RedisBackend class reference
In most cases, you don't need to interact with backends directly, as they are used internally by Queue. For usual usage, see the Queue reference and Getting Started guides to learn how to configure and use different backends.
If you need to implement a custom backend or want to understand how existing backends work, here's the reference information for the backend classes.
RedisBackend(
url: str = "redis://127.0.0.1:6379",
consumer_group: str = "workers",
ttl: int | None = 24 * 60 * 60,
**kwargs: Any,
)
Bases: Backend
Source code in src/sheppy/backend/redis.py
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39 | def __init__(
self,
url: str = "redis://127.0.0.1:6379",
consumer_group: str = "workers",
ttl: int | None = 24 * 60 * 60, # 24 hours
**kwargs: Any
):
self.url = url
self.consumer_group = consumer_group
self.consumer_name = generate_unique_worker_id("consumer")
self.ttl = ttl
self.redis_kwargs = kwargs
self._client: redis.Redis | None = None
self._pool: redis.ConnectionPool | None = None
self._pending_messages: dict[str, tuple[str, str]] = {} # task_id -> (queue_name, message_id)
self._initialized_groups: set[str] = set()
self._results_stream_ttl = 60
|
consumer_group = consumer_group
consumer_name = generate_unique_worker_id('consumer')
Source code in src/sheppy/backend/redis.py
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55 | async def connect(self) -> None:
try:
self._pool = redis.ConnectionPool.from_url(
self.url,
#decode_responses=self.decode_responses,
#max_connections=self.max_connections,
#protocol=3, # enable RESP version 3
**self.redis_kwargs
)
self._client = redis.Redis.from_pool(self._pool)
await self._client.ping()
except Exception as e:
self._client = None
self._pool = None
raise BackendError(f"Failed to connect to Redis: {e}") from e
|
Source code in src/sheppy/backend/redis.py
| async def disconnect(self) -> None:
if self._client:
await self._client.aclose()
self._client = None
self._pool = None
self._pending_messages.clear()
self._initialized_groups.clear()
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append(
queue_name: str,
tasks: list[dict[str, Any]],
unique: bool = True,
) -> list[bool]
Add new tasks to be processed.
Source code in src/sheppy/backend/redis.py
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141 | async def append(self, queue_name: str, tasks: list[dict[str, Any]], unique: bool = True) -> list[bool]:
"""Add new tasks to be processed."""
tasks_metadata_key = self._tasks_metadata_key(queue_name)
pending_tasks_key = self._pending_tasks_key(queue_name)
await self._ensure_consumer_group(pending_tasks_key)
if unique:
success = await self._create_tasks(queue_name, tasks)
to_queue = [t for i, t in enumerate(tasks) if success[i]]
else:
success = [True] * len(tasks)
to_queue = tasks
try:
async with self.client.pipeline(transaction=False) as pipe:
for t in to_queue:
_task_data = json.dumps(t)
if not unique:
pipe.set(f"{tasks_metadata_key}:{t['id']}", _task_data)
# add to pending stream
pipe.xadd(pending_tasks_key, {"data": _task_data})
await pipe.execute()
except Exception as e:
raise BackendError(f"Failed to enqueue task: {e}") from e
return success
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pop(
queue_name: str,
limit: int = 1,
timeout: float | None = None,
) -> list[dict[str, Any]]
Get next tasks to process. Used primarily by workers.
Source code in src/sheppy/backend/redis.py
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177 | async def pop(self, queue_name: str, limit: int = 1, timeout: float | None = None) -> list[dict[str, Any]]:
"""Get next tasks to process. Used primarily by workers."""
pending_tasks_key = self._pending_tasks_key(queue_name)
await self._ensure_consumer_group(pending_tasks_key)
try:
result = await self.client.xreadgroup(
groupname=self.consumer_group,
consumername=self.consumer_name,
streams={pending_tasks_key: ">"}, # ">" means only new messages (not delivered to other consumers)
count=limit,
block=None if timeout is None or timeout == 0 else int(timeout * 1000)
)
if not result:
return []
messages = result[0][1] # [['stream-name', [(message_id, dict_data)]]]
if not messages:
return []
tasks = []
for message_id, fields in messages:
task_data = json.loads(fields[b"data"])
# store message_id for acknowledge()
self._pending_messages[task_data["id"]] = (queue_name, message_id.decode())
tasks.append(task_data)
return tasks
except Exception as e:
raise BackendError(f"Failed to dequeue task: {e}") from e
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get_pending(
queue_name: str, count: int = 1
) -> list[dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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186 | async def get_pending(self, queue_name: str, count: int = 1) -> list[dict[str, Any]]:
pending_tasks_key = self._pending_tasks_key(queue_name)
await self._ensure_consumer_group(pending_tasks_key)
messages = await self.client.xrange(pending_tasks_key, count=count)
return [json.loads(fields[b"data"]) for _message_id, fields in messages]
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size(queue_name: str) -> int
Source code in src/sheppy/backend/redis.py
| async def size(self, queue_name: str) -> int:
pending_tasks_key = self._pending_tasks_key(queue_name)
await self._ensure_consumer_group(pending_tasks_key)
return int(await self.client.xlen(pending_tasks_key))
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clear(queue_name: str) -> int
Source code in src/sheppy/backend/redis.py
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212 | async def clear(self, queue_name: str) -> int:
tasks_metadata_key = self._tasks_metadata_key(queue_name)
pending_tasks_key = self._pending_tasks_key(queue_name)
scheduled_key = self._scheduled_tasks_key(queue_name)
await self._ensure_consumer_group(pending_tasks_key)
keys = await self.client.keys(f"{tasks_metadata_key}:*")
if not keys:
return 0
count = await self.client.delete(*keys)
await self.client.xtrim(pending_tasks_key, maxlen=0)
await self.client.delete(scheduled_key)
# await self.client.delete(tasks_metadata_key)
return int(count)
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get_tasks(
queue_name: str, task_ids: list[str]
) -> dict[str, dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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223 | async def get_tasks(self, queue_name: str, task_ids: list[str]) -> dict[str,dict[str, Any]]:
tasks_metadata_key = self._tasks_metadata_key(queue_name)
if not task_ids:
return {}
task_json = await self.client.mget([f"{tasks_metadata_key}:{t}" for t in task_ids])
tasks = [json.loads(d) for d in task_json if d]
return {t['id']: t for t in tasks}
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schedule(
queue_name: str,
task_data: dict[str, Any],
at: datetime,
unique: bool = True,
) -> bool
Source code in src/sheppy/backend/redis.py
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246 | async def schedule(self, queue_name: str, task_data: dict[str, Any], at: datetime, unique: bool = True) -> bool:
tasks_metadata_key = self._tasks_metadata_key(queue_name)
scheduled_key = self._scheduled_tasks_key(queue_name)
if unique:
success = await self._create_tasks(queue_name, [task_data])
if not success[0]:
return False
try:
_task_data = json.dumps(task_data)
if not unique:
await self.client.set(f"{tasks_metadata_key}:{task_data['id']}", _task_data)
# add to sorted set with timestamp as score
score = at.timestamp()
await self.client.zadd(scheduled_key, {_task_data: score})
return True
except Exception as e:
raise BackendError(f"Failed to schedule task: {e}") from e
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pop_scheduled(
queue_name: str, now: datetime | None = None
) -> list[dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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265 | async def pop_scheduled(self, queue_name: str, now: datetime | None = None) -> list[dict[str, Any]]:
scheduled_key = self._scheduled_tasks_key(queue_name)
score = now.timestamp() if now else time()
task_jsons = await self.client.zrangebyscore(scheduled_key, 0, score)
tasks = []
for task_json in task_jsons:
removed = await self.client.zrem(scheduled_key, task_json)
if removed <= 0:
# some other worker already got this task at the same time, skip
continue
tasks.append(json.loads(task_json))
return tasks
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store_result(
queue_name: str, task_data: dict[str, Any]
) -> bool
Source code in src/sheppy/backend/redis.py
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299 | async def store_result(self, queue_name: str, task_data: dict[str, Any]) -> bool:
tasks_metadata_key = self._tasks_metadata_key(queue_name)
finished_tasks_key = self._finished_tasks_key(queue_name)
pending_tasks_key = self._pending_tasks_key(queue_name)
await self._ensure_consumer_group(finished_tasks_key)
message_id = None
if task_data["id"] in self._pending_messages:
stored_queue, message_id = self._pending_messages[task_data["id"]]
if queue_name != stored_queue: # this should never happen
raise BackendError("queue name mismatch")
try:
# trim older messages to keep the stream small
min_id = f"{int((time() - self._results_stream_ttl) * 1000)}-0"
async with self.client.pipeline(transaction=True) as pipe:
# update task metadata with the results
pipe.set(f"{tasks_metadata_key}:{task_data['id']}", json.dumps(task_data), ex=self.ttl)
# add to finished stream for get_result notifications
if task_data["finished_at"] is not None: # only send notification on finished task (for retriable tasks we continue to wait)
pipe.xadd(finished_tasks_key, {"task_id": task_data["id"]}, minid=min_id)
# ack and delete the task from the stream (cleanup)
if message_id:
pipe.xackdel(pending_tasks_key, self.consumer_group, message_id)
await (pipe.execute())
return True
except Exception as e:
raise BackendError(f"Failed to store task result: {e}") from e
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get_stats(queue_name: str) -> dict[str, int]
Source code in src/sheppy/backend/redis.py
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313 | async def get_stats(self, queue_name: str) -> dict[str, int]:
scheduled_tasks_key = self._scheduled_tasks_key(queue_name)
pending_tasks_key = self._pending_tasks_key(queue_name)
finished_tasks_key = self._finished_tasks_key(queue_name)
pending = await self.client.xlen(pending_tasks_key)
completed = await self.client.xlen(finished_tasks_key)
return {
"pending": pending,
"completed": completed,
"scheduled": await self.client.zcard(scheduled_tasks_key),
}
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get_all_tasks(queue_name: str) -> list[dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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324 | async def get_all_tasks(self, queue_name: str) -> list[dict[str, Any]]:
tasks_metadata_key = self._tasks_metadata_key(queue_name)
keys = await self.client.keys(f"{tasks_metadata_key}:*")
if not keys:
return []
all_tasks_data = await self.client.mget(keys)
return [json.loads(task_json) for task_json in all_tasks_data]
|
get_results(
queue_name: str,
task_ids: list[str],
timeout: float | None = None,
) -> dict[str, dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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393 | async def get_results(self, queue_name: str, task_ids: list[str], timeout: float | None = None) -> dict[str,dict[str, Any]]:
tasks_metadata_key = self._tasks_metadata_key(queue_name)
finished_tasks_key = self._finished_tasks_key(queue_name)
if not task_ids:
return {}
results = {}
remaining_ids = task_ids[:]
last_id = "0-0"
if timeout is not None and timeout >= 0:
with contextlib.suppress(redis.ResponseError):
last_id = (await self.client.xinfo_stream(finished_tasks_key))["last-generated-id"]
tasks = await self.client.mget([f"{tasks_metadata_key}:{t}" for t in task_ids])
for task_json in tasks:
if not task_json:
continue
t = json.loads(task_json)
if t.get("finished_at"):
results[t["id"]] = t
remaining_ids.remove(t["id"])
if not remaining_ids:
return results
if timeout is None or timeout < 0:
return results
# endless wait if timeout == 0
deadline = None if timeout == 0 else asyncio.get_event_loop().time() + timeout
while True:
if deadline:
remaining = deadline - asyncio.get_event_loop().time()
if remaining <= 0:
raise TimeoutError(f"Did not complete within {timeout} seconds")
else:
remaining = 0
messages = await self.client.xread(
{finished_tasks_key: last_id},
block=int(remaining * 1000),
count=100
)
if not messages:
continue
for _, stream_messages in messages:
for msg_id, data in stream_messages:
last_id = msg_id
task_id = data.get(b"task_id").decode()
if task_id in remaining_ids:
task_json = await self.client.get(f"{tasks_metadata_key}:{task_id}")
if not task_json:
continue
t = json.loads(task_json)
if t.get("finished_at"): # should be always true because we only get notifications for finished tasks
results[t["id"]] = t
remaining_ids.remove(t["id"])
if not remaining_ids:
return results
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list_queues() -> dict[str, int]
Source code in src/sheppy/backend/redis.py
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423 | async def list_queues(self) -> dict[str, int]:
queue_names = set()
for key in await self.client.keys("sheppy:*:*"):
queue_names.add(key.decode().split(":")[2])
queues = {}
for queue_name in sorted(queue_names):
try:
pending_count = await self.client.xlen(self._pending_tasks_key(queue_name))
queues[queue_name] = int(pending_count)
except redis.ResponseError:
queues[queue_name] = 0
return queues
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get_scheduled(queue_name: str) -> list[dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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434 | async def get_scheduled(self, queue_name: str) -> list[dict[str, Any]]:
scheduled_key = self._scheduled_tasks_key(queue_name)
task_jsons = await self.client.zrange(scheduled_key, 0, -1, withscores=True)
tasks = []
for task_json, _score in task_jsons:
tasks.append(json.loads(task_json))
return tasks
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add_cron(
queue_name: str,
deterministic_id: str,
task_cron: dict[str, Any],
) -> bool
Source code in src/sheppy/backend/redis.py
| async def add_cron(self, queue_name: str, deterministic_id: str, task_cron: dict[str, Any]) -> bool:
cron_tasks_key = self._cron_tasks_key(queue_name)
return bool(await self.client.set(f"{cron_tasks_key}:{deterministic_id}", json.dumps(task_cron), nx=True))
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delete_cron(queue_name: str, deterministic_id: str) -> bool
Source code in src/sheppy/backend/redis.py
| async def delete_cron(self, queue_name: str, deterministic_id: str) -> bool:
cron_tasks_key = self._cron_tasks_key(queue_name)
return bool(await self.client.delete(f"{cron_tasks_key}:{deterministic_id}"))
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get_crons(queue_name: str) -> list[dict[str, Any]]
Source code in src/sheppy/backend/redis.py
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451 | async def get_crons(self, queue_name: str) -> list[dict[str, Any]]:
cron_tasks_key = self._cron_tasks_key(queue_name)
cron_tasks = await self.client.keys(f"{cron_tasks_key}:*")
if not cron_tasks:
return []
return [json.loads(d) for d in await self.client.mget(cron_tasks) if d is not None]
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