From a8ee67caceb645b83a0857a88009c7b9b1a6e408 Mon Sep 17 00:00:00 2001
From: おさむのひと <46447427+samunohito@users.noreply.github.com>
Date: Fri, 27 Oct 2023 18:34:02 +0900
Subject: Fix: チャンネルのフォロー・アンフォローの反映速度を改善 (#12149)
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* チャンネルのフォロー・アンフォローの反映速度を改善

* fix lint

* userFollowingChannelsCacheの場所をCacheServiceからChannelFollowingServiceに移動

---------

Co-authored-by: osamu <46447427+sam-osamu@users.noreply.github.com>
---
 .../backend/src/core/ChannelFollowingService.ts    | 104 +++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 packages/backend/src/core/ChannelFollowingService.ts

(limited to 'packages/backend/src/core/ChannelFollowingService.ts')

diff --git a/packages/backend/src/core/ChannelFollowingService.ts b/packages/backend/src/core/ChannelFollowingService.ts
new file mode 100644
index 0000000000..75843b9773
--- /dev/null
+++ b/packages/backend/src/core/ChannelFollowingService.ts
@@ -0,0 +1,104 @@
+import { Inject, Injectable, OnModuleInit } from '@nestjs/common';
+import Redis from 'ioredis';
+import { DI } from '@/di-symbols.js';
+import type { ChannelFollowingsRepository } from '@/models/_.js';
+import { MiChannel } from '@/models/_.js';
+import { IdService } from '@/core/IdService.js';
+import { GlobalEvents, GlobalEventService } from '@/core/GlobalEventService.js';
+import { bindThis } from '@/decorators.js';
+import type { MiLocalUser } from '@/models/User.js';
+import { RedisKVCache } from '@/misc/cache.js';
+
+@Injectable()
+export class ChannelFollowingService implements OnModuleInit {
+	public userFollowingChannelsCache: RedisKVCache<Set<string>>;
+
+	constructor(
+		@Inject(DI.redis)
+		private redisClient: Redis.Redis,
+		@Inject(DI.redisForSub)
+		private redisForSub: Redis.Redis,
+		@Inject(DI.channelFollowingsRepository)
+		private channelFollowingsRepository: ChannelFollowingsRepository,
+		private idService: IdService,
+		private globalEventService: GlobalEventService,
+	) {
+		this.userFollowingChannelsCache = new RedisKVCache<Set<string>>(this.redisClient, 'userFollowingChannels', {
+			lifetime: 1000 * 60 * 30, // 30m
+			memoryCacheLifetime: 1000 * 60, // 1m
+			fetcher: (key) => this.channelFollowingsRepository.find({
+				where: { followerId: key },
+				select: ['followeeId'],
+			}).then(xs => new Set(xs.map(x => x.followeeId))),
+			toRedisConverter: (value) => JSON.stringify(Array.from(value)),
+			fromRedisConverter: (value) => new Set(JSON.parse(value)),
+		});
+
+		this.redisForSub.on('message', this.onMessage);
+	}
+
+	onModuleInit() {
+	}
+
+	@bindThis
+	public async follow(
+		requestUser: MiLocalUser,
+		targetChannel: MiChannel,
+	): Promise<void> {
+		await this.channelFollowingsRepository.insert({
+			id: this.idService.gen(),
+			followerId: requestUser.id,
+			followeeId: targetChannel.id,
+		});
+
+		this.globalEventService.publishInternalEvent('followChannel', {
+			userId: requestUser.id,
+			channelId: targetChannel.id,
+		});
+	}
+
+	@bindThis
+	public async unfollow(
+		requestUser: MiLocalUser,
+		targetChannel: MiChannel,
+	): Promise<void> {
+		await this.channelFollowingsRepository.delete({
+			followerId: requestUser.id,
+			followeeId: targetChannel.id,
+		});
+
+		this.globalEventService.publishInternalEvent('unfollowChannel', {
+			userId: requestUser.id,
+			channelId: targetChannel.id,
+		});
+	}
+
+	@bindThis
+	private async onMessage(_: string, data: string): Promise<void> {
+		const obj = JSON.parse(data);
+
+		if (obj.channel === 'internal') {
+			const { type, body } = obj.message as GlobalEvents['internal']['payload'];
+			switch (type) {
+				case 'followChannel': {
+					this.userFollowingChannelsCache.refresh(body.userId);
+					break;
+				}
+				case 'unfollowChannel': {
+					this.userFollowingChannelsCache.delete(body.userId);
+					break;
+				}
+			}
+		}
+	}
+
+	@bindThis
+	public dispose(): void {
+		this.userFollowingChannelsCache.dispose();
+	}
+
+	@bindThis
+	public onApplicationShutdown(signal?: string | undefined): void {
+		this.dispose();
+	}
+}
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