Use utility for redis locks

This makes it easier to test.

djtriggers/__init__.py

@@ -1 +1 @@
-__version__ = '2.1.0'
+__version__ = '2.1.1'

djtriggers/locking.py

@@ -0,0 +1,25 @@
+from contextlib import contextmanager
+from django.conf import settings
+from redis import Redis
+from redis.lock import Lock
+from typing import Generator
+
+
+@contextmanager
+def redis_lock(name: str, **kwargs) -> Generator:
+    """
+    Acquire a Redis lock. This is a wrapper around redis.lock.Lock(), that also works in tests (there, the lock is
+    always granted without any checks).
+
+    Relevant kwargs are:
+     - blocking_timeout: how many seconds to try to acquire the lock. Use 0 for a non-blocking lock.
+       The default is None, which means we wait forever.
+     - timeout: how many seconds to keep the lock for. The default is None, which means it remains locked forever.
+
+    Raises redis.exceptions.LockError if the lock couldn't be acquired or released.
+    """
+    if settings.DJTRIGGERS_REDIS_URL.startswith('redis'):  # pragma: no cover
+        with Lock(redis=Redis.from_url(settings.DJTRIGGERS_REDIS_URL), name=name, **kwargs):
+            yield
+    else:
+        yield

djtriggers/models.py

@@ -1,7 +1,5 @@
 from logging import ERROR, WARNING
-from redis import Redis
 from redis.exceptions import LockError
-from redis.lock import Lock
 
 from django.conf import settings
 from django.db import models
@@ -10,6 +8,7 @@
 
 from .managers import TriggerManager
 from .exceptions import ProcessLaterError
+from .locking import redis_lock
 from .loggers import get_logger
 from .loggers.base import TriggerLogger
 
@@ -103,8 +102,7 @@ def process(self, force=False, logger=None, dictionary=None, use_statsd=False):
         # The lock assures no two tasks can process a trigger simultaneously.
         # The check for date_processed assures a trigger is not executed multiple times.
         try:
-            with Lock(redis=Redis.from_url(settings.DJTRIGGERS_REDIS_URL), name='djtriggers-' + str(self.id),
-                      blocking_timeout=0):
+            with redis_lock('djtriggers-' + str(self.id), blocking_timeout=0):
                 if logger:
                     self.logger = get_logger(logger)
                 now = timezone.now()

djtriggers/tests/test_logic.py

@@ -15,15 +15,13 @@ def setUp(self):
 
     def test_process_after_now(self):
         trigger = DummyTriggerFactory()
-        with patch('djtriggers.models.Lock'):
-            process_triggers()
+        process_triggers()
         trigger.refresh_from_db()
         assert trigger.date_processed is not None
 
     def test_process_after_yesterday(self):
         trigger = DummyTriggerFactory(process_after=self.now - timedelta(days=1))
-        with patch('djtriggers.models.Lock'):
-            process_triggers()
+        process_triggers()
         trigger.refresh_from_db()
         assert trigger.date_processed is not None
 

djtriggers/tests/test_models.py

@@ -141,8 +141,7 @@ def test_handle_execution_failure_use_statsd(self, mock_statsd):
     @patch.object(TriggerLogger, 'log_result')
     def test_process(self, mock_logger):
         trigger = DummyTriggerFactory()
-        with patch('djtriggers.models.Lock'):
-            trigger.process()
+        trigger.process()
 
         mock_logger.assert_called_with(trigger, trigger._process({}))
 
@@ -155,21 +154,20 @@ def test_process_already_processed(self, mock_logger):
 
     def test_process_process_later(self):
         trigger = DummyTriggerFactory(process_after=timezone.now() + timedelta(minutes=1))
-        with raises(ProcessLaterError), patch('djtriggers.models.Lock'):
+        with raises(ProcessLaterError):
             trigger.process()
 
     @patch.object(Trigger, '_handle_execution_failure')
     def test_process_exception_during_execution(self, mock_fail):
         trigger = DummyTriggerFactory()
-        with patch.object(trigger, '_process', side_effect=Exception), raises(Exception), \
-                patch('djtriggers.models.Lock'):
+        with patch.object(trigger, '_process', side_effect=Exception), raises(Exception):
             trigger.process()
         assert mock_fail.called
 
     @patch.object(TriggerLogger, 'log_result')
     def test_process_locked(self, mock_logger):
         trigger = DummyTriggerFactory()
-        with patch('djtriggers.models.Lock', side_effect=LockError):
+        with patch('djtriggers.models.redis_lock', side_effect=LockError):
             trigger.process()
 
         assert not mock_logger.called

settings_test.py

@@ -1,6 +1,6 @@
 SECRET_KEY = 'fake-key'
 
-DJTRIGGERS_REDIS_URL = 'redis://localhost:6379/0'
+DJTRIGGERS_REDIS_URL = ''
 
 INSTALLED_APPS = [
     'djtriggers',

setup.py

@@ -32,6 +32,7 @@
     license='BSD',
     description='Framework to create and process triggers.',
     long_description=open('README.md', 'r').read(),
+    long_description_content_type='text/markdown',
     author='Unleashed NV',
     author_email='[email protected]',
     packages=find_packages('.'),