nodejs-event-driven/lib/main/infra/event-bus/redis/redis-event-bus.service.js

NodeJS agnostic event driven with EventEmitter support

import { BaseEventBusService } from '../../../base-event-bus.service.js';
export default class RedisEventBusService extends BaseEventBusService {
    static DEFAULT_KEY_PREFIX = 'events';
    #logger;
    #redisPublisher = null;
    #redisSubscriber = null;
    #keyPrefix;
    #redisConfig;
    constructor(config) {
        super();
        this.#logger = config.logger;
        this.#keyPrefix =
            config.keyPrefix ?? RedisEventBusService.DEFAULT_KEY_PREFIX;
        this.#redisConfig = { ...config, keyPrefix: this.#keyPrefix };
    }
    #createRedisListener(eventName, listener, once = false) {
        return (message) => {
            if (once) {
                this.off(eventName);
            }
            const data = JSON.parse(message);
            listener(data);
        };
    }
    on(eventName, listener) {
        const redisSubscriber = this.#redisSubscriber;
        if (!redisSubscriber) {
            return;
        }
        const channel = `${this.#keyPrefix}:${eventName}`;
        this.#logger?.debug(`register listener for channel: ${channel}`);
        const redisListener = this.#createRedisListener(eventName, listener);
        void redisSubscriber.subscribe(channel, redisListener);
    }
    once(eventName, listener) {
        const redisSubscriber = this.#redisSubscriber;
        if (!redisSubscriber) {
            return;
        }
        const channel = `${this.#keyPrefix}:${eventName}`;
        this.#logger?.debug(`register once listener for channel: ${channel}`);
        const redisListener = this.#createRedisListener(eventName, listener, true);
        void redisSubscriber.subscribe(channel, redisListener);
    }
    off(eventName) {
        const redisSubscriber = this.#redisSubscriber;
        if (!redisSubscriber) {
            return;
        }
        const channel = `${this.#keyPrefix}:${eventName}`;
        this.#logger?.debug(`unregister listener for channel: ${channel}`);
        void redisSubscriber.unsubscribe(channel);
    }
    send(eventName, data) {
        const redisPublisher = this.#redisPublisher;
        if (!redisPublisher) {
            return;
        }
        const channel = `${this.#keyPrefix}:${eventName}`;
        this.#logger?.debug(`sending ${String(data)} to channel ${channel}`);
        void redisPublisher.publish(channel, JSON.stringify(data));
    }
    sendAndWait(sendEventName, successEventName, errorEventName, data) {
        this.#logger?.debug(`sending event ${sendEventName} and waiting for event ${successEventName}…`);
        return super.sendAndWait(sendEventName, successEventName, errorEventName, data);
    }
    async start() {
        const { createClient } = await import('redis');
        this.#redisPublisher = createClient(this.#redisConfig);
        this.#redisSubscriber = createClient(this.#redisConfig);
        await this.#redisPublisher.connect();
        await this.#redisSubscriber.connect();
    }
    async stop() {
        const redisPublisher = this.#redisPublisher;
        if (redisPublisher) {
            await redisPublisher.quit();
            this.#redisPublisher = null;
        }
        const redisSubscriber = this.#redisSubscriber;
        if (redisSubscriber) {
            await redisSubscriber.quit();
            this.#redisSubscriber = null;
        }
    }
}
//# sourceMappingURL=redis-event-bus.service.js.map