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fix(cluster): robust solution for pub/sub in cluster (#697)
* fix(cluster): robust solution for pub/sub in cluster Previously (v3 & v4.0.0), ioredis reuse the existing connection for subscription, which will cause problem when executing commands on the reused connection. From now on, a specialized connection will be created when any subscription has made. This solves the problem above perfectly. Close #696
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,122 @@ | ||
| import {EventEmitter} from 'events' | ||
| import ConnectionPool from './ConnectionPool' | ||
| import {sample, noop} from '../utils/lodash' | ||
| import {getNodeKey} from './util' | ||
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| const Redis = require('../redis') | ||
| const debug = require('../utils/debug')('ioredis:cluster:subscriber') | ||
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| const SUBSCRIBER_CONNECTION_NAME = 'ioredisClusterSubscriber' | ||
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| export default class ClusterSubscriber { | ||
| private started: boolean = false | ||
| private subscriber: any = null | ||
| private lastActiveSubscriber: any | ||
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| constructor (private connectionPool: ConnectionPool, private emitter: EventEmitter) { | ||
| this.connectionPool.on('-node', (_, key: string) => { | ||
| if (!this.started || !this.subscriber) { | ||
| return | ||
| } | ||
| if (getNodeKey(this.subscriber.options) === key) { | ||
| debug('subscriber has left, selecting a new one...') | ||
| this.selectSubscriber() | ||
| } | ||
| }) | ||
| this.connectionPool.on('+node', () => { | ||
| if (!this.started || this.subscriber) { | ||
| return | ||
| } | ||
| debug('a new node is discovered and there is no subscriber, selecting a new one...') | ||
| this.selectSubscriber() | ||
| }) | ||
| } | ||
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| getInstance (): any { | ||
| return this.subscriber | ||
| } | ||
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| private selectSubscriber () { | ||
| const lastActiveSubscriber = this.lastActiveSubscriber | ||
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| // Disconnect the previous subscriber even if there | ||
| // will not be a new one. | ||
| if (lastActiveSubscriber) { | ||
| lastActiveSubscriber.disconnect() | ||
| } | ||
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| const sampleNode = sample(this.connectionPool.getNodes()) | ||
| if (!sampleNode) { | ||
| debug('selecting subscriber failed since there is no node discovered in the cluster yet') | ||
| this.subscriber = null | ||
| return | ||
| } | ||
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| const {port, host} = sampleNode.options | ||
| debug('selected a subscriber %s:%s', host, port) | ||
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| // Create a specialized Redis connection for the subscription. | ||
| // Note that auto reconnection is enabled here. | ||
| // `enableReadyCheck` is disabled because subscription is allowed | ||
| // when redis is loading data from the disk. | ||
| this.subscriber = new Redis({ | ||
| port, | ||
| host, | ||
| enableReadyCheck: false, | ||
| connectionName: SUBSCRIBER_CONNECTION_NAME, | ||
| lazyConnect: true | ||
| }) | ||
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| // Re-subscribe previous channels | ||
| var previousChannels = { subscribe: [], psubscribe: [] } | ||
| if (lastActiveSubscriber) { | ||
| const condition = lastActiveSubscriber.condition || lastActiveSubscriber.prevCondition | ||
| if (condition && condition.subscriber) { | ||
| previousChannels.subscribe = condition.subscriber.channels('subscribe') | ||
| previousChannels.psubscribe = condition.subscriber.channels('psubscribe') | ||
| } | ||
| } | ||
| if (previousChannels.subscribe.length || previousChannels.psubscribe.length) { | ||
| var pending = 0 | ||
| for (const type of ['subscribe', 'psubscribe']) { | ||
| var channels = previousChannels[type] | ||
| if (channels.length) { | ||
| pending += 1 | ||
| debug('%s %d channels', type, channels.length) | ||
| this.subscriber[type](channels).then(() => { | ||
| if (!--pending) { | ||
| this.lastActiveSubscriber = this.subscriber | ||
| } | ||
| }).catch(noop) | ||
| } | ||
| } | ||
| } else { | ||
| this.lastActiveSubscriber = this.subscriber | ||
| } | ||
| for (const event of ['message', 'messageBuffer']) { | ||
| this.subscriber.on(event, (arg1, arg2) => { | ||
| this.emitter.emit(event, arg1, arg2) | ||
| }) | ||
| } | ||
| for (const event of ['pmessage', 'pmessageBuffer']) { | ||
| this.subscriber.on(event, (arg1, arg2, arg3) => { | ||
| this.emitter.emit(event, arg1, arg2, arg3) | ||
| }) | ||
| } | ||
| } | ||
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| start (): void { | ||
| this.started = true | ||
| this.selectSubscriber() | ||
| debug('started') | ||
| } | ||
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| stop (): void { | ||
| this.started = false | ||
| if (this.subscriber) { | ||
| this.subscriber.disconnect() | ||
| this.subscriber = null | ||
| } | ||
| debug('stopped') | ||
| } | ||
| } |
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