Gracefully handle a pending logging connection during shutdown. (#8685)

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Patrick Cloke 2020-10-29 12:53:57 -04:00 committed by GitHub
parent f21e24ffc2
commit 8b42a4eefd
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5 changed files with 36 additions and 10 deletions

1
changelog.d/8607.feature Normal file
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@ -0,0 +1 @@
Support generating structured logs via the standard logging configuration.

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@ -1 +0,0 @@
Re-organize the structured logging code to separate the TCP transport handling from the JSON formatting.

1
changelog.d/8685.feature Normal file
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@ -0,0 +1 @@
Support generating structured logs via the standard logging configuration.

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@ -26,7 +26,7 @@ from typing_extensions import Deque
from zope.interface import implementer
from twisted.application.internet import ClientService
from twisted.internet.defer import Deferred
from twisted.internet.defer import CancelledError, Deferred
from twisted.internet.endpoints import (
HostnameEndpoint,
TCP4ClientEndpoint,
@ -34,6 +34,7 @@ from twisted.internet.endpoints import (
)
from twisted.internet.interfaces import IPushProducer, ITransport
from twisted.internet.protocol import Factory, Protocol
from twisted.python.failure import Failure
logger = logging.getLogger(__name__)
@ -131,9 +132,11 @@ class RemoteHandler(logging.Handler):
factory = Factory.forProtocol(Protocol)
self._service = ClientService(endpoint, factory, clock=_reactor)
self._service.startService()
self._stopping = False
self._connect()
def close(self):
self._stopping = True
self._service.stopService()
def _connect(self) -> None:
@ -146,17 +149,21 @@ class RemoteHandler(logging.Handler):
self._connection_waiter = self._service.whenConnected(failAfterFailures=1)
@self._connection_waiter.addErrback
def fail(r):
r.printTraceback(file=sys.__stderr__)
def fail(failure: Failure) -> None:
# If the Deferred was cancelled (e.g. during shutdown) do not try to
# reconnect (this will cause an infinite loop of errors).
if failure.check(CancelledError) and self._stopping:
return
# For a different error, print the traceback and re-connect.
failure.printTraceback(file=sys.__stderr__)
self._connection_waiter = None
self._connect()
@self._connection_waiter.addCallback
def writer(r):
def writer(result: Protocol) -> None:
# We have a connection. If we already have a producer, and its
# transport is the same, just trigger a resumeProducing.
if self._producer and r.transport is self._producer.transport:
if self._producer and result.transport is self._producer.transport:
self._producer.resumeProducing()
self._connection_waiter = None
return
@ -167,12 +174,14 @@ class RemoteHandler(logging.Handler):
# Make a new producer and start it.
self._producer = LogProducer(
buffer=self._buffer, transport=r.transport, format=self.format,
buffer=self._buffer, transport=result.transport, format=self.format,
)
r.transport.registerProducer(self._producer, True)
result.transport.registerProducer(self._producer, True)
self._producer.resumeProducing()
self._connection_waiter = None
self._connection_waiter.addCallbacks(writer, fail)
def _handle_pressure(self) -> None:
"""
Handle backpressure by shedding records.

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@ -151,3 +151,19 @@ class RemoteHandlerTestCase(LoggerCleanupMixin, TestCase):
+ ["warn %s" % (i,) for i in range(15, 20)],
logs,
)
def test_cancel_connection(self):
"""
Gracefully handle the connection being cancelled.
"""
handler = RemoteHandler(
"127.0.0.1", 9000, maximum_buffer=10, _reactor=self.reactor
)
logger = self.get_logger(handler)
# Send a message.
logger.info("Hello there, %s!", "wally")
# Do not accept the connection and shutdown. This causes the pending
# connection to be cancelled (and should not raise any exceptions).
handler.close()