Johann150
89c5fd0931
The cache implementation did previously not store the results of the computation and was thus not a cache at all. This can cause a significant number of database queries each time someone with a large number of followers does something that causes an activity to be federated.
80 lines
2.1 KiB
TypeScript
80 lines
2.1 KiB
TypeScript
export class Cache<T> {
|
|
public cache: Map<string | null, { date: number; value: T; }>;
|
|
private lifetime: number;
|
|
|
|
constructor(lifetime: Cache<never>['lifetime']) {
|
|
this.cache = new Map();
|
|
this.lifetime = lifetime;
|
|
}
|
|
|
|
public set(key: string | null, value: T): void {
|
|
this.cache.set(key, {
|
|
date: Date.now(),
|
|
value,
|
|
});
|
|
}
|
|
|
|
public get(key: string | null): T | undefined {
|
|
const cached = this.cache.get(key);
|
|
if (cached == null) return undefined;
|
|
if ((Date.now() - cached.date) > this.lifetime) {
|
|
this.cache.delete(key);
|
|
return undefined;
|
|
}
|
|
return cached.value;
|
|
}
|
|
|
|
public delete(key: string | null) {
|
|
this.cache.delete(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
|
|
*/
|
|
public async fetch(key: string | null, fetcher: () => Promise<T>, validator?: (cachedValue: T) => boolean): Promise<T> {
|
|
const cachedValue = 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;
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
*/
|
|
public async fetchMaybe(key: string | null, fetcher: () => Promise<T | undefined>, validator?: (cachedValue: T) => boolean): Promise<T | undefined> {
|
|
const cachedValue = 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();
|
|
if (value !== undefined) {
|
|
this.set(key, value);
|
|
}
|
|
return value;
|
|
}
|
|
}
|