@node-dlc/core/dist/AsyncProcessingQueue.js

DLC Core

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.AsyncProcessingQueue = void 0;
const events_1 = require("events");
const Queue_1 = require("./Queue");
/**
 * Serializes execution of events. This class is constructed with
 * a delegate function that is executed for each item that is enqueued.
 */
class AsyncProcessingQueue extends events_1.EventEmitter {
    constructor(fn) {
        super();
        this._fn = fn;
        this._queue = new Queue_1.Queue();
        this._flush = this._flush.bind(this);
    }
    /**
     * Adds a new item to the processing queue
     */
    enqueue(value) {
        this._queue.enqueue(value);
        // Postpone flushing until end of event loop to allow multiple operations
        // to enqueue. This handle will be cleared once flushing has completed.
        if (!this._flushHandle)
            this._flushHandle = setImmediate(this._flush);
    }
    /**
     * Gets the number of pending items in the processor queue
     * @type {number}
     */
    get size() {
        return this._queue.length;
    }
    async _flush() {
        // emit that flushing is starting
        this.emit('flushing');
        // process all items on the queue, even items that
        // are added to the queue while flushing is occuring
        while (this._queue.length > 0) {
            try {
                const value = this._queue.dequeue();
                await this._fn(value);
            }
            catch (ex) {
                this.emit('error', ex);
            }
        }
        // emit flushing has completed
        this.emit('flushed');
        // clear flush handle so that next enqueue will trigger a flush
        this._flushHandle = undefined;
    }
}
exports.AsyncProcessingQueue = AsyncProcessingQueue;
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