feat(performance): Add async utility functions and filesystem utilities

- Implemented async utilities including delay, retryWithBackoff, withTimeout, parallelLimit, debounceAsync, AsyncMutex, and CircuitBreaker.
- Created tests for async utilities to ensure functionality and reliability.
- Developed AsyncFileSystem class with methods for file and directory operations, including ensureDir, readFile, writeFile, remove, and more.
- Added tests for filesystem utilities to validate file operations and error handling.

ts/proxies/http-proxy/certificate-manager.ts

@@ -2,6 +2,7 @@ import * as plugins from '../../plugins.js';
 import * as fs from 'fs';
 import * as path from 'path';
 import { fileURLToPath } from 'url';
+import { AsyncFileSystem } from '../../core/utils/fs-utils.js';
 import { type IHttpProxyOptions, type ICertificateEntry, type ILogger, createLogger } from './models/types.js';
 import type { IRouteConfig } from '../smart-proxy/models/route-types.js';
 
@@ -17,6 +18,7 @@ export class CertificateManager {
   private certificateStoreDir: string;
   private logger: ILogger;
   private httpsServer: plugins.https.Server | null = null;
+  private initialized = false;
 
   constructor(private options: IHttpProxyOptions) {
     this.certificateStoreDir = path.resolve(options.acme?.certificateStore || './certs');
@@ -24,6 +26,15 @@ export class CertificateManager {
     
     this.logger.warn('CertificateManager is deprecated - use SmartCertManager instead');
     
+    // Initialize synchronously for backward compatibility but log warning
+    this.initializeSync();
+  }
+
+  /**
+   * Synchronous initialization for backward compatibility
+   * @deprecated This uses sync filesystem operations which block the event loop
+   */
+  private initializeSync(): void {
     // Ensure certificate store directory exists
     try {
       if (!fs.existsSync(this.certificateStoreDir)) {
@@ -36,9 +47,28 @@ export class CertificateManager {
     
     this.loadDefaultCertificates();
   }
+
+  /**
+   * Async initialization - preferred method
+   */
+  public async initialize(): Promise<void> {
+    if (this.initialized) return;
+    
+    // Ensure certificate store directory exists
+    try {
+      await AsyncFileSystem.ensureDir(this.certificateStoreDir);
+      this.logger.info(`Ensured certificate store directory: ${this.certificateStoreDir}`);
+    } catch (error) {
+      this.logger.warn(`Failed to create certificate store directory: ${error}`);
+    }
+    
+    await this.loadDefaultCertificatesAsync();
+    this.initialized = true;
+  }
   
   /**
    * Loads default certificates from the filesystem
+   * @deprecated This uses sync filesystem operations which block the event loop
    */
   public loadDefaultCertificates(): void {
     const __dirname = path.dirname(fileURLToPath(import.meta.url));
@@ -49,7 +79,28 @@ export class CertificateManager {
         key: fs.readFileSync(path.join(certPath, 'key.pem'), 'utf8'),
         cert: fs.readFileSync(path.join(certPath, 'cert.pem'), 'utf8')
       };
-      this.logger.info('Loaded default certificates from filesystem');
+      this.logger.info('Loaded default certificates from filesystem (sync - deprecated)');
+    } catch (error) {
+      this.logger.error(`Failed to load default certificates: ${error}`);
+      this.generateSelfSignedCertificate();
+    }
+  }
+
+  /**
+   * Loads default certificates from the filesystem asynchronously
+   */
+  public async loadDefaultCertificatesAsync(): Promise<void> {
+    const __dirname = path.dirname(fileURLToPath(import.meta.url));
+    const certPath = path.join(__dirname, '..', '..', '..', 'assets', 'certs');
+
+    try {
+      const [key, cert] = await Promise.all([
+        AsyncFileSystem.readFile(path.join(certPath, 'key.pem')),
+        AsyncFileSystem.readFile(path.join(certPath, 'cert.pem'))
+      ]);
+      
+      this.defaultCertificates = { key, cert };
+      this.logger.info('Loaded default certificates from filesystem (async)');
     } catch (error) {
       this.logger.error(`Failed to load default certificates: ${error}`);
       this.generateSelfSignedCertificate();