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index.ts
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index.ts
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/**
* Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
import {setFlagsFromString} from 'v8';
import {runInNewContext} from 'vm';
import weak from 'weak-napi';
import prettyFormat from 'pretty-format';
import {isPrimitive} from 'jest-get-type';
export default class {
private _isReferenceBeingHeld: boolean;
constructor(value: unknown) {
if (isPrimitive(value)) {
throw new TypeError(
[
'Primitives cannot leak memory.',
'You passed a ' + typeof value + ': <' + prettyFormat(value) + '>',
].join(' '),
);
}
weak(value as object, () => (this._isReferenceBeingHeld = false));
this._isReferenceBeingHeld = true;
// Ensure value is not leaked by the closure created by the "weak" callback.
value = null;
}
isLeaking(): Promise<boolean> {
this._runGarbageCollector();
return new Promise(resolve =>
setImmediate(() => resolve(this._isReferenceBeingHeld)),
);
}
private _runGarbageCollector() {
const isGarbageCollectorHidden = !global.gc;
// GC is usually hidden, so we have to expose it before running.
setFlagsFromString('--expose-gc');
runInNewContext('gc')();
// The GC was not initially exposed, so let's hide it again.
if (isGarbageCollectorHidden) {
setFlagsFromString('--no-expose-gc');
}
}
}