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deferred.ts
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deferred.ts
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import { Deferred, deferred } from "../deps.ts";
/** @ignore */
export class DeferredStack<T> {
private _queue: Deferred<T>[] = [];
private _size = 0;
constructor(
readonly _maxSize: number,
private _array: T[] = [],
private readonly creator: () => Promise<T>,
) {
this._size = _array.length;
}
get size(): number {
return this._size;
}
get maxSize(): number {
return this._maxSize;
}
get available(): number {
return this._array.length;
}
async pop(): Promise<T> {
if (this._array.length) {
return this._array.pop()!;
} else if (this._size < this._maxSize) {
this._size++;
let item: T;
try {
item = await this.creator();
} catch (err) {
this._size--;
throw err;
}
return item;
}
const defer = deferred<T>();
this._queue.push(defer);
return await defer;
}
/** Returns false if the item is consumed by a deferred pop */
push(item: T): boolean {
if (this._queue.length) {
this._queue.shift()!.resolve(item);
return false;
} else {
this._array.push(item);
return true;
}
}
tryPopAvailable() {
return this._array.pop();
}
remove(item: T): boolean {
const index = this._array.indexOf(item);
if (index < 0) return false;
this._array.splice(index, 1);
this._size--;
return true;
}
reduceSize() {
this._size--;
}
}