Separate base task from redis logic

celery_unique/__init__.py

@@ -0,0 +1,8 @@
+from celery_unique.core import unique_task_factory
+from celery_unique.core import UniqueTaskMixin
+
+
+__all__ = [
+    'unique_task_factory',
+    'UniqueTaskMixin',
+]

celery_unique/backends.py

@@ -0,0 +1,83 @@
+class BaseBackend:
+    """
+    Abstract reference backend.
+
+    An abstract backend that defines the interface that other backends must
+    implement.
+    """
+
+    def create_task_record(self, key, task_id, ttl):  # pragma: no cover
+        """
+        Creates a new record for the recently-published unique task.
+
+        :param str key: The unique key which identifies the task and its
+            configuration.
+        :param str task_id: The ID of the recently-published unique task.
+        :param ttl: The TTL for the record, which should be (approximately)
+            equal to the number of seconds remaining until the earliest time
+            that the task is expected to be executed by Celery.
+        """
+        raise NotImplementedError()
+
+    def get_task_id(self, key):  # pragma: no cover
+        """
+        Returns the task_id for an exiting task
+        """
+        raise NotImplementedError()
+
+    def revoke_extant_task(self, key):  # pragma: no cover
+        """
+        Deletes a task for a given key.
+
+        This deletes both the task and the cache entry.
+
+        :param key: The string (potentially) used by the backend as the key for
+            the record.
+        :type redis_key: str | unicode
+        """
+        raise NotImplementedError()
+
+
+class RedisBackend(BaseBackend):
+    """
+    A uniqueness backend that uses redis as a key/value store.
+
+    See :class:`~.BaseBackend` for documentation on indivitual methods.
+    """
+
+    def __init__(self, redis_client):
+        self.redis_client = redis_client
+
+    def get_task_id(self, key):
+        task_id = self.redis_client.get(key)
+        return task_id.decode() if task_id else None
+
+    def revoke_extant_task(self, key):
+        self.redis_client.delete(key)
+
+    def create_task_record(self, key, task_id, ttl):
+        self.redis_client.set(key, task_id, ex=ttl)
+
+
+class InMemoryBackend(BaseBackend):
+    """
+    Dummy backend which uses an in-memory store.
+
+    This is a dummy backend which uses an in-memory store. It is mostly
+    suitable for development and testing, and should not be using in production
+    environments.
+
+    See :class:`~.BaseBackend` for documentation on indivitual methods.
+    """
+
+    def __init__(self):
+        self.tasks = {}
+
+    def get_task_id(self, key):
+        return self.tasks.get(key, None)
+
+    def revoke_extant_task(self, key):
+        self.tasks.pop(key, None)
+
+    def create_task_record(self, key, task_id, ttl=None):
+        self.tasks[key] = task_id