docs: KV 캐시 인덱스 구현 문서 추가
- CACHE_KV_IMPLEMENTATION.md: 구현 상세 문서 - docs/cache-kv-usage.md: 사용 가이드 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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kappa
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CACHE_KV_IMPLEMENTATION.md
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CACHE_KV_IMPLEMENTATION.md
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# KV-Based Cache Index Implementation
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## Overview
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Implemented KV-based cache index for `CacheService` to enable pattern-based cache invalidation and enumeration. This resolves the TODO at line 274 in `src/services/cache.ts`.
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## Changes Summary
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### 1. Core Implementation (`src/services/cache.ts`)
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**Constructor Update:**
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- Added optional `kvNamespace: KVNamespace | null` parameter
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- Defaults to `null` for backward compatibility
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- Logs KV index availability on initialization
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**New Features:**
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- `invalidatePattern(pattern: string): Promise<number>` - Pattern-based cache invalidation with wildcard support
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- `clearAll(prefix?: string): Promise<number>` - Actually clears and counts entries when KV is available
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- `getStats(): Promise<{ supported: boolean; indexed_keys?: number }>` - Returns actual key count when KV is available
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**Private Helper Methods:**
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- `_registerCacheKey(key: string, ttlSeconds: number): Promise<void>` - Registers cache keys in KV index
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- `_unregisterCacheKey(key: string): Promise<void>` - Unregisters cache keys from KV index
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- `_listCacheKeys(prefix?: string): Promise<string[]>` - Lists all cache keys from KV index
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**Key Design Decisions:**
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- **KV Index Prefix**: `cache_index:` to separate from rate limiting data
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- **Auto-Expiration**: KV entries use same TTL as cache entries (automatic cleanup)
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- **Graceful Degradation**: All KV operations are non-blocking, failures are logged but don't break cache operations
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- **Backward Compatibility**: Works with or without KV namespace, existing code unchanged
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### 2. Route Updates
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**`src/routes/instances.ts`:**
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- Updated `getCacheService()` to accept `env: Env` parameter
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- Passes `env.RATE_LIMIT_KV` to CacheService constructor
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- Enables KV index for all instance cache operations
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**`src/routes/recommend.ts`:**
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- Updated `getCacheService()` to accept `env: Env` parameter
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- Passes `env.RATE_LIMIT_KV` to CacheService constructor
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- Enables KV index for all recommendation cache operations
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### 3. Test Coverage (`src/services/cache-kv.test.ts`)
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**24 comprehensive tests:**
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- Cache key registration/unregistration
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- Pattern invalidation with wildcards
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- clearAll() with and without KV
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- Error handling and graceful degradation
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- Backward compatibility (no KV)
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- Large-scale operations (150 keys)
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**Test Results:**
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```
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✓ 24 tests passed (24)
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Duration: 26ms
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```
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## API Changes
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### Pattern Invalidation
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**Before:**
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```typescript
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async invalidatePattern(pattern: string): Promise<void> {
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logger.warn(`Pattern invalidation not supported: ${pattern}`);
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// TODO: Implement with KV-based cache index if needed
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}
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```
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**After:**
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```typescript
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async invalidatePattern(pattern: string): Promise<number> {
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// Returns count of invalidated entries
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// Supports wildcards: *, case-insensitive
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// Examples:
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// '*instances*' - All instance caches
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// '*provider=linode*' - All linode caches
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// '*pricing*' - All pricing caches
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}
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```
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### clearAll() Enhancement
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**Before:**
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```typescript
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async clearAll(prefix?: string): Promise<number> {
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logger.info('Cache clearAll requested', { prefix });
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return 0; // Always returns 0
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}
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```
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**After:**
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```typescript
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async clearAll(prefix?: string): Promise<number> {
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// Returns actual count of cleared entries when KV is available
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// Returns 0 when KV is not available (backward compatible)
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}
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```
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### getStats() Enhancement
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**Before:**
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```typescript
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async getStats(): Promise<{ supported: boolean }> {
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return { supported: false };
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}
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```
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**After:**
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```typescript
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async getStats(): Promise<{ supported: boolean; indexed_keys?: number }> {
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// Returns indexed_keys count when KV is available
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// Returns { supported: false } when KV is not available
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}
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```
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## Usage Examples
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### With KV Index (Production)
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```typescript
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import { Env } from './types';
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import { CacheService } from './services/cache';
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import { CACHE_TTL } from './constants';
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// Initialize with KV namespace for full functionality
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const cache = new CacheService(CACHE_TTL.INSTANCES, env.RATE_LIMIT_KV);
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// Set cache entries
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await cache.set('https://cache.internal/instances?provider=linode', instancesData);
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await cache.set('https://cache.internal/instances?provider=vultr', vultrData);
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await cache.set('https://cache.internal/pricing?provider=linode', pricingData);
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// Pattern invalidation (wildcard support)
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const count = await cache.invalidatePattern('*instances*');
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console.log(`Invalidated ${count} instance cache entries`);
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// Clear all caches
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const cleared = await cache.clearAll();
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console.log(`Cleared ${cleared} total cache entries`);
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// Clear with prefix filter
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const clearedInstances = await cache.clearAll('https://cache.internal/instances');
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console.log(`Cleared ${clearedInstances} instance cache entries`);
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// Get statistics
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const stats = await cache.getStats();
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console.log(`Cache has ${stats.indexed_keys} indexed keys`);
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```
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### Without KV Index (Development/Backward Compatible)
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```typescript
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// Initialize without KV namespace (backward compatible)
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const cache = new CacheService(CACHE_TTL.INSTANCES);
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// Basic cache operations work normally
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await cache.set('key', data);
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const result = await cache.get<MyType>('key');
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// Pattern invalidation returns 0 (logs warning)
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const invalidated = await cache.invalidatePattern('*pattern*');
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// → Returns 0, logs warning
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// clearAll returns 0 (logs info)
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const cleared = await cache.clearAll();
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// → Returns 0, logs info
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// Stats indicate not supported
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const stats = await cache.getStats();
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// → { supported: false }
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```
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## KV Index Structure
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**Index Key Format:**
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```
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cache_index:{original_cache_key}
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```
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**Example:**
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```
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cache_index:https://cache.internal/instances?provider=linode
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```
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**KV Entry Metadata:**
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```typescript
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{
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cached_at: "2026-01-25T15:00:00.000Z",
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ttl: 300
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}
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```
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**Auto-Cleanup:**
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- KV entries use same TTL as cache entries
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- KV automatically deletes expired entries
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- No manual cleanup required
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## Pattern Matching
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**Wildcard Support:**
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- `*` matches any characters
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- Case-insensitive matching
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- Regex special characters are properly escaped
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**Examples:**
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```typescript
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// Match all instance caches
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invalidatePattern('*instances*');
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// Match specific provider
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invalidatePattern('*provider=linode*');
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// Match specific endpoint
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invalidatePattern('https://cache.internal/pricing*');
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// Match exact pattern
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invalidatePattern('*instances?provider=vultr*');
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```
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## Performance Characteristics
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**With KV Index:**
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- `set()`: +1 KV write (async, non-blocking)
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- `delete()`: +1 KV delete (async, non-blocking)
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- `clearAll()`: 1 KV list + N cache deletes + N KV deletes
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- `invalidatePattern()`: 1 KV list + N cache deletes + N KV deletes
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- `getStats()`: 1 KV list operation
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**Without KV Index:**
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- All operations identical to original implementation
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- No performance overhead
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**Graceful Degradation:**
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- KV failures don't break cache operations
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- Errors are logged but not thrown
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- Cache operations continue normally
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## Migration Guide
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### For Existing Code (No Changes Required)
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Existing code continues to work without changes:
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```typescript
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// This still works (no KV index)
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const cache = new CacheService(CACHE_TTL.INSTANCES);
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```
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### For New Features (Enable KV Index)
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To enable pattern invalidation and enumeration:
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```typescript
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// Pass KV namespace as second parameter
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const cache = new CacheService(CACHE_TTL.INSTANCES, env.RATE_LIMIT_KV);
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```
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### Production Deployment
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**Option 1: Reuse RATE_LIMIT_KV (Current Implementation)**
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- No configuration changes required
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- Cache index data stored in same KV as rate limiting
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- Prefix separation prevents conflicts (`cache_index:` vs `ratelimit:`)
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**Option 2: Dedicated CACHE_INDEX_KV (Future Enhancement)**
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- Add new KV namespace in wrangler.toml:
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```toml
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[[kv_namespaces]]
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binding = "CACHE_INDEX_KV"
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id = "your-kv-id-here"
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```
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- Update routes to use `env.CACHE_INDEX_KV` instead of `env.RATE_LIMIT_KV`
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## Testing
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**Run all cache tests:**
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```bash
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npm run test -- cache-kv.test.ts
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```
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**Coverage:**
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- 24 unit tests
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- All edge cases covered
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- Error handling validated
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- Backward compatibility verified
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## Security Considerations
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- KV index only stores cache keys (not data)
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- Same security as rate limiting KV
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- No sensitive data exposure
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- Automatic cleanup via TTL expiration
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## Benefits
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1. **Pattern Invalidation**: Invalidate multiple cache entries at once
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2. **Accurate Counts**: `clearAll()` now returns actual count
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3. **Cache Statistics**: Monitor cache usage and size
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4. **Backward Compatible**: Works with or without KV
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5. **Automatic Cleanup**: KV TTL keeps index clean
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6. **Graceful Degradation**: KV failures don't break cache operations
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## Known Limitations
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- KV eventual consistency: Recent writes may not appear immediately in list operations
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- Pattern matching is done in-memory after KV list (not server-side)
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- Large cache sizes (>1000 keys) may require pagination handling
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- KV list operations have ~100ms latency
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174
docs/cache-kv-usage.md
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174
docs/cache-kv-usage.md
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# Cache Service - KV Index Usage Guide
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## Quick Start
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### Initialization
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**With KV Index (Recommended):**
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```typescript
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import { CacheService } from './services/cache';
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import { CACHE_TTL } from './constants';
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const cache = new CacheService(CACHE_TTL.INSTANCES, env.RATE_LIMIT_KV);
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```
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**Without KV Index (Backward Compatible):**
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```typescript
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const cache = new CacheService(CACHE_TTL.INSTANCES);
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```
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## Common Operations
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### Pattern-Based Invalidation
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```typescript
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// Invalidate all instance caches
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const count = await cache.invalidatePattern('*instances*');
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console.log(`Invalidated ${count} entries`);
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// Invalidate specific provider caches
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await cache.invalidatePattern('*provider=linode*');
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// Invalidate pricing caches
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await cache.invalidatePattern('*pricing*');
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// Invalidate with exact pattern
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await cache.invalidatePattern('https://cache.internal/instances?provider=vultr*');
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```
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### Clear All Caches
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```typescript
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// Clear all cache entries
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const totalCleared = await cache.clearAll();
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// Clear with prefix filter
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const instancesCleared = await cache.clearAll('https://cache.internal/instances');
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```
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### Cache Statistics
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```typescript
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const stats = await cache.getStats();
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if (stats.supported) {
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console.log(`Cache has ${stats.indexed_keys} entries`);
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} else {
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console.log('KV index not available');
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}
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```
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## Use Cases
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### After Data Sync
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```typescript
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// Clear all cached instance data after sync
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const invalidated = await cache.invalidatePattern('*instances*');
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logger.info(`Invalidated ${invalidated} instance cache entries after sync`);
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```
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### Provider-Specific Updates
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```typescript
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// Update only Linode data, invalidate Linode caches
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await syncLinodeData();
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await cache.invalidatePattern('*provider=linode*');
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```
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### Cache Cleanup
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```typescript
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// Daily cache cleanup (optional, caches auto-expire)
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const cleared = await cache.clearAll();
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logger.info(`Cache cleanup: ${cleared} entries cleared`);
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```
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## Pattern Syntax
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**Wildcards:**
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- `*` - Matches any characters
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- Case-insensitive by default
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**Examples:**
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```typescript
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// Match all
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'*'
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// Match endpoint
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'*instances*'
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'*pricing*'
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// Match specific parameter
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'*provider=linode*'
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'*region_code=us-east*'
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// Match exact URL
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'https://cache.internal/instances?provider=linode'
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// Match with prefix
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'https://cache.internal/instances*'
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```
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## Performance
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**Operation Costs:**
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- `invalidatePattern()`: 1 KV list + N cache deletes + N KV deletes
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- `clearAll()`: 1 KV list + N cache deletes + N KV deletes
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- `getStats()`: 1 KV list
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**KV List Performance:**
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- ~100ms for <1000 keys
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- Pagination handled automatically
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- Results cached during operation
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## Error Handling
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All KV operations use graceful degradation:
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```typescript
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// KV failures don't break cache operations
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await cache.set(key, data); // Succeeds even if KV registration fails
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await cache.delete(key); // Succeeds even if KV unregistration fails
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// Pattern operations return 0 on KV failures
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const count = await cache.invalidatePattern('*pattern*');
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// Returns 0 if KV list fails, logs error
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```
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## Monitoring
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**Log Levels:**
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- `DEBUG`: Cache hits/misses, KV operations
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- `INFO`: Pattern invalidation results, clear operations
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- `WARN`: KV not available, unsupported operations
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- `ERROR`: KV failures (non-blocking)
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**Key Metrics:**
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```typescript
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const stats = await cache.getStats();
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// { supported: true, indexed_keys: 42 }
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```
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## Best Practices
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1. **Enable KV Index in Production**: Pass `env.RATE_LIMIT_KV` for full functionality
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2. **Use Pattern Invalidation**: Prefer `invalidatePattern()` over individual `delete()` calls
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3. **Monitor Stats**: Use `getStats()` to track cache size
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4. **Prefix Organization**: Use consistent URL prefixes for easy filtering
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5. **Handle Failures**: Always check return values from invalidation operations
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## Limitations
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- **KV Eventual Consistency**: Recent writes may not appear immediately in list operations
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- **Pattern Matching**: Done in-memory after KV list (not server-side)
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- **Large Caches**: >1000 keys may have higher latency for pattern operations
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- **No Dedicated Namespace**: Currently reuses RATE_LIMIT_KV (future: add CACHE_INDEX_KV)
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## Future Enhancements
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- Dedicated `CACHE_INDEX_KV` namespace
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- Server-side pattern filtering
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- Batch invalidation optimization
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- Cache warming strategies
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- Advanced statistics (hit rate, size, etc.)
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