Reddit Buddy MCP

/** * Smart in-memory cache with LRU eviction and adaptive TTL */ interface CacheEntry<T> { data: T; timestamp: number; size: number; hits: number; } interface CacheOptions { maxSize?: number; // Max size in bytes (default: 50MB) defaultTTL?: number; // Default TTL in ms cleanupInterval?: number; // Cleanup interval in ms } export class CacheManager { private cache = new Map<string, CacheEntry<any>>(); private sizeUsed = 0; private readonly maxSize: number; private readonly defaultTTL: number; private cleanupTimer: NodeJS.Timeout | null = null; private readonly ttlByPattern: Map<RegExp, number>; constructor(options: CacheOptions = {}) { this.maxSize = options.maxSize ?? 50 * 1024 * 1024; // 50MB default this.defaultTTL = options.defaultTTL ?? 5 * 60 * 1000; // 5 minutes default // Adaptive TTL based on content type this.ttlByPattern = new Map([ [/^subreddit:.*:hot$/, 5 * 60 * 1000], // Hot posts: 5 minutes [/^subreddit:.*:new$/, 2 * 60 * 1000], // New posts: 2 minutes [/^subreddit:.*:top$/, 30 * 60 * 1000], // Top posts: 30 minutes [/^post:/, 10 * 60 * 1000], // Individual posts: 10 minutes [/^user:/, 15 * 60 * 1000], // User data: 15 minutes [/^search:/, 10 * 60 * 1000], // Search results: 10 minutes ]); // Start cleanup interval if (options.cleanupInterval !== 0) { this.startCleanup(options.cleanupInterval ?? 60000); // Every minute } } /** * Get item from cache */ get<T>(key: string): T | null { const entry = this.cache.get(key); if (!entry) { return null; } // Check if expired const ttl = this.getTTLForKey(key); if (Date.now() - entry.timestamp > ttl) { this.delete(key); return null; } // Update hit count for LRU tracking entry.hits++; return entry.data as T; } /** * Set item in cache with automatic size management */ set<T>(key: string, data: T, _customTTL?: number): void { const size = this.estimateSize(data); // Evict entries if needed to make room while (this.sizeUsed + size > this.maxSize && this.cache.size > 0) { this.evictLRU(); } // Remove old entry if exists if (this.cache.has(key)) { this.delete(key); } // Add new entry const entry: CacheEntry<T> = { data, timestamp: Date.now(), size, hits: 0 }; this.cache.set(key, entry); this.sizeUsed += size; } /** * Delete item from cache */ delete(key: string): boolean { const entry = this.cache.get(key); if (!entry) return false; this.sizeUsed -= entry.size; return this.cache.delete(key); } /** * Clear all cache */ clear(): void { this.cache.clear(); this.sizeUsed = 0; } /** * Get cache statistics */ getStats() { const totalHits = Array.from(this.cache.values()) .reduce((sum, entry) => sum + entry.hits, 0); return { entries: this.cache.size, sizeUsed: this.sizeUsed, maxSize: this.maxSize, sizeUsedMB: (this.sizeUsed / 1024 / 1024).toFixed(2), maxSizeMB: (this.maxSize / 1024 / 1024).toFixed(2), hitRate: this.cache.size > 0 ? (totalHits / this.cache.size).toFixed(2) : 0, oldestEntry: this.getOldestEntry(), mostUsed: this.getMostUsedKeys(5) }; } /** * Generate cache key */ static createKey(...parts: (string | number | boolean | undefined)[]): string { return parts .filter(p => p !== undefined && p !== null) .join(':') .toLowerCase(); } /** * Private: Get TTL for a specific key based on patterns */ private getTTLForKey(key: string): number { for (const [pattern, ttl] of this.ttlByPattern) { if (pattern.test(key)) { return ttl; } } return this.defaultTTL; } /** * Private: Estimate size of data in bytes */ private estimateSize(data: any): number { try { return JSON.stringify(data).length * 2; // Rough estimate (UTF-16) } catch { return 1024; // Default 1KB for non-serializable } } /** * Private: Evict least recently used entry */ private evictLRU(): void { let lruKey: string | null = null; let minScore = Infinity; for (const [key, entry] of this.cache.entries()) { // Score based on hits and age const age = Date.now() - entry.timestamp; const score = entry.hits / (age / 1000); // Hits per second if (score < minScore) { minScore = score; lruKey = key; } } if (lruKey) { this.delete(lruKey); } } /** * Private: Cleanup expired entries */ private cleanup(): void { const now = Date.now(); const keysToDelete: string[] = []; for (const [key, entry] of this.cache.entries()) { const ttl = this.getTTLForKey(key); if (now - entry.timestamp > ttl) { keysToDelete.push(key); } } keysToDelete.forEach(key => this.delete(key)); } /** * Private: Start cleanup timer */ private startCleanup(interval: number): void { this.cleanupTimer = setInterval(() => this.cleanup(), interval); } /** * Private: Get oldest cache entry */ private getOldestEntry(): string | null { let oldestKey: string | null = null; let oldestTime = Infinity; for (const [key, entry] of this.cache.entries()) { if (entry.timestamp < oldestTime) { oldestTime = entry.timestamp; oldestKey = key; } } return oldestKey; } /** * Private: Get most used keys */ private getMostUsedKeys(count: number): string[] { return Array.from(this.cache.entries()) .sort((a, b) => b[1].hits - a[1].hits) .slice(0, count) .map(([key]) => key); } /** * Cleanup on destroy */ destroy(): void { if (this.cleanupTimer) { clearInterval(this.cleanupTimer); this.cleanupTimer = null; } this.clear(); } }