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import {Deferred} from './Deferred.js';
import {disposeSymbol} from './disposable.js';
/**
* @internal
*/
export class Mutex {
static Guard = class Guard {
#mutex: Mutex;
constructor(mutex: Mutex) {
this.#mutex = mutex;
}
[disposeSymbol](): void {
return this.#mutex.release();
}
};
#locked = false;
#acquirers: Array<() => void> = [];
// This is FIFO.
async acquire(): Promise<InstanceType<typeof Mutex.Guard>> {
if (!this.#locked) {
this.#locked = true;
return new Mutex.Guard(this);
}
const deferred = Deferred.create<void>();
this.#acquirers.push(deferred.resolve.bind(deferred));
await deferred.valueOrThrow();
return new Mutex.Guard(this);
}
release(): void {
const resolve = this.#acquirers.shift();
if (!resolve) {
this.#locked = false;
return;
}
resolve();
}
}
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