enhance(backend): improve featured system

1 files changed, 126 insertions, 0 deletions

diff --git a/packages/backend/src/core/FeaturedService.ts b/packages/backend/src/core/FeaturedService.ts
new file mode 100644
index 0000000000..89b86b2e30
--- /dev/null
+++ b/packages/backend/src/core/FeaturedService.ts
@@ -0,0 +1,126 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and other misskey contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Inject, Injectable } from '@nestjs/common';
+import * as Redis from 'ioredis';
+import type { MiNote } from '@/models/_.js';
+import { DI } from '@/di-symbols.js';
+import { bindThis } from '@/decorators.js';
+
+@Injectable()
+export class FeaturedService {
+	constructor(
+		@Inject(DI.redis)
+		private redisClient: Redis.Redis,
+	) {
+	}
+
+	@bindThis
+	private getCurrentPerUserFriendRankingWindow(): number {
+		const passed = new Date().getTime() - new Date(new Date().getFullYear(), 0, 1).getTime();
+		return Math.floor(passed / (1000 * 60 * 60 * 24 * 7)); // 1週間ごと
+	}
+
+	@bindThis
+	private getCurrentGlobalNotesRankingWindow(): number {
+		const passed = new Date().getTime() - new Date(new Date().getFullYear(), 0, 1).getTime();
+		return Math.floor(passed / (1000 * 60 * 60 * 24 * 3)); // 3日ごと
+	}
+
+	@bindThis
+	public async updateGlobalNotesRanking(noteId: MiNote['id'], score = 1): Promise<void> {
+		// TODO: フォロワー数の多い人が常にランキング上位になるのを防ぎたい
+		const currentWindow = this.getCurrentGlobalNotesRankingWindow();
+		const redisTransaction = this.redisClient.multi();
+		redisTransaction.zincrby(
+			`featuredGlobalNotesRanking:${currentWindow}`,
+			score.toString(),
+			noteId);
+		redisTransaction.expire(
+			`featuredGlobalNotesRanking:${currentWindow}`,
+			60 * 60 * 24 * 9, // 9日間保持
+			'NX'); // "NX -- Set expiry only when the key has no expiry" = 有効期限がないときだけ設定
+		await redisTransaction.exec();
+	}
+
+	@bindThis
+	public async updateInChannelNotesRanking(noteId: MiNote['id'], channelId: MiNote['channelId'], score = 1): Promise<void> {
+		const currentWindow = this.getCurrentGlobalNotesRankingWindow();
+		const redisTransaction = this.redisClient.multi();
+		redisTransaction.zincrby(
+			`featuredInChannelNotesRanking:${channelId}:${currentWindow}`,
+			score.toString(),
+			noteId);
+		redisTransaction.expire(
+			`featuredInChannelNotesRanking:${channelId}:${currentWindow}`,
+			60 * 60 * 24 * 9, // 9日間保持
+			'NX'); // "NX -- Set expiry only when the key has no expiry" = 有効期限がないときだけ設定
+		await redisTransaction.exec();
+	}
+
+	@bindThis
+	public async getGlobalNotesRanking(limit: number): Promise<MiNote['id'][]> {
+		const currentWindow = this.getCurrentGlobalNotesRankingWindow();
+		const previousWindow = currentWindow - 1;
+
+		const [currentRankingResult, previousRankingResult] = await Promise.all([
+			this.redisClient.zrange(
+				`featuredGlobalNotesRanking:${currentWindow}`, 0, limit, 'REV', 'WITHSCORES'),
+			this.redisClient.zrange(
+				`featuredGlobalNotesRanking:${previousWindow}`, 0, limit, 'REV', 'WITHSCORES'),
+		]);
+
+		const ranking = new Map<MiNote['id'], number>();
+		for (let i = 0; i < currentRankingResult.length; i += 2) {
+			const noteId = currentRankingResult[i];
+			const score = parseInt(currentRankingResult[i + 1], 10);
+			ranking.set(noteId, score);
+		}
+		for (let i = 0; i < previousRankingResult.length; i += 2) {
+			const noteId = previousRankingResult[i];
+			const score = parseInt(previousRankingResult[i + 1], 10);
+			const exist = ranking.get(noteId);
+			if (exist != null) {
+				ranking.set(noteId, (exist + score) / 2);
+			} else {
+				ranking.set(noteId, score);
+			}
+		}
+
+		return Array.from(ranking.keys());
+	}
+
+	@bindThis
+	public async getInChannelNotesRanking(channelId: MiNote['channelId'], limit: number): Promise<MiNote['id'][]> {
+		const currentWindow = this.getCurrentGlobalNotesRankingWindow();
+		const previousWindow = currentWindow - 1;
+
+		const [currentRankingResult, previousRankingResult] = await Promise.all([
+			this.redisClient.zrange(
+				`featuredInChannelNotesRanking:${channelId}:${currentWindow}`, 0, limit, 'REV', 'WITHSCORES'),
+			this.redisClient.zrange(
+				`featuredInChannelNotesRanking:${channelId}:${previousWindow}`, 0, limit, 'REV', 'WITHSCORES'),
+		]);
+
+		const ranking = new Map<MiNote['id'], number>();
+		for (let i = 0; i < currentRankingResult.length; i += 2) {
+			const noteId = currentRankingResult[i];
+			const score = parseInt(currentRankingResult[i + 1], 10);
+			ranking.set(noteId, score);
+		}
+		for (let i = 0; i < previousRankingResult.length; i += 2) {
+			const noteId = previousRankingResult[i];
+			const score = parseInt(previousRankingResult[i + 1], 10);
+			const exist = ranking.get(noteId);
+			if (exist != null) {
+				ranking.set(noteId, (exist + score) / 2);
+			} else {
+				ranking.set(noteId, score);
+			}
+		}
+
+		return Array.from(ranking.keys());
+	}
+}