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109 lines
3.7 KiB
JavaScript
109 lines
3.7 KiB
JavaScript
// META: script=/common/gc.js
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// META: script=resources/maybe-garbage-collect.js
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// ├──> maybeGarbageCollectAndCleanupAsync
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// ├──> maybeGarbageCollectAsync
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// └──> resolveGarbageCollection
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/*---
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esid: sec-finalization-registry-target
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info: |
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FinalizationRegistry ( cleanupCallback )
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FinalizationRegistry.prototype.cleanupSome ( [ callback ] )
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...
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4. If callback is not undefined and IsCallable(callback) is false, throw a TypeError exception.
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5. Perform ? CleanupFinalizationRegistry(finalizationRegistry, callback).
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6. Return undefined.
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Execution
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At any time, if an object obj is not live, an ECMAScript implementation may perform the following steps atomically:
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1. For each WeakRef ref such that ref.[[Target]] is obj,
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a. Set ref.[[Target]] to empty.
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2. For each FinalizationRegistry finalizationRegistry such that finalizationRegistry.[[Cells]] contains cell, such that cell.[[Target]] is obj,
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a. Set cell.[[Target]] to empty.
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b. Optionally, perform ! HostCleanupFinalizationRegistry(finalizationRegistry).
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---*/
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let cleanupCallback = 0;
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let holdings = [];
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function cb(holding) {
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holdings.push(holding);
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}
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let finalizationRegistry = new FinalizationRegistry(function() {
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cleanupCallback += 1;
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});
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function emptyCells() {
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let target = {};
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finalizationRegistry.register(target, 'a');
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let prom = maybeGarbageCollectAndCleanupAsync(target);
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target = null;
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return prom;
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}
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promise_test(() => {
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return (async () => {
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assert_implements(
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typeof FinalizationRegistry.prototype.cleanupSome === 'function',
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'FinalizationRegistry.prototype.cleanupSome is not implemented.'
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);
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assert_implements(
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typeof queueMicrotask === 'function',
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'queueMicrotask is not implemented.'
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);
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let ticks = 0;
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await emptyCells();
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await queueMicrotask(() => ticks++);
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finalizationRegistry.cleanupSome(cb);
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// cleanupSome will be invoked if there are empty cells left. If the
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// cleanupCallback already ran, then cb won't be called.
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let expectedCalled = cleanupCallback === 1 ? 0 : 1;
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// This asserts the registered object was emptied in the previous GC.
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assert_equals(holdings.length, expectedCalled, 'cleanupSome callback for the first time');
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// At this point, we can't assert if cleanupCallback was called, because it's
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// optional. Although, we can finally assert it's not gonna be called anymore
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// for the other executions of the Garbage Collector.
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// The chance of having it called only happens right after the
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// cell.[[Target]] is set to empty.
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assert_true(cleanupCallback >= 0, 'cleanupCallback might be 0');
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assert_true(cleanupCallback <= 1, 'cleanupCallback might be 1');
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// Restoring the cleanupCallback variable to 0 will help us asserting the
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// finalizationRegistry callback is not called again.
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cleanupCallback = 0;
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await maybeGarbageCollectAsync();
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await queueMicrotask(() => ticks++);
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finalizationRegistry.cleanupSome(cb);
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assert_equals(holdings.length, expectedCalled, 'cleanupSome callback is not called anymore, no empty cells');
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assert_equals(cleanupCallback, 0, 'cleanupCallback is not called again #1');
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await maybeGarbageCollectAsync();
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await queueMicrotask(() => ticks++);
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finalizationRegistry.cleanupSome(cb);
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assert_equals(holdings.length, expectedCalled, 'cleanupSome callback is not called again #2');
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assert_equals(cleanupCallback, 0, 'cleanupCallback is not called again #2');
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assert_equals(ticks, 3, 'ticks is 3');
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if (holdings.length) {
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assert_array_equals(holdings, ['a']);
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}
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await maybeGarbageCollectAsync();
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})().catch(resolveGarbageCollection);
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}, 'cleanupCallback has only one optional chance to be called for a GC that cleans up a registered target.');
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