From ccc1a3d54d08a90152100f3d57b1b912482281a6 Mon Sep 17 00:00:00 2001
From: "Paul \"LeoNerd\" Evans" <paul@matrix.org>
Date: Thu, 27 Oct 2016 18:07:34 +0100
Subject: [PATCH 1/3] Allow creation of a 'subspace' within a Metrics object,
 returning another one

---
 synapse/metrics/__init__.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index a6b868775d..f6c084169b 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -41,6 +41,9 @@ class Metrics(object):
     def __init__(self, name):
         self.name_prefix = name
 
+    def make_subspace(self, name):
+        return Metrics("%s_%s" % (self.name_prefix, name))
+
     def register_collector(self, func):
         all_collectors.append(func)
 

From aac13b1f9a940f5661d5989e3045b4fc086f1e20 Mon Sep 17 00:00:00 2001
From: "Paul \"LeoNerd\" Evans" <paul@matrix.org>
Date: Thu, 27 Oct 2016 18:08:15 +0100
Subject: [PATCH 2/3] Pass the Metrics group into the process collector instead
 of having it find its own one; this avoids it needing to import from
 synapse.metrics

---
 synapse/app/homeserver.py            |  2 +-
 synapse/metrics/process_collector.py | 10 +++-------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index f27150d411..6766befc4e 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -338,7 +338,7 @@ def setup(config_options):
         hs.get_replication_layer().start_get_pdu_cache()
 
         register_memory_metrics(hs)
-        register_process_collector()
+        register_process_collector(get_metrics_for("process"))
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/metrics/process_collector.py b/synapse/metrics/process_collector.py
index 1c851d9234..0e95582368 100644
--- a/synapse/metrics/process_collector.py
+++ b/synapse/metrics/process_collector.py
@@ -20,8 +20,6 @@ import os
 import stat
 from resource import getrusage, RUSAGE_SELF
 
-from synapse.metrics import get_metrics_for
-
 
 TICKS_PER_SEC = 100
 BYTES_PER_PAGE = 4096
@@ -111,10 +109,10 @@ def _process_fds():
     return counts
 
 
-def register_process_collector():
+def register_process_collector(process_metrics):
     # Legacy synapse-invented metric names
 
-    resource_metrics = get_metrics_for("process.resource")
+    resource_metrics = process_metrics.make_subspace("resource")
 
     resource_metrics.register_collector(update_resource_metrics)
 
@@ -125,12 +123,10 @@ def register_process_collector():
     # kilobytes
     resource_metrics.register_callback("maxrss", lambda: rusage.ru_maxrss * 1024)
 
-    get_metrics_for("process").register_callback("fds", _process_fds, labels=["type"])
+    process_metrics.register_callback("fds", _process_fds, labels=["type"])
 
     # New prometheus-standard metric names
 
-    process_metrics = get_metrics_for("process")
-
     if HAVE_PROC_SELF_STAT:
         process_metrics.register_callback(
             "cpu_user_seconds_total",

From 1cc22da6002bc12b11e2e9455143c9f16ed0f5c4 Mon Sep 17 00:00:00 2001
From: "Paul \"LeoNerd\" Evans" <paul@matrix.org>
Date: Thu, 27 Oct 2016 18:09:34 +0100
Subject: [PATCH 3/3] Set up the process collector during metrics __init__;
 that way all split-process workers have it

---
 synapse/app/homeserver.py   | 2 --
 synapse/metrics/__init__.py | 3 +++
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 6766befc4e..54f35900f8 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -52,7 +52,6 @@ from synapse.config.homeserver import HomeServerConfig
 from synapse.crypto import context_factory
 from synapse.util.logcontext import LoggingContext
 from synapse.metrics import register_memory_metrics, get_metrics_for
-from synapse.metrics.process_collector import register_process_collector
 from synapse.metrics.resource import MetricsResource, METRICS_PREFIX
 from synapse.replication.resource import ReplicationResource, REPLICATION_PREFIX
 from synapse.federation.transport.server import TransportLayerServer
@@ -338,7 +337,6 @@ def setup(config_options):
         hs.get_replication_layer().start_get_pdu_cache()
 
         register_memory_metrics(hs)
-        register_process_collector(get_metrics_for("process"))
 
     reactor.callWhenRunning(start)
 
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index f6c084169b..7041da25ce 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -24,6 +24,7 @@ from .metric import (
     CounterMetric, CallbackMetric, DistributionMetric, CacheMetric,
     MemoryUsageMetric,
 )
+from .process_collector import register_process_collector
 
 
 logger = logging.getLogger(__name__)
@@ -121,6 +122,8 @@ reactor_metrics.register_callback(
     "gc_counts", lambda: {(i,): v for i, v in enumerate(gc.get_count())}, labels=["gen"]
 )
 
+register_process_collector(get_metrics_for("process"))
+
 
 def runUntilCurrentTimer(func):