From cc80d8fcd8a926bfa77f325d24897df192c8fa8b Mon Sep 17 00:00:00 2001
From: Valentin Gosu <valentin.gosu@gmail.com>
Date: Thu, 20 Apr 2017 16:42:10 +0800
Subject: [PATCH] Bug 1354409 - Add telemetry for how often we race network and
 cache r=michal

MozReview-Commit-ID: 1D1KyGbLxdW

--HG--
extra : rebase_source : 5bfeed6c1fb8f1379844947bd391ac352700b411
---
 netwerk/protocol/http/nsHttpChannel.cpp      | 17 +++++++++++++++++
 toolkit/components/telemetry/Histograms.json |  8 ++++++++
 2 files changed, 25 insertions(+)

diff --git a/netwerk/protocol/http/nsHttpChannel.cpp b/netwerk/protocol/http/nsHttpChannel.cpp
index f00fb8bb4e1c..c21fe4a1ec1b 100644
--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -7003,6 +7003,23 @@ nsHttpChannel::OnStopRequest(nsIRequest *request, nsISupports *ctxt, nsresult st
         }
     }
 
+    enum RaceCacheAndNetStatus
+    {
+        kDidNotRaceUsedNetwork = 0,
+        kDidNotRaceUsedCache = 1,
+        kRaceUsedNetwork = 2,
+        kRaceUsedCache = 3
+    };
+
+    RaceCacheAndNetStatus rcwnStatus = kDidNotRaceUsedNetwork;
+    if (request == mTransactionPump) {
+        rcwnStatus = mRaceCacheWithNetwork ?  kRaceUsedNetwork : kDidNotRaceUsedNetwork;
+    } else if (request == mCachePump) {
+        rcwnStatus = mRaceCacheWithNetwork ? kRaceUsedCache : kDidNotRaceUsedCache;
+    }
+    Telemetry::Accumulate(Telemetry::NETWORK_RACE_CACHE_WITH_NETWORK_USAGE,
+                          rcwnStatus);
+
     nsCOMPtr<nsICompressConvStats> conv = do_QueryInterface(mCompressListener);
     if (conv) {
         conv->GetDecodedDataLength(&mDecodedBodySize);
diff --git a/toolkit/components/telemetry/Histograms.json b/toolkit/components/telemetry/Histograms.json
index f3bfc4ab439b..57532d16669e 100644
--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -2057,6 +2057,14 @@
       "n_buckets": 100,
       "description": "Time in milliseconds that http channel spent suspended between AsyncOpen and OnStartRequest."
   },
+  "NETWORK_RACE_CACHE_WITH_NETWORK_USAGE": {
+    "expires_in_version": "58",
+    "alert_emails": ["necko@mozilla.com"],
+    "bug_numbers": [1354409],
+    "kind": "enumerated",
+    "n_values": 4,
+    "description": "Whether we raced network with the cache. (0=network & no racing, 1=cache & no racing, 2=network & raced, 3=cache & raced)"
+  },
   "HTTP_AUTH_DIALOG_STATS": {
     "expires_in_version": "never",
     "kind": "enumerated",