From ecaf152b4a6eb702375debaef0dddc2cca798116 Mon Sep 17 00:00:00 2001
From: syuilo <Syuilotan@yahoo.co.jp>
Date: Tue, 4 Apr 2023 17:32:09 +0900
Subject: enhance(backend): improve cache

---
 packages/backend/src/misc/cache.ts | 97 +++++++++++++++++++++++++++++++++++---
 1 file changed, 91 insertions(+), 6 deletions(-)

(limited to 'packages/backend/src/misc')

diff --git a/packages/backend/src/misc/cache.ts b/packages/backend/src/misc/cache.ts
index a805d18421..870dfd237c 100644
--- a/packages/backend/src/misc/cache.ts
+++ b/packages/backend/src/misc/cache.ts
@@ -1,9 +1,94 @@
+import Redis from 'ioredis';
 import { bindThis } from '@/decorators.js';
 
+// redis通すとDateのインスタンスはstringに変換されるので
+type Serialized<T> = {
+	[K in keyof T]:
+		T[K] extends Date
+			? string
+			: T[K] extends (Date | null)
+				? (string | null)
+				: T[K] extends Record<string, any>
+					? Serialized<T[K]>
+					: T[K];
+};
+
+export class RedisKVCache<T> {
+	private redisClient: Redis.Redis;
+	private name: string;
+	private lifetime: number;
+	private memoryCache: MemoryKVCache<T>;
+
+	constructor(redisClient: RedisKVCache<never>['redisClient'], name: RedisKVCache<never>['name'], lifetime: RedisKVCache<never>['lifetime'], memoryCacheLifetime: number) {
+		this.redisClient = redisClient;
+		this.name = name;
+		this.lifetime = lifetime;
+		this.memoryCache = new MemoryKVCache(memoryCacheLifetime);
+	}
+
+	@bindThis
+	public async set(key: string, value: T): Promise<void> {
+		this.memoryCache.set(key, value);
+		if (this.lifetime === Infinity) {
+			await this.redisClient.set(
+				`kvcache:${this.name}:${key}`,
+				JSON.stringify(value),
+			);
+		} else {
+			await this.redisClient.set(
+				`kvcache:${this.name}:${key}`,
+				JSON.stringify(value),
+				'ex', Math.round(this.lifetime / 1000),
+			);
+		}
+	}
+
+	@bindThis
+	public async get(key: string): Promise<Serialized<T> | T | undefined> {
+		const memoryCached = this.memoryCache.get(key);
+		if (memoryCached !== undefined) return memoryCached;
+
+		const cached = await this.redisClient.get(`kvcache:${this.name}:${key}`);
+		if (cached == null) return undefined;
+		return JSON.parse(cached);
+	}
+
+	@bindThis
+	public async delete(key: string): Promise<void> {
+		this.memoryCache.delete(key);
+		await this.redisClient.del(`kvcache:${this.name}:${key}`);
+	}
+
+	/**
+ * キャッシュがあればそれを返し、無ければfetcherを呼び出して結果をキャッシュ&返します
+ * optional: キャッシュが存在してもvalidatorでfalseを返すとキャッシュ無効扱いにします
+ */
+	@bindThis
+	public async fetch(key: string, fetcher: () => Promise<T>, validator?: (cachedValue: Serialized<T> | T) => boolean): Promise<Serialized<T> | T> {
+		const cachedValue = await this.get(key);
+		if (cachedValue !== undefined) {
+			if (validator) {
+				if (validator(cachedValue)) {
+					// Cache HIT
+					return cachedValue;
+				}
+			} else {
+				// Cache HIT
+				return cachedValue;
+			}
+		}
+
+		// Cache MISS
+		const value = await fetcher();
+		this.set(key, value);
+		return value;
+	}
+}
+
 // TODO: メモリ節約のためあまり参照されないキーを定期的に削除できるようにする？
 
 export class MemoryKVCache<T> {
-	public cache: Map<string | null, { date: number; value: T; }>;
+	public cache: Map<string, { date: number; value: T; }>;
 	private lifetime: number;
 
 	constructor(lifetime: MemoryKVCache<never>['lifetime']) {
@@ -12,7 +97,7 @@ export class MemoryKVCache<T> {
 	}
 
 	@bindThis
-	public set(key: string | null, value: T): void {
+	public set(key: string, value: T): void {
 		this.cache.set(key, {
 			date: Date.now(),
 			value,
@@ -20,7 +105,7 @@ export class MemoryKVCache<T> {
 	}
 
 	@bindThis
-	public get(key: string | null): T | undefined {
+	public get(key: string): T | undefined {
 		const cached = this.cache.get(key);
 		if (cached == null) return undefined;
 		if ((Date.now() - cached.date) > this.lifetime) {
@@ -31,7 +116,7 @@ export class MemoryKVCache<T> {
 	}
 
 	@bindThis
-	public delete(key: string | null) {
+	public delete(key: string) {
 		this.cache.delete(key);
 	}
 
@@ -40,7 +125,7 @@ export class MemoryKVCache<T> {
 	 * optional: キャッシュが存在してもvalidatorでfalseを返すとキャッシュ無効扱いにします
 	 */
 	@bindThis
-	public async fetch(key: string | null, fetcher: () => Promise<T>, validator?: (cachedValue: T) => boolean): Promise<T> {
+	public async fetch(key: string, fetcher: () => Promise<T>, validator?: (cachedValue: T) => boolean): Promise<T> {
 		const cachedValue = this.get(key);
 		if (cachedValue !== undefined) {
 			if (validator) {
@@ -65,7 +150,7 @@ export class MemoryKVCache<T> {
 	 * optional: キャッシュが存在してもvalidatorでfalseを返すとキャッシュ無効扱いにします
 	 */
 	@bindThis
-	public async fetchMaybe(key: string | null, fetcher: () => Promise<T | undefined>, validator?: (cachedValue: T) => boolean): Promise<T | undefined> {
+	public async fetchMaybe(key: string, fetcher: () => Promise<T | undefined>, validator?: (cachedValue: T) => boolean): Promise<T | undefined> {
 		const cachedValue = this.get(key);
 		if (cachedValue !== undefined) {
 			if (validator) {
-- 
cgit v1.2.3-freya