mirror of
https://github.com/sprockets/sprockets-statsd.git
synced 2024-11-28 11:19:52 +00:00
348 lines
12 KiB
Python
348 lines
12 KiB
Python
import asyncio
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import logging
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import typing
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class Connector:
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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: TCP port that the server is listening on
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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 TCP 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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When the connector is *should_terminate*, metric payloads are sent by
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calling the :meth:`.inject_metric` method. The payloads are
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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:: 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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def __init__(self, host: str, port: int = 8125, **kwargs):
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self.processor = Processor(host=host, port=port, **kwargs)
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self._processor_task = None
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async def start(self):
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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):
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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, type_code: str):
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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: metric value as a number or a string. The
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string form is required for relative gauges.
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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'{path}:{value}|{type_code}'
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self.processor.queue.put_nowait(payload.encode('utf-8'))
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class StatsdProtocol:
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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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logger: logging.Logger
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def __init__(self):
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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.Transport):
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"""Capture the new transport and set the connected event."""
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server, port = transport.get_extra_info('peername')
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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.connected.set()
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def connection_lost(self, exc: typing.Optional[Exception]):
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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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transport: asyncio.WriteTransport
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def eof_received(self):
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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 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 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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protocol: typing.Union[StatsdProtocol, None]
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def __init__(self,
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*,
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host,
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port: int = 8125,
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reconnect_sleep: float = 1.0,
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wait_timeout: float = 0.1):
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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:
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raise RuntimeError(f'port must be a positive integer: {port!r}')
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self.host = host
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self.port = port
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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()
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self._failed_sends = []
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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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if self.protocol is None:
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return False
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return self.protocol.connected.is_set()
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async def run(self):
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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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break
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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):
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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 _connect_if_necessary(self):
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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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loop = asyncio.get_running_loop()
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transport, protocol = await loop.create_connection(
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protocol_factory=TCPProtocol,
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host=self.host,
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port=self.port)
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self.protocol = typing.cast(TCPProtocol, protocol)
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self.protocol.buffered_data = buffered_data
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self.logger.info('connection established to %s',
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transport.get_extra_info('peername'))
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except IOError as error:
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self.logger.warning('connection to %s:%s failed: %s',
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self.host, self.port, error)
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await asyncio.sleep(self._reconnect_sleep)
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async def _process_metric(self):
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try:
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metric = await asyncio.wait_for(self.queue.get(),
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self._wait_timeout)
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self.logger.debug('received %r from queue', metric)
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self.queue.task_done()
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except asyncio.TimeoutError:
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# we still want to invoke the protocol send in case
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# it has queued metrics to send
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metric = b''
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try:
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self.protocol.send(metric)
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except Exception as error:
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self.logger.exception('exception occurred when sending metric: %s',
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error)
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