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# -*- coding: utf-8 -*-
# Copyright 2015 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
from .metric import CounterMetric, CallbackMetric, CacheMetric
logger = logging.getLogger(__name__)
# We'll keep all the available metrics in a single toplevel dict, one shared
# for the entire process. We don't currently support per-HomeServer instances
# of metrics, because in practice any one python VM will host only one
# HomeServer anyway. This makes a lot of implementation neater
all_metrics = {}
class Metrics(object):
""" A single Metrics object gives a (mutable) slice view of the all_metrics
dict, allowing callers to easily register new metrics that are namespaced
nicely."""
def __init__(self, name):
self.name_prefix = name
def _register(self, metric):
all_metrics[metric.name] = metric
def register_counter(self, name, *args, **kwargs):
full_name = "%s.%s" % (self.name_prefix, name)
metric = CounterMetric(full_name, *args, **kwargs)
self._register(metric)
return metric
def register_callback(self, name, callback, *args, **kwargs):
full_name = "%s.%s" % (self.name_prefix, name)
metric = CallbackMetric(full_name, *args, callback=callback, **kwargs)
self._register(metric)
return metric
def register_cache(self, name, *args, **kwargs):
full_name = "%s.%s" % (self.name_prefix, name)
metric = CacheMetric(full_name, *args, **kwargs)
self._register(metric)
return metric
def counted(self, func):
""" A method decorator that registers a counter, to count invocations
of this method. """
counter = self.register_counter(func.__name__)
def wrapped(*args, **kwargs):
counter.inc()
return func(*args, **kwargs)
return wrapped
def get_metrics_for(name):
""" Returns a Metrics instance for conveniently creating metrics
namespaced with the given name prefix. """
return Metrics(name)
def render_all():
strs = []
for name in sorted(all_metrics.keys()):
try:
strs += all_metrics[name].render()
except Exception as e:
strs += ["# FAILED to render %s" % name]
logger.exception("Failed to render %s metric", name)
return "\n".join(strs)
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