Use file existence for registry mutex

stack_orchestrator/deploy/webapp/registry_mutex.py

@@ -1,13 +1,52 @@
 import fcntl
 from functools import wraps
+import os
 import time
 
 # Define default file path for the lock
 DEFAULT_LOCK_FILE_PATH = "/tmp/registry_mutex_lock_file"
-
+LOCK_TIMEOUT = 30
 LOCK_RETRY_INTERVAL = 3
 
 
+def acquire_lock(lock_file_path, timeout):
+    while True:
+        try:
+            # Check if lock file exists and is potentially stale
+            if os.path.exists(lock_file_path):
+                with open(lock_file_path, 'r') as lock_file:
+                    timestamp = float(lock_file.read().strip())
+
+                # If lock is stale, remove the lock file
+                if time.time() - timestamp > timeout:
+                    print(f"Stale lock detected, removing lock file {lock_file_path}")
+                    os.remove(lock_file_path)
+                else:
+                    print(f"Lock file {lock_file_path} exists and is recent, waiting...")
+                    time.sleep(LOCK_RETRY_INTERVAL)
+                    continue
+
+            # Try to create a new lock file with the current timestamp
+            fd = os.open(lock_file_path, os.O_CREAT | os.O_EXCL | os.O_RDWR)
+            with os.fdopen(fd, 'w') as lock_file:
+                lock_file.write(str(time.time()))
+            print(f"Registry lock acquired, {lock_file_path}")
+
+            # Lock successfully acquired
+            return
+
+        except FileExistsError:
+            print(f"Lock file {lock_file_path} exists, waiting...")
+            time.sleep(LOCK_RETRY_INTERVAL)
+
+def release_lock(lock_file_path):
+    try:
+        os.remove(lock_file_path)
+        print(f"Registry lock released, {lock_file_path}")
+    except FileNotFoundError:
+        # Lock file already removed
+        pass
+
 def registry_mutex():
     def decorator(func):
         @wraps(func)
@@ -16,27 +55,13 @@ def registry_mutex():
             if self.mutex_lock_file:
                 lock_file_path = self.mutex_lock_file
 
-            result = None
-            with open(lock_file_path, 'w') as lock_file:
-                while True:
+            # Acquire the lock before running the function
+            acquire_lock(lock_file_path, LOCK_TIMEOUT)
             try:
-                        # Try to acquire the lock
-                        fcntl.flock(lock_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
-                        print(f"Registry lock acquired, {lock_file_path}")
-
-                        # Call the actual function
-                        result = func(self, *args, **kwargs)
-                        break
-                    except BlockingIOError:
-                        # Retry on error
-                        print(f"Not able to acquire lock on {lock_file_path}, retrying in {LOCK_RETRY_INTERVAL}s...")
-                        time.sleep(LOCK_RETRY_INTERVAL)
-
-                # Always release the lock
-                fcntl.flock(lock_file, fcntl.LOCK_UN)
-                print(f"Registry lock released, {lock_file_path}")
-
-            return result
+                return func(self, *args, **kwargs)
+            finally:
+                # Release the lock after the function completes
+                release_lock(lock_file_path)
 
         return wrapper