mailu-sync: cap wait in listener

services/mailu/scripts/mailu_sync_listener.py

@@ -1,5 +1,6 @@
 import http.server
 import json
+import os
 import subprocess
 import threading
 
@@ -7,15 +8,17 @@ from time import time
 
 # Simple debounce to avoid hammering on bursts
 MIN_INTERVAL_SECONDS = 10
+WAIT_TIMEOUT_SECONDS = float(os.environ.get("MAILU_SYNC_WAIT_TIMEOUT_SEC", "20"))
 last_run = 0.0
 lock = threading.Lock()
 sync_done = threading.Event()
 sync_done.set()
 sync_running = False
+last_rc = None
 
 
 def _run_sync_blocking() -> int:
-    global last_run, sync_running
+    global last_run, sync_running, last_rc
     with lock:
         if sync_running:
             return 0
@@ -27,6 +30,7 @@ def _run_sync_blocking() -> int:
         proc = subprocess.run(["python", "/app/sync.py"], check=False)
         rc = int(proc.returncode)
         print(f"mailu-sync-listener: sync completed rc={rc}", flush=True)
+        last_rc = rc
         return rc
     finally:
         with lock:
@@ -66,16 +70,20 @@ class Handler(http.server.BaseHTTPRequestHandler):
         if wait:
             with lock:
                 already_running = sync_running
-            if already_running:
-                sync_done.wait(timeout=120)
-                with lock:
-                    still_running = sync_running
-                self.send_response(200 if not still_running else 503)
-                self.end_headers()
-                return
 
-            rc = _run_sync_blocking()
+            if not already_running:
-            self.send_response(200 if rc == 0 else 500)
+                _trigger_sync_async()
+
+            sync_done.wait(timeout=WAIT_TIMEOUT_SECONDS)
+            with lock:
+                still_running = sync_running
+                rc = last_rc
+
+            if still_running:
+                # Avoid blocking callers while a sync is in flight.
+                self.send_response(200)
+            else:
+                self.send_response(200 if rc == 0 else 500)
             self.end_headers()
             return