diff --git a/synapse/metrics/_exposition.py b/synapse/metrics/_exposition.py
deleted file mode 100644
index 353d0a63b6..0000000000
--- a/synapse/metrics/_exposition.py
+++ /dev/null
@@ -1,262 +0,0 @@
-# Copyright 2015-2019 Prometheus Python Client Developers
-# Copyright 2019 Matrix.org Foundation C.I.C.
-#
-# 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.
-
-"""
-This code is based off `prometheus_client/exposition.py` from version 0.7.1.
-
-Due to the renaming of metrics in prometheus_client 0.4.0, this customised
-vendoring of the code will emit both the old versions that Synapse dashboards
-expect, and the newer "best practice" version of the up-to-date official client.
-"""
-
-import math
-import threading
-from http.server import BaseHTTPRequestHandler, HTTPServer
-from socketserver import ThreadingMixIn
-from typing import Any, Dict, List, Type, Union
-from urllib.parse import parse_qs, urlparse
-
-from prometheus_client import REGISTRY, CollectorRegistry
-from prometheus_client.core import Sample
-
-from twisted.web.resource import Resource
-from twisted.web.server import Request
-
-from synapse.util import caches
-
-CONTENT_TYPE_LATEST = "text/plain; version=0.0.4; charset=utf-8"
-
-
-def floatToGoString(d: Union[int, float]) -> str:
- d = float(d)
- if d == math.inf:
- return "+Inf"
- elif d == -math.inf:
- return "-Inf"
- elif math.isnan(d):
- return "NaN"
- else:
- s = repr(d)
- dot = s.find(".")
- # Go switches to exponents sooner than Python.
- # We only need to care about positive values for le/quantile.
- if d > 0 and dot > 6:
- mantissa = f"{s[0]}.{s[1:dot]}{s[dot + 1 :]}".rstrip("0.")
- return f"{mantissa}e+0{dot - 1}"
- return s
-
-
-def sample_line(line: Sample, name: str) -> str:
- if line.labels:
- labelstr = "{{{0}}}".format(
- ",".join(
- [
- '{}="{}"'.format(
- k,
- v.replace("\\", r"\\").replace("\n", r"\n").replace('"', r"\""),
- )
- for k, v in sorted(line.labels.items())
- ]
- )
- )
- else:
- labelstr = ""
- timestamp = ""
- if line.timestamp is not None:
- # Convert to milliseconds.
- timestamp = f" {int(float(line.timestamp) * 1000):d}"
- return "{}{} {}{}\n".format(name, labelstr, floatToGoString(line.value), timestamp)
-
-
-def generate_latest(registry: CollectorRegistry, emit_help: bool = False) -> bytes:
-
- # Trigger the cache metrics to be rescraped, which updates the common
- # metrics but do not produce metrics themselves
- for collector in caches.collectors_by_name.values():
- collector.collect()
-
- output = []
-
- for metric in registry.collect():
- if not metric.samples:
- # No samples, don't bother.
- continue
-
- mname = metric.name
- mnewname = metric.name
- mtype = metric.type
-
- # OpenMetrics -> Prometheus
- if mtype == "counter":
- mnewname = mnewname + "_total"
- elif mtype == "info":
- mtype = "gauge"
- mnewname = mnewname + "_info"
- elif mtype == "stateset":
- mtype = "gauge"
- elif mtype == "gaugehistogram":
- mtype = "histogram"
- elif mtype == "unknown":
- mtype = "untyped"
-
- # Output in the old format for compatibility.
- if emit_help:
- output.append(
- "# HELP {} {}\n".format(
- mname,
- metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
- )
- )
- output.append(f"# TYPE {mname} {mtype}\n")
-
- om_samples: Dict[str, List[str]] = {}
- for s in metric.samples:
- for suffix in ["_created", "_gsum", "_gcount"]:
- if s.name == metric.name + suffix:
- # OpenMetrics specific sample, put in a gauge at the end.
- # (these come from gaugehistograms which don't get renamed,
- # so no need to faff with mnewname)
- om_samples.setdefault(suffix, []).append(sample_line(s, s.name))
- break
- else:
- newname = s.name.replace(mnewname, mname)
- if ":" in newname and newname.endswith("_total"):
- newname = newname[: -len("_total")]
- output.append(sample_line(s, newname))
-
- for suffix, lines in sorted(om_samples.items()):
- if emit_help:
- output.append(
- "# HELP {}{} {}\n".format(
- metric.name,
- suffix,
- metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
- )
- )
- output.append(f"# TYPE {metric.name}{suffix} gauge\n")
- output.extend(lines)
-
- # Get rid of the weird colon things while we're at it
- if mtype == "counter":
- mnewname = mnewname.replace(":total", "")
- mnewname = mnewname.replace(":", "_")
-
- if mname == mnewname:
- continue
-
- # Also output in the new format, if it's different.
- if emit_help:
- output.append(
- "# HELP {} {}\n".format(
- mnewname,
- metric.documentation.replace("\\", r"\\").replace("\n", r"\n"),
- )
- )
- output.append(f"# TYPE {mnewname} {mtype}\n")
-
- for s in metric.samples:
- # Get rid of the OpenMetrics specific samples (we should already have
- # dealt with them above anyway.)
- for suffix in ["_created", "_gsum", "_gcount"]:
- if s.name == metric.name + suffix:
- break
- else:
- output.append(
- sample_line(s, s.name.replace(":total", "").replace(":", "_"))
- )
-
- return "".join(output).encode("utf-8")
-
-
-class MetricsHandler(BaseHTTPRequestHandler):
- """HTTP handler that gives metrics from ``REGISTRY``."""
-
- registry = REGISTRY
-
- def do_GET(self) -> None:
- registry = self.registry
- params = parse_qs(urlparse(self.path).query)
-
- if "help" in params:
- emit_help = True
- else:
- emit_help = False
-
- try:
- output = generate_latest(registry, emit_help=emit_help)
- except Exception:
- self.send_error(500, "error generating metric output")
- raise
- self.send_response(200)
- self.send_header("Content-Type", CONTENT_TYPE_LATEST)
- self.send_header("Content-Length", str(len(output)))
- self.end_headers()
- self.wfile.write(output)
-
- def log_message(self, format: str, *args: Any) -> None:
- """Log nothing."""
-
- @classmethod
- def factory(cls, registry: CollectorRegistry) -> Type:
- """Returns a dynamic MetricsHandler class tied
- to the passed registry.
- """
- # This implementation relies on MetricsHandler.registry
- # (defined above and defaulted to REGISTRY).
-
- # As we have unicode_literals, we need to create a str()
- # object for type().
- cls_name = str(cls.__name__)
- MyMetricsHandler = type(cls_name, (cls, object), {"registry": registry})
- return MyMetricsHandler
-
-
-class _ThreadingSimpleServer(ThreadingMixIn, HTTPServer):
- """Thread per request HTTP server."""
-
- # Make worker threads "fire and forget". Beginning with Python 3.7 this
- # prevents a memory leak because ``ThreadingMixIn`` starts to gather all
- # non-daemon threads in a list in order to join on them at server close.
- # Enabling daemon threads virtually makes ``_ThreadingSimpleServer`` the
- # same as Python 3.7's ``ThreadingHTTPServer``.
- daemon_threads = True
-
-
-def start_http_server(
- port: int, addr: str = "", registry: CollectorRegistry = REGISTRY
-) -> None:
- """Starts an HTTP server for prometheus metrics as a daemon thread"""
- CustomMetricsHandler = MetricsHandler.factory(registry)
- httpd = _ThreadingSimpleServer((addr, port), CustomMetricsHandler)
- t = threading.Thread(target=httpd.serve_forever)
- t.daemon = True
- t.start()
-
-
-class MetricsResource(Resource):
- """
- Twisted ``Resource`` that serves prometheus metrics.
- """
-
- isLeaf = True
-
- def __init__(self, registry: CollectorRegistry = REGISTRY):
- self.registry = registry
-
- def render_GET(self, request: Request) -> bytes:
- request.setHeader(b"Content-Type", CONTENT_TYPE_LATEST.encode("ascii"))
- response = generate_latest(self.registry)
- request.setHeader(b"Content-Length", str(len(response)))
- return response
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