Since this thing is on the innerwebs I suppose it should have a

[python_utils.git] / lockfile.py

diff --git a/lockfile.py b/lockfile.py
index 6993cb84d5e88f8dd6fc1a9d28a849f0cfd28713..ae48e576ccbcfb123ddfcde6ab32c71dfc381ad0 100644 (file)
--- a/lockfile.py
+++ b/lockfile.py
@@ -1,7 +1,11 @@
 #!/usr/bin/env python3
 
+# © Copyright 2021-2022, Scott Gasch
+
 """File-based locking helper."""
 
+from __future__ import annotations
+import contextlib
 import datetime
 import json
 import logging
@@ -10,7 +14,7 @@ import signal
 import sys
 import warnings
 from dataclasses import dataclass
-from typing import Optional
+from typing import Literal, Optional
 
 import config
 import datetime_utils
@@ -42,7 +46,7 @@ class LockFileContents:
     expiration_timestamp: Optional[float]
 
 
-class LockFile(object):
+class LockFile(contextlib.AbstractContextManager):
     """A file locking mechanism that has context-manager support so you
     can use it in a with statement.  e.g.
 
@@ -131,16 +135,18 @@ class LockFile(object):
         logger.warning(msg)
         raise LockFileException(msg)
 
-    def __exit__(self, _, value, traceback):
+    def __exit__(self, _, value, traceback) -> Literal[False]:
         if self.locktime:
             ts = datetime.datetime.now().timestamp()
             duration = ts - self.locktime
             if duration >= config.config['lockfile_held_duration_warning_threshold_sec']:
-                str_duration = datetime_utils.describe_duration_briefly(duration)
+                # Note: describe duration briefly only does 1s granularity...
+                str_duration = datetime_utils.describe_duration_briefly(int(duration))
                 msg = f'Held {self.lockfile} for {str_duration}'
                 logger.warning(msg)
                 warnings.warn(msg, stacklevel=2)
         self.release()
+        return False
 
     def __del__(self):
         if self.is_locked:
@@ -176,16 +182,21 @@ class LockFile(object):
                     try:
                         os.kill(contents.pid, 0)
                     except OSError:
-                        msg = f'Lockfile {self.lockfile}\'s pid ({contents.pid}) is stale; force acquiring'
-                        logger.warning(msg)
+                        logger.warning(
+                            'Lockfile %s\'s pid (%d) is stale; force acquiring...',
+                            self.lockfile,
+                            contents.pid,
+                        )
                         self.release()
 
                     # Has the lock expiration expired?
                     if contents.expiration_timestamp is not None:
                         now = datetime.datetime.now().timestamp()
                         if now > contents.expiration_timestamp:
-                            msg = f'Lockfile {self.lockfile} expiration time has passed; force acquiring'
-                            logger.warning(msg)
+                            logger.warning(
+                                'Lockfile %s\'s expiration time has passed; force acquiring',
+                                self.lockfile,
+                            )
                             self.release()
         except Exception:
-            pass
+            pass  # If the lockfile doesn't exist or disappears, good.