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async-gc.js
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async-gc.js
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// Copyright (C) 2019 Ecma International. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
description: >
Collection of functions used to capture references cleanup from garbage collectors
features: [FinalizationRegistry.prototype.cleanupSome, FinalizationRegistry, Symbol, async-functions]
flags: [non-deterministic]
defines: [asyncGC, asyncGCDeref, resolveAsyncGC]
---*/
function asyncGC(...targets) {
var finalizationRegistry = new FinalizationRegistry(() => {});
var length = targets.length;
for (let target of targets) {
finalizationRegistry.register(target, 'target');
target = null;
}
targets = null;
return Promise.resolve('tick').then(() => asyncGCDeref()).then(() => {
var names = [];
// consume iterator to capture names
finalizationRegistry.cleanupSome(name => { names.push(name); });
if (!names || names.length != length) {
throw asyncGC.notCollected;
}
});
}
asyncGC.notCollected = Symbol('Object was not collected');
async function asyncGCDeref() {
var trigger;
// TODO: Remove this when $262.clearKeptObject becomes documented and required
if ($262.clearKeptObjects) {
trigger = $262.clearKeptObjects();
}
await $262.gc();
return Promise.resolve(trigger);
}
function resolveAsyncGC(err) {
if (err === asyncGC.notCollected) {
// Do not fail as GC can't provide necessary resources.
$DONE();
return;
}
$DONE(err);
}