Bug 1795775 - Add a telemetry probe to measure the time spent relaying the completion of a network request from the parent process to the child r=necko-reviewers,valentin

We are looking for any unexpected delays in the delivering of this event to the child process.

Differential Revision: https://phabricator.services.mozilla.com/D159892

netwerk/protocol/http/HttpChannelChild.cpp

@@ -908,6 +908,14 @@ void HttpChannelChild::OnStopRequest(
   PerfStats::RecordMeasurement(PerfStats::Metric::HttpChannelCompletion,
                                channelCompletionDuration);
 
+  if (!aTiming.responseEnd().IsNull()) {
+    nsAutoCString cosString;
+    ClassOfService::ToString(mClassOfService, cosString);
+    Telemetry::AccumulateTimeDelta(
+        Telemetry::NETWORK_RESPONSE_END_PARENT_TO_CONTENT_MS, cosString,
+        aTiming.responseEnd(), TimeStamp::Now());
+  }
+
   mResponseTrailers = MakeUnique<nsHttpHeaderArray>(aResponseTrailers);
 
   DoPreOnStopRequest(aChannelStatus);

toolkit/components/telemetry/Histograms.json

@@ -3114,6 +3114,18 @@
     "n_buckets": 50,
     "description": "The time spent from dns resolution to connect start, in milliseconds, keyed by protocol version and the classOfService flags"
   },
+  "NETWORK_RESPONSE_END_PARENT_TO_CONTENT_MS" :{
+    "record_in_processes": ["content"],
+    "products": [ "firefox", "fennec" ],
+    "alert_emails": ["necko@mozilla.com", "acreskey@mozilla.com"],
+    "bug_numbers": [1795775],
+    "expires_in_version": "never",
+    "keyed": true,
+    "kind": "exponential",
+    "high": 2000,
+    "n_buckets": 50,
+    "description": "The time spent relaying response completion from the socket thread of the parent process to the content process, in milliseconds, keyed by the classOfService flags"
+  },
   "HTTP_AUTH_DIALOG_STATS_3": {
     "record_in_processes": ["main", "content"],
     "products": ["firefox", "fennec"],