# ------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for
# license information.
# -------------------------------------------------------------------------
import asyncio
import logging
import datetime
from typing import Optional, Iterable, Any, Union, Callable, Awaitable, List
from ._async_message import ReceivedMessage
from ._servicebus_session_async import ServiceBusSession
from .._common.utils import renewable_start_time, utc_now
from ._async_utils import get_running_loop
from ..exceptions import AutoLockRenewTimeout, AutoLockRenewFailed, ServiceBusError
AsyncLockRenewFailureCallback = Callable[[Union[ServiceBusSession, ReceivedMessage],
Optional[Exception]], Awaitable[None]]
_log = logging.getLogger(__name__)
[docs]class AutoLockRenew:
"""Auto lock renew.
An asynchronous AutoLockRenew handler for renewing the lock
tokens of messages and/or sessions in the background.
:param loop: An async event loop.
:type loop: ~asyncio.BaseEventLoop
.. admonition:: Example:
.. literalinclude:: ../samples/async_samples/sample_code_servicebus_async.py
:start-after: [START auto_lock_renew_message_async]
:end-before: [END auto_lock_renew_message_async]
:language: python
:dedent: 4
:caption: Automatically renew a message lock
.. literalinclude:: ../samples/async_samples/sample_code_servicebus_async.py
:start-after: [START auto_lock_renew_session_async]
:end-before: [END auto_lock_renew_session_async]
:language: python
:dedent: 4
:caption: Automatically renew a session lock
"""
def __init__(self, loop: Optional[asyncio.BaseEventLoop] = None) -> None:
self._shutdown = asyncio.Event()
self._futures = [] # type: List[asyncio.Future]
self._loop = loop or get_running_loop()
self._sleep_time = 1
self._renew_period = 10
async def __aenter__(self) -> "AutoLockRenew":
if self._shutdown.is_set():
raise ServiceBusError("The AutoLockRenew has already been shutdown. Please create a new instance for"
" auto lock renewing.")
return self
async def __aexit__(self, *args: Iterable[Any]) -> None:
await self.close()
def _renewable(self, renewable: Union[ReceivedMessage, ServiceBusSession]) -> bool:
# pylint: disable=protected-access
if self._shutdown.is_set():
return False
if hasattr(renewable, '_settled') and renewable._settled: # type: ignore
return False
if renewable._lock_expired:
return False
try:
if not renewable._receiver._running: # type: ignore
return False
except AttributeError: # If for whatever reason the renewable isn't hooked up to a receiver
raise ServiceBusError("Cannot renew an entity without an associated receiver. "
"ReceivedMessage and active ServiceBusReceiver.Session objects are expected.")
return True
async def _auto_lock_renew(self,
renewable: Union[ReceivedMessage, ServiceBusSession],
starttime: datetime.datetime,
timeout: float,
on_lock_renew_failure: Optional[AsyncLockRenewFailureCallback] = None) -> None:
# pylint: disable=protected-access
_log.debug("Running async lock auto-renew for %r seconds", timeout)
error = None # type: Optional[Exception]
clean_shutdown = False # Only trigger the on_lock_renew_failure if halting was not expected (shutdown, etc)
try:
while self._renewable(renewable):
if (utc_now() - starttime) >= datetime.timedelta(seconds=timeout):
_log.debug("Reached auto lock renew timeout - letting lock expire.")
raise AutoLockRenewTimeout("Auto-renew period ({} seconds) elapsed.".format(timeout))
if (renewable.locked_until_utc - utc_now()) <= datetime.timedelta(seconds=self._renew_period):
_log.debug("%r seconds or less until lock expires - auto renewing.", self._renew_period)
await renewable.renew_lock()
await asyncio.sleep(self._sleep_time)
clean_shutdown = not renewable._lock_expired
except AutoLockRenewTimeout as e:
error = e
renewable.auto_renew_error = e
clean_shutdown = not renewable._lock_expired
except Exception as e: # pylint: disable=broad-except
_log.debug("Failed to auto-renew lock: %r. Closing thread.", e)
error = AutoLockRenewFailed(
"Failed to auto-renew lock",
inner_exception=e)
renewable.auto_renew_error = error
finally:
if on_lock_renew_failure and not clean_shutdown:
await on_lock_renew_failure(renewable, error)
[docs] def register(self,
renewable: Union[ReceivedMessage, ServiceBusSession],
timeout: float = 300,
on_lock_renew_failure: Optional[AsyncLockRenewFailureCallback] = None) -> None:
"""Register a renewable entity for automatic lock renewal.
:param renewable: A locked entity that needs to be renewed.
:type renewable: Union[~azure.servicebus.aio.ReceivedMessage,~azure.servicebus.aio.ServiceBusSession]
:param float timeout: A time in seconds that the lock should be maintained for.
Default value is 300 (5 minutes).
:param Optional[AsyncLockRenewFailureCallback] on_lock_renew_failure:
An async callback may be specified to be called when the lock is lost on the renewable being registered.
Default value is None (no callback).
"""
if self._shutdown.is_set():
raise ServiceBusError("The AutoLockRenew has already been shutdown. Please create a new instance for"
" auto lock renewing.")
starttime = renewable_start_time(renewable)
renew_future = asyncio.ensure_future(
self._auto_lock_renew(renewable, starttime, timeout, on_lock_renew_failure),
loop=self._loop)
self._futures.append(renew_future)
[docs] async def close(self) -> None:
"""Cease autorenewal by cancelling any remaining open lock renewal futures."""
self._shutdown.set()
await asyncio.wait(self._futures)