Add in-memory caching strategy for aggregated queries with TTL and automatic invalidation on data changes

server/cache.js

@@ -0,0 +1,54 @@
+// Simple in-memory cache with TTL support
+class CacheManager {
+  constructor() {
+    this.cache = new Map();
+  }
+
+  set(key, value, ttlSeconds = 300) {
+    const expiresAt = Date.now() + (ttlSeconds * 1000);
+    this.cache.set(key, { value, expiresAt });
+  }
+
+  get(key) {
+    const item = this.cache.get(key);
+    if (!item) return null;
+    
+    if (Date.now() > item.expiresAt) {
+      this.cache.delete(key);
+      return null;
+    }
+    
+    return item.value;
+  }
+
+  has(key) {
+    return this.get(key) !== null;
+  }
+
+  delete(key) {
+    this.cache.delete(key);
+  }
+
+  clear() {
+    this.cache.clear();
+  }
+
+  // Invalidate all cache keys matching a pattern
+  invalidatePattern(pattern) {
+    for (const key of this.cache.keys()) {
+      if (key.includes(pattern)) {
+        this.cache.delete(key);
+      }
+    }
+  }
+
+  // Get cache statistics
+  getStats() {
+    return {
+      size: this.cache.size,
+      keys: Array.from(this.cache.keys()),
+    };
+  }
+}
+
+module.exports = new CacheManager();