# ------------------------------------------------------------------------
# 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 azure.servicebus.common.utils import renewable_start_time, get_running_loop
from azure.servicebus.common.errors import AutoLockRenewTimeout, AutoLockRenewFailed
_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.EventLoop
Example:
.. literalinclude:: ../examples/async_examples/test_examples_async.py
:start-after: [START auto_lock_renew_async_message]
:end-before: [END auto_lock_renew_async_message]
:language: python
:dedent: 4
:caption: Automatically renew a message lock
.. literalinclude:: ../examples/async_examples/test_examples_async.py
:start-after: [START auto_lock_renew_async_session]
:end-before: [END auto_lock_renew_async_session]
:language: python
:dedent: 4
:caption: Automatically renew a session lock
"""
def __init__(self, loop=None):
self._shutdown = asyncio.Event()
self._futures = []
self.loop = loop or get_running_loop()
self.sleep_time = 1
self.renew_period = 10
def __aenter__(self):
return self
async def __aexit__(self, *args):
await self.shutdown()
def _renewable(self, renewable):
if self._shutdown.is_set():
return False
if hasattr(renewable, 'settled') and renewable.settled:
return False
if renewable.expired:
return False
return True
async def _auto_lock_renew(self, renewable, starttime, timeout):
_log.debug("Running async lock auto-renew for %r seconds", timeout)
try:
while self._renewable(renewable):
if (datetime.datetime.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 - datetime.datetime.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)
except AutoLockRenewTimeout as e:
renewable.auto_renew_error = e
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
[docs] def register(self, renewable, timeout=300):
"""Register a renewable entity for automatic lock renewal.
:param renewable: A locked entity that needs to be renewed.
:type renewable: ~azure.servicebus.aio.async_message.Message or
~azure.servicebus.aio.async_receive_handler.SessionReceiver
:param timeout: A time in seconds that the lock should be maintained for.
Default value is 300 (5 minutes).
:type timeout: int
"""
starttime = renewable_start_time(renewable)
renew_future = asyncio.ensure_future(self._auto_lock_renew(renewable, starttime, timeout), loop=self.loop)
self._futures.append(renew_future)
[docs] async def shutdown(self):
"""Cancel remaining open lock renewal futures."""
self._shutdown.set()
await asyncio.wait(self._futures)