252 lines
8.2 KiB
Python
252 lines
8.2 KiB
Python
# Copyright 2020 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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import sys
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import traceback
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from collections import deque
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from ipaddress import IPv4Address, IPv6Address, ip_address
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from math import floor
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from typing import Callable, Optional
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import attr
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from typing_extensions import Deque
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from zope.interface import implementer
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from twisted.application.internet import ClientService
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from twisted.internet.defer import CancelledError, Deferred
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from twisted.internet.endpoints import (
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HostnameEndpoint,
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TCP4ClientEndpoint,
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TCP6ClientEndpoint,
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)
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from twisted.internet.interfaces import IPushProducer, IStreamClientEndpoint
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from twisted.internet.protocol import Factory, Protocol
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from twisted.internet.tcp import Connection
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from twisted.python.failure import Failure
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logger = logging.getLogger(__name__)
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@attr.s
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@implementer(IPushProducer)
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class LogProducer:
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"""
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An IPushProducer that writes logs from its buffer to its transport when it
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is resumed.
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Args:
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buffer: Log buffer to read logs from.
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transport: Transport to write to.
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format: A callable to format the log record to a string.
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"""
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# This is essentially ITCPTransport, but that is missing certain fields
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# (connected and registerProducer) which are part of the implementation.
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transport = attr.ib(type=Connection)
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_format = attr.ib(type=Callable[[logging.LogRecord], str])
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_buffer = attr.ib(type=deque)
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_paused = attr.ib(default=False, type=bool, init=False)
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def pauseProducing(self):
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self._paused = True
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def stopProducing(self):
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self._paused = True
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self._buffer = deque()
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def resumeProducing(self):
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# If we're already producing, nothing to do.
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self._paused = False
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# Loop until paused.
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while self._paused is False and (self._buffer and self.transport.connected):
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try:
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# Request the next record and format it.
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record = self._buffer.popleft()
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msg = self._format(record)
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# Send it as a new line over the transport.
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self.transport.write(msg.encode("utf8"))
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self.transport.write(b"\n")
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except Exception:
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# Something has gone wrong writing to the transport -- log it
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# and break out of the while.
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traceback.print_exc(file=sys.__stderr__)
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break
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class RemoteHandler(logging.Handler):
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"""
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An logging handler that writes logs to a TCP target.
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Args:
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host: The host of the logging target.
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port: The logging target's port.
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maximum_buffer: The maximum buffer size.
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"""
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def __init__(
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self,
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host: str,
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port: int,
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maximum_buffer: int = 1000,
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level=logging.NOTSET,
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_reactor=None,
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):
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super().__init__(level=level)
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self.host = host
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self.port = port
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self.maximum_buffer = maximum_buffer
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self._buffer: Deque[logging.LogRecord] = deque()
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self._connection_waiter: Optional[Deferred] = None
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self._producer: Optional[LogProducer] = None
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# Connect without DNS lookups if it's a direct IP.
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if _reactor is None:
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from twisted.internet import reactor
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_reactor = reactor
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try:
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ip = ip_address(self.host)
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if isinstance(ip, IPv4Address):
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endpoint: IStreamClientEndpoint = TCP4ClientEndpoint(
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_reactor, self.host, self.port
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)
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elif isinstance(ip, IPv6Address):
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endpoint = TCP6ClientEndpoint(_reactor, self.host, self.port)
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else:
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raise ValueError("Unknown IP address provided: %s" % (self.host,))
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except ValueError:
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endpoint = HostnameEndpoint(_reactor, self.host, self.port)
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factory = Factory.forProtocol(Protocol)
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self._service = ClientService(endpoint, factory, clock=_reactor)
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self._service.startService()
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self._stopping = False
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self._connect()
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def close(self):
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self._stopping = True
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self._service.stopService()
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def _connect(self) -> None:
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"""
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Triggers an attempt to connect then write to the remote if not already writing.
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"""
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# Do not attempt to open multiple connections.
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if self._connection_waiter:
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return
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def fail(failure: Failure) -> None:
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# If the Deferred was cancelled (e.g. during shutdown) do not try to
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# reconnect (this will cause an infinite loop of errors).
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if failure.check(CancelledError) and self._stopping:
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return
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# For a different error, print the traceback and re-connect.
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failure.printTraceback(file=sys.__stderr__)
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self._connection_waiter = None
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self._connect()
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def writer(result: Protocol) -> None:
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# Force recognising transport as a Connection and not the more
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# generic ITransport.
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transport: Connection = result.transport # type: ignore
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# We have a connection. If we already have a producer, and its
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# transport is the same, just trigger a resumeProducing.
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if self._producer and transport is self._producer.transport:
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self._producer.resumeProducing()
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self._connection_waiter = None
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return
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# If the producer is still producing, stop it.
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if self._producer:
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self._producer.stopProducing()
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# Make a new producer and start it.
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self._producer = LogProducer(
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buffer=self._buffer,
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transport=transport,
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format=self.format,
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)
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transport.registerProducer(self._producer, True)
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self._producer.resumeProducing()
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self._connection_waiter = None
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deferred: Deferred = self._service.whenConnected(failAfterFailures=1)
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deferred.addCallbacks(writer, fail)
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self._connection_waiter = deferred
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def _handle_pressure(self) -> None:
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"""
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Handle backpressure by shedding records.
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The buffer will, in this order, until the buffer is below the maximum:
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- Shed DEBUG records.
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- Shed INFO records.
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- Shed the middle 50% of the records.
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"""
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if len(self._buffer) <= self.maximum_buffer:
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return
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# Strip out DEBUGs
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self._buffer = deque(
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filter(lambda record: record.levelno > logging.DEBUG, self._buffer)
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)
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if len(self._buffer) <= self.maximum_buffer:
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return
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# Strip out INFOs
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self._buffer = deque(
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filter(lambda record: record.levelno > logging.INFO, self._buffer)
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)
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if len(self._buffer) <= self.maximum_buffer:
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return
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# Cut the middle entries out
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buffer_split = floor(self.maximum_buffer / 2)
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old_buffer = self._buffer
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self._buffer = deque()
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for _ in range(buffer_split):
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self._buffer.append(old_buffer.popleft())
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end_buffer = []
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for _ in range(buffer_split):
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end_buffer.append(old_buffer.pop())
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self._buffer.extend(reversed(end_buffer))
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def emit(self, record: logging.LogRecord) -> None:
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self._buffer.append(record)
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# Handle backpressure, if it exists.
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try:
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self._handle_pressure()
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except Exception:
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# If handling backpressure fails, clear the buffer and log the
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# exception.
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self._buffer.clear()
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logger.warning("Failed clearing backpressure")
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# Try and write immediately.
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self._connect()
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