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BaseRedis.ts
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BaseRedis.ts
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import type { Buffer } from 'node:buffer';
import { randomBytes } from 'node:crypto';
import { readFileSync } from 'node:fs';
import { resolve } from 'node:path';
import { AsyncEventEmitter } from '@vladfrangu/async_event_emitter';
import type { Redis } from 'ioredis';
import { ReplyError } from 'ioredis';
import type { BaseBrokerOptions, IBaseBroker, ToEventMap } from '../Broker.js';
import { DefaultBrokerOptions } from '../Broker.js';
// For some reason ioredis doesn't have this typed, but it exists
declare module 'ioredis' {
interface Redis {
xreadgroupBuffer(...args: (Buffer | string)[]): Promise<[Buffer, [Buffer, Buffer[]][]][] | null>;
}
}
/**
* Options specific for a Redis broker
*/
export interface RedisBrokerOptions extends BaseBrokerOptions {
/**
* How long to block for messages when polling
*/
blockTimeout?: number;
/**
* Max number of messages to poll at once
*/
maxChunk?: number;
/**
* Unique consumer name.
*
* @see {@link https://redis.io/commands/xreadgroup/}
*/
name?: string;
}
/**
* Default broker options for redis
*/
export const DefaultRedisBrokerOptions = {
...DefaultBrokerOptions,
name: randomBytes(20).toString('hex'),
maxChunk: 10,
blockTimeout: 5_000,
} as const satisfies Required<RedisBrokerOptions>;
/**
* Helper class with shared Redis logic
*/
export abstract class BaseRedisBroker<TEvents extends Record<string, any>>
extends AsyncEventEmitter<ToEventMap<TEvents>>
implements IBaseBroker<TEvents>
{
/**
* Used for Redis queues, see the 3rd argument taken by {@link https://redis.io/commands/xadd | xadd}
*/
public static readonly STREAM_DATA_KEY = 'data';
/**
* Options this broker is using
*/
protected readonly options: Required<RedisBrokerOptions>;
/**
* Events this broker has subscribed to
*/
protected readonly subscribedEvents = new Set<string>();
/**
* Internal copy of the Redis client being used to read incoming payloads
*/
protected readonly streamReadClient: Redis;
/**
* Whether this broker is currently polling events
*/
protected listening = false;
public constructor(
protected readonly redisClient: Redis,
options: RedisBrokerOptions,
) {
super();
this.options = { ...DefaultRedisBrokerOptions, ...options };
redisClient.defineCommand('xcleangroup', {
numberOfKeys: 1,
lua: readFileSync(resolve(__dirname, '..', 'scripts', 'xcleangroup.lua'), 'utf8'),
});
this.streamReadClient = redisClient.duplicate();
}
/**
* {@inheritDoc IBaseBroker.subscribe}
*/
public async subscribe(group: string, events: (keyof TEvents)[]): Promise<void> {
await Promise.all(
// @ts-expect-error: Intended
events.map(async (event) => {
this.subscribedEvents.add(event as string);
try {
return await this.redisClient.xgroup('CREATE', event as string, group, 0, 'MKSTREAM');
} catch (error) {
if (!(error instanceof ReplyError)) {
throw error;
}
}
}),
);
void this.listen(group);
}
/**
* {@inheritDoc IBaseBroker.unsubscribe}
*/
public async unsubscribe(group: string, events: (keyof TEvents)[]): Promise<void> {
const commands: unknown[][] = Array.from({ length: events.length * 2 });
for (let idx = 0; idx < commands.length; idx += 2) {
const event = events[idx / 2];
commands[idx] = ['xgroup', 'delconsumer', event as string, group, this.options.name];
commands[idx + 1] = ['xcleangroup', event as string, group];
}
await this.redisClient.pipeline(commands).exec();
for (const event of events) {
this.subscribedEvents.delete(event as string);
}
}
/**
* Begins polling for events, firing them to {@link BaseRedisBroker.listen}
*/
protected async listen(group: string): Promise<void> {
if (this.listening) {
return;
}
this.listening = true;
while (true) {
try {
const data = await this.streamReadClient.xreadgroupBuffer(
'GROUP',
group,
this.options.name,
'COUNT',
String(this.options.maxChunk),
'BLOCK',
String(this.options.blockTimeout),
'STREAMS',
...this.subscribedEvents,
...Array.from({ length: this.subscribedEvents.size }, () => '>'),
);
if (!data) {
continue;
}
for (const [event, info] of data) {
for (const [id, packet] of info) {
const idx = packet.findIndex((value, idx) => value.toString('utf8') === 'data' && idx % 2 === 0);
if (idx < 0) {
continue;
}
const data = packet[idx + 1];
if (!data) {
continue;
}
this.emitEvent(id, group, event.toString('utf8'), this.options.decode(data));
}
}
} catch (error) {
this.emit('error', error);
break;
}
}
this.listening = false;
}
/**
* Destroys the broker, closing all connections
*/
public async destroy() {
this.streamReadClient.disconnect();
this.redisClient.disconnect();
}
/**
* Handles an incoming Redis event
*/
protected abstract emitEvent(id: Buffer, group: string, event: string, data: unknown): unknown;
}