70 lines
1.9 KiB
JavaScript
70 lines
1.9 KiB
JavaScript
import { EventEmitter } from 'events';
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import { v4 as uuidv4 } from 'uuid';
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const LOGGER = require('@calzoneman/jsli')('redis-messagebus');
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class RedisMessageBus extends EventEmitter {
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constructor(pubClient, subClient, channel) {
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super();
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this.pubClient = pubClient;
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this.subClient = subClient;
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this.channel = channel;
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this.publisherID = uuidv4();
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subClient.once('ready', this.subscribe.bind(this));
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}
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subscribe() {
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this.subClient.subscribe(this.channel);
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this.subClient.on('message', this.onMessage.bind(this));
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LOGGER.info('Subscribed to Redis messages on channel %s', this.channel);
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}
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onMessage(channel, message) {
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if (channel !== this.channel) {
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LOGGER.warn('Ignoring message from mismatched channel "%s"', channel);
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return;
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}
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try {
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const { event, payload } = JSON.parse(message);
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this._emit(event, payload);
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} catch (error) {
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if (error instanceof SyntaxError) {
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LOGGER.error(
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'Malformed message received: %s (message: "%s")',
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message,
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error
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);
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} else {
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LOGGER.error('Unexpected error decoding message: %s', error.stack);
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}
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return;
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}
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}
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async emit(event, payload) {
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try {
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const message = JSON.stringify({
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time: new Date(),
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publisher: this.publisherID,
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event,
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payload
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});
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await this.pubClient.publish(this.channel, message);
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} catch (error) {
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LOGGER.error('Unable to send event %s: %s', event, error);
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}
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}
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}
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Object.assign(RedisMessageBus.prototype, {
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_emit: EventEmitter.prototype.emit
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});
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export { RedisMessageBus };
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