From 11b517e2cc3bc9c37ae6508ce4ae5d25f09946b0 Mon Sep 17 00:00:00 2001
From: Matthias Sohn <matthias.sohn@sap.com>
Date: Thu, 5 Mar 2020 17:43:12 +0100
Subject: [PATCH] JGit metrics: expose total load time for block cache entries

This allows to calculate current average load time within a time
interval by dividing increase of total_load_time by increase of
load_success_count within a given time interval.

The already exposed metric avg_load_time gives the average since the
gerrit process was started.

Change-Id: I40eb61cc716b7d545aeae4eb522a439cc48bd74d
---
 Documentation/metrics.txt                             |  7 ++++---
 .../google/gerrit/metrics/proc/JGitMetricModule.java  | 11 +++++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/Documentation/metrics.txt b/Documentation/metrics.txt
index 9fe2df9395..e6654c3de4 100644
--- a/Documentation/metrics.txt
+++ b/Documentation/metrics.txt
@@ -139,9 +139,10 @@ topic submissions that concluded successfully.
 
 === JGit
 
-* `jgit/block_cache/cache_used`: Bytes of memory retained in JGit block cache.
-* `jgit/block_cache/open_files`: File handles held open by JGit block cache.
-* `avg_load_time` Average time to load a cache entry for JGit block cache.
+* `jgit/block_cache/cache_used` : Bytes of memory retained in JGit block cache.
+* `jgit/block_cache/open_files` : File handles held open by JGit block cache.
+* `avg_load_time` : Average time to load a cache entry for JGit block cache.
+* `total_load_time` : Total time to load cache entries for JGit block cache.
 * `eviction_count` : Cache evictions for JGit block cache.
 * `eviction_ratio` : Cache eviction ratio for JGit block cache.
 * `hit_count` : Cache hits for JGit block cache.
diff --git a/java/com/google/gerrit/metrics/proc/JGitMetricModule.java b/java/com/google/gerrit/metrics/proc/JGitMetricModule.java
index b9d86504fe..a44f907cc7 100644
--- a/java/com/google/gerrit/metrics/proc/JGitMetricModule.java
+++ b/java/com/google/gerrit/metrics/proc/JGitMetricModule.java
@@ -65,6 +65,17 @@ public class JGitMetricModule extends MetricModule {
           }
         });
 
+    metrics.newCallbackMetric(
+        "jgit/block_cache/total_load_time",
+        Long.class,
+        new Description("Total time to load cache entries for JGit block cache.").setGauge(),
+        new Supplier<Long>() {
+          @Override
+          public Long get() {
+            return WindowCacheStats.getStats().getTotalLoadTime();
+          }
+        });
+
     metrics.newCallbackMetric(
         "jgit/block_cache/eviction_count",
         Long.class,