cx.take_subscription_keys();
Ok((html, keys, signals_json))
}
/// Extract conn_id and tree from a signal store.
fn extract_conn_and_tree(signals: &SignalStore) -> (Uuid, ComponentTree) { fn extract_conn_and_tree(signals: &SignalStore) -> (Uuid, ComponentTree) {
let conn_id = signals let conn_id = signals
.get("connId") .get("connId")
@@ -153,133 +116,65 @@ fn extract_conn_and_tree(signals: &SignalStore) -> (Uuid, ComponentTree) {
} }
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Handlers // Initial page load handlers
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// `GET /` — Initial page load for the todo list.
async fn initial_page_load(State(state): State<SharedState>) -> impl IntoResponse { async fn initial_page_load(State(state): State<SharedState>) -> impl IntoResponse {
let conn_id = Uuid::new_v4(); let conn_id = Uuid::new_v4();
let tree = ComponentTree { // Seed the initial signal state so the SSE handler can trigger the first
page: "TodoList".into(), // render as soon as the pipe opens, without a client round-trip.
..Default::default() let tree = ComponentTree { page: "TodoList".into(), ..Default::default() };
};
let signals = SignalStore::from_pairs(vec![ let signals = SignalStore::from_pairs(vec![
("connId".into(), serde_json::json!(conn_id.to_string())), ("connId".into(), serde_json::json!(conn_id.to_string())),
("tree".into(), serde_json::to_value(&tree).unwrap()), ("tree".into(), serde_json::to_value(&tree).unwrap()),
("newTodo".into(), serde_json::json!("")), ("newTodo".into(), serde_json::json!("")),
]); ]);
state.connections.update_signals(&conn_id, signals.to_json_string());
let initial_signals_attr = signals.to_data_signals_attr(); Html(document_shell(conn_id))
match render_page(&state.db, conn_id, signals, tree).await {
Ok((html, _keys, _signals_json)) => {
Html(document_shell(conn_id, &initial_signals_attr, &html))
}
Err(e) => Html(document_shell(
conn_id,
&initial_signals_attr,
&format!("<p>Render error: {}</p>", e),
)),
}
} }
/// `GET /about` — Initial page load for the about page.
async fn initial_about_load(State(state): State<SharedState>) -> impl IntoResponse { async fn initial_about_load(State(state): State<SharedState>) -> impl IntoResponse {
let conn_id = Uuid::new_v4(); let conn_id = Uuid::new_v4();
let tree = ComponentTree { page: "About".into(), ..Default::default() };
let tree = ComponentTree {
page: "About".into(),
..Default::default()
};
let signals = SignalStore::from_pairs(vec![ let signals = SignalStore::from_pairs(vec![
("connId".into(), serde_json::json!(conn_id.to_string())), ("connId".into(), serde_json::json!(conn_id.to_string())),
("tree".into(), serde_json::to_value(&tree).unwrap()), ("tree".into(), serde_json::to_value(&tree).unwrap()),
]); ]);
state.connections.update_signals(&conn_id, signals.to_json_string());
let initial_signals_attr = signals.to_data_signals_attr(); Html(document_shell(conn_id))
match render_page(&state.db, conn_id, signals, tree).await {
Ok((html, _keys, _signals_json)) => {
Html(document_shell(conn_id, &initial_signals_attr, &html))
}
Err(e) => Html(document_shell(
conn_id,
&initial_signals_attr,
&format!("<p>Render error: {}</p>", e),
)),
}
} }
/// `POST /render` — Signal-triggered rerender. // ---------------------------------------------------------------------------
/// // Action handlers
/// DataStar sends all non-`_` signals as JSON body on every signal patch. // ---------------------------------------------------------------------------
/// Returns `text/html` with the full `<div id="app">` wrapper — DataStar
/// morphs it into the existing DOM by matching the element id.
async fn render_handler(
State(state): State<SharedState>,
Json(body): Json<serde_json::Value>,
) -> impl IntoResponse {
let signals = SignalStore::from_json(body);
let (conn_id, tree) = extract_conn_and_tree(&signals);
match render_page(&state.db, conn_id, signals.clone(), tree).await {
Ok((html, keys, signals_json)) => {
state.connections.update_signals(&conn_id, signals_json.clone());
state.subscriptions.update(conn_id, keys);
Html(app_wrapper(conn_id, &signals_json, &html))
}
Err(e) => Html(app_wrapper(
conn_id,
&signals.to_json_string(),
&format!("<p>Render error: {}</p>", e),
)),
}
}
/// Query params for action endpoints that need an entity id.
#[derive(serde::Deserialize)] #[derive(serde::Deserialize)]
struct ActionIdParams { struct ActionIdParams {
id: i64, id: i64,
} }
/// Helper: run a mutation, push the rerendered page down the SSE pipe, return 200. /// Ingest signals, run a mutation, then publish an invalidation event so the
/// /// fanout task handles the rerender. Returns 202 Accepted.
/// Actions do not return a body — the result comes down the SSE pipe as a async fn action_then_publish(
/// `datastar-patch-elements` event.
async fn action_then_push(
state: &AppState, state: &AppState,
signals: SignalStore, body: serde_json::Value,
mutation: impl std::future::Future<Output = anyhow::Result<()>> + Send, mutation: impl std::future::Future<Output = anyhow::Result<()>> + Send,
invalidation_key: CacheKey,
) -> StatusCode { ) -> StatusCode {
let (conn_id, tree) = extract_conn_and_tree(&signals); let signals = ingest_signals(state, extract_conn_and_tree(&SignalStore::from_json(body.clone())).0, body);
let _ = signals; // signals are stored; mutation drives the rerender
if let Err(e) = mutation.await { if let Err(e) = mutation.await {
eprintln!("Action error for {}: {}", conn_id, e); eprintln!("Action mutation error: {}", e);
return StatusCode::INTERNAL_SERVER_ERROR; return StatusCode::INTERNAL_SERVER_ERROR;
} }
match render_page(&state.db, conn_id, signals, tree).await { state.store.publish(invalidation_key);
Ok((html, keys, signals_json)) => { StatusCode::ACCEPTED
state.connections.update_signals(&conn_id, signals_json.clone());
state.subscriptions.update(conn_id, keys);
if let Some(sender) = state.connections.get_sender(&conn_id) {
let event = format_patch_elements(&app_wrapper(conn_id, &signals_json, &html));
// Non-blocking: if the pipe is closed the cleanup task handles it
let _ = sender.try_send(event);
} }
StatusCode::OK
}
Err(e) => {
eprintln!("Render error for {}: {}", conn_id, e);
StatusCode::INTERNAL_SERVER_ERROR
}
}
}
/// `POST /action/add_todo` — Insert a new todo, push rerender down SSE pipe.
async fn action_add_todo( async fn action_add_todo(
State(state): State<SharedState>, State(state): State<SharedState>,
Json(body): Json<serde_json::Value>, Json(body): Json<serde_json::Value>,
@@ -290,55 +185,52 @@ async fn action_add_todo(
.unwrap_or("") .unwrap_or("")
.trim() .trim()
.to_string(); .to_string();
let db = state.store.db.clone();
let signals = SignalStore::from_json(body); action_then_publish(
let db = state.db.clone();
action_then_push(
&state, &state,
signals, body,
async move { async move {
if !title.is_empty() { if !title.is_empty() {
crate::queries::create_todo(&db, &title).await?; crate::queries::create_todo(&db, &title).await?;
} }
Ok(()) Ok(())
}, },
CacheKey::Table { table: "todos" },
) )
.await .await
} }
/// `POST /action/toggle_todo?id=<i64>` — Toggle completion, push rerender.
async fn action_toggle_todo( async fn action_toggle_todo(
State(state): State<SharedState>, State(state): State<SharedState>,
AxumQuery(params): AxumQuery<ActionIdParams>, AxumQuery(params): AxumQuery<ActionIdParams>,
Json(body): Json<serde_json::Value>, Json(body): Json<serde_json::Value>,
) -> impl IntoResponse { ) -> impl IntoResponse {
let signals = SignalStore::from_json(body); let db = state.store.db.clone();
let db = state.db.clone();
let id = params.id; let id = params.id;
action_then_push( action_then_publish(
&state, &state,
signals, body,
async move { crate::queries::toggle_todo(&db, id).await }, async move { crate::queries::toggle_todo(&db, id).await },
CacheKey::Table { table: "todos" },
) )
.await .await
} }
/// `POST /action/delete_todo?id=<i64>` — Delete a todo, push rerender.
async fn action_delete_todo( async fn action_delete_todo(
State(state): State<SharedState>, State(state): State<SharedState>,
AxumQuery(params): AxumQuery<ActionIdParams>, AxumQuery(params): AxumQuery<ActionIdParams>,
Json(body): Json<serde_json::Value>, Json(body): Json<serde_json::Value>,
) -> impl IntoResponse { ) -> impl IntoResponse {
let signals = SignalStore::from_json(body); let db = state.store.db.clone();
let db = state.db.clone();
let id = params.id; let id = params.id;
action_then_push( action_then_publish(
&state, &state,
signals, body,
async move { crate::queries::delete_todo(&db, id).await }, async move { crate::queries::delete_todo(&db, id).await },
CacheKey::Table { table: "todos" },
) )
.await .await
} }
examples/todo/main.rs
+58 -10
View File
@@ -3,8 +3,10 @@ mod queries;
mod todo_list; mod todo_list;
mod about; mod about;
use livevue_rs::{AppState, ConnectionManager, SubscriptionRegistry}; use livevue_rs::{AppState, CacheKey, RenderContext, Store, spawn_fanout};
use crate::app::{app_wrapper, resolve_and_render};
use std::sync::Arc; use std::sync::Arc;
use std::time::Duration;
#[tokio::main] #[tokio::main]
async fn main() -> anyhow::Result<()> { async fn main() -> anyhow::Result<()> {
@@ -12,10 +14,8 @@ async fn main() -> anyhow::Result<()> {
// Database setup // Database setup
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
// SQLite with create-if-missing. In-memory `:memory:` also works for dev.
let db = sqlx::SqlitePool::connect("sqlite:todo.db?mode=rwc").await?; let db = sqlx::SqlitePool::connect("sqlite:todo.db?mode=rwc").await?;
// Run migrations inline (no migration files needed for v0).
sqlx::query( sqlx::query(
"CREATE TABLE IF NOT EXISTS todos ( "CREATE TABLE IF NOT EXISTS todos (
id INTEGER PRIMARY KEY AUTOINCREMENT, id INTEGER PRIMARY KEY AUTOINCREMENT,
@@ -26,7 +26,6 @@ async fn main() -> anyhow::Result<()> {
.execute(&db) .execute(&db)
.await?; .await?;
// Seed a few todos if the table is empty (nice for first run)
let count: (i64,) = sqlx::query_as("SELECT COUNT(*) FROM todos") let count: (i64,) = sqlx::query_as("SELECT COUNT(*) FROM todos")
.fetch_one(&db) .fetch_one(&db)
.await?; .await?;
@@ -39,14 +38,65 @@ async fn main() -> anyhow::Result<()> {
} }
} }
// -----------------------------------------------------------------------
// Store
// -----------------------------------------------------------------------
let store = Store::new(db);
// -----------------------------------------------------------------------
// Render function
// -----------------------------------------------------------------------
// The render_fn is the app's half of the framework contract. It receives
// a RenderContext (with signals, tree, store access) and returns the
// rendered inner HTML plus the accumulated subscription keys.
//
// The fanout task calls this for every server-initiated rerender.
let render_fn: livevue_rs::RenderFn = Arc::new(|mut cx: RenderContext| {
Box::pin(async move {
println!("Render Called");
let signals_json = cx.signals.to_json_string();
let conn_id = cx.connection_id;
let html = resolve_and_render(&mut cx).await?;
let keys = cx.take_subscription_keys();
// Wrap in app_wrapper so DataStar morphs the full #app element.
// Signals are re-emitted from the stored json so the client stays
// in sync even on server-initiated rerenders.
let wrapped = app_wrapper(conn_id, &signals_json, &html);
Ok((wrapped, keys))
})
});
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
// Application state // Application state
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
let state = Arc::new(AppState { let state = AppState::new(store.clone(), render_fn);
db,
connections: ConnectionManager::new(), // -----------------------------------------------------------------------
subscriptions: SubscriptionRegistry::new(), // Fanout task
// -----------------------------------------------------------------------
spawn_fanout(state.clone());
// -----------------------------------------------------------------------
// Clock ticker
//
// Publishes CacheKey::Channel { key: "clock" } every second. Any
// connection whose last render called cx.kv_run("clock") will be
// scheduled for a rerender by the fanout task.
// -----------------------------------------------------------------------
let clock_store = store.clone();
tokio::spawn(async move {
let mut interval = tokio::time::interval(Duration::from_secs(1));
loop {
interval.tick().await;
let now = chrono::Utc::now().format("%H:%M:%S UTC").to_string();
// set() writes the value and publishes the invalidation event.
clock_store.kv.set("clock", serde_json::json!(now));
}
}); });
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
@@ -54,10 +104,8 @@ async fn main() -> anyhow::Result<()> {
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
let app = app::router(state); let app = app::router(state);
let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await?; let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await?;
println!("Todo example listening on http://localhost:3000"); println!("Todo example listening on http://localhost:3000");
axum::serve(listener, app).await?; axum::serve(listener, app).await?;
Ok(()) Ok(())
examples/todo/todo_list.rs
+13 -47
View File
@@ -2,24 +2,17 @@ use crate::queries::{ListTodos, Todo};
use livevue_rs::{RenderContext, global, mangle}; use livevue_rs::{RenderContext, global, mangle};
use maud::{html, Markup}; use maud::{html, Markup};
/// Root page component: renders the full todo list with add form.
///
/// Reads signals:
/// - `newTodo` (global, server-relevant): the text input value
///
/// Exercises:
/// - `cx.run()` for data fetching
/// - `cx.signal()` with `global()` scoping + `Signal::val` in expressions
/// - `cx.signal()` with `mangle().client_only()` scoping (in todo_item)
/// - DataStar `data-bind`, `data-on:click`, `data-attr` attributes
/// - `@post()` actions for mutations
pub async fn todo_list(cx: &mut RenderContext) -> anyhow::Result<Markup> { pub async fn todo_list(cx: &mut RenderContext) -> anyhow::Result<Markup> {
// Fetch all todos // Fetch all todos (registers CacheKey::Table { table: "todos" })
let todos = cx.run(ListTodos).await?; let todos = cx.run(ListTodos).await?;
// Global signal for the "new todo" input. This call does two things: // Read the clock from KV (registers CacheKey::Channel { key: "clock" })
// 1. Records "newTodo" as a touched signal (for demangling tracking) let clock = cx
// 2. Returns a Signal struct whose .val is "$newTodo" for expressions .kv_run("clock")
.await
.and_then(|v| v.as_str().map(|s| s.to_string()))
.unwrap_or_else(|| "—".to_string());
let new_todo = cx.signal("newTodo", global()); let new_todo = cx.signal("newTodo", global());
let todo_count = todos.len(); let todo_count = todos.len();
@@ -29,21 +22,17 @@ pub async fn todo_list(cx: &mut RenderContext) -> anyhow::Result<Markup> {
div.todo-app { div.todo-app {
h1 { "LiveVue.rs — Todo List" } h1 { "LiveVue.rs — Todo List" }
// Navigation link to About page (exercises tree signal + page routing)
nav { nav {
span.nav-current { "Todos" } span.nav-current { "Todos" }
" | " " | "
button.nav-link button.nav-link
data-on:click="$tree = {page: 'About'};" { data-on:click="$tree = {page: 'About'}" {
"About" "About"
} }
} }
// Add todo form. p.clock { "🕐 " (clock) }
// data-bind="newTodo" binds the input to the $newTodo signal.
// Value syntax is used instead of data-bind-newTodo because HTML
// normalises attribute names to lowercase, which would corrupt the
// camelCase signal name (newTodo → newtodo).
div.add-form { div.add-form {
input input
type="text" type="text"
@@ -57,12 +46,10 @@ pub async fn todo_list(cx: &mut RenderContext) -> anyhow::Result<Markup> {
} }
} }
// Stats
p.stats { p.stats {
(format!("{} items, {} completed", todo_count, done_count)) (format!("{} items, {} completed", todo_count, done_count))
} }
// Todo items
ul.todo-list { ul.todo-list {
@for todo in &todos { @for todo in &todos {
(todo_item(cx, todo)) (todo_item(cx, todo))
@@ -76,21 +63,9 @@ pub async fn todo_list(cx: &mut RenderContext) -> anyhow::Result<Markup> {
}) })
} }
/// Renders a single todo item.
///
/// This is a static child component — called directly from `todo_list`,
/// not resolved through the component registry.
///
/// Demonstrates per-instance, client-only signal via `mangle().client_only()`.
fn todo_item(cx: &mut RenderContext, todo: &Todo) -> Markup { fn todo_item(cx: &mut RenderContext, todo: &Todo) -> Markup {
// Per-instance, client-only signal for edit mode.
// Not used in v0 rendering, but demonstrates the mangled signal API
// and ensures it's tracked as touched. Produces: "_editing__<id>"
let _editing = cx.signal("editing", mangle(todo.id).client_only()); let _editing = cx.signal("editing", mangle(todo.id).client_only());
// Build class string server-side. Since we do a full rerender on every
// state change, there's no need for data-class here — the server knows
// whether the todo is completed.
let title_class = if todo.completed { let title_class = if todo.completed {
"todo-title completed" "todo-title completed"
} else { } else {
@@ -99,23 +74,14 @@ fn todo_item(cx: &mut RenderContext, todo: &Todo) -> Markup {
html! { html! {
li.todo-item id=(format!("todo-{}", todo.id)) { li.todo-item id=(format!("todo-{}", todo.id)) {
// Checkbox to toggle completion.
// `checked[expr]` is maud's syntax for conditional boolean attributes.
input input
type="checkbox" type="checkbox"
checked[todo.completed] checked[todo.completed]
data-on:click=(format!("@post('/action/toggle_todo?id={}')", todo.id)) data-on:click=(format!("@post('/action/toggle_todo?id={}')", todo.id))
; ;
span class=(title_class) { (todo.title) }
// Title with strikethrough when completed (class set server-side)
span class=(title_class) {
(todo.title)
}
// Delete button
button.delete-btn button.delete-btn
data-on:click=(format!("@post('/action/delete_todo?id={}')", todo.id)) data-on:click=(format!("@post('/action/delete_todo?id={}')", todo.id)) {
{
"×" "×"
} }
} }
src/connection.rs
+47 -18
View File
@@ -1,4 +1,5 @@
use crate::query::CacheKey; use crate::query::CacheKey;
use axum::response::sse::Event;
use dashmap::DashMap; use dashmap::DashMap;
use std::collections::HashSet; use std::collections::HashSet;
use tokio::sync::mpsc; use tokio::sync::mpsc;
@@ -10,13 +11,17 @@ use uuid::Uuid;
/// Per-connection state stored in the manager. /// Per-connection state stored in the manager.
pub struct ConnectionState { pub struct ConnectionState {
/// Sender half of the SSE channel. Messages written here get forwarded /// Sender half of the per-connection SSE channel.
/// to the client's long-lived SSE pipe (`GET /sse`). ///
pub sse_sender: mpsc::Sender<String>, /// The fanout task sends fully-constructed axum `Event`s here; the SSE
/// handler streams them directly to the client without re-wrapping.
pub sse_sender: mpsc::Sender<Event>,
/// The full signal JSON from the most recent render for this connection. /// The full signal JSON from the most recent render for this connection.
/// Phase 2 uses this to re-enter the render pipeline on data invalidation ///
/// without a client request. /// Stored so the fanout task can reconstruct a `SignalStore` and build a
/// `RenderContext` for server-initiated rerenders, without a client
/// request carrying the signals.
pub last_signals_json: Option<String>, pub last_signals_json: Option<String>,
} }
@@ -28,9 +33,9 @@ pub struct ConnectionState {
/// ///
/// Accessed from: /// Accessed from:
/// - `GET /sse` handler (insert) /// - `GET /sse` handler (insert)
/// - `POST /render` handler (read sender, update signals) /// - `POST /action` handler (update signals)
/// - SSE drop cleanup (remove) /// - SSE drop cleanup (remove)
/// - Phase 2: invalidation handler (read sender + signals) /// - Fanout task (read sender + signals for rerender)
pub struct ConnectionManager { pub struct ConnectionManager {
connections: DashMap<Uuid, ConnectionState>, connections: DashMap<Uuid, ConnectionState>,
} }
@@ -43,7 +48,7 @@ impl ConnectionManager {
} }
/// Register a new connection with its SSE sender. /// Register a new connection with its SSE sender.
pub fn insert(&self, id: Uuid, sender: mpsc::Sender<String>) { pub fn insert(&self, id: Uuid, sender: mpsc::Sender<Event>) {
self.connections.insert( self.connections.insert(
id, id,
ConnectionState { ConnectionState {
@@ -53,12 +58,24 @@ impl ConnectionManager {
); );
} }
/// Get the SSE sender for a connection (for sending server-initiated events). /// Get the SSE sender for a connection.
pub fn get_sender(&self, id: &Uuid) -> Option<mpsc::Sender<String>> { pub fn get_sender(&self, id: &Uuid) -> Option<mpsc::Sender<Event>> {
self.connections.get(id).map(|c| c.sse_sender.clone()) self.connections.get(id).map(|c| c.sse_sender.clone())
} }
/// Update the stored signals for a connection after a render. /// Get the last signals JSON for a connection.
///
/// Called by the fanout task to reconstruct signal state for a
/// server-initiated rerender.
pub fn get_signals(&self, id: &Uuid) -> Option<String> {
self.connections
.get(id)
.and_then(|c| c.last_signals_json.clone())
}
/// Update the stored signals for a connection.
///
/// Called by `POST /action` after ingesting the client's signal blob.
pub fn update_signals(&self, id: &Uuid, signals_json: String) { pub fn update_signals(&self, id: &Uuid, signals_json: String) {
if let Some(mut conn) = self.connections.get_mut(id) { if let Some(mut conn) = self.connections.get_mut(id) {
conn.last_signals_json = Some(signals_json); conn.last_signals_json = Some(signals_json);
@@ -83,16 +100,27 @@ impl ConnectionManager {
/// Bidirectional map: CacheKey ↔ ConnectionId. /// Bidirectional map: CacheKey ↔ ConnectionId.
/// ///
/// After each render, the connection's key associations are replaced with /// After each render, the connection's key associations are replaced with
/// the new set from `cx.subscription_keys`. On connection drop, all entries /// the new set from `cx.take_subscription_keys()`. On connection drop, all
/// for that connection are removed. /// entries for that connection are removed.
/// ///
/// Phase 2: on data invalidation event, look up `key_to_conns` to find /// This is the hot path of the reactive pipeline: the fanout task calls
/// which connections need rerender. /// `get_connections_for_key` on every broadcast invalidation event to find
/// which connections need rerendering.
pub struct SubscriptionRegistry { pub struct SubscriptionRegistry {
// DashMap is Arc-backed internally, so clone is cheap.
key_to_conns: DashMap<CacheKey, HashSet<Uuid>>, key_to_conns: DashMap<CacheKey, HashSet<Uuid>>,
conn_to_keys: DashMap<Uuid, HashSet<CacheKey>>, conn_to_keys: DashMap<Uuid, HashSet<CacheKey>>,
} }
impl Clone for SubscriptionRegistry {
fn clone(&self) -> Self {
Self {
key_to_conns: self.key_to_conns.clone(),
conn_to_keys: self.conn_to_keys.clone(),
}
}
}
impl SubscriptionRegistry { impl SubscriptionRegistry {
pub fn new() -> Self { pub fn new() -> Self {
Self { Self {
@@ -103,7 +131,7 @@ impl SubscriptionRegistry {
/// Replace a connection's subscription keys after a render. /// Replace a connection's subscription keys after a render.
/// ///
/// Removes old associations and inserts new ones. /// Removes old associations and inserts new ones atomically per-key.
pub fn update(&self, conn_id: Uuid, new_keys: Vec<CacheKey>) { pub fn update(&self, conn_id: Uuid, new_keys: Vec<CacheKey>) {
// Remove old associations // Remove old associations
if let Some((_, old_keys)) = self.conn_to_keys.remove(&conn_id) { if let Some((_, old_keys)) = self.conn_to_keys.remove(&conn_id) {
@@ -136,8 +164,9 @@ impl SubscriptionRegistry {
} }
} }
/// Phase 2: look up which connections are subscribed to a given key. /// Look up which connections are subscribed to a given key.
#[allow(dead_code)] ///
/// Called by the fanout task on every invalidation event.
pub fn get_connections_for_key(&self, key: &CacheKey) -> HashSet<Uuid> { pub fn get_connections_for_key(&self, key: &CacheKey) -> HashSet<Uuid> {
self.key_to_conns self.key_to_conns
.get(key) .get(key)
src/context.rs
+53 -31
View File
@@ -1,7 +1,9 @@
use crate::signal::{Signal, SignalOpts, SignalStore}; use crate::signal::{Signal, SignalOpts, SignalStore};
use crate::query::{CacheKey, Query}; use crate::query::{CacheKey, Query};
use crate::store::Store;
use serde::{Deserialize, Serialize}; use serde::{Deserialize, Serialize};
use std::collections::HashMap; use std::collections::HashMap;
use std::sync::Arc;
use uuid::Uuid; use uuid::Uuid;
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
@@ -12,9 +14,8 @@ use uuid::Uuid;
/// signal. /// signal.
/// ///
/// Static children (always rendered by their parent) do NOT appear here — /// Static children (always rendered by their parent) do NOT appear here —
/// only dynamic/conditional slots. In v0 we primarily use `page` to resolve /// only dynamic/conditional slots. `page` resolves the root component;
/// the root component. The `children` map is the seam for nested dynamic /// `children` is the seam for nested dynamic components.
/// components in Phase 2.
#[derive(Debug, Clone, Serialize, Deserialize)] #[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ComponentTree { pub struct ComponentTree {
/// The root page component name, e.g. `"TodoList"`. /// The root page component name, e.g. `"TodoList"`.
@@ -47,26 +48,25 @@ impl Default for ComponentTree {
/// The component's window into the framework. /// The component's window into the framework.
/// ///
/// Passed as `&mut cx` to every component function. Provides access to /// Passed as `&mut cx` to every component function. Provides access to
/// signals, database queries, and subscription key collection. /// signals, DB queries, KV reads, and subscription key collection.
/// ///
/// Phase 2 adds: cache handle, auth/session info. /// After rendering, call `take_subscription_keys()` to flush subscriptions
/// to the `SubscriptionRegistry` for this connection.
pub struct RenderContext { pub struct RenderContext {
/// This connection's UUID. /// This connection's UUID.
pub connection_id: Uuid, pub connection_id: Uuid,
/// Signal values populated from the incoming POST body (or initial /// Signal values populated from `last_signals_json` (or initial defaults
/// defaults on first page load). /// on first render).
pub signals: SignalStore, pub signals: SignalStore,
/// Parsed component tree from the `tree` signal. /// Parsed component tree from the `tree` signal.
pub tree: ComponentTree, pub tree: ComponentTree,
/// Database pool. Cloneable (it's an Arc internally). /// Access to DB, KV store, and the broadcast event channel.
pub db: sqlx::SqlitePool, pub store: Arc<Store>,
/// Subscription keys accumulated during this render. After render /// Subscription keys accumulated during this render.
/// completes, these are flushed to the SubscriptionRegistry for this
/// connection.
pub(crate) subscription_keys: Vec<CacheKey>, pub(crate) subscription_keys: Vec<CacheKey>,
/// Signal names touched during this render (for demangling tracking). /// Signal names touched during this render (for demangling tracking).
@@ -78,13 +78,13 @@ impl RenderContext {
connection_id: Uuid, connection_id: Uuid,
signals: SignalStore, signals: SignalStore,
tree: ComponentTree, tree: ComponentTree,
db: sqlx::SqlitePool, store: Arc<Store>,
) -> Self { ) -> Self {
Self { Self {
connection_id, connection_id,
signals, signals,
tree, tree,
db, store,
subscription_keys: Vec::new(), subscription_keys: Vec::new(),
touched_signals: Vec::new(), touched_signals: Vec::new(),
} }
@@ -109,10 +109,10 @@ impl RenderContext {
} }
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
// Queries // DB Queries
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
/// Execute a single query, collecting its subscription key. /// Execute a single DB query, collecting its subscription key.
/// ///
/// ```ignore /// ```ignore
/// let todos = cx.run(ListTodos).await?; /// let todos = cx.run(ListTodos).await?;
@@ -122,14 +122,10 @@ impl RenderContext {
if key != CacheKey::None { if key != CacheKey::None {
self.subscription_keys.push(key); self.subscription_keys.push(key);
} }
query.execute(&self.db).await query.execute(&self.store.db).await
} }
/// Execute two queries concurrently, collecting both subscription keys. /// Execute two DB queries concurrently, collecting both subscription keys.
///
/// This avoids the `&mut self` borrow conflict by collecting keys
/// synchronously first, then running the async executions against a
/// cloned pool handle (pool clones are cheap — they share the inner Arc).
/// ///
/// ```ignore /// ```ignore
/// let (board, columns) = cx.run_all( /// let (board, columns) = cx.run_all(
@@ -142,7 +138,6 @@ impl RenderContext {
a: A, a: A,
b: B, b: B,
) -> anyhow::Result<(A::Output, B::Output)> { ) -> anyhow::Result<(A::Output, B::Output)> {
// Collect subscription keys synchronously (no borrow conflict)
let key_a = a.cache_key(); let key_a = a.cache_key();
let key_b = b.cache_key(); let key_b = b.cache_key();
if key_a != CacheKey::None { if key_a != CacheKey::None {
@@ -151,14 +146,12 @@ impl RenderContext {
if key_b != CacheKey::None { if key_b != CacheKey::None {
self.subscription_keys.push(key_b); self.subscription_keys.push(key_b);
} }
let db = self.store.db.clone();
// Execute concurrently against a cloned pool handle
let db = self.db.clone();
let (ra, rb) = tokio::try_join!(a.execute(&db), b.execute(&db))?; let (ra, rb) = tokio::try_join!(a.execute(&db), b.execute(&db))?;
Ok((ra, rb)) Ok((ra, rb))
} }
/// Three-query variant of `run_all`. /// Three-query concurrent variant.
pub async fn run_all3<A: Query, B: Query, C: Query>( pub async fn run_all3<A: Query, B: Query, C: Query>(
&mut self, &mut self,
a: A, a: A,
@@ -177,18 +170,47 @@ impl RenderContext {
if key_c != CacheKey::None { if key_c != CacheKey::None {
self.subscription_keys.push(key_c); self.subscription_keys.push(key_c);
} }
let db = self.store.db.clone();
let db = self.db.clone();
let (ra, rb, rc) = tokio::try_join!(a.execute(&db), b.execute(&db), c.execute(&db))?; let (ra, rb, rc) = tokio::try_join!(a.execute(&db), b.execute(&db), c.execute(&db))?;
Ok((ra, rb, rc)) Ok((ra, rb, rc))
} }
// -----------------------------------------------------------------------
// KV / Channel queries
// -----------------------------------------------------------------------
/// Read a value from the KV store and register a subscription to its key.
///
/// When `store.kv.set(key, ...)` is called (or `store.publish(...)` for
/// that key), all connections that called `kv_run` with that key during
/// their last render will be scheduled for rerender.
///
/// Returns `None` if the key has not been set yet.
///
/// ```ignore
/// let tick: Option<serde_json::Value> = cx.kv_run("clock").await;
/// ```
pub async fn kv_run(&mut self, key: impl Into<String>) -> Option<serde_json::Value> {
let key = key.into();
self.subscription_keys
.push(CacheKey::Channel { key: key.clone() });
self.store.kv.get(&key)
}
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
// Post-render access // Post-render access
// ----------------------------------------------------------------------- // -----------------------------------------------------------------------
/// Take the subscription keys collected during this render. /// Take the subscription keys accumulated during this render.
/// Called by the handler after rendering to flush them to the registry. ///
/// Call this at the top of the component call stack before returning from
/// `render_fn`. The returned `Vec<CacheKey>` is the second element of the
/// `(String, Vec<CacheKey>)` tuple — the framework uses it to update the
/// `SubscriptionRegistry` for this connection after each successful render.
///
/// Keys accumulate naturally as the call stack unwinds: each `cx.run()`
/// and `cx.kv_run()` call pushes its key, so the top-level collect gets
/// the full set from the entire render.
pub fn take_subscription_keys(&mut self) -> Vec<CacheKey> { pub fn take_subscription_keys(&mut self) -> Vec<CacheKey> {
std::mem::take(&mut self.subscription_keys) std::mem::take(&mut self.subscription_keys)
} }
src/lib.rs
+3 -1
View File
@@ -1,5 +1,6 @@
pub mod signal; pub mod signal;
pub mod query; pub mod query;
pub mod store;
pub mod context; pub mod context;
pub mod connection; pub mod connection;
pub mod sse; pub mod sse;
@@ -7,7 +8,8 @@ pub mod server;
pub use signal::{Signal, SignalStore, SignalOpts, mangle, client_only, global, data_signals}; pub use signal::{Signal, SignalStore, SignalOpts, mangle, client_only, global, data_signals};
pub use query::{CacheKey, Query}; pub use query::{CacheKey, Query};
pub use store::{Store, KVStore};
pub use context::{RenderContext, ComponentTree, ComponentNode}; pub use context::{RenderContext, ComponentTree, ComponentNode};
pub use connection::{ConnectionManager, ConnectionState, SubscriptionRegistry}; pub use connection::{ConnectionManager, ConnectionState, SubscriptionRegistry};
pub use sse::{format_patch_elements, format_patch_signals}; pub use sse::{format_patch_elements, format_patch_signals};
pub use server::{AppState, SharedState, sse_handler}; pub use server::{AppState, SharedState, RenderFn, sse_handler, spawn_fanout, ingest_signals, ActionParams, SseParams};
src/query.rs
+24 -21
View File
@@ -5,37 +5,50 @@ use std::pin::Pin;
// CacheKey // CacheKey
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// Identifies what data a query depends on, for subscription tracking. /// Identifies what data a query depends on, for subscription tracking and
/// reactive invalidation.
/// ///
/// In v0 these are collected but not acted on. Phase 2 uses them to map /// When something changes (a DB mutation, a KV write, an external event),
/// data changes → affected connections → rerender. /// the responsible code publishes the relevant `CacheKey` to the broadcast
/// /// channel in `Store`. The fanout task maps that key to subscribed connections
/// Phase 2 adds: `Derived { key: String, value: i64 }` for composite keys /// and triggers rerenders.
/// like `"posts:user_id:42"`.
#[derive(Debug, Clone, PartialEq, Eq, Hash)] #[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum CacheKey { pub enum CacheKey {
/// Query has no cacheable identity (rare — side-effect-only reads). /// Query has no cacheable identity (rare — side-effect-only reads).
None, None,
/// Single row by primary key: `("todos", 42)`. /// Single row by primary key: `("todos", 42)`.
PrimaryKey { table: &'static str, id: i64 }, PrimaryKey { table: &'static str, id: i64 },
/// future, something like this
//ColumnValue { table: &'static str, column: &'static str, val: Box<dyn Any> },
/// Entire table: `("todos")`. Used for list queries. /// Entire table: `("todos")`. Used for list queries.
Table { table: &'static str }, Table { table: &'static str },
/// A named channel key, used by KVStore entries and pure pubsub events.
///
/// KV reads register a subscription under this key. KV writes (and any
/// external publisher — timers, webhooks, etc.) publish this key to the
/// broadcast channel, triggering rerenders for all subscribed connections.
///
/// ```ignore
/// // Component reads:
/// let val = cx.kv_run("clock").await?;
///
/// // Timer publishes:
/// store.events.send(CacheKey::Channel { key: "clock".into() }).ok();
/// ```
Channel { key: String },
} }
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Query trait // Query trait
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// The central data-access abstraction. /// The central data-access abstraction for DB-backed queries.
/// ///
/// Every read goes through `cx.run(SomeQuery { ... })`, which: /// Every read goes through `cx.run(SomeQuery { ... })`, which:
/// 1. Collects the query's `cache_key` for subscription tracking. /// 1. Collects the query's `cache_key` for subscription tracking.
/// 2. Executes the query against the database. /// 2. Executes the query against the database.
/// ///
/// Phase 2 inserts a cache check between steps 1 and 2.
///
/// The trait uses `Pin<Box<dyn Future>>` instead of `async fn` to guarantee /// The trait uses `Pin<Box<dyn Future>>` instead of `async fn` to guarantee
/// `Send` bounds needed for `tokio::try_join!` in `cx.run_all()`. The /// `Send` bounds needed for `tokio::try_join!` in `cx.run_all()`. The
/// `query_one!` / `query_all!` macros hide this behind a clean declaration. /// `query_one!` / `query_all!` macros hide this behind a clean declaration.
@@ -56,9 +69,6 @@ pub trait Query: Send + Sync {
/// Generate a `Query` impl that fetches a single row. /// Generate a `Query` impl that fetches a single row.
/// ///
/// Both `params` and `cache` take closures receiving `&StructName`, so `self`
/// is always available without hygiene issues.
///
/// ```ignore /// ```ignore
/// pub struct GetTodo { pub id: i64 } /// pub struct GetTodo { pub id: i64 }
/// ///
@@ -69,8 +79,6 @@ pub trait Query: Send + Sync {
/// cache: |s: &GetTodo| CacheKey::PrimaryKey { table: "todos", id: s.id }, /// cache: |s: &GetTodo| CacheKey::PrimaryKey { table: "todos", id: s.id },
/// }); /// });
/// ``` /// ```
///
/// The `output` type must implement `sqlx::FromRow<'_, SqliteRow>`.
#[macro_export] #[macro_export]
macro_rules! query_one { macro_rules! query_one {
($name:ident { ($name:ident {
@@ -111,9 +119,6 @@ macro_rules! query_one {
/// Generate a `Query` impl that fetches multiple rows. /// Generate a `Query` impl that fetches multiple rows.
/// ///
/// Both `params` and `cache` take closures receiving `&StructName`, so the
/// style is consistent with `query_one!` even when `s` goes unused.
///
/// ```ignore /// ```ignore
/// pub struct ListTodos; /// pub struct ListTodos;
/// ///
@@ -124,8 +129,6 @@ macro_rules! query_one {
/// cache: |_s: &ListTodos| CacheKey::Table { table: "todos" }, /// cache: |_s: &ListTodos| CacheKey::Table { table: "todos" },
/// }); /// });
/// ``` /// ```
///
/// `Output` is `Vec<output_type>`.
#[macro_export] #[macro_export]
macro_rules! query_all { macro_rules! query_all {
($name:ident { ($name:ident {
src/server.rs
+257 -32
View File
@@ -1,7 +1,12 @@
use crate::connection::{ConnectionManager, SubscriptionRegistry}; use crate::connection::{ConnectionManager, SubscriptionRegistry};
use crate::context::{ComponentTree, RenderContext};
use crate::signal::SignalStore;
use crate::store::Store;
use crate::query::CacheKey;
use axum::extract::{Query as AxumQuery, State}; use axum::extract::{Query as AxumQuery, State};
use axum::response::sse::{Event, KeepAlive, Sse}; use axum::response::sse::{Event, KeepAlive, Sse};
use futures::future::BoxFuture;
use std::convert::Infallible; use std::convert::Infallible;
use std::sync::Arc; use std::sync::Arc;
use tokio::sync::mpsc; use tokio::sync::mpsc;
@@ -9,21 +14,167 @@ use tokio_stream::wrappers::ReceiverStream;
use uuid::Uuid; use uuid::Uuid;
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// Shared application state // RenderFn
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
/// All shared state, wrapped in Arc for axum's State extractor. /// Type alias for the app-registered render callback.
/// ///
/// Applications can use this directly or define their own state type. /// The app registers this at startup. The fanout task calls it to produce
/// The framework's `sse_handler` is tied to this type. /// an SSE `datastar-patch-elements` payload for a given connection's state.
///
/// The function receives a fully constructed `RenderContext` and must return
/// the rendered HTML string plus the full set of `CacheKey`s accumulated
/// during the render (via `cx.take_subscription_keys()`). Keys naturally
/// bubble up through the component call stack — the top-level render function
/// just collects them all before returning.
///
/// The framework handles SSE framing and updates the `SubscriptionRegistry`
/// from the returned keys after each successful render.
///
/// ```ignore
/// let render_fn: RenderFn = Arc::new(|mut cx| Box::pin(async move {
/// let html = render_page(&mut cx).await?;
/// let keys = cx.take_subscription_keys();
/// Ok((html, keys))
/// }));
/// ```
pub type RenderFn = Arc<dyn Fn(RenderContext) -> BoxFuture<'static, anyhow::Result<(String, Vec<CacheKey>)>> + Send + Sync>;
// ---------------------------------------------------------------------------
// AppState
// ---------------------------------------------------------------------------
/// All shared framework + app state.
///
/// Construct with `AppState::new(store, render_fn)` and wrap in `Arc` to
/// produce a `SharedState` for axum's `State` extractor.
pub struct AppState { pub struct AppState {
pub db: sqlx::SqlitePool, pub store: Arc<Store>,
pub connections: ConnectionManager, pub connections: ConnectionManager,
pub subscriptions: SubscriptionRegistry, pub subscriptions: SubscriptionRegistry,
pub render_fn: RenderFn,
} }
pub type SharedState = Arc<AppState>; pub type SharedState = Arc<AppState>;
impl AppState {
pub fn new(store: Arc<Store>, render_fn: RenderFn) -> SharedState {
Arc::new(Self {
store,
connections: ConnectionManager::new(),
subscriptions: SubscriptionRegistry::new(),
render_fn,
})
}
}
// ---------------------------------------------------------------------------
// Fanout task
// ---------------------------------------------------------------------------
/// Spawn the global invalidation fanout task.
///
/// Must be called once at startup, after building `AppState`. The task owns
/// a `broadcast::Receiver<CacheKey>` and runs for the lifetime of the server.
///
/// On each invalidation event:
/// 1. Look up subscribed connections via `SubscriptionRegistry`.
/// 2. For each connection, fetch `last_signals_json` + SSE sender.
/// 3. Reconstruct `SignalStore` + `ComponentTree`, build `RenderContext`.
/// 4. Call `render_fn` to produce HTML.
/// 5. Frame as SSE and send down the connection's SSE channel.
/// 6. Update subscription keys and `last_signals_json` from the new render.
///
/// ```ignore
/// let state = AppState::new(store.clone(), render_fn);
/// spawn_fanout(state.clone());
/// ```
pub fn spawn_fanout(state: SharedState) {
let mut rx = state.store.subscribe();
tokio::spawn(async move {
loop {
let key = match rx.recv().await {
Ok(k) => k,
Err(tokio::sync::broadcast::error::RecvError::Lagged(n)) => {
tracing::warn!("fanout lagged, missed {} invalidation events", n);
continue;
}
Err(tokio::sync::broadcast::error::RecvError::Closed) => {
tracing::info!("fanout channel closed, shutting down");
break;
}
};
let conn_ids = state.subscriptions.get_connections_for_key(&key);
for conn_id in conn_ids {
let Some(signals_json) = state.connections.get_signals(&conn_id) else {
continue;
};
let Some(sse_tx) = state.connections.get_sender(&conn_id) else {
continue;
};
let signals = match serde_json::from_str::<serde_json::Value>(&signals_json) {
Ok(v) => SignalStore::from_json(v),
Err(e) => {
tracing::error!("fanout: failed to parse signals for {}: {}", conn_id, e);
continue;
}
};
// Parse the component tree from the `tree` signal.
let tree = signals
.get("tree")
.and_then(|v| serde_json::from_value(v.clone()).ok())
.unwrap_or_default();
let mut cx = RenderContext::new(
conn_id,
signals,
tree,
state.store.clone(),
);
let render_fn = state.render_fn.clone();
let state_ref = state.clone();
tokio::spawn(async move {
match render_fn(cx).await {
Ok((html, keys)) => {
state_ref.subscriptions.update(conn_id, keys);
// Build a single datastar-patch-elements SSE event.
// DataStar expects the event name set once, then one
// `data: elements <line>` entry per line of HTML.
// axum's Event::data() sets a single data field, so
// we pre-format the multi-line data payload manually
// and send it as one data value.
let data_payload: String = html
.lines()
.map(|line| format!("elements {}", line))
.collect::<Vec<_>>()
.join("\ndata: ");
let event = Event::default()
.event("datastar-patch-elements")
.data(data_payload);
if sse_tx.send(event).await.is_err() {
tracing::debug!("fanout: SSE channel closed for {}", conn_id);
}
}
Err(e) => {
tracing::error!("fanout: render error for {}: {}", conn_id, e);
}
}
});
}
}
});
}
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
// SSE handler // SSE handler
// --------------------------------------------------------------------------- // ---------------------------------------------------------------------------
@@ -36,50 +187,124 @@ pub struct SseParams {
/// `GET /sse?conn=<uuid>` — Long-lived SSE pipe for server-initiated push. /// `GET /sse?conn=<uuid>` — Long-lived SSE pipe for server-initiated push.
/// ///
/// In v0, nothing actively pushes events through this pipe (no invalidation /// The conn_id is generated by `GET /` and pre-seeded with initial signals
/// events yet). It exists to: /// in `ConnectionManager` before this handler is called. On connect, the
/// 1. Register the connection in ConnectionManager. /// handler immediately triggers a render and pushes the result down the pipe,
/// 2. Keep the SSE connection alive (DataStar expects it). /// so the client sees content without any further round-trip.
/// 3. Provide the Phase 2 seam for server-initiated rerenders.
///
/// On drop, the connection is cleaned up from both the ConnectionManager
/// and the SubscriptionRegistry.
pub async fn sse_handler( pub async fn sse_handler(
State(state): State<SharedState>, State(state): State<SharedState>,
AxumQuery(params): AxumQuery<SseParams>, AxumQuery(params): AxumQuery<SseParams>,
) -> Sse<impl tokio_stream::Stream<Item = Result<Event, Infallible>>> { ) -> Sse<impl tokio_stream::Stream<Item = Result<Event, Infallible>>> {
let conn_id = params.conn; let conn_id = params.conn;
let (tx, rx) = mpsc::channel::<Event>(32);
// Create a channel for sending events to this connection
let (tx, rx) = mpsc::channel::<String>(32);
// Clone sender for the cleanup watcher. Sender::closed() resolves when
// the receiver is dropped (i.e. client disconnects and the SSE stream
// drops). This is the proper cleanup mechanism — no arbitrary sleep.
let tx_watch = tx.clone(); let tx_watch = tx.clone();
// Register the connection state.connections.insert(conn_id, tx.clone());
state.connections.insert(conn_id, tx);
// Spawn cleanup task: waits for the receiver to drop (client disconnect), // Cleanup on disconnect
// then removes the connection from all registries.
let state_cleanup = state.clone(); let state_cleanup = state.clone();
tokio::spawn(async move { tokio::spawn(async move {
tx_watch.closed().await; tx_watch.closed().await;
state_cleanup.connections.remove(&conn_id); state_cleanup.connections.remove(&conn_id);
state_cleanup.subscriptions.remove_connection(&conn_id); state_cleanup.subscriptions.remove_connection(&conn_id);
tracing::debug!("cleaned up connection {}", conn_id);
});
println!("SSE Handler called");
// Trigger first render immediately using the pre-seeded signals.
let signals_json = state.connections.get_signals(&conn_id)
.unwrap_or_else(|| "{}".to_string());
let render_fn = state.render_fn.clone();
let store = state.store.clone();
let subscriptions = state.subscriptions.clone();
let tx_init = tx.clone();
tokio::spawn(async move {
let signals = match serde_json::from_str::<serde_json::Value>(&signals_json) {
Ok(v) => SignalStore::from_json(v),
Err(e) => {
tracing::error!("sse_handler: failed to parse seeded signals: {}", e);
return;
}
};
let tree = signals
.get("tree")
.and_then(|v| serde_json::from_value(v.clone()).ok())
.unwrap_or_default();
let cx = RenderContext::new(conn_id, signals, tree, store);
match render_fn(cx).await {
Ok((html, keys)) => {
subscriptions.update(conn_id, keys);
let data_payload = html
.lines()
.map(|line| format!("elements {}", line))
.collect::<Vec<_>>()
.join("\ndata: ");
let event = Event::default()
.event("datastar-patch-elements")
.data(data_payload);
tx_init.send(event).await.ok();
}
Err(e) => tracing::error!("sse_handler: initial render failed: {}", e),
}
}); });
// Convert the receiver into an SSE stream.
// DESIGN NOTE: For v0, the SSE pipe is mostly idle — POST /render
// returns SSE directly in its response, not through this pipe. This
// channel exists for Phase 2 server-initiated pushes (data invalidation).
// Messages sent via the channel should be plain content strings (not
// pre-formatted SSE); axum's Sse wrapper handles the SSE framing.
let stream = ReceiverStream::new(rx); let stream = ReceiverStream::new(rx);
let event_stream = tokio_stream::StreamExt::map(stream, |msg| { let event_stream = tokio_stream::StreamExt::map(stream, |event| {
Ok(Event::default().data(msg)) Ok::<Event, Infallible>(event)
}); });
Sse::new(event_stream).keep_alive(KeepAlive::default()) Sse::new(event_stream).keep_alive(KeepAlive::default())
} }
// ---------------------------------------------------------------------------
// Action handler helper
// ---------------------------------------------------------------------------
/// Query params for the action endpoint.
#[derive(serde::Deserialize)]
pub struct ActionParams {
pub conn: Uuid,
}
/// Ingest a signal update from the client and store it for future rerenders.
///
/// This is the framework's half of the action pipeline. The app's action
/// handler should call this to persist the updated signal state, then perform
/// its own side effects (DB writes, KV writes, event publishes) which will
/// drive rerenders through the fanout task.
///
/// Returns the parsed `SignalStore` so the app handler can read signal values.
///
/// ```ignore
/// async fn delete_todo(
/// State(state): State<SharedState>,
/// AxumQuery(params): AxumQuery<ActionParams>,
/// Json(body): Json<serde_json::Value>,
/// ) -> impl IntoResponse {
/// let signals = ingest_signals(&state, params.conn, body);
/// let todo_id: i64 = signals.get("todoId")
/// .and_then(|v| v.as_i64())
/// .unwrap_or_default();
/// sqlx::query!("DELETE FROM todos WHERE id = ?", todo_id)
/// .execute(&state.store.db)
/// .await
/// .ok();
/// state.store.publish(CacheKey::Table { table: "todos" });
/// StatusCode::ACCEPTED
/// }
/// ```
pub fn ingest_signals(
state: &AppState,
conn_id: Uuid,
body: serde_json::Value,
) -> SignalStore {
let store = SignalStore::from_json(body);
state
.connections
.update_signals(&conn_id, store.to_json_string());
store
}
src/store.rs
+140
View File
@@ -0,0 +1,140 @@
use crate::query::CacheKey;
use dashmap::DashMap;
use std::sync::Arc;
use tokio::sync::broadcast;
// ---------------------------------------------------------------------------
// KVStore
// ---------------------------------------------------------------------------
/// A reactive key-value store backed by a `DashMap`.
///
/// Reads are plain lookups. Writes automatically publish a `CacheKey::Channel`
/// invalidation event to the broadcast channel, which the fanout task uses to
/// trigger rerenders for all connections subscribed to that key.
///
/// The KV store is the source of truth for non-relational state: counters,
/// flags, computed values, timer ticks, etc.
///
/// ```ignore
/// // In a component:
/// let tick = cx.kv_run("clock").await?; // registers subscription
///
/// // In an action handler or timer task:
/// store.kv.set("clock", serde_json::json!(timestamp));
/// // ↑ automatically publishes CacheKey::Channel { key: "clock" }
/// ```
pub struct KVStore {
store: DashMap<String, serde_json::Value>,
events: broadcast::Sender<CacheKey>,
}
impl KVStore {
pub fn new(events: broadcast::Sender<CacheKey>) -> Self {
Self {
store: DashMap::new(),
events,
}
}
/// Read a value by key. Does not register a subscription — use
/// `cx.kv_run(key)` in components to also track the subscription.
pub fn get(&self, key: &str) -> Option<serde_json::Value> {
self.store.get(key).map(|v| v.clone())
}
/// Write a value and publish an invalidation event.
///
/// All connections subscribed to `CacheKey::Channel { key }` will be
/// scheduled for rerender by the fanout task.
pub fn set(&self, key: impl Into<String>, value: serde_json::Value) {
let key = key.into();
self.store.insert(key.clone(), value);
// Ignore send errors — no receivers just means no connections are
// currently subscribed, which is fine.
self.events
.send(CacheKey::Channel { key })
.ok();
}
/// Delete a key and publish an invalidation event.
pub fn delete(&self, key: &str) {
self.store.remove(key);
self.events
.send(CacheKey::Channel { key: key.to_string() })
.ok();
}
}
// ---------------------------------------------------------------------------
// Store
// ---------------------------------------------------------------------------
/// The cluster of data resources available to both the framework and the app.
///
/// `Arc<Store>` is embedded in `AppState` and passed to action handlers.
/// The app uses it to read/write data; writes to `kv` or direct publishes
/// to `events` drive the reactive rerender pipeline.
///
/// ```ignore
/// // Register at startup:
/// let store = Store::new(db_pool);
///
/// // In an action handler:
/// store.kv.set("counter", json!(42));
///
/// // Publishing a pure event (no stored value, e.g. for PubSub-style triggers):
/// store.publish(CacheKey::Channel { key: "refresh".into() });
/// ```
pub struct Store {
/// SQLite connection pool. Cloneable (Arc internally).
pub db: sqlx::SqlitePool,
/// Reactive key-value store. Writes auto-publish invalidation events.
pub kv: Arc<KVStore>,
/// Broadcast sender for invalidation events. Clone this to publish from
/// anywhere (action handlers, timer tasks, webhooks).
///
/// Use `store.publish(key)` as a convenience wrapper.
pub events: broadcast::Sender<CacheKey>,
}
impl Store {
/// Construct with the given DB pool. Creates the broadcast channel and
/// KV store internally.
///
/// The broadcast channel capacity (256) is the number of unread events
/// that can be buffered before slow receivers start lagging. The fanout
/// task should be fast enough that this is never hit in practice.
pub fn new(db: sqlx::SqlitePool) -> Arc<Self> {
let (events_tx, _) = broadcast::channel(256);
let kv = Arc::new(KVStore::new(events_tx.clone()));
Arc::new(Self {
db,
kv,
events: events_tx,
})
}
/// Publish a raw invalidation event without writing to KV.
///
/// Use this for pure pubsub triggers (timers, external webhooks) where
/// there is no stored value to update — only a rerender signal to send.
///
/// ```ignore
/// // Every second, trigger rerenders for connections subscribed to "clock":
/// store.publish(CacheKey::Channel { key: "clock".into() });
/// ```
pub fn publish(&self, key: CacheKey) {
self.events.send(key).ok();
}
/// Subscribe to the invalidation broadcast channel.
///
/// Called once at startup by the fanout task. Each call returns an
/// independent receiver that sees all published events from this point on.
pub fn subscribe(&self) -> broadcast::Receiver<CacheKey> {
self.events.subscribe()
}
}