Replace django-db-locking with Redis locks

README.md

@@ -17,6 +17,19 @@ common data structures and logic for all child triggers. The only thing a
 child should have to do is override the `_process` method and set `typed` to
 a unique slug.
 
+Settings
+--------
+
+The following settings are used:
+- `DJTRIGGERS_TRIES_BEFORE_WARNING`: the number of times a task can be retried before a warning is logged. Defaults to 3.
+- `DJTRIGGERS_TRIES_BEFORE_ERROR`: the number of times a task can be retried before an error is raised. Defaults to 5.
+- `DJTRIGGERS_ASYNC_HANDLING`: whether processing should be asynchronous (using Celery) or not. Default to False.
+- `DJTRIGGERS_CELERY_TASK_MAX_RETRIES`: the number of times the Celery task for a trigger should be retried. Defaults to 0.
+- `DJTRIGGERS_TYPE_TO_TABLE`: mapping of trigger types to database tables. Used for the cleanup script. Defaults to `{}`.
+- `DJTRIGGERS_REDIS_URL`: the URL of the Redis instance used for locks.
+- `DJTRIGGERS_LOGGERS`: separate logging config for django-triggers. Defaults to `()`.
+
+
 Examples
 --------
 

djtriggers/__init__.py

@@ -1 +1 @@
-__version__ = '2.0.13'
+__version__ = '2.1.0'

djtriggers/models.py

@@ -1,13 +1,13 @@
 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
 from django.db.models.base import ModelBase
 from django.utils import timezone
 
-from locking.exceptions import AlreadyLocked
-from locking.models import NonBlockingLock
-
 from .managers import TriggerManager
 from .exceptions import ProcessLaterError
 from .loggers import get_logger
@@ -103,7 +103,8 @@ 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 NonBlockingLock.objects.acquire_lock(self):
+            with Lock(redis=Redis.from_url(settings.DJTRIGGERS_REDIS_URL), name='djtriggers-' + str(self.id),
+                      blocking_timeout=0):
                 if logger:
                     self.logger = get_logger(logger)
                 now = timezone.now()
@@ -123,7 +124,7 @@ def process(self, force=False, logger=None, dictionary=None, use_statsd=False):
                 except Exception as e:
                     self._handle_execution_failure(e, use_statsd)
                     raise
-        except AlreadyLocked:
+        except LockError:
             pass
 
     def _process(self, dictionary):

djtriggers/tests/test_logic.py

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

djtriggers/tests/test_models.py

@@ -1,12 +1,12 @@
 from datetime import timedelta
 from logging import ERROR, WARNING
+from redis.exceptions import LockError
 
 from mock import patch
 from pytest import raises
 from django.test import override_settings
 from django.test.testcases import TestCase
 from django.utils import timezone
-from locking.models import NonBlockingLock
 
 from djtriggers.exceptions import ProcessLaterError
 from djtriggers.loggers.base import TriggerLogger
@@ -141,7 +141,8 @@ def test_handle_execution_failure_use_statsd(self, mock_statsd):
     @patch.object(TriggerLogger, 'log_result')
     def test_process(self, mock_logger):
         trigger = DummyTriggerFactory()
-        trigger.process()
+        with patch('djtriggers.models.Lock'):
+            trigger.process()
 
         mock_logger.assert_called_with(trigger, trigger._process({}))
 
@@ -154,20 +155,21 @@ 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):
+        with raises(ProcessLaterError), patch('djtriggers.models.Lock'):
             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):
+        with patch.object(trigger, '_process', side_effect=Exception), raises(Exception), \
+                patch('djtriggers.models.Lock'):
             trigger.process()
         assert mock_fail.called
 
     @patch.object(TriggerLogger, 'log_result')
     def test_process_locked(self, mock_logger):
         trigger = DummyTriggerFactory()
-        with NonBlockingLock.objects.acquire_lock(trigger):
+        with patch('djtriggers.models.Lock', side_effect=LockError):
             trigger.process()
 
         assert not mock_logger.called

requirements/requirements.txt

@@ -1,4 +1,4 @@
 Django>=2.1.5,<2.3
 celery>=4.0.0
 python-dateutil
-django-db-locking>=2.0.4
+redis>=3.0.0

settings_test.py

@@ -1,8 +1,9 @@
 SECRET_KEY = 'fake-key'
 
+DJTRIGGERS_REDIS_URL = 'redis://localhost:6379/0'
+
 INSTALLED_APPS = [
     'djtriggers',
-    'locking'
 ]
 
 DATABASES = {