Bug 1652104 - Add telemtery about HTTP3 usage. r=michal,necko-reviewers

Differential Revision: https://phabricator.services.mozilla.com/D83168

netwerk/protocol/http/Http3Session.cpp

@@ -181,6 +181,9 @@ void Http3Session::Shutdown() {
 Http3Session::~Http3Session() {
   LOG3(("Http3Session::~Http3Session %p", this));
 
+  Telemetry::Accumulate(Telemetry::HTTP3_REQUEST_PER_CONN,
+                        mTransactionCount);
+
   Shutdown();
 }
 
@@ -655,6 +658,7 @@ nsresult Http3Session::TryActivating(
 
   MOZ_ASSERT(*aStreamId != UINT64_MAX);
   mStreamIdHash.Put(*aStreamId, RefPtr{aStream});
+  mTransactionCount++;
   return NS_OK;
 }
 

netwerk/protocol/http/Http3Session.h

@@ -178,6 +178,8 @@ class Http3Session final : public nsAHttpTransaction,
 
   RefPtr<QuicSocketControl> mSocketControl;
   nsCString mAlpnToken;
+
+  uint64_t mTransactionCount = 0;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(Http3Session, NS_HTTP3SESSION_IID);

netwerk/protocol/http/nsHttpHandler.cpp

@@ -483,6 +483,8 @@ nsresult nsHttpHandler::Init() {
   Preferences::RegisterPrefixCallbacks(nsHttpHandler::PrefsChanged,
                                        gCallbackPrefs, this);
   PrefsChanged(nullptr);
+  Telemetry::ScalarSet(
+      Telemetry::ScalarID::NETWORKING_HTTP3_ENABLED, mHttp3Enabled);
 
   mMisc.AssignLiteral("rv:" MOZILLA_UAVERSION);
 

toolkit/components/telemetry/Histograms.json

@@ -3319,6 +3319,17 @@
     "keyed": true,
     "description": "Error code when http3 connection is closed. Look at Http3Session for more details."
   },
+  "HTTP3_REQUEST_PER_CONN": {
+    "record_in_processes": ["main", "content"],
+    "products": ["firefox"],
+    "alert_emails": ["necko@mozilla.com", "ddamjanovic@mozilla.com"],
+    "expires_in_version": "never",
+    "kind": "exponential",
+    "high": 1000,
+    "n_buckets": 50,
+    "bug_numbers": [1652104],
+    "description": "HTTP3: Streams created per connection"
+  },
   "HTTP_CONTENT_ENCODING": {
     "record_in_processes": ["main", "content"],
     "products": ["firefox", "fennec"],

toolkit/components/telemetry/Scalars.yaml

@@ -4675,6 +4675,24 @@ networking:
       - 'main'
     release_channel_collection: opt-out
 
+  http3_enabled:
+    bug_numbers:
+      - 1652104
+    description: >
+      True if HTTP3 is enabled at the start of a session.
+    expires: never
+    kind: boolean
+    keyed: false
+    notification_emails:
+      - necko@mozilla.com
+      - ddamjanovic@mozilla.com
+    release_channel_collection: opt-out
+    products:
+      - 'firefox'
+    record_in_processes:
+      - 'main'
+      - 'content'
+
 blocklist:
   lastModified_rs_addons:
     bug_numbers: