From 120fbbd4875f340b5c863b7e0e3eabcb2796e15d Mon Sep 17 00:00:00 2001
From: Paco Guzman <pacoguzmanp@gmail.com>
Date: Mon, 13 Jun 2016 18:41:37 +0200
Subject: [PATCH] Measure CPU time for instrumented methods

---
 CHANGELOG                                       |  1 +
 doc/development/instrumentation.md              | 11 ++++++-----
 lib/gitlab/metrics/instrumentation.rb           | 11 +++++++----
 spec/lib/gitlab/metrics/instrumentation_spec.rb |  4 ++--
 4 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 2aed8eb322b..e71a154d1d5 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -77,6 +77,7 @@ v 8.9.0 (unreleased)
   - All classes in the Banzai::ReferenceParser namespace are now instrumented
   - Remove deprecated issues_tracker and issues_tracker_id from project model
   - Allow users to create confidential issues in private projects
+  - Measure CPU time for instrumented methods
 
 v 8.8.5 (unreleased)
   - Ensure branch cleanup regardless of whether the GitHub import process succeeds
diff --git a/doc/development/instrumentation.md b/doc/development/instrumentation.md
index 9168c70945a..50d2866ca46 100644
--- a/doc/development/instrumentation.md
+++ b/doc/development/instrumentation.md
@@ -97,15 +97,16 @@ def #{name}(#{args_signature})
   trans = Gitlab::Metrics::Instrumentation.transaction
 
   if trans
-    start    = Time.now
-    retval   = super
-    duration = (Time.now - start) * 1000.0
+    start     = Time.now
+    cpu_start = Gitlab::Metrics::System.cpu_time
+    retval    = super
+    duration  = (Time.now - start) * 1000.0
 
     if duration >= Gitlab::Metrics.method_call_threshold
-      trans.increment(:method_duration, duration)
+      cpu_duration = Gitlab::Metrics::System.cpu_time - cpu_start
 
       trans.add_metric(Gitlab::Metrics::Instrumentation::SERIES,
-                       { duration: duration },
+                       { duration: duration, cpu_duration: cpu_duration },
                        method: #{label.inspect})
     end
 
diff --git a/lib/gitlab/metrics/instrumentation.rb b/lib/gitlab/metrics/instrumentation.rb
index 0f115893a15..ad9ce3fa442 100644
--- a/lib/gitlab/metrics/instrumentation.rb
+++ b/lib/gitlab/metrics/instrumentation.rb
@@ -149,13 +149,16 @@ module Gitlab
             trans = Gitlab::Metrics::Instrumentation.transaction
 
             if trans
-              start    = Time.now
-              retval   = super
-              duration = (Time.now - start) * 1000.0
+              start     = Time.now
+              cpu_start = Gitlab::Metrics::System.cpu_time
+              retval    = super
+              duration  = (Time.now - start) * 1000.0
 
               if duration >= Gitlab::Metrics.method_call_threshold
+                cpu_duration = Gitlab::Metrics::System.cpu_time - cpu_start
+
                 trans.add_metric(Gitlab::Metrics::Instrumentation::SERIES,
-                                 { duration: duration },
+                                 { duration: duration, cpu_duration: cpu_duration },
                                  method: #{label.inspect})
               end
 
diff --git a/spec/lib/gitlab/metrics/instrumentation_spec.rb b/spec/lib/gitlab/metrics/instrumentation_spec.rb
index 220e86924a2..c6e979b69a4 100644
--- a/spec/lib/gitlab/metrics/instrumentation_spec.rb
+++ b/spec/lib/gitlab/metrics/instrumentation_spec.rb
@@ -57,7 +57,7 @@ describe Gitlab::Metrics::Instrumentation do
           and_return(transaction)
 
         expect(transaction).to receive(:add_metric).
-          with(described_class::SERIES, an_instance_of(Hash),
+          with(described_class::SERIES, hash_including(:duration, :cpu_duration),
                method: 'Dummy.foo')
 
         @dummy.foo
@@ -137,7 +137,7 @@ describe Gitlab::Metrics::Instrumentation do
           and_return(transaction)
 
         expect(transaction).to receive(:add_metric).
-          with(described_class::SERIES, an_instance_of(Hash),
+          with(described_class::SERIES, hash_including(:duration, :cpu_duration),
                method: 'Dummy#bar')
 
         @dummy.new.bar