228 lines
8.2 KiB
Python
228 lines
8.2 KiB
Python
import logging
|
|
import queue
|
|
import threading
|
|
import types
|
|
from collections.abc import Generator, Iterator
|
|
from typing import Self
|
|
|
|
from libs.broadcast_channel.channel import Subscription
|
|
from libs.broadcast_channel.exc import SubscriptionClosedError
|
|
from redis.client import PubSub
|
|
|
|
_logger = logging.getLogger(__name__)
|
|
|
|
|
|
class RedisSubscriptionBase(Subscription):
|
|
"""Base class for Redis pub/sub subscriptions with common functionality.
|
|
|
|
This class provides shared functionality for both regular and sharded
|
|
Redis pub/sub subscriptions, reducing code duplication and improving
|
|
maintainability.
|
|
"""
|
|
|
|
def __init__(
|
|
self,
|
|
pubsub: PubSub,
|
|
topic: str,
|
|
):
|
|
# The _pubsub is None only if the subscription is closed.
|
|
self._pubsub: PubSub | None = pubsub
|
|
self._topic = topic
|
|
self._closed = threading.Event()
|
|
self._queue: queue.Queue[bytes] = queue.Queue(maxsize=1024)
|
|
self._dropped_count = 0
|
|
self._listener_thread: threading.Thread | None = None
|
|
self._start_lock = threading.Lock()
|
|
self._started = False
|
|
|
|
def _start_if_needed(self) -> None:
|
|
"""Start the subscription if not already started."""
|
|
with self._start_lock:
|
|
if self._started:
|
|
return
|
|
if self._closed.is_set():
|
|
raise SubscriptionClosedError(f"The Redis {self._get_subscription_type()} subscription is closed")
|
|
if self._pubsub is None:
|
|
raise SubscriptionClosedError(
|
|
f"The Redis {self._get_subscription_type()} subscription has been cleaned up"
|
|
)
|
|
|
|
self._subscribe()
|
|
_logger.debug("Subscribed to %s channel %s", self._get_subscription_type(), self._topic)
|
|
|
|
self._listener_thread = threading.Thread(
|
|
target=self._listen,
|
|
name=f"redis-{self._get_subscription_type().replace(' ', '-')}-broadcast-{self._topic}",
|
|
daemon=True,
|
|
)
|
|
self._listener_thread.start()
|
|
self._started = True
|
|
|
|
def _listen(self) -> None:
|
|
"""Main listener loop for processing messages."""
|
|
pubsub = self._pubsub
|
|
assert pubsub is not None, "PubSub should not be None while starting listening."
|
|
while not self._closed.is_set():
|
|
try:
|
|
raw_message = self._get_message()
|
|
except Exception as e:
|
|
# Log the exception and exit the listener thread gracefully
|
|
# This handles Redis connection errors and other exceptions
|
|
_logger.error(
|
|
"Error getting message from Redis %s subscription, topic=%s: %s",
|
|
self._get_subscription_type(),
|
|
self._topic,
|
|
e,
|
|
exc_info=True,
|
|
)
|
|
break
|
|
|
|
if raw_message is None:
|
|
continue
|
|
|
|
if raw_message.get("type") != self._get_message_type():
|
|
continue
|
|
|
|
channel_field = raw_message.get("channel")
|
|
if isinstance(channel_field, bytes):
|
|
channel_name = channel_field.decode("utf-8")
|
|
elif isinstance(channel_field, str):
|
|
channel_name = channel_field
|
|
else:
|
|
channel_name = str(channel_field)
|
|
|
|
if channel_name != self._topic:
|
|
_logger.warning(
|
|
"Ignoring %s message from unexpected channel %s", self._get_subscription_type(), channel_name
|
|
)
|
|
continue
|
|
|
|
payload_bytes: bytes | None = raw_message.get("data")
|
|
if not isinstance(payload_bytes, bytes):
|
|
_logger.error(
|
|
"Received invalid data from %s channel %s, type=%s",
|
|
self._get_subscription_type(),
|
|
self._topic,
|
|
type(payload_bytes),
|
|
)
|
|
continue
|
|
|
|
self._enqueue_message(payload_bytes)
|
|
|
|
_logger.debug("%s listener thread stopped for channel %s", self._get_subscription_type().title(), self._topic)
|
|
try:
|
|
self._unsubscribe()
|
|
pubsub.close()
|
|
_logger.debug("%s PubSub closed for topic %s", self._get_subscription_type().title(), self._topic)
|
|
except Exception as e:
|
|
_logger.error(
|
|
"Error during cleanup of Redis %s subscription, topic=%s: %s",
|
|
self._get_subscription_type(),
|
|
self._topic,
|
|
e,
|
|
exc_info=True,
|
|
)
|
|
finally:
|
|
self._pubsub = None
|
|
|
|
def _enqueue_message(self, payload: bytes) -> None:
|
|
"""Enqueue a message to the internal queue with dropping behavior."""
|
|
while not self._closed.is_set():
|
|
try:
|
|
self._queue.put_nowait(payload)
|
|
return
|
|
except queue.Full:
|
|
try:
|
|
self._queue.get_nowait()
|
|
self._dropped_count += 1
|
|
_logger.debug(
|
|
"Dropped message from Redis %s subscription, topic=%s, total_dropped=%d",
|
|
self._get_subscription_type(),
|
|
self._topic,
|
|
self._dropped_count,
|
|
)
|
|
except queue.Empty:
|
|
continue
|
|
return
|
|
|
|
def _message_iterator(self) -> Generator[bytes, None, None]:
|
|
"""Iterator for consuming messages from the subscription."""
|
|
while not self._closed.is_set():
|
|
try:
|
|
item = self._queue.get(timeout=0.1)
|
|
except queue.Empty:
|
|
continue
|
|
|
|
yield item
|
|
|
|
def __iter__(self) -> Iterator[bytes]:
|
|
"""Return an iterator over messages from the subscription."""
|
|
if self._closed.is_set():
|
|
raise SubscriptionClosedError(f"The Redis {self._get_subscription_type()} subscription is closed")
|
|
self._start_if_needed()
|
|
return iter(self._message_iterator())
|
|
|
|
def receive(self, timeout: float | None = None) -> bytes | None:
|
|
"""Receive the next message from the subscription."""
|
|
if self._closed.is_set():
|
|
raise SubscriptionClosedError(f"The Redis {self._get_subscription_type()} subscription is closed")
|
|
self._start_if_needed()
|
|
|
|
try:
|
|
item = self._queue.get(timeout=timeout)
|
|
except queue.Empty:
|
|
return None
|
|
|
|
return item
|
|
|
|
def __enter__(self) -> Self:
|
|
"""Context manager entry point."""
|
|
self._start_if_needed()
|
|
return self
|
|
|
|
def __exit__(
|
|
self,
|
|
exc_type: type[BaseException] | None,
|
|
exc_value: BaseException | None,
|
|
traceback: types.TracebackType | None,
|
|
) -> bool | None:
|
|
"""Context manager exit point."""
|
|
self.close()
|
|
return None
|
|
|
|
def close(self) -> None:
|
|
"""Close the subscription and clean up resources."""
|
|
if self._closed.is_set():
|
|
return
|
|
|
|
self._closed.set()
|
|
# NOTE: PubSub is not thread-safe. More specifically, the `PubSub.close` method and the
|
|
# message retrieval method should NOT be called concurrently.
|
|
#
|
|
# Due to the restriction above, the PubSub cleanup logic happens inside the consumer thread.
|
|
listener = self._listener_thread
|
|
if listener is not None:
|
|
listener.join(timeout=1.0)
|
|
self._listener_thread = None
|
|
|
|
# Abstract methods to be implemented by subclasses
|
|
def _get_subscription_type(self) -> str:
|
|
"""Return the subscription type (e.g., 'regular' or 'sharded')."""
|
|
raise NotImplementedError
|
|
|
|
def _subscribe(self) -> None:
|
|
"""Subscribe to the Redis topic using the appropriate command."""
|
|
raise NotImplementedError
|
|
|
|
def _unsubscribe(self) -> None:
|
|
"""Unsubscribe from the Redis topic using the appropriate command."""
|
|
raise NotImplementedError
|
|
|
|
def _get_message(self) -> dict | None:
|
|
"""Get a message from Redis using the appropriate method."""
|
|
raise NotImplementedError
|
|
|
|
def _get_message_type(self) -> str:
|
|
"""Return the expected message type (e.g., 'message' or 'smessage')."""
|
|
raise NotImplementedError
|