@barchart/common-node-js/messaging/publishers/CompositePublisher.js

Common classes, utilities, and functions for building Node.js servers

const log4js = require('log4js');

const assert = require('@barchart/common-js/lang/assert'),
	DisposableStack = require('@barchart/common-js/collections/specialized/DisposableStack');

const Publisher = require('./Publisher');

module.exports = (() => {
	'use strict';

	const logger = log4js.getLogger('common-node/messaging/publishers/CompositePublisher');

	class CompositePublisher extends Publisher {
		constructor(publishers, suppressExpressions) {
			super(suppressExpressions);

			assert.argumentIsArray(publishers, 'publishers', Publisher, 'Publisher');

			this._publishers = publishers;
		}

		_start() {
			return Promise.all(this._publishers.map((publisher) => {
				return publisher.start();
			})).then(() => {
				return true;
			});
		}

		_publish(messageType, payload) {
			const publishPromises = this._publishers.map((publisher) => {
				return publisher.publish(messageType, payload);
			});

			return Promise.all(publishPromises)
				.then((ignored) => {
					return;
				});
		}

		_subscribe(messageType, handler) {
			const subscribePromises = this._publishers.map((publisher) => {
				return publisher.subscribe(messageType, handler);
			});

			return Promise.all(subscribePromises)
				.then((subscriptions) => {
					const disposableStack = new DisposableStack();

					subscriptions.forEach((subscription) => {
						disposableStack.push(subscription);
					});

					return disposableStack;
				});
		}

		_onDispose() {
			this._publishers.forEach((publisher) => {
				publisher.dispose();
			});

			this._publishers = null;

			logger.debug('Composite publisher disposed');
		}

		toString() {
			return '[CompositePublisher]';
		}
	}

	return CompositePublisher;
})();