refactor: 코드 리뷰 2차 품질 개선

- Cron 핸들러 retry 로직 executeWithRetry 헬퍼로 추출 (DRY)
- Singleton 설정 변경 감지 추가 (CacheService, QueryService)
- SYNC_BATCH_SIZE 환경변수 일관되게 사용 (100)
- GPU/G8/VPU 인스턴스 fetch Promise.all로 병렬화
- parsePositiveNumber 빈 문자열 처리 추가
- Health check DB 쿼리 5초 timeout 추가

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/index.ts

@@ -9,6 +9,61 @@ import app from './app';
 import { createLogger } from './utils/logger';
 import { SyncOrchestrator } from './services/sync';
 
+/**
+ * Generic retry helper with exponential backoff
+ * Executes an operation with automatic retry on failure
+ */
+async function executeWithRetry<T>(
+  operation: () => Promise<T>,
+  options: {
+    maxRetries: number;
+    operationName: string;
+    logger: ReturnType<typeof createLogger>;
+  }
+): Promise<T> {
+  const { maxRetries, operationName, logger } = options;
+
+  for (let attempt = 1; attempt <= maxRetries; attempt++) {
+    try {
+      logger.info(`Starting ${operationName} attempt`, {
+        attempt_number: attempt,
+        max_retries: maxRetries
+      });
+
+      const result = await operation();
+      return result;
+
+    } catch (error) {
+      const willRetry = attempt < maxRetries;
+      const retryDelayMs = willRetry ? Math.min(Math.pow(2, attempt - 1) * 1000, 10000) : 0;
+
+      logger.error(`${operationName} attempt failed`, {
+        attempt_number: attempt,
+        max_retries: maxRetries,
+        will_retry: willRetry,
+        retry_delay_ms: retryDelayMs,
+        error: error instanceof Error ? error.message : String(error),
+        stack: error instanceof Error ? error.stack : undefined
+      });
+
+      if (willRetry) {
+        // Wait before retry with exponential backoff
+        await new Promise(resolve => setTimeout(resolve, retryDelayMs));
+      } else {
+        // Final failure - re-throw to make cron failure visible
+        logger.error(`${operationName} failed after all retries`, {
+          total_attempts: maxRetries,
+          error: error instanceof Error ? error.message : String(error)
+        });
+        throw error;
+      }
+    }
+  }
+
+  // TypeScript exhaustiveness check - should never reach here
+  throw new Error(`${operationName}: Unexpected retry loop exit`);
+}
+
 export default {
   /**
    * HTTP Request Handler (delegated to Hono)
@@ -45,68 +100,37 @@ export default {
       const executeSyncWithRetry = async (): Promise<void> => {
         const orchestrator = new SyncOrchestrator(env.DB, env);
 
-        for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+        const report = await executeWithRetry(
-          try {
+          async () => orchestrator.syncAll(['linode', 'vultr', 'aws']),
-            logger.info('Starting full sync attempt', {
+          {
-              attempt_number: attempt,
+            maxRetries: MAX_RETRIES,
-              max_retries: MAX_RETRIES
+            operationName: 'full sync',
-            });
+            logger
-
-            const report = await orchestrator.syncAll(['linode', 'vultr', 'aws']);
-
-            logger.info('Daily full sync complete', {
-              attempt_number: attempt,
-              total_regions: report.summary.total_regions,
-              total_instances: report.summary.total_instances,
-              total_pricing: report.summary.total_pricing,
-              successful_providers: report.summary.successful_providers,
-              failed_providers: report.summary.failed_providers,
-              duration_ms: report.total_duration_ms
-            });
-
-            // Alert on partial failures
-            if (report.summary.failed_providers > 0) {
-              const failedProviders = report.providers
-                .filter(p => !p.success)
-                .map(p => p.provider);
-
-              logger.warn('Some providers failed during sync', {
-                failed_count: report.summary.failed_providers,
-                failed_providers: failedProviders,
-                errors: report.providers
-                  .filter(p => !p.success)
-                  .map(p => ({ provider: p.provider, error: p.error }))
-              });
-            }
-
-            // Success - exit retry loop
-            return;
-
-          } catch (error) {
-            const willRetry = attempt < MAX_RETRIES;
-            const retryDelayMs = willRetry ? Math.min(Math.pow(2, attempt - 1) * 1000, 10000) : 0;
-
-            logger.error('Sync attempt failed', {
-              attempt_number: attempt,
-              max_retries: MAX_RETRIES,
-              will_retry: willRetry,
-              retry_delay_ms: retryDelayMs,
-              error: error instanceof Error ? error.message : String(error),
-              stack: error instanceof Error ? error.stack : undefined
-            });
-
-            if (willRetry) {
-              // Wait before retry with exponential backoff
-              await new Promise(resolve => setTimeout(resolve, retryDelayMs));
-            } else {
-              // Final failure - re-throw to make cron failure visible
-              logger.error('Daily sync failed after all retries', {
-                total_attempts: MAX_RETRIES,
-                error: error instanceof Error ? error.message : String(error)
-              });
-              throw error;
-            }
           }
+        );
+
+        logger.info('Daily full sync complete', {
+          total_regions: report.summary.total_regions,
+          total_instances: report.summary.total_instances,
+          total_pricing: report.summary.total_pricing,
+          successful_providers: report.summary.successful_providers,
+          failed_providers: report.summary.failed_providers,
+          duration_ms: report.total_duration_ms
+        });
+
+        // Alert on partial failures
+        if (report.summary.failed_providers > 0) {
+          const failedProviders = report.providers
+            .filter(p => !p.success)
+            .map(p => p.provider);
+
+          logger.warn('Some providers failed during sync', {
+            failed_count: report.summary.failed_providers,
+            failed_providers: failedProviders,
+            errors: report.providers
+              .filter(p => !p.success)
+              .map(p => ({ provider: p.provider, error: p.error }))
+          });
         }
       };
 
@@ -119,66 +143,35 @@ export default {
       const executePricingSyncWithRetry = async (): Promise<void> => {
         const orchestrator = new SyncOrchestrator(env.DB, env);
 
-        for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
+        const report = await executeWithRetry(
-          try {
+          async () => orchestrator.syncAllPricingOnly(['linode', 'vultr', 'aws']),
-            logger.info('Starting pricing sync attempt', {
+          {
-              attempt_number: attempt,
+            maxRetries: MAX_RETRIES,
-              max_retries: MAX_RETRIES
+            operationName: 'pricing sync',
-            });
+            logger
-
-            const report = await orchestrator.syncAllPricingOnly(['linode', 'vultr', 'aws']);
-
-            logger.info('Pricing sync complete', {
-              attempt_number: attempt,
-              total_pricing: report.summary.total_pricing,
-              successful_providers: report.summary.successful_providers,
-              failed_providers: report.summary.failed_providers,
-              duration_ms: report.total_duration_ms
-            });
-
-            // Alert on partial failures
-            if (report.summary.failed_providers > 0) {
-              const failedProviders = report.providers
-                .filter(p => !p.success)
-                .map(p => p.provider);
-
-              logger.warn('Some providers failed during pricing sync', {
-                failed_count: report.summary.failed_providers,
-                failed_providers: failedProviders,
-                errors: report.providers
-                  .filter(p => !p.success)
-                  .map(p => ({ provider: p.provider, error: p.error }))
-              });
-            }
-
-            // Success - exit retry loop
-            return;
-
-          } catch (error) {
-            const willRetry = attempt < MAX_RETRIES;
-            const retryDelayMs = willRetry ? Math.min(Math.pow(2, attempt - 1) * 1000, 10000) : 0;
-
-            logger.error('Pricing sync attempt failed', {
-              attempt_number: attempt,
-              max_retries: MAX_RETRIES,
-              will_retry: willRetry,
-              retry_delay_ms: retryDelayMs,
-              error: error instanceof Error ? error.message : String(error),
-              stack: error instanceof Error ? error.stack : undefined
-            });
-
-            if (willRetry) {
-              // Wait before retry with exponential backoff
-              await new Promise(resolve => setTimeout(resolve, retryDelayMs));
-            } else {
-              // Final failure - re-throw to make cron failure visible
-              logger.error('Pricing sync failed after all retries', {
-                total_attempts: MAX_RETRIES,
-                error: error instanceof Error ? error.message : String(error)
-              });
-              throw error;
-            }
           }
+        );
+
+        logger.info('Pricing sync complete', {
+          total_pricing: report.summary.total_pricing,
+          successful_providers: report.summary.successful_providers,
+          failed_providers: report.summary.failed_providers,
+          duration_ms: report.total_duration_ms
+        });
+
+        // Alert on partial failures
+        if (report.summary.failed_providers > 0) {
+          const failedProviders = report.providers
+            .filter(p => !p.success)
+            .map(p => p.provider);
+
+          logger.warn('Some providers failed during pricing sync', {
+            failed_count: report.summary.failed_providers,
+            failed_providers: failedProviders,
+            errors: report.providers
+              .filter(p => !p.success)
+              .map(p => ({ provider: p.provider, error: p.error }))
+          });
         }
       };
 

src/routes/health.ts

@@ -61,6 +61,27 @@ interface DetailedHealthResponse extends PublicHealthResponse {
   };
 }
 
+/**
+ * Wraps a promise with a timeout
+ * @param promise - The promise to wrap
+ * @param ms - Timeout in milliseconds
+ * @param operation - Operation name for error message
+ * @returns Promise result if completed within timeout
+ * @throws Error if operation times out
+ */
+async function withTimeout<T>(promise: Promise<T>, ms: number, operation: string): Promise<T> {
+  let timeoutId: ReturnType<typeof setTimeout>;
+  const timeoutPromise = new Promise<never>((_, reject) => {
+    timeoutId = setTimeout(() => reject(new Error(`${operation} timed out after ${ms}ms`)), ms);
+  });
+
+  try {
+    return await Promise.race([promise, timeoutPromise]);
+  } finally {
+    clearTimeout(timeoutId!);
+  }
+}
+
 /**
  * Check database connectivity and measure latency
  */
@@ -68,8 +89,12 @@ async function checkDatabaseHealth(db: D1Database): Promise<DatabaseHealth> {
   try {
     const startTime = Date.now();
 
-    // Simple connectivity check
+    // Simple connectivity check with 5-second timeout
-    await db.prepare('SELECT 1').first();
+    await withTimeout(
+      db.prepare('SELECT 1').first(),
+      5000,
+      'Database health check'
+    );
 
     const latency = Date.now() - startTime;
 

src/routes/instances.ts

@@ -33,17 +33,19 @@ import {
  */
 let cachedQueryService: QueryService | null = null;
 let cachedDb: D1Database | null = null;
+let cachedEnv: Env | null = null;
 
 /**
  * Get or create QueryService singleton
  * Lazy initialization on first request, then reused for subsequent requests
- * Invalidates cache if database binding changes (rolling deploy scenario)
+ * Invalidates cache if database or environment binding changes (rolling deploy scenario)
  */
 function getQueryService(db: D1Database, env: Env): QueryService {
-  // Invalidate cache if db binding changed (rolling deploy scenario)
+  // Invalidate cache if db or env binding changed (rolling deploy scenario)
-  if (!cachedQueryService || cachedDb !== db) {
+  if (!cachedQueryService || cachedDb !== db || cachedEnv !== env) {
     cachedQueryService = new QueryService(db, env);
     cachedDb = db;
+    cachedEnv = env;
     logger.debug('[Instances] QueryService singleton initialized/refreshed');
   }
   return cachedQueryService;
@@ -128,7 +130,7 @@ function parseQueryParams(url: URL): {
     name: string,
     value: string | null
   ): number | undefined | { error: { code: string; message: string; parameter: string } } {
-    if (value === null) return undefined;
+    if (value === null || value === '') return undefined;
 
     const parsed = Number(value);
     if (isNaN(parsed) || parsed < 0) {

src/services/cache.ts

@@ -48,10 +48,13 @@ export interface CacheResult<T> {
  * Prevents race conditions from multiple route-level singletons
  */
 let globalCacheService: CacheService | null = null;
+let cachedTtl: number | null = null;
+let cachedKv: KVNamespace | null = null;
 
 /**
  * Get or create global CacheService singleton
  * Thread-safe factory function that ensures only one CacheService instance exists
+ * Detects configuration changes (TTL or KV namespace) and refreshes singleton
  *
  * @param ttl - TTL in seconds for cache entries
  * @param kv - KV namespace for cache index (enables pattern invalidation)
@@ -61,9 +64,11 @@ let globalCacheService: CacheService | null = null;
  * const cache = getGlobalCacheService(CACHE_TTL.INSTANCES, env.RATE_LIMIT_KV);
  */
 export function getGlobalCacheService(ttl: number, kv: KVNamespace | null): CacheService {
-  if (!globalCacheService) {
+  if (!globalCacheService || cachedTtl !== ttl || cachedKv !== kv) {
     globalCacheService = new CacheService(ttl, kv);
-    logger.debug('[CacheService] Global singleton initialized');
+    cachedTtl = ttl;
+    cachedKv = kv;
+    logger.debug('[CacheService] Global singleton initialized/refreshed');
   }
   return globalCacheService;
 }

src/services/sync.ts

@@ -189,37 +189,39 @@ export class SyncOrchestrator {
       let vpuInstancesCount = 0;
 
       if (provider.toLowerCase() === 'linode') {
-        // GPU instances
+        // Parallel fetch all specialized instances for Linode
-        if (connector.getGpuInstances) {
+        const [gpuInstances, g8Instances, vpuInstances] = await Promise.all([
-          const gpuInstances = await withTimeout(connector.getGpuInstances(), 15000, `${provider} fetch GPU instances`);
+          connector.getGpuInstances
-          if (gpuInstances && gpuInstances.length > 0) {
+            ? withTimeout(connector.getGpuInstances(), 15000, `${provider} fetch GPU instances`)
-            gpuInstancesCount = await this.repos.gpuInstances.upsertMany(
+            : Promise.resolve([]),
-              providerRecord.id,
+          connector.getG8Instances
-              gpuInstances
+            ? withTimeout(connector.getG8Instances(), 15000, `${provider} fetch G8 instances`)
-            );
+            : Promise.resolve([]),
-          }
+          connector.getVpuInstances
+            ? withTimeout(connector.getVpuInstances(), 15000, `${provider} fetch VPU instances`)
+            : Promise.resolve([])
+        ]);
+
+        // Sequential upsert (database operations)
+        if (gpuInstances.length > 0) {
+          gpuInstancesCount = await this.repos.gpuInstances.upsertMany(
+            providerRecord.id,
+            gpuInstances
+          );
         }
 
-        // G8 instances
+        if (g8Instances.length > 0) {
-        if (connector.getG8Instances) {
+          g8InstancesCount = await this.repos.g8Instances.upsertMany(
-          const g8Instances = await withTimeout(connector.getG8Instances(), 15000, `${provider} fetch G8 instances`);
+            providerRecord.id,
-          if (g8Instances && g8Instances.length > 0) {
+            g8Instances
-            g8InstancesCount = await this.repos.g8Instances.upsertMany(
+          );
-              providerRecord.id,
-              g8Instances
-            );
-          }
         }
 
-        // VPU instances
+        if (vpuInstances.length > 0) {
-        if (connector.getVpuInstances) {
+          vpuInstancesCount = await this.repos.vpuInstances.upsertMany(
-          const vpuInstances = await withTimeout(connector.getVpuInstances(), 15000, `${provider} fetch VPU instances`);
+            providerRecord.id,
-          if (vpuInstances && vpuInstances.length > 0) {
+            vpuInstances
-            vpuInstancesCount = await this.repos.vpuInstances.upsertMany(
+          );
-              providerRecord.id,
-              vpuInstances
-            );
-          }
         }
       }
 
@@ -813,24 +815,29 @@ export class SyncOrchestrator {
 
   /**
    * Generate AWS pricing records in batches using Generator pattern
-   * Minimizes memory usage by yielding batches of 100 records at a time
+   * Minimizes memory usage by yielding batches at a time (configurable)
    *
    * @param instanceTypeIds - Array of database instance type IDs
    * @param regionIds - Array of database region IDs
    * @param dbInstanceMap - Map of instance type ID to DB instance data
    * @param rawInstanceMap - Map of instance_id (API ID) to raw AWS data
-   * @yields Batches of PricingInput records (100 per batch)
+   * @param env - Environment configuration for SYNC_BATCH_SIZE
+   * @yields Batches of PricingInput records (configurable batch size)
    *
    * Manual Test:
-   * Generator yields ~252 batches for ~25,230 total records (870 instances × 29 regions)
+   * Generator yields batches for ~25,230 total records (870 instances × 29 regions)
    */
   private *generateAWSPricingBatches(
     instanceTypeIds: number[],
     regionIds: number[],
     dbInstanceMap: Map<number, { instance_id: string }>,
-    rawInstanceMap: Map<string, { Cost: number; MonthlyPrice: number }>
+    rawInstanceMap: Map<string, { Cost: number; MonthlyPrice: number }>,
+    env?: Env
   ): Generator<PricingInput[], void, void> {
-    const BATCH_SIZE = 500;
+    const BATCH_SIZE = Math.min(
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
+      1000
+    );
     let batch: PricingInput[] = [];
 
     for (const regionId of regionIds) {
@@ -894,7 +901,7 @@ export class SyncOrchestrator {
     env?: Env
   ): Generator<PricingInput[], void, void> {
     const BATCH_SIZE = Math.min(
-      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '500', 10) || 500, 1),
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
       1000
     );
     let batch: PricingInput[] = [];
@@ -960,7 +967,7 @@ export class SyncOrchestrator {
     env?: Env
   ): Generator<PricingInput[], void, void> {
     const BATCH_SIZE = Math.min(
-      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '500', 10) || 500, 1),
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
       1000
     );
     let batch: PricingInput[] = [];
@@ -1029,7 +1036,7 @@ export class SyncOrchestrator {
     env?: Env
   ): Generator<GpuPricingInput[], void, void> {
     const BATCH_SIZE = Math.min(
-      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '500', 10) || 500, 1),
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
       1000
     );
     let batch: GpuPricingInput[] = [];
@@ -1095,7 +1102,7 @@ export class SyncOrchestrator {
     env?: Env
   ): Generator<GpuPricingInput[], void, void> {
     const BATCH_SIZE = Math.min(
-      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '500', 10) || 500, 1),
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
       1000
     );
     let batch: GpuPricingInput[] = [];
@@ -1151,7 +1158,7 @@ export class SyncOrchestrator {
     env?: Env
   ): Generator<G8PricingInput[], void, void> {
     const BATCH_SIZE = Math.min(
-      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '500', 10) || 500, 1),
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
       1000
     );
     let batch: G8PricingInput[] = [];
@@ -1204,7 +1211,7 @@ export class SyncOrchestrator {
     env?: Env
   ): Generator<VpuPricingInput[], void, void> {
     const BATCH_SIZE = Math.min(
-      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '500', 10) || 500, 1),
+      Math.max(parseInt(env?.SYNC_BATCH_SIZE || '100', 10) || 100, 1),
       1000
     );
     let batch: VpuPricingInput[] = [];
@@ -1903,7 +1910,8 @@ export class SyncOrchestrator {
               instanceTypeIds,
               regionIds,
               dbInstanceMap,
-              rawInstanceMap
+              rawInstanceMap,
+              this.env
             );
 
             // Process batches incrementally