From 28f9f32d91bb045f0ef7b852d55a1f0523fa309e Mon Sep 17 00:00:00 2001
From: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>
Date: Mon, 30 Jul 2012 10:54:43 -0400
Subject: [PATCH] Add decorator helper for simple locks

---
 apps/lock_manager/decorators.py | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 apps/lock_manager/decorators.py

diff --git a/apps/lock_manager/decorators.py b/apps/lock_manager/decorators.py
new file mode 100644
index 0000000000..c98a7ae1c9
--- /dev/null
+++ b/apps/lock_manager/decorators.py
@@ -0,0 +1,33 @@
+from __future__ import absolute_import
+
+from functools import wraps
+
+from . import logger
+from . import Lock
+from .exceptions import LockError
+
+    
+def simple_locking(lock_id, expiration=None):
+    """
+    A decorator that wraps a function in a single lock getting algorithm
+    """
+    def inner_decorator(function):
+        def wrapper(*args, **kwargs):
+            try:
+                # Trying to acquire lock
+                lock = Lock.acquire_lock(lock_id, expiration)
+            except LockError:
+                # Unable to acquire lock
+                pass
+            except Exception:
+                # Unhandled error, release lock
+                lock.release()
+                raise
+            else:
+                # Lock acquired, proceed normally, release lock afterwards
+                logger.debug('acquired lock: %s' % lock_id)
+                result = function(*args, **kwargs)
+                lock.release()
+                return result
+        return wraps(function)(wrapper)
+    return inner_decorator