fixed race condition, added systemctl integration

imap_idle_caldav/imap_client.py

@@ -10,8 +10,9 @@ from .config import ImapConfig
 
 log = logging.getLogger(__name__)
 
-IDLE_TIMEOUT = 300  # 5 minutes, per RFC 2177
-MAX_BACKOFF = 300   # 5 minutes max backoff
+IDLE_TIMEOUT = 300   # 5 minutes total IDLE before re-idle (RFC 2177)
+IDLE_POLL = 30       # check shutdown every 30 seconds within an IDLE
+MAX_BACKOFF = 300    # 5 minutes max backoff
 
 
 def run_idle_loop(
@@ -60,23 +61,31 @@ def _idle_session(
         while not (shutdown_event and shutdown_event.is_set()):
             client.idle()
             try:
-                responses = client.idle_check(timeout=IDLE_TIMEOUT)
+                # Poll in short intervals so we can check shutdown_event
+                # between iterations, rather than blocking for the full
+                # IDLE_TIMEOUT (which causes a hang on Ctrl-C).
+                responses = []
+                deadline = time.monotonic() + IDLE_TIMEOUT
+                while time.monotonic() < deadline:
+                    if shutdown_event and shutdown_event.is_set():
+                        break
+                    chunk = client.idle_check(timeout=IDLE_POLL)
+                    if chunk:
+                        responses.extend(chunk)
+                        break  # got activity, exit IDLE to process
             finally:
-                client.idle_done()
+                done_result = client.idle_done()
+                if done_result and done_result[0]:
+                    responses.extend(done_result[0])
 
             if shutdown_event and shutdown_event.is_set():
                 break
 
-            # Check if any EXISTS response indicates new mail
-            has_new = any(
-                isinstance(resp, tuple) and len(resp) >= 2 and resp[1] == b"EXISTS"
-                for resp in responses
-            )
-
-            if not has_new:
-                continue
-
-            # Fetch new messages since last_uid
+            # Always search for new UIDs, not just when we see EXISTS.
+            # A message can arrive between idle_done() and the next idle()
+            # call — the server already sent EXISTS while we weren't
+            # listening, so we'd never see it.  The UID SEARCH is cheap
+            # and eliminates this race condition entirely.
             new_uids = _fetch_new_uids(client, last_uid)
             if not new_uids:
                 continue