cache

src/market/RegionalMarketCache.ts

@@ -0,0 +1,50 @@
+class CacheEntry<T> {
+    public value: T;
+    public expiration: Date;
+
+    constructor(value: T, expiration: Date) {
+        this.value = value;
+        this.expiration = expiration;
+    }
+}
+
+export type ExpirationSupplier<T> = (v: T) => Date;
+
+export class RegionalMarketCache<T>  {
+    private cache: Record<number, Record<number, CacheEntry<T>>>;
+    private expirationSupplier: (v: T) => Date;
+
+    constructor(expiration: ExpirationSupplier<T> | number) {
+        this.cache = {};
+        this.expirationSupplier = expiration instanceof Function ? expiration : () => new Date(Date.now() + expiration);
+    }
+
+    public get(regionId: number, typeId: number): T | undefined {
+        const entry = this.cache[regionId]?.[typeId];
+
+        if (entry && entry.expiration > new Date()) {
+            return entry.value;
+        }
+        this.remove(regionId, typeId);
+        return undefined;
+    }
+
+    public set(regionId: number, typeId: number, value: T): void {
+        this.cache[regionId] = this.cache[regionId] ?? {};
+        this.cache[regionId][typeId] = new CacheEntry(value, this.expirationSupplier(value));
+    }
+
+    public remove(regionId: number, typeId: number): void {
+        delete this.cache[regionId]?.[typeId];
+    }
+
+    public async computeIfAbsent(regionId: number, typeId: number, supplier: () => (Promise<T> | T)): Promise<T> {
+        let value = this.get(regionId, typeId);
+
+        if (!value) {
+            value = await supplier();
+            this.set(regionId, typeId, value);
+        }
+        return value;
+    }
+};