Source code for swh.core.statsd

# Copyright (C) 2018  The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

# Initially imported from https://github.com/DataDog/datadogpy/
# at revision 62b3a3e89988dc18d78c282fe3ff5d1813917436
#
# Copyright (c) 2015, Datadog <info@datadoghq.com>
# All rights reserved.
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#       used to endorse or promote products derived from this software without
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#
# Vastly adapted for integration in swh.core:
#
# - Removed python < 3.5 compat code
# - trimmed the imports down to be a single module
# - adjust some options:
#   - drop unix socket connection option
#   - add environment variable support for setting the statsd host and
#     port (pulled the idea from the main python statsd module)
#   - only send timer metrics in milliseconds (that's what
#     prometheus-statsd-exporter expects)
#   - drop DataDog-specific metric types (that are unsupported in
#     prometheus-statsd-exporter)
# - made the tags a dict instead of a list (prometheus-statsd-exporter only
#   supports tags with a value, mirroring prometheus)
# - switch from time.time to time.monotonic
# - improve unit test coverage
# - documentation cleanup


from asyncio import iscoroutinefunction
from functools import wraps
import itertools
import logging
import os
from random import random
import socket
import threading
from time import monotonic
import warnings

log = logging.getLogger("swh.core.statsd")


[docs]class TimedContextManagerDecorator(object): """ A context manager and a decorator which will report the elapsed time in the context OR in a function call. Attributes: elapsed (float): the elapsed time at the point of completion """ def __init__( self, statsd, metric=None, error_metric=None, tags=None, sample_rate=1 ): self.statsd = statsd self.metric = metric self.error_metric = error_metric self.tags = tags self.sample_rate = sample_rate self.elapsed = None # this is for testing purpose def __call__(self, func): """ Decorator which returns the elapsed time of the function call. Default to the function name if metric was not provided. """ if not self.metric: self.metric = "%s.%s" % (func.__module__, func.__name__) # Coroutines if iscoroutinefunction(func): @wraps(func) async def wrapped_co(*args, **kwargs): start = monotonic() try: result = await func(*args, **kwargs) except: # noqa self._send_error() raise self._send(start) return result return wrapped_co # Others @wraps(func) def wrapped(*args, **kwargs): start = monotonic() try: result = func(*args, **kwargs) except: # noqa self._send_error() raise self._send(start) return result return wrapped def __enter__(self): if not self.metric: raise TypeError("Cannot used timed without a metric!") self._start = monotonic() return self def __exit__(self, type, value, traceback): # Report the elapsed time of the context manager if no error. if type is None: self._send(self._start) else: self._send_error() def _send(self, start): elapsed = (monotonic() - start) * 1000 self.statsd.timing( self.metric, elapsed, tags=self.tags, sample_rate=self.sample_rate ) self.elapsed = elapsed def _send_error(self): if self.error_metric is None: self.error_metric = self.metric + "_error_count" self.statsd.increment(self.error_metric, tags=self.tags)
[docs] def start(self): """Start the timer""" self.__enter__()
[docs] def stop(self): """Stop the timer, send the metric value""" self.__exit__(None, None, None)
[docs]class Statsd(object): """Initialize a client to send metrics to a StatsD server. Arguments: host (str): the host of the StatsD server. Defaults to localhost. port (int): the port of the StatsD server. Defaults to 8125. max_buffer_size (int): Maximum number of metrics to buffer before sending to the server if sending metrics in batch namespace (str): Namespace to prefix all metric names constant_tags (Dict[str, str]): Tags to attach to all metrics Note: This class also supports the following environment variables: STATSD_HOST Override the default host of the statsd server STATSD_PORT Override the default port of the statsd server STATSD_TAGS Tags to attach to every metric reported. Example value: "label:value,other_label:other_value" """ def __init__( self, host=None, port=None, max_buffer_size=50, namespace=None, constant_tags=None, ): # Connection if host is None: host = os.environ.get("STATSD_HOST") or "localhost" self.host = host if port is None: port = os.environ.get("STATSD_PORT") or 8125 self.port = int(port) # Socket self._socket = None self.lock = threading.Lock() self.max_buffer_size = max_buffer_size self._send = self._send_to_server self.encoding = "utf-8" # Tags self.constant_tags = {} tags_envvar = os.environ.get("STATSD_TAGS", "") for tag in tags_envvar.split(","): if not tag: continue if ":" not in tag: warnings.warn( "STATSD_TAGS needs to be in key:value format, " "%s invalid" % tag, UserWarning, ) continue k, v = tag.split(":", 1) self.constant_tags[k] = v if constant_tags: self.constant_tags.update( {str(k): str(v) for k, v in constant_tags.items()} ) # Namespace if namespace is not None: namespace = str(namespace) self.namespace = namespace def __enter__(self): self.open_buffer(self.max_buffer_size) return self def __exit__(self, type, value, traceback): self.close_buffer()
[docs] def gauge(self, metric, value, tags=None, sample_rate=1): """ Record the value of a gauge, optionally setting a list of tags and a sample rate. >>> statsd.gauge('users.online', 123) >>> statsd.gauge('active.connections', 1001, tags={"protocol": "http"}) """ return self._report(metric, "g", value, tags, sample_rate)
[docs] def increment(self, metric, value=1, tags=None, sample_rate=1): """ Increment a counter, optionally setting a value, tags and a sample rate. >>> statsd.increment('page.views') >>> statsd.increment('files.transferred', 124) """ self._report(metric, "c", value, tags, sample_rate)
[docs] def decrement(self, metric, value=1, tags=None, sample_rate=1): """ Decrement a counter, optionally setting a value, tags and a sample rate. >>> statsd.decrement('files.remaining') >>> statsd.decrement('active.connections', 2) """ metric_value = -value if value else value self._report(metric, "c", metric_value, tags, sample_rate)
[docs] def histogram(self, metric, value, tags=None, sample_rate=1): """ Sample a histogram value, optionally setting tags and a sample rate. >>> statsd.histogram('uploaded.file.size', 1445) >>> statsd.histogram('file.count', 26, tags={"filetype": "python"}) """ self._report(metric, "h", value, tags, sample_rate)
[docs] def timing(self, metric, value, tags=None, sample_rate=1): """ Record a timing, optionally setting tags and a sample rate. >>> statsd.timing("query.response.time", 1234) """ self._report(metric, "ms", value, tags, sample_rate)
[docs] def timed(self, metric=None, error_metric=None, tags=None, sample_rate=1): """ A decorator or context manager that will measure the distribution of a function's/context's run time. Optionally specify a list of tags or a sample rate. If the metric is not defined as a decorator, the module name and function name will be used. The metric is required as a context manager. :: @statsd.timed('user.query.time', sample_rate=0.5) def get_user(user_id): # Do what you need to ... pass # Is equivalent to ... with statsd.timed('user.query.time', sample_rate=0.5): # Do what you need to ... pass # Is equivalent to ... start = time.monotonic() try: get_user(user_id) finally: statsd.timing('user.query.time', time.monotonic() - start) """ return TimedContextManagerDecorator( statsd=self, metric=metric, error_metric=error_metric, tags=tags, sample_rate=sample_rate, )
[docs] def set(self, metric, value, tags=None, sample_rate=1): """ Sample a set value. >>> statsd.set('visitors.uniques', 999) """ self._report(metric, "s", value, tags, sample_rate)
@property def socket(self): """ Return a connected socket. Note: connect the socket before assigning it to the class instance to avoid bad thread race conditions. """ with self.lock: if not self._socket: sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock.connect((self.host, self.port)) self._socket = sock return self._socket
[docs] def open_buffer(self, max_buffer_size=50): """ Open a buffer to send a batch of metrics in one packet. You can also use this as a context manager. >>> with Statsd() as batch: ... batch.gauge('users.online', 123) ... batch.gauge('active.connections', 1001) """ self.max_buffer_size = max_buffer_size self.buffer = [] self._send = self._send_to_buffer
[docs] def close_buffer(self): """ Flush the buffer and switch back to single metric packets. """ self._send = self._send_to_server if self.buffer: # Only send packets if there are packets to send self._flush_buffer()
[docs] def close_socket(self): """ Closes connected socket if connected. """ with self.lock: if self._socket: self._socket.close() self._socket = None
def _report(self, metric, metric_type, value, tags, sample_rate): """ Create a metric packet and send it. """ if value is None: return if sample_rate != 1 and random() > sample_rate: return # Resolve the full tag list tags = self._add_constant_tags(tags) # Create/format the metric packet payload = "%s%s:%s|%s%s%s" % ( (self.namespace + ".") if self.namespace else "", metric, value, metric_type, ("|@" + str(sample_rate)) if sample_rate != 1 else "", ("|#" + ",".join("%s:%s" % (k, v) for (k, v) in sorted(tags.items()))) if tags else "", ) # Send it self._send(payload) def _send_to_server(self, packet): try: # If set, use socket directly self.socket.send(packet.encode("utf-8")) except socket.timeout: return except socket.error: log.debug( "Error submitting statsd packet." " Dropping the packet and closing the socket." ) self.close_socket() def _send_to_buffer(self, packet): self.buffer.append(packet) if len(self.buffer) >= self.max_buffer_size: self._flush_buffer() def _flush_buffer(self): self._send_to_server("\n".join(self.buffer)) self.buffer = [] def _add_constant_tags(self, tags): return { str(k): str(v) for k, v in itertools.chain( self.constant_tags.items(), (tags if tags else {}).items(), ) }
statsd = Statsd()