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Test Info:
- Manifest: dom/workers/test/mochitest.toml
<!--
Any copyright is dedicated to the Public Domain.
-->
<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>Test freezing/thawing a worker parked in a sync loop with the RemoteWorkerDebugger (bug 2053827)</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css">
</head>
<body>
<script type="application/javascript">
"use strict";
// RemoteWorkerDebugger enabled, a worker that is parked in a nested sync
// loop (here, a synchronous XHR whose response is delayed) used to
// deadlock the content process when the owner page was frozen/thawed via
// bfcache: WorkerPrivate::Disable/EnableRemoteDebugger blocks the parent
// thread waiting for a debugger IPC handshake reply that the sync loop
// never serviced. If the fix regresses, the worker never finishes its XHR
// and the guard timer below fails the test instead of letting it hang.
SimpleTest.waitForExplicitFinish();
SimpleTest.requestFlakyTimeout("Intentionally waits on a delayed server response across a bfcache freeze/thaw.");
// Test-verify runs this test many times in one browser (and in chaos
// mode). Give every run a unique token so the SharedWorker and the
// BroadcastChannels of one run cannot collide with stale pages left over
// from a previous run, which would desync the freeze/thaw state machine.
const token = Array.from(
crypto.getRandomValues(new Uint8Array(8)),
b => b.toString(16).padStart(2, "0")
).join("");
const bcName = "remoteDebugger_freeze_syncloop_" + token;
const bcNavName = "remoteDebugger_freeze_syncloop_nav_" + token;
let win;
let bc;
let bcNav;
let frameShownCount = 0;
let finished = false;
let guardTimer;
function done(success, message) {
if (finished) {
return;
}
finished = true;
clearTimeout(guardTimer);
ok(success, message);
if (win && !win.closed) {
win.close();
}
bc.close();
bcNav.close();
SimpleTest.finish();
}
function runTest() {
bc = SpecialPowers.wrap(BroadcastChannel).unpartitionedTestingChannel(
bcName
);
bcNav = SpecialPowers.wrap(BroadcastChannel).unpartitionedTestingChannel(
bcNavName
);
bc.onmessage = event => {
const msg = event.data;
if (msg.from == "frame" && msg.event == "pageshow") {
frameShownCount++;
if (frameShownCount == 1) {
// Frame is up; ask the shared worker to enter its sync loop.
is(msg.persisted, false, "First pageshow is not persisted");
bc.postMessage({ command: "start" });
} else {
info("Frame thawed (pageshow persisted=" + msg.persisted + ")");
}
} else if (msg.from == "worker") {
if (msg.data == "insync") {
// The worker is now parked in the synchronous XHR. Freeze the
// owner page (and hence the worker) via bfcache.
info("Worker is in the sync loop; freezing the owner page");
bc.postMessage({ command: "freeze" });
} else if (typeof msg.data == "string" && msg.data.startsWith("done:")) {
done(true, "Worker completed its sync loop after freeze/thaw (no deadlock)");
} else if (typeof msg.data == "string" && msg.data.startsWith("error:")) {
done(false, "Worker reported an error: " + msg.data);
}
}
};
bcNav.onmessage = event => {
if (event.data.event == "navloaded") {
// The owner page is now in bfcache; go back to thaw it.
info("Owner page is in bfcache; thawing");
bcNav.postMessage({ command: "thaw" });
}
};
// If the deadlock regresses, none of the follow-up messages arrive.
guardTimer = setTimeout(() => {
done(false, "Timed out: the worker never finished, content process likely deadlocked");
}, 30000);
win = window.open(
"remoteDebugger_freeze_syncloop_frame.html?token=" + encodeURIComponent(token),
"_blank",
"noopener"
);
}
SpecialPowers.pushPrefEnv(
{
set: [
["dom.worker.remoteDebugger.enabled", true],
// If Fission is disabled, the pref is a no-op.
["fission.bfcacheInParent", true],
],
},
runTest
);
</script>
</body>
</html>