fix(sync): bound request lifetime

req: operations/003

examples/kanban/static/sync.js

@@ -7,6 +7,7 @@ const LEGACY_COMMAND_SCHEMA = 1;
 const MIGRATION_KEY = "commandSchemaMigration";
 const MAX_ATTEMPTS = 3;
 const BACKOFF_MS = [25, 50];
+const REQUEST_TIMEOUT_MS = 1_000;
 const root = document.querySelector("[data-kanban-sync]");
 const TAB_ID = sessionStorage.getItem("hemx-kanban-sync-tab-id") || crypto.randomUUID();
 const LEASE_MS = 5000;
@@ -16,6 +17,8 @@ let accountPartition;
 let uploadLimit;
 let retryTimer;
 let leaseTimer;
+let acknowledgementSource;
+const activeRequests = new Set();
 let synchronizing = false;
 let uploadsThisRun = 0;
 let uploadedTotal = 0;
@@ -39,6 +42,30 @@ class UploadError extends Error {
   }
 }
 
+// req: operations/003
+export async function fetchWithTimeout(
+  input,
+  init = {},
+  fetchImplementation = fetch,
+  timeoutMs = REQUEST_TIMEOUT_MS,
+) {
+  if (!Number.isSafeInteger(timeoutMs) || timeoutMs < 1) {
+    throw new TypeError("sync request timeout must be a positive integer");
+  }
+  const controller = new AbortController();
+  const timeout = setTimeout(
+    () => controller.abort(new DOMException(`sync request timed out after ${timeoutMs} ms`, "TimeoutError")),
+    timeoutMs,
+  );
+  activeRequests.add(controller);
+  try {
+    return await fetchImplementation(input, { ...init, signal: controller.signal });
+  } finally {
+    clearTimeout(timeout);
+    activeRequests.delete(controller);
+  }
+}
+
 function requestResult(request) {
   return new Promise((resolve, reject) => {
     request.addEventListener("success", () => resolve(request.result), { once: true });
@@ -322,7 +349,7 @@ async function upload(command) {
     setPhase(attempt === 1 ? "uploading" : "retrying", `Uploading ${command.id} (attempt ${attempt} of ${MAX_ATTEMPTS}).`);
     try {
       const query = new URLSearchParams({ command_id: command.id, card_id: command.cardId, column: command.targetColumn });
-      const response = await fetch(`/sync/commands?${query}`, { method: "POST" });
+      const response = await fetchWithTimeout(`/sync/commands?${query}`, { method: "POST" });
       if (response.status === 503 && attempt < MAX_ATTEMPTS) {
         const base = BACKOFF_MS[attempt - 1];
         const delay = base + Math.floor(Math.random() * base);
@@ -413,6 +440,7 @@ async function synchronize(command) {
 
     const reconnect = command.session || command.actor || "kanban";
     const source = new EventSource(`/sync/acknowledgements?after=0&reconnect=${encodeURIComponent(reconnect)}`);
+    acknowledgementSource = source;
     let opens = 0;
     source.addEventListener("open", () => {
       opens += 1;
@@ -422,6 +450,7 @@ async function synchronize(command) {
       const canonical = JSON.parse(event.data);
       if (canonical.commandId !== command.id) return;
       source.close();
+      if (acknowledgementSource === source) acknowledgementSource = undefined;
       root.setAttribute("data-sync-pending-before-ack", String((await pendingCommands(database)).length));
       const queueCommandId = command.queueCommandId || command.id;
       await removePendingCommand(database, queueCommandId);
@@ -454,7 +483,7 @@ async function synchronize(command) {
     });
     source.addEventListener("snapshot-required", async (event) => {
       const missing = JSON.parse(event.data);
-      const response = await fetch(missing.snapshotUrl);
+      const response = await fetchWithTimeout(missing.snapshotUrl);
       if (!response.ok) throw new Error(`snapshot failed with ${response.status}`);
       const snapshot = await response.json();
       const queued = await pendingCommands(database);
@@ -497,6 +526,7 @@ async function synchronize(command) {
       }
       synchronizing = false;
       source.close();
+      if (acknowledgementSource === source) acknowledgementSource = undefined;
       clearTimeout(leaseTimer);
       await releaseUploaderLease(database);
       root.setAttribute("data-sync-leader", "false");
@@ -564,7 +594,8 @@ async function runLeaseLoop(command) {
 
 async function start() {
   if (!root) return;
-  const contextResponse = await fetch("/sync/context", { credentials: "same-origin", cache: "no-store" });
+  root.setAttribute("data-sync-request-timeout-ms", String(REQUEST_TIMEOUT_MS));
+  const contextResponse = await fetchWithTimeout("/sync/context", { credentials: "same-origin", cache: "no-store" });
   if (!contextResponse.ok) throw new Error(`account context failed with ${contextResponse.status}`);
   const context = await contextResponse.json();
   if (!context || typeof context.accountPartition !== "string" || !context.accountPartition) {
@@ -633,6 +664,12 @@ async function start() {
 window.addEventListener("pagehide", () => {
   stopped = true;
   clearTimeout(leaseTimer);
+  clearTimeout(retryTimer);
+  acknowledgementSource?.close();
+  acknowledgementSource = undefined;
+  for (const controller of activeRequests) {
+    controller.abort(new DOMException("sync cancelled because page is hidden", "AbortError"));
+  }
   if (database) releaseUploaderLease(database).catch(() => {});
 });
 

examples/kanban/tests/browser_e2e.rs

@@ -599,7 +599,7 @@ async fn account_partition_hides_replay_and_export_until_owner_returns() -> WebD
 
 #[tokio::test]
 async fn canonical_snapshot_and_history_are_tenant_scoped() -> WebDriverResult<()> {
-    // test req: sync/007 req: security/004 req: auth/005
+    // test req: sync/007 req: security/004 req: auth/005 req: performance/004
     let app_port = available_port();
     let app_addr = format!("127.0.0.1:{app_port}");
     let mut app_command = Command::new(env!("CARGO_BIN_EXE_hemx-kanban-example"));
@@ -1708,7 +1708,7 @@ async fn missing_history_rebase_and_user_conflict_resolution_preserve_suffix() -
 #[tokio::test]
 async fn redacted_sync_diagnostics_are_bounded_and_leak_no_sensitive_material(
 ) -> WebDriverResult<()> {
-    // test req: operations/001 req: security/002 req: sync/016 req: sync/021
+    // test req: operations/001 req: operations/005 req: security/002 req: sync/016 req: sync/021
     let app_port = available_port();
     let app_addr = format!("127.0.0.1:{app_port}");
     let mut app_command = Command::new(env!("CARGO_BIN_EXE_hemx-kanban-example"));
@@ -2077,6 +2077,81 @@ async fn keep_local_retry_preserves_conflicted_command_and_suffix_order() -> Web
     result.and(quit)
 }
 
+#[tokio::test]
+async fn sync_requests_timeout_and_cancel_on_pagehide() -> WebDriverResult<()> {
+    // test req: operations/003
+    let app_port = available_port();
+    let app_addr = format!("127.0.0.1:{app_port}");
+    let mut app_command = Command::new(env!("CARGO_BIN_EXE_hemx-kanban-example"));
+    app_command.env("HEMX_KANBAN_ADDR", &app_addr);
+    let _app = TestProcess::start(app_command, "hemx-kanban", &app_addr, STARTUP_TIMEOUT)
+        .expect("start hemx-kanban");
+
+    let webdriver_port = available_port();
+    let webdriver_addr = format!("127.0.0.1:{webdriver_port}");
+    let mut webdriver = Command::new("geckodriver");
+    webdriver.arg("--port").arg(webdriver_port.to_string());
+    let _webdriver = TestProcess::start(webdriver, "geckodriver", &webdriver_addr, STARTUP_TIMEOUT)
+        .expect("start ready geckodriver");
+    let mut caps = DesiredCapabilities::firefox();
+    caps.set_headless()?;
+    let driver = WebDriver::new(&format!("http://{webdriver_addr}"), caps).await?;
+
+    let result = async {
+        driver.goto(&format!("http://{app_addr}/sync-demo")).await?;
+        wait_until(
+            &driver,
+            "return document.querySelector('[data-kanban-sync]')?.getAttribute('data-sync-phase') === 'idle'",
+        )
+        .await?;
+        let proof = driver
+            .execute_async(
+                r#"
+                const done = arguments[arguments.length - 1];
+                (async () => {
+                  const { fetchWithTimeout } = await import('/sync.js');
+                  const pendingFetch = (_input, init) => new Promise((_resolve, reject) => {
+                    init.signal.addEventListener('abort', () => reject(init.signal.reason), { once: true });
+                  });
+                  const started = performance.now();
+                  let timeout;
+                  try {
+                    await fetchWithTimeout('/never-timeout', {}, pendingFetch, 40);
+                  } catch (error) {
+                    timeout = { name: error.name, message: error.message, elapsedMs: performance.now() - started };
+                  }
+                  const cancellationPromise = fetchWithTimeout('/never-pagehide', {}, pendingFetch, 10_000)
+                    .then(() => ({ resolved: true }))
+                    .catch((error) => ({ name: error.name, message: error.message }));
+                  window.dispatchEvent(new PageTransitionEvent('pagehide'));
+                  done({ timeout, cancellation: await cancellationPromise });
+                })().catch((error) => done({ error: String(error), stack: error?.stack }));
+                "#,
+                Vec::new(),
+            )
+            .await?
+            .json()
+            .clone();
+        assert!(proof["error"].is_null(), "bounded request failed: {proof}");
+        assert_eq!(proof["timeout"]["name"], "TimeoutError", "{proof}");
+        assert!(proof["timeout"]["message"]
+            .as_str()
+            .is_some_and(|message| message.contains("40 ms")));
+        assert!(proof["timeout"]["elapsedMs"]
+            .as_f64()
+            .is_some_and(|elapsed| (35.0..1_000.0).contains(&elapsed)));
+        assert_eq!(proof["cancellation"]["name"], "AbortError", "{proof}");
+        assert_eq!(
+            proof["cancellation"]["message"],
+            "sync cancelled because page is hidden"
+        );
+        Ok(())
+    }
+    .await;
+    let quit = driver.quit().await;
+    result.and(quit)
+}
+
 #[tokio::test]
 async fn identical_sync_inputs_reconcile_deterministically() -> WebDriverResult<()> {
     // test req: sync/022