Added Rates Service: Base, Coinbase, Composite

packages/stack/src/utils/memoizer.ts

@@ -1,7 +1,25 @@
 // TODO: We may want to move this to @xocash/primitives.
 
+export type MemoizerItem<T> = {
+  value: T;
+  timestamp: number;
+}
+
 export class Memoizer {
-  private cache = new Map<string, any>();
+  private cache = new Map<string, MemoizerItem<any>>();
+
+  /**
+   * Sets a cached value for the given key.
+   *
+   * @param key - The key to store the value under
+   * @param value - The value to store
+   */
+  set(key: string, value: any): void {
+    this.cache.set(key, {
+      value,
+      timestamp: Date.now(),
+    });
+  }
 
   /**
    * Gets a cached value for the given key, computing it if it doesn't exist.
@@ -10,11 +28,16 @@ export class Memoizer {
    * @param compute - Function to compute the value if it's not cached
    * @returns The cached or computed value
    */
-  get<K extends string, V>(key: K, compute: () => V): V {
-    if (!this.cache.has(key)) {
-      this.cache.set(key, compute());
+  get<K extends string, V>(key: K, compute: () => V, ttl?: number): V {
+    if (ttl) {
+      this.removeIfExpired(key, ttl);
     }
-    return this.cache.get(key) as V;
+    
+    if (!this.cache.has(key)) {
+      this.set(key, compute());
+    }
+
+    return this.cache.get(key)!.value as V;
   }
 
   /**
@@ -23,7 +46,11 @@ export class Memoizer {
    * @param key - The key to check
    * @returns Whether the key exists in the cache
    */
-  has(key: string): boolean {
+  has(key: string, ttl?: number): boolean {
+    if (ttl) {
+      this.removeIfExpired(key, ttl);
+    }
+
     return this.cache.has(key);
   }
 
@@ -52,4 +79,16 @@ export class Memoizer {
   keys(): string[] {
     return Array.from(this.cache.keys());
   }
+
+  private removeIfExpired(key: string, ttl: number): void {
+    if (!this.cache.has(key)) {
+      return;
+    }
+
+    const item = this.cache.get(key);
+
+    if (Date.now() - item!.timestamp > ttl) {
+      this.cache.delete(key);
+    }
+  }
 }