743ce7726d
Previously, this was run as a microtask and this CL changes it to run
as a separate task as mandated by the current WeakRef spec.
This CL also introduces a FinalizationGroup type to the V8 API
representing the JSFinalizationGroup. This has a `Cleanup`
function that runs the cleanup callback associated with it.
SetHostCleanupFinalizationGroupCallback is added to set
the embedder defined HostCleanupFinalizationGroupCallback.
ClearKeptObject is exposed on the v8::Isolate to reset the strongly
held set of objects.
The general workflow is the following:
(a) When the GC notices that a given finalization group has dirty
cells, it calls HostCleanupFinalizationGroupCallback with the given
finalization group.
(b) As part of HostCleanupFinalizationGroupCallback, the embedder
enqueues a task that at some point later calls
FinalizationGroup::Cleanup.
(c) At some point in the future, FinalizationGroup::Cleanup is called,
which runs the cleanup callback of the finalization group.
This patch also includes d8 changes to use these new APIs. Currently,
d8 cycles through the enqueued finalization groups after a synchronous
turn (and it's microtask checkpoint) and runs the cleanup callbacks.
Change-Id: I06eb4da2c103b2792a9c62bc4b98fd4e5c4892fc
Bug: v8:8179
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1655655
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62984}
46 lines
1.0 KiB
JavaScript
46 lines
1.0 KiB
JavaScript
// Copyright 2018 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// Flags: --harmony-weak-refs --expose-gc --noincremental-marking
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let wr;
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let wr_control; // control WeakRef for testing what happens without deref
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(function() {
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let o1 = {};
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wr = new WeakRef(o1);
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let o2 = {};
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wr_control = new WeakRef(o2);
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})();
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let strong = {a: wr.deref(), b: wr_control.deref()};
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gc();
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// Next task.
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setTimeout(function() {
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// Call deref inside a closure, trying to avoid accidentally storing a strong
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// reference into the object in the stack frame.
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(function() {
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wr.deref();
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})();
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strong = null;
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// This GC will clear wr_control.
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gc();
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(function() {
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assertNotEquals(undefined, wr.deref());
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// Now the control WeakRef got cleared, since nothing was keeping it alive.
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assertEquals(undefined, wr_control.deref());
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})();
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// Next task.
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setTimeout(function() {
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gc();
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assertEquals(undefined, wr.deref());
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}, 0);
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}, 0);
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