feat(worker): Listen for proxy_added notifications

- Workers now use PostgreSQL LISTEN/NOTIFY to wake up immediately when proxies are added
- Added trigger on proxies table to NOTIFY 'proxy_added' when active proxy inserted/updated
- Falls back to 30s polling if LISTEN fails

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/migrations/082_proxy_notification_trigger.sql

@@ -0,0 +1,27 @@
+-- Migration: 082_proxy_notification_trigger
+-- Date: 2024-12-11
+-- Description: Add PostgreSQL NOTIFY trigger to alert workers when proxies are added
+
+-- Create function to notify workers when active proxy is added/activated
+CREATE OR REPLACE FUNCTION notify_proxy_added()
+RETURNS TRIGGER AS $$
+BEGIN
+  -- Only notify if proxy is active
+  IF NEW.active = true THEN
+    PERFORM pg_notify('proxy_added', NEW.id::text);
+  END IF;
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+-- Drop existing trigger if any
+DROP TRIGGER IF EXISTS proxy_added_trigger ON proxies;
+
+-- Create trigger on insert and update of active column
+CREATE TRIGGER proxy_added_trigger
+AFTER INSERT OR UPDATE OF active ON proxies
+FOR EACH ROW
+EXECUTE FUNCTION notify_proxy_added();
+
+COMMENT ON FUNCTION notify_proxy_added() IS
+'Sends PostgreSQL NOTIFY to proxy_added channel when an active proxy is added or activated. Workers LISTEN on this channel to wake up immediately.';

backend/src/tasks/task-worker.ts

@@ -117,40 +117,79 @@ export class TaskWorker {
    * Called once on worker startup before processing any tasks.
    *
    * IMPORTANT: Proxies are REQUIRED. Workers will wait until proxies are available.
+   * Workers listen for PostgreSQL NOTIFY 'proxy_added' to wake up immediately when proxies are added.
    */
   private async initializeStealth(): Promise<void> {
     const MAX_WAIT_MINUTES = 60;
-    const RETRY_INTERVAL_MS = 30000; // 30 seconds
-    const maxAttempts = (MAX_WAIT_MINUTES * 60 * 1000) / RETRY_INTERVAL_MS;
+    const POLL_INTERVAL_MS = 30000; // 30 seconds fallback polling
+    const maxAttempts = (MAX_WAIT_MINUTES * 60 * 1000) / POLL_INTERVAL_MS;
     let attempts = 0;
+    let notifyClient: any = null;
 
-    while (attempts < maxAttempts) {
-      try {
-        // Load proxies from database
-        await this.crawlRotator.initialize();
-
-        const stats = this.crawlRotator.proxy.getStats();
-        if (stats.activeProxies > 0) {
-          console.log(`[TaskWorker] Loaded ${stats.activeProxies} proxies (${stats.avgSuccessRate.toFixed(1)}% avg success rate)`);
-
-          // Wire rotator to Dutchie client - proxies will be used for ALL requests
-          setCrawlRotator(this.crawlRotator);
-
-          console.log(`[TaskWorker] Stealth initialized: ${this.crawlRotator.userAgent.getCount()} fingerprints, proxy REQUIRED for all requests`);
-          return;
-        }
-
-        attempts++;
-        console.log(`[TaskWorker] No active proxies available (attempt ${attempts}). Waiting ${RETRY_INTERVAL_MS / 1000}s for proxies to be added...`);
-        await this.sleep(RETRY_INTERVAL_MS);
-      } catch (error: any) {
-        attempts++;
-        console.log(`[TaskWorker] Error loading proxies (attempt ${attempts}): ${error.message}. Retrying in ${RETRY_INTERVAL_MS / 1000}s...`);
-        await this.sleep(RETRY_INTERVAL_MS);
-      }
+    // Set up PostgreSQL LISTEN for proxy notifications
+    try {
+      notifyClient = await this.pool.connect();
+      await notifyClient.query('LISTEN proxy_added');
+      console.log(`[TaskWorker] Listening for proxy_added notifications...`);
+    } catch (err: any) {
+      console.log(`[TaskWorker] Could not set up LISTEN (will poll): ${err.message}`);
     }
 
-    throw new Error(`No active proxies available after waiting ${MAX_WAIT_MINUTES} minutes. Add proxies to the database.`);
+    // Create a promise that resolves when notified
+    let notifyResolve: (() => void) | null = null;
+    if (notifyClient) {
+      notifyClient.on('notification', (msg: any) => {
+        if (msg.channel === 'proxy_added') {
+          console.log(`[TaskWorker] Received proxy_added notification!`);
+          if (notifyResolve) notifyResolve();
+        }
+      });
+    }
+
+    try {
+      while (attempts < maxAttempts) {
+        try {
+          // Load proxies from database
+          await this.crawlRotator.initialize();
+
+          const stats = this.crawlRotator.proxy.getStats();
+          if (stats.activeProxies > 0) {
+            console.log(`[TaskWorker] Loaded ${stats.activeProxies} proxies (${stats.avgSuccessRate.toFixed(1)}% avg success rate)`);
+
+            // Wire rotator to Dutchie client - proxies will be used for ALL requests
+            setCrawlRotator(this.crawlRotator);
+
+            console.log(`[TaskWorker] Stealth initialized: ${this.crawlRotator.userAgent.getCount()} fingerprints, proxy REQUIRED for all requests`);
+            return;
+          }
+
+          attempts++;
+          console.log(`[TaskWorker] No active proxies available (attempt ${attempts}). Waiting for proxies...`);
+
+          // Wait for either notification or timeout
+          await new Promise<void>((resolve) => {
+            notifyResolve = resolve;
+            setTimeout(resolve, POLL_INTERVAL_MS);
+          });
+        } catch (error: any) {
+          attempts++;
+          console.log(`[TaskWorker] Error loading proxies (attempt ${attempts}): ${error.message}. Retrying...`);
+          await this.sleep(POLL_INTERVAL_MS);
+        }
+      }
+
+      throw new Error(`No active proxies available after waiting ${MAX_WAIT_MINUTES} minutes. Add proxies to the database.`);
+    } finally {
+      // Clean up LISTEN connection
+      if (notifyClient) {
+        try {
+          await notifyClient.query('UNLISTEN proxy_added');
+          notifyClient.release();
+        } catch {
+          // Ignore cleanup errors
+        }
+      }
+    }
   }
 
   /**