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-rw-r--r--synapse/http/request_metrics.py231
1 files changed, 231 insertions, 0 deletions
diff --git a/synapse/http/request_metrics.py b/synapse/http/request_metrics.py
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+++ b/synapse/http/request_metrics.py
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+# -*- coding: utf-8 -*-
+# Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2018 New Vector 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 prometheus_client.core import Counter, Histogram
+
+from synapse.metrics import LaterGauge
+from synapse.util.logcontext import LoggingContext
+
+logger = logging.getLogger(__name__)
+
+
+# total number of responses served, split by method/servlet/tag
+response_count = Counter(
+    "synapse_http_server_response_count", "", ["method", "servlet", "tag"]
+)
+
+requests_counter = Counter(
+    "synapse_http_server_requests_received", "", ["method", "servlet"]
+)
+
+outgoing_responses_counter = Counter(
+    "synapse_http_server_responses", "", ["method", "code"]
+)
+
+response_timer = Histogram(
+    "synapse_http_server_response_time_seconds", "sec",
+    ["method", "servlet", "tag", "code"],
+)
+
+response_ru_utime = Counter(
+    "synapse_http_server_response_ru_utime_seconds", "sec", ["method", "servlet", "tag"]
+)
+
+response_ru_stime = Counter(
+    "synapse_http_server_response_ru_stime_seconds", "sec", ["method", "servlet", "tag"]
+)
+
+response_db_txn_count = Counter(
+    "synapse_http_server_response_db_txn_count", "", ["method", "servlet", "tag"]
+)
+
+# seconds spent waiting for db txns, excluding scheduling time, when processing
+# this request
+response_db_txn_duration = Counter(
+    "synapse_http_server_response_db_txn_duration_seconds",
+    "",
+    ["method", "servlet", "tag"],
+)
+
+# seconds spent waiting for a db connection, when processing this request
+response_db_sched_duration = Counter(
+    "synapse_http_server_response_db_sched_duration_seconds",
+    "",
+    ["method", "servlet", "tag"],
+)
+
+# size in bytes of the response written
+response_size = Counter(
+    "synapse_http_server_response_size", "", ["method", "servlet", "tag"]
+)
+
+# In flight metrics are incremented while the requests are in flight, rather
+# than when the response was written.
+
+in_flight_requests_ru_utime = Counter(
+    "synapse_http_server_in_flight_requests_ru_utime_seconds",
+    "",
+    ["method", "servlet"],
+)
+
+in_flight_requests_ru_stime = Counter(
+    "synapse_http_server_in_flight_requests_ru_stime_seconds",
+    "",
+    ["method", "servlet"],
+)
+
+in_flight_requests_db_txn_count = Counter(
+    "synapse_http_server_in_flight_requests_db_txn_count", "", ["method", "servlet"]
+)
+
+# seconds spent waiting for db txns, excluding scheduling time, when processing
+# this request
+in_flight_requests_db_txn_duration = Counter(
+    "synapse_http_server_in_flight_requests_db_txn_duration_seconds",
+    "",
+    ["method", "servlet"],
+)
+
+# seconds spent waiting for a db connection, when processing this request
+in_flight_requests_db_sched_duration = Counter(
+    "synapse_http_server_in_flight_requests_db_sched_duration_seconds",
+    "",
+    ["method", "servlet"],
+)
+
+# The set of all in flight requests, set[RequestMetrics]
+_in_flight_requests = set()
+
+
+def _get_in_flight_counts():
+    """Returns a count of all in flight requests by (method, server_name)
+
+    Returns:
+        dict[tuple[str, str], int]
+    """
+    # Cast to a list to prevent it changing while the Prometheus
+    # thread is collecting metrics
+    reqs = list(_in_flight_requests)
+
+    for rm in reqs:
+        rm.update_metrics()
+
+    # Map from (method, name) -> int, the number of in flight requests of that
+    # type
+    counts = {}
+    for rm in reqs:
+        key = (rm.method, rm.name,)
+        counts[key] = counts.get(key, 0) + 1
+
+    return counts
+
+
+LaterGauge(
+    "synapse_http_server_in_flight_requests_count",
+    "",
+    ["method", "servlet"],
+    _get_in_flight_counts,
+)
+
+
+class RequestMetrics(object):
+    def start(self, time_sec, name, method):
+        self.start = time_sec
+        self.start_context = LoggingContext.current_context()
+        self.name = name
+        self.method = method
+
+        # _request_stats records resource usage that we have already added
+        # to the "in flight" metrics.
+        self._request_stats = self.start_context.get_resource_usage()
+
+        _in_flight_requests.add(self)
+
+    def stop(self, time_sec, request):
+        _in_flight_requests.discard(self)
+
+        context = LoggingContext.current_context()
+
+        tag = ""
+        if context:
+            tag = context.tag
+
+            if context != self.start_context:
+                logger.warn(
+                    "Context have unexpectedly changed %r, %r",
+                    context, self.start_context
+                )
+                return
+
+        response_code = str(request.code)
+
+        outgoing_responses_counter.labels(request.method, response_code).inc()
+
+        response_count.labels(request.method, self.name, tag).inc()
+
+        response_timer.labels(request.method, self.name, tag, response_code).observe(
+            time_sec - self.start
+        )
+
+        resource_usage = context.get_resource_usage()
+
+        response_ru_utime.labels(request.method, self.name, tag).inc(
+            resource_usage.ru_utime,
+        )
+        response_ru_stime.labels(request.method, self.name, tag).inc(
+            resource_usage.ru_stime,
+        )
+        response_db_txn_count.labels(request.method, self.name, tag).inc(
+            resource_usage.db_txn_count
+        )
+        response_db_txn_duration.labels(request.method, self.name, tag).inc(
+            resource_usage.db_txn_duration_sec
+        )
+        response_db_sched_duration.labels(request.method, self.name, tag).inc(
+            resource_usage.db_sched_duration_sec
+        )
+
+        response_size.labels(request.method, self.name, tag).inc(request.sentLength)
+
+        # We always call this at the end to ensure that we update the metrics
+        # regardless of whether a call to /metrics while the request was in
+        # flight.
+        self.update_metrics()
+
+    def update_metrics(self):
+        """Updates the in flight metrics with values from this request.
+        """
+        new_stats = self.start_context.get_resource_usage()
+
+        diff = new_stats - self._request_stats
+        self._request_stats = new_stats
+
+        in_flight_requests_ru_utime.labels(self.method, self.name).inc(diff.ru_utime)
+        in_flight_requests_ru_stime.labels(self.method, self.name).inc(diff.ru_stime)
+
+        in_flight_requests_db_txn_count.labels(self.method, self.name).inc(
+            diff.db_txn_count
+        )
+
+        in_flight_requests_db_txn_duration.labels(self.method, self.name).inc(
+            diff.db_txn_duration_sec
+        )
+
+        in_flight_requests_db_sched_duration.labels(self.method, self.name).inc(
+            diff.db_sched_duration_sec
+        )