From 4747c039084167143b9c567c9b4a69efef28c1f1 Mon Sep 17 00:00:00 2001
From: Jonathan Weth <git@jonathanweth.de>
Date: Thu, 30 Jul 2020 16:09:10 +0200
Subject: Stop service if lock file was removed

---
 lock.py    | 25 +++++++++++++++++++++++++
 service.py | 24 ++++++++++++++++--------
 2 files changed, 41 insertions(+), 8 deletions(-)
 create mode 100644 lock.py

diff --git a/lock.py b/lock.py
new file mode 100644
index 0000000..8be0651
--- /dev/null
+++ b/lock.py
@@ -0,0 +1,25 @@
+import os
+import tempfile
+
+lock_dir_path = os.path.join(tempfile.gettempdir(), "rwa-session-service")
+lock_file_path = os.path.join(lock_dir_path, "rwa-session-service.lock")
+
+
+def lock():
+    """Create lock file."""
+    os.makedirs(lock_dir_path, exist_ok=True)
+    with open(lock_file_path, "w") as f:
+        f.write("lock")
+
+
+def is_locked():
+    """Check if the lock file exists."""
+    return os.path.exists(lock_file_path)
+
+
+def unlock():
+    """Remove the lock file."""
+    try:
+        os.remove(lock_file_path)
+    except FileNotFoundError:
+        pass
diff --git a/service.py b/service.py
index 339008e..daa35e5 100755
--- a/service.py
+++ b/service.py
@@ -14,6 +14,7 @@ import dbus.mainloop.glib
 import dbus.service
 from gi.repository import GLib
 
+from lock import is_locked, lock, unlock
 from session import Session
 from trigger import TriggerServerThread
 
@@ -41,6 +42,9 @@ class RWAService(dbus.service.Object):
         self.bus = dbus.SessionBus()
         name = dbus.service.BusName("org.ArcticaProject.RWA", bus=self.bus)
 
+        self.check_lock_thread = Thread(target=self._check_lock)
+        self.check_lock_thread.start()
+
         self.trigger_service = TriggerServerThread(self._trigger)
         self.trigger_service.start()
 
@@ -219,6 +223,15 @@ class RWAService(dbus.service.Object):
         self.trigger_service.shutdown()
         self.loop.quit()
 
+    def _check_lock(self):
+        """Check if lock file exists."""
+        while True:
+            if not is_locked():
+                logging.error("The lock file was removed, so stop this service.")
+                self._stop_all()
+                break
+            time.sleep(1)
+
 
 def str2bool(v: Union[str, bool, int]) -> bool:
     """Return true or false if the given string can be interpreted as a boolean otherwise raise an exception."""
@@ -233,18 +246,13 @@ def str2bool(v: Union[str, bool, int]) -> bool:
 
 
 if __name__ == "__main__":
-    lock_dir_path = os.path.join(tempfile.gettempdir(), "rwa-session-service")
-    os.makedirs(lock_dir_path, exist_ok=True)
-    lock_file_path = os.path.join(lock_dir_path, "rwa-session-service.lock")
-
     # Check for lock file
-    if os.path.exists(lock_file_path):
+    if is_locked():
         logging.error("The service is already running.")
         exit(1)
 
     # Create lock file
-    with open(lock_file_path, "w") as f:
-        f.write("lock")
+    lock()
 
     parser = argparse.ArgumentParser(description="D-Bus Session Service for RWA")
     parser.add_argument(
@@ -289,4 +297,4 @@ if __name__ == "__main__":
     loop.run()
 
     logging.info("Remove lock file ...")
-    os.remove(lock_file_path)
+    unlock()
-- 
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