mirror of
https://github.com/sprockets/sprockets-statsd.git
synced 2024-11-22 03:00:20 +00:00
572 lines
20 KiB
Python
572 lines
20 KiB
Python
import asyncio
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import contextlib
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import logging
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import socket
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import time
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import typing
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class ThrottleGuard:
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"""Prevent code from executing repeatedly.
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:param threshold: guarding threshold
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This abstraction allows code to execute the first "threshold"
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times and then only once per "threshold" times afterwards. Use
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it to ensure that log statements are continuously written during
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persistent error conditions. The goal is to provide regular
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feedback while limiting the amount of log spam.
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The following snippet will log the first 100 failures and then
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once every 100 failures thereafter:
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.. code-block:: python
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executions = 0
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guard = ThrottleGuard(100)
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for _ in range(1000):
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if guard.allow_execution():
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executions += 1
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logging.info('called %s times instead of %s times',
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executions, guard.counter)
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"""
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def __init__(self, threshold: int):
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self.counter = 0
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self.threshold = threshold
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def allow_execution(self) -> bool:
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"""Should this execution be allowed?"""
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self.counter += 1
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allow = (self.counter < self.threshold
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or (self.counter % self.threshold) == 0)
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return allow
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def reset(self) -> None:
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"""Reset counter after error has resolved."""
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self.counter = 0
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class AbstractConnector:
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"""StatsD connector that does not send metrics or connect.
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Use this connector when you want to maintain the application
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interface without doing any real work.
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"""
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async def start(self) -> None:
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pass
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async def stop(self) -> None:
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pass
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def inject_metric(self, path: str, value: str, type_code: str) -> None:
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pass
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def incr(self, path: str, value: int = 1) -> None:
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"""Increment a counter metric.
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:param path: counter to increment
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:param value: amount to increment the counter by
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"""
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self.inject_metric(f'counters.{path}', str(value), 'c')
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def decr(self, path: str, value: int = 1) -> None:
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"""Decrement a counter metric.
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:param path: counter to decrement
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:param value: amount to decrement the counter by
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This is equivalent to ``self.incr(path, -value)``.
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"""
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self.inject_metric(f'counters.{path}', str(-value), 'c')
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def gauge(self, path: str, value: int, delta: bool = False) -> None:
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"""Manipulate a gauge metric.
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:param path: gauge to adjust
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:param value: value to send
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:param delta: is this an adjustment of the gauge?
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If the `delta` parameter is ``False`` (or omitted), then
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`value` is the new value to set the gauge to. Otherwise,
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`value` is an adjustment for the current gauge.
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"""
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if delta:
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payload = f'{value:+d}'
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else:
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payload = str(value)
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self.inject_metric(f'gauges.{path}', payload, 'g')
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def timing(self, path: str, seconds: float) -> None:
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"""Send a timer metric.
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:param path: timer to append a value to
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:param seconds: number of **seconds** to record
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"""
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self.inject_metric(f'timers.{path}', str(seconds * 1000.0), 'ms')
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@contextlib.contextmanager
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def timer(self, path):
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"""Send a timer metric using a context manager.
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:param path: timer to append the measured time to
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"""
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start = time.time()
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try:
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yield
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finally:
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fini = time.time()
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self.timing(path, max(fini, start) - start)
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class Connector(AbstractConnector):
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"""Sends metrics to a statsd server.
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:param host: statsd server to send metrics to
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:param port: socket port that the server is listening on
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:keyword ip_protocol: IP protocol to use for the underlying
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socket -- either ``socket.IPPROTO_TCP`` for TCP or
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``socket.IPPROTO_UDP`` for UDP sockets.
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:keyword prefix: optional string to prepend to metric paths
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:param kwargs: additional keyword parameters are passed
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to the :class:`.Processor` initializer
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This class maintains a connection to a statsd server and
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sends metric lines to it asynchronously. You must call the
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:meth:`start` method when your application is starting. It
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creates a :class:`~asyncio.Task` that manages the connection
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to the statsd server. You must also call :meth:`.stop` before
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terminating to ensure that all metrics are flushed to the
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statsd server.
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Metrics are optionally prefixed with :attr:`prefix` before the
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metric type prefix. This *should* be used to prevent metrics
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from being overwritten when multiple applications share a StatsD
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instance. Each metric type is also prefixed by one of the
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following strings based on the metric type:
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+-------------------+---------------+-----------+
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| Method call | Prefix | Type code |
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+-------------------+---------------+-----------+
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| :meth:`.incr` | ``counters.`` | ``c`` |
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+-------------------+---------------+-----------+
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| :meth:`.decr` | ``counters.`` | ``c`` |
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+-------------------+---------------+-----------+
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| :meth:`.gauge` | ``gauges.`` | ``g`` |
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+-------------------+---------------+-----------+
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| :meth:`.timing` | ``timers.`` | ``ms`` |
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+-------------------+---------------+-----------+
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When the connector is *should_terminate*, metric payloads are
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sent by calling the :meth:`.inject_metric` method. The payloads
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are stored in an internal queue that is consumed whenever the
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connection to the server is active.
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.. attribute:: prefix
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:type: str
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String to prefix to all metrics *before* the metric type prefix.
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.. attribute:: processor
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:type: Processor
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The statsd processor that maintains the connection and
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sends the metric payloads.
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"""
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logger: logging.Logger
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prefix: str
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processor: 'Processor'
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def __init__(self,
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host: str,
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port: int = 8125,
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*,
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prefix: str = '',
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**kwargs: typing.Any) -> None:
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super().__init__()
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self.logger = logging.getLogger(__package__).getChild('Connector')
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self.prefix = f'{prefix}.' if prefix else prefix
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self.processor = Processor(host=host, port=port, **kwargs)
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self._enqueue_log_guard = ThrottleGuard(100)
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self._processor_task: typing.Optional[asyncio.Task[None]] = None
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async def start(self) -> None:
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"""Start the processor in the background.
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This is a *blocking* method and does not return until the
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processor task is actually running.
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"""
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self._processor_task = asyncio.create_task(self.processor.run())
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await self.processor.running.wait()
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async def stop(self) -> None:
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"""Stop the background processor.
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Items that are currently in the queue will be flushed to
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the statsd server if possible. This is a *blocking* method
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and does not return until the background processor has
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stopped.
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"""
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await self.processor.stop()
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def inject_metric(self, path: str, value: str, type_code: str) -> None:
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"""Send a metric to the statsd server.
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:param path: formatted metric name
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:param value: formatted metric value
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:param type_code: type of the metric to send
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This method formats the payload and inserts it on the
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internal queue for future processing.
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"""
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payload = f'{self.prefix}{path}:{value}|{type_code}'
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try:
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self.processor.enqueue(payload.encode('utf-8'))
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self._enqueue_log_guard.reset()
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except asyncio.QueueFull:
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if self._enqueue_log_guard.allow_execution():
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self.logger.warning('statsd queue is full, discarding metric')
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class StatsdProtocol(asyncio.BaseProtocol):
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"""Common interface for backend protocols/transports.
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UDP and TCP transports have different interfaces (sendto vs write)
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so this class adapts them to a common protocol that our code
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can depend on.
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.. attribute:: buffered_data
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:type: bytes
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Bytes that are buffered due to low-level transport failures.
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Since protocols & transports are created anew with each connect
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attempt, the :class:`.Processor` instance ensures that data
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buffered on a transport is copied over to the new transport
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when creating a connection.
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.. attribute:: connected
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:type: asyncio.Event
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Is the protocol currently connected?
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"""
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buffered_data: bytes
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ip_protocol: int = socket.IPPROTO_NONE
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logger: logging.Logger
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transport: typing.Optional[asyncio.BaseTransport]
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def __init__(self) -> None:
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self.buffered_data = b''
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self.connected = asyncio.Event()
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self.logger = logging.getLogger(__package__).getChild(
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self.__class__.__name__)
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self.transport = None
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def send(self, metric: bytes) -> None:
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"""Send a metric payload over the transport."""
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raise NotImplementedError()
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async def shutdown(self) -> None:
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"""Shutdown the transport and wait for it to close."""
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raise NotImplementedError()
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def connection_made(self, transport: asyncio.BaseTransport) -> None:
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"""Capture the new transport and set the connected event."""
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# NB - this will return a 4-part tuple in some cases
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server, port = transport.get_extra_info('peername')[:2]
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self.logger.info('connected to statsd %s:%s', server, port)
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self.transport = transport
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self.transport.set_protocol(self)
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self.connected.set()
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def connection_lost(self, exc: typing.Optional[Exception]) -> None:
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"""Clear the connected event."""
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self.logger.warning('statsd server connection lost: %s', exc)
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self.connected.clear()
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class TCPProtocol(StatsdProtocol, asyncio.Protocol):
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"""StatsdProtocol implementation over a TCP/IP connection."""
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ip_protocol = socket.IPPROTO_TCP
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transport: asyncio.WriteTransport
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def eof_received(self) -> None:
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self.logger.warning('received EOF from statsd server')
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self.connected.clear()
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def send(self, metric: bytes) -> None:
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"""Send `metric` to the server.
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If sending the metric fails, it will be saved in
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``self.buffered_data``. The processor will save and
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restore the buffered data if it needs to create a
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new protocol object.
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"""
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if not self.buffered_data and not metric:
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return
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self.buffered_data = self.buffered_data + metric + b'\n'
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while (self.transport is not None and self.connected.is_set()
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and self.buffered_data):
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line, maybe_nl, rest = self.buffered_data.partition(b'\n')
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line += maybe_nl
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self.transport.write(line)
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if self.transport.is_closing():
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self.logger.warning('transport closed during write')
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break
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self.buffered_data = rest
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async def shutdown(self) -> None:
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"""Close the transport after flushing any outstanding data."""
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self.logger.info('shutting down')
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if self.connected.is_set():
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self.send(b'') # flush buffered data
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self.transport.close()
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while self.connected.is_set():
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await asyncio.sleep(0.1)
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class UDPProtocol(StatsdProtocol, asyncio.DatagramProtocol):
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"""StatsdProtocol implementation over a UDP/IP connection."""
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ip_protocol = socket.IPPROTO_UDP
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transport: asyncio.DatagramTransport
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def send(self, metric: bytes) -> None:
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if metric:
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self.transport.sendto(metric)
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async def shutdown(self) -> None:
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self.logger.info('shutting down')
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self.transport.close()
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class Processor:
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"""Maintains the statsd connection and sends metric payloads.
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:param host: statsd server to send metrics to
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:param port: TCP port that the server is listening on
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:param max_queue_size: only allow this many elements to be
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stored in the queue before discarding metrics
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:param reconnect_sleep: number of seconds to sleep after socket
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error occurs when connecting
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:param wait_timeout: number os seconds to wait for a message to
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arrive on the queue
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This class implements :class:`~asyncio.Protocol` for the statsd
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TCP connection. The :meth:`.run` method is run as a background
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:class:`~asyncio.Task` that consumes payloads from an internal
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queue, connects to the TCP server as required, and sends the
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already formatted payloads.
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.. attribute:: host
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:type: str
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IP address or DNS name for the statsd server to send metrics to
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.. attribute:: port
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:type: int
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TCP port number that the statsd server is listening on
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.. attribute:: should_terminate
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:type: bool
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Flag that controls whether the background task is active or
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not. This flag is set to :data:`False` when the task is started.
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Setting it to :data:`True` will cause the task to shutdown in
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an orderly fashion.
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.. attribute:: queue
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:type: asyncio.Queue
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Formatted metric payloads to send to the statsd server. Enqueue
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payloads to send them to the server.
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.. attribute:: running
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:type: asyncio.Event
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Is the background task currently running? This is the event that
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:meth:`.run` sets when it starts and it remains set until the task
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exits.
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.. attribute:: stopped
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:type: asyncio.Event
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Is the background task currently stopped? This is the event that
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:meth:`.run` sets when it exits and that :meth:`.stop` blocks on
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until the task stops.
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"""
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logger: logging.Logger
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protocol: typing.Optional[StatsdProtocol]
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queue: asyncio.Queue
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_create_transport: typing.Callable[[], typing.Coroutine[
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typing.Any, typing.Any, typing.Tuple[asyncio.BaseTransport,
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StatsdProtocol]]]
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def __init__(self,
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*,
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host: str,
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port: int = 8125,
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ip_protocol: int = socket.IPPROTO_TCP,
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max_queue_size: int = 1000,
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reconnect_sleep: float = 1.0,
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wait_timeout: float = 0.1) -> None:
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super().__init__()
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if not host:
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raise RuntimeError('host must be set')
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try:
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port = int(port)
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if not port or port < 1:
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raise RuntimeError(
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f'port must be a positive integer: {port!r}')
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except (TypeError, ValueError):
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raise RuntimeError(f'port must be a positive integer: {port!r}')
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transport_creators = {
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socket.IPPROTO_TCP: self._create_tcp_transport,
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socket.IPPROTO_UDP: self._create_udp_transport,
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}
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try:
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factory = transport_creators[ip_protocol]
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except KeyError:
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raise RuntimeError(f'ip_protocol {ip_protocol} is not supported')
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else:
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self._create_transport = factory # type: ignore
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self.host = host
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self.port = port
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self._ip_protocol = ip_protocol
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self._connect_log_guard = ThrottleGuard(100)
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self._reconnect_sleep = reconnect_sleep
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self._wait_timeout = wait_timeout
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self.running = asyncio.Event()
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self.stopped = asyncio.Event()
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self.stopped.set()
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self.logger = logging.getLogger(__package__).getChild('Processor')
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self.should_terminate = False
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self.protocol = None
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self.queue = asyncio.Queue(maxsize=max_queue_size)
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@property
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def connected(self) -> bool:
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"""Is the processor connected?"""
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return self.protocol is not None and self.protocol.connected.is_set()
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def enqueue(self, metric: bytes) -> None:
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self.queue.put_nowait(metric)
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async def run(self) -> None:
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"""Maintains the connection and processes metric payloads."""
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self.running.set()
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self.stopped.clear()
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self.should_terminate = False
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while not self.should_terminate:
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try:
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await self._connect_if_necessary()
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if self.connected:
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await self._process_metric()
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except asyncio.CancelledError:
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self.logger.info('task cancelled, exiting')
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self.should_terminate = True
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except Exception as error:
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self.logger.exception('unexpected error occurred: %s', error)
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self.should_terminate = True
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self.should_terminate = True
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self.logger.info('loop finished with %d metrics in the queue',
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self.queue.qsize())
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if self.connected:
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num_ready = max(self.queue.qsize(), 1)
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self.logger.info('draining %d metrics', num_ready)
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for _ in range(num_ready):
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await self._process_metric()
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self.logger.debug('closing transport')
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if self.protocol is not None:
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await self.protocol.shutdown()
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self.logger.info('processor is exiting')
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self.running.clear()
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self.stopped.set()
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async def stop(self) -> None:
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"""Stop the processor.
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This is an asynchronous but blocking method. It does not
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return until enqueued metrics are flushed and the processor
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connection is closed.
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"""
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self.should_terminate = True
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await self.stopped.wait()
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async def _create_tcp_transport(
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self) -> typing.Tuple[asyncio.BaseTransport, StatsdProtocol]:
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t, p = await asyncio.get_running_loop().create_connection(
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protocol_factory=TCPProtocol, host=self.host, port=self.port)
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return t, typing.cast(StatsdProtocol, p)
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async def _create_udp_transport(
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self) -> typing.Tuple[asyncio.BaseTransport, StatsdProtocol]:
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t, p = await asyncio.get_running_loop().create_datagram_endpoint(
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protocol_factory=UDPProtocol,
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remote_addr=(self.host, self.port),
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reuse_port=True)
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return t, typing.cast(StatsdProtocol, p)
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async def _connect_if_necessary(self) -> None:
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if self.protocol is not None:
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try:
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await asyncio.wait_for(self.protocol.connected.wait(),
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self._wait_timeout)
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except asyncio.TimeoutError:
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self.logger.debug('protocol is no longer connected')
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if not self.connected:
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try:
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buffered_data = b''
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if self.protocol is not None:
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buffered_data = self.protocol.buffered_data
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t, p = await self._create_transport() # type: ignore[misc]
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|
transport, self.protocol = t, p
|
|
self.protocol.buffered_data = buffered_data
|
|
self.logger.info(
|
|
'connection established to %s after %s attempts',
|
|
transport.get_extra_info('peername'),
|
|
self._connect_log_guard.counter)
|
|
self._connect_log_guard.reset()
|
|
except IOError as error:
|
|
if self._connect_log_guard.allow_execution():
|
|
self.logger.warning(
|
|
'connection to %s:%s failed: %s (%s attempts)',
|
|
self.host, self.port, error,
|
|
self._connect_log_guard.counter)
|
|
await asyncio.sleep(self._reconnect_sleep)
|
|
|
|
async def _process_metric(self) -> None:
|
|
try:
|
|
metric = await asyncio.wait_for(self.queue.get(),
|
|
self._wait_timeout)
|
|
self.logger.debug('received %r from queue', metric)
|
|
self.queue.task_done()
|
|
except asyncio.TimeoutError:
|
|
# we still want to invoke the protocol send in case
|
|
# it has queued metrics to send
|
|
metric = b''
|
|
|
|
assert self.protocol is not None # AFAICT, this cannot happen
|
|
self.protocol.send(metric)
|