From 13417d618944a7342137e67fe4a61c4b4fc3a763 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=96mer=20Faruk=20Irmak?= <omerfirmak@gmail.com>
Date: Thu, 31 Mar 2022 12:31:12 +0300
Subject: [PATCH] Stats: Append scrape duration to the end of `/metrics`
 response

---
 source/agora/node/Runner.d             |  2 +-
 source/agora/stats/CollectorRegistry.d | 16 +++++++++++-----
 source/agora/stats/Stats.d             |  7 ++++---
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/source/agora/node/Runner.d b/source/agora/node/Runner.d
index 261d87bf1fc..5de6a514b57 100644
--- a/source/agora/node/Runner.d
+++ b/source/agora/node/Runner.d
@@ -106,7 +106,7 @@ public void runNode (Config config, ref Listeners result)
         scope HTTPServerRequest, scope HTTPServerResponse res)
     {
         res.writeBody(cast(const(ubyte[])) Utils.getCollectorRegistry().collect(),
-                      "text/plain");
+                      "text/plain; charset=utf-8");
     }
 
     if (hasStatsInterface)
diff --git a/source/agora/stats/CollectorRegistry.d b/source/agora/stats/CollectorRegistry.d
index a69162d8db5..f1fe9f76983 100644
--- a/source/agora/stats/CollectorRegistry.d
+++ b/source/agora/stats/CollectorRegistry.d
@@ -17,6 +17,8 @@ module agora.stats.CollectorRegistry;
 
 import agora.stats.Collector : Collector;
 
+version (unittest) import std.algorithm;
+
 /// ditto
 public class CollectorRegistry
 {
@@ -76,6 +78,9 @@ public class CollectorRegistry
 
     public const(char)[] collect ( )
     {
+        import core.time;
+        import std.format;
+        auto start = MonoTime.currTime;
         this.collector.reset();
 
         try
@@ -90,7 +95,8 @@ public class CollectorRegistry
             throw ex;
         }
 
-        return this.collector.getCollection();
+        return this.collector.getCollection() ~
+            format("scrape_duration \"%s\"", MonoTime.currTime - start);
     }
 }
 
@@ -139,10 +145,10 @@ unittest
 
     stats.setTestStats(Statistics(3600, 347, 3.14, 6.023, 0.43));
 
-    assert(registry.collect() ==
+    assert(registry.collect().startsWith(
         "up_time_s {id=\"123.034\"} 3600\ncount {id=\"123.034\"} 347\n" ~
         "ratio {id=\"123.034\"} 3.14\nfraction {id=\"123.034\"} 6.023\n" ~
-        "very_real {id=\"123.034\"} 0.43\n");
+        "very_real {id=\"123.034\"} 0.43\n"));
 }
 
 /// Test collection from more than one delegates
@@ -155,7 +161,7 @@ unittest
     stats.setTestStats(Statistics(3600, 347, 3.14, 6.023, 0.43));
     stats.setTestLabels(Labels(1_235_813, "ocean", 3.14159));
 
-    assert(registry.collect() ==
+    assert(registry.collect().startsWith(
         "up_time_s {id=\"123.034\"} 3600\ncount {id=\"123.034\"} 347\n" ~
         "ratio {id=\"123.034\"} 3.14\nfraction {id=\"123.034\"} 6.023\n" ~
         "very_real {id=\"123.034\"} 0.43\n" ~
@@ -164,7 +170,7 @@ unittest
         "count {id=\"1235813\",job=\"ocean\",perf=\"3.14159\"} 347\n" ~
         "ratio {id=\"1235813\",job=\"ocean\",perf=\"3.14159\"} 3.14\n" ~
         "fraction {id=\"1235813\",job=\"ocean\",perf=\"3.14159\"} 6.023\n" ~
-        "very_real {id=\"1235813\",job=\"ocean\",perf=\"3.14159\"} 0.43\n");
+        "very_real {id=\"1235813\",job=\"ocean\",perf=\"3.14159\"} 0.43\n"));
 }
 
 /// Test that the collections are not accumulated upon more than one call to
diff --git a/source/agora/stats/Stats.d b/source/agora/stats/Stats.d
index ab47c736a11..9ccd5c9d114 100644
--- a/source/agora/stats/Stats.d
+++ b/source/agora/stats/Stats.d
@@ -170,6 +170,7 @@ version (unittest)
 unittest
 {
     import std.functional : toDelegate;
+    import std.algorithm;
 
     // stats with one label
     CollectorRegistry collector_registry_with_label = new CollectorRegistry([]);
@@ -178,14 +179,14 @@ unittest
     test_stats_with_label.increaseMetricBy!"test_metric_value"(1, "interesting_label1");
     test_stats_with_label.setMetricTo!"test_metric_value"(5, "interesting_label2");
     test_stats_with_label.increaseMetricBy!"test_metric_value"(2, "interesting_label2");
-    assert(collector_registry_with_label.collect() ==
+    assert(collector_registry_with_label.collect().startsWith(
         "test_metric_value {test_metric_label=\"interesting_label1\"} 42\n" ~
-        "test_metric_value {test_metric_label=\"interesting_label2\"} 7\n");
+        "test_metric_value {test_metric_label=\"interesting_label2\"} 7\n"));
 
     // stats without label
     CollectorRegistry collector_registry_without_label = new CollectorRegistry([]);
     collector_registry_without_label.addCollector(toDelegate(&collectTestStatWithoutLabel));
     test_stats_without_label.setMetricTo!"test_metric_value"(41);
     test_stats_without_label.increaseMetricBy!"test_metric_value"(1);
-    assert(collector_registry_without_label.collect() == "test_metric_value 42\n");
+    assert(collector_registry_without_label.collect().startsWith("test_metric_value 42\n"));
 }