Add plugable locking backend support. Add threadsafe file lock backend.

mayan/apps/lock_manager/tests/test_backends.py

@@ -0,0 +1,69 @@
+from __future__ import unicode_literals
+
+import time
+
+from django.test import TestCase
+from django.utils.module_loading import import_string
+
+from ..exceptions import LockError
+
+
+class FileLockTestCase(TestCase):
+    backend_string = 'lock_manager.backends.file_lock.FileLock'
+
+    def setUp(self):
+        self.locking_backend = import_string(self.backend_string)
+
+    def test_exclusive(self):
+        lock_1 = self.locking_backend.acquire_lock(name='test_lock_1')
+        with self.assertRaises(LockError):
+            self.locking_backend.acquire_lock(name='test_lock_1')
+
+        # Cleanup
+        lock_1.release()
+
+    def test_release(self):
+        lock_1 = self.locking_backend.acquire_lock(name='test_lock_1')
+        lock_1.release()
+        lock_2 = self.locking_backend.acquire_lock(name='test_lock_1')
+
+        # Cleanup
+        lock_2.release()
+
+    def test_timeout_expired(self):
+        self.locking_backend.acquire_lock(name='test_lock_1', timeout=1)
+
+        # lock_1 not release and not expired, should raise LockError
+        with self.assertRaises(LockError):
+            self.locking_backend.acquire_lock(name='test_lock_1')
+
+        time.sleep(2)
+        # lock_1 not release but has expired, should not raise LockError
+        lock_2 = self.locking_backend.acquire_lock(name='test_lock_1')
+
+        # Cleanup
+        lock_2.release()
+
+    def test_double_release(self):
+        lock_1 = self.locking_backend.acquire_lock(name='test_lock_1')
+        lock_1.release()
+
+    def test_release_expired(self):
+        lock_1 = self.locking_backend.acquire_lock(name='test_lock_1', timeout=1)
+        time.sleep(2)
+        lock_1.release()
+        # No exception is raised even though the lock has expired.
+        # The logic is that checking for expired locks during release is
+        # not necesary as any attempt by someone else to aquire the lock
+        # would be successfull, even after an extended lapse of time
+
+    def test_release_expired_reaquired(self):
+        time.sleep(2)
+        lock_2 = self.locking_backend.acquire_lock(name='test_lock_1', timeout=1)
+
+        # Cleanup
+        lock_2.release()
+
+
+class ModelLockTestCase(FileLockTestCase):
+    backend_string = 'lock_manager.backends.model_lock.ModelLock'