From c8f9b45bc25ecbd3cd99c2bcfe61d3e3af69641a Mon Sep 17 00:00:00 2001
From: Mark Haines <mark.haines@matrix.org>
Date: Mon, 22 Aug 2016 15:31:12 +0100
Subject: [PATCH 1/2] Add usage stats to prometheus monitoring

---
 synapse/app/homeserver.py | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 40e6f65236..ce4ba60920 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -51,7 +51,7 @@ from synapse.api.urls import (
 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
+from synapse.metrics import register_memory_metrics, get_metrics_for
 from synapse.metrics.resource import MetricsResource, METRICS_PREFIX
 from synapse.replication.resource import ReplicationResource, REPLICATION_PREFIX
 from synapse.federation.transport.server import TransportLayerServer
@@ -385,6 +385,8 @@ def run(hs):
 
     start_time = hs.get_clock().time()
 
+    stats = {}
+
     @defer.inlineCallbacks
     def phone_stats_home():
         logger.info("Gathering stats for reporting")
@@ -393,7 +395,10 @@ def run(hs):
         if uptime < 0:
             uptime = 0
 
-        stats = {}
+        # If the stats directory is empty then this is the first time we've
+        # reported stats.
+        first_time = not stats
+
         stats["homeserver"] = hs.config.server_name
         stats["timestamp"] = now
         stats["uptime_seconds"] = uptime
@@ -406,6 +411,24 @@ def run(hs):
         daily_messages = yield hs.get_datastore().count_daily_messages()
         if daily_messages is not None:
             stats["daily_messages"] = daily_messages
+        else:
+            stats.pop("daily_messages", None)
+
+        if first_time:
+            # Report the stats as synapse metrics.
+            # As some of the stats are expensive to calculate we only update
+            # them when synapse phones home to matrix.org every 24 hours.
+            metrics = get_metrics_for("synapse.usage")
+            metrics.add_callback("timestamp", lambda: stats["timestamp"])
+            metrics.add_callback("uptime_seconds", lambda: stats["uptime_seconds"])
+            metrics.add_callback("total_users", lambda: stats["total_users"])
+            metrics.add_callback("total_room_count", lambda: stats["total_room_count"])
+            metrics.add_callback(
+                "daily_active_users", lambda: stats["daily_active_users"]
+            )
+            metrics.add_callback(
+                "daily_messages", lambda: stats.get("daily_messages", 0)
+            )
 
         logger.info("Reporting stats to matrix.org: %s" % (stats,))
         try:

From 689f4cb9147d4c9a04edde3a3728f5ca0bdbbe2f Mon Sep 17 00:00:00 2001
From: Mark Haines <mark.haines@matrix.org>
Date: Mon, 22 Aug 2016 16:17:31 +0100
Subject: [PATCH 2/2] Update comment

---
 synapse/app/homeserver.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index ce4ba60920..54f35900f8 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -415,7 +415,8 @@ def run(hs):
             stats.pop("daily_messages", None)
 
         if first_time:
-            # Report the stats as synapse metrics.
+            # Add callbacks to report the synapse stats as metrics whenever
+            # prometheus requests them, typically every 30s.
             # As some of the stats are expensive to calculate we only update
             # them when synapse phones home to matrix.org every 24 hours.
             metrics = get_metrics_for("synapse.usage")