QUIC - add new UMA histograms to help understand HPACK head of line blocking.

net/quic/quic_chromium_client_session.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_chromium_client_session.h"
 
 #include <utility>
 
 #include "base/callback_helpers.h"
 #include "base/location.h"
@@ skipping 167 matching lines @@
   *stream_ = stream;
   base::ResetAndReturn(&callback_).Run(OK);
 }
 
 void QuicChromiumClientSession::StreamRequest::OnRequestCompleteFailure(
     int rv) {
   session_.reset();
   base::ResetAndReturn(&callback_).Run(rv);
 }
 
+void QuicChromiumClientSession::HpackEncoderDebugVisitor::OnUseEntry(
+    const QuicTime::Delta elapsed) {
+  UMA_HISTOGRAM_TIMES(
+      "Net.QuicHpackEncoderIndexedEntryAge",
+      base::TimeDelta::FromMicroseconds(elapsed.ToMicroseconds()));
+}
+
+void QuicChromiumClientSession::HpackDecoderDebugVisitor::OnUseEntry(
+    const QuicTime::Delta elapsed) {
+  UMA_HISTOGRAM_TIMES(
+      "Net.QuicHpackDecoderIndexedEntryAge",
+      base::TimeDelta::FromMicroseconds(elapsed.ToMicroseconds()));
+}
+
 QuicChromiumClientSession::QuicChromiumClientSession(
     QuicConnection* connection,
     std::unique_ptr<DatagramClientSocket> socket,
     QuicStreamFactory* stream_factory,
     QuicCryptoClientStreamFactory* crypto_client_stream_factory,
     QuicClock* clock,
     TransportSecurityState* transport_security_state,
     std::unique_ptr<QuicServerInfo> server_info,
     const QuicServerId& server_id,
     int yield_after_packets,
@@ skipping 163 matching lines @@
                               0, kMaxReordering, 50);
   if (stats.min_rtt_us > 100 * 1000) {
     UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.MaxReorderingTimeLongRtt",
                                 reordering, 0, kMaxReordering, 50);
   }
   UMA_HISTOGRAM_COUNTS(
       "Net.QuicSession.MaxReordering",
       static_cast<base::HistogramBase::Sample>(stats.max_sequence_reordering));
 }
 
+void QuicChromiumClientSession::Initialize() {
+  QuicClientSessionBase::Initialize();
+  headers_stream()->SetHpackEncoderDebugVisitor(
+      std::unique_ptr<HpackEncoderDebugVisitor>(

[Ryan Hamilton, 2016/05/20 21:27:18]

fwiw, you can use base::WrapUnique(new ...) to save some verbosity.

[Buck, 2016/05/20 21:41:31]

Done.

+          new HpackEncoderDebugVisitor()));
+  headers_stream()->SetHpackDecoderDebugVisitor(
+      std::unique_ptr<HpackDecoderDebugVisitor>(
+          new HpackDecoderDebugVisitor()));
+}
+
 void QuicChromiumClientSession::OnHeadersHeadOfLineBlocking(
     QuicTime::Delta delta) {
   UMA_HISTOGRAM_TIMES(
       "Net.QuicSession.HeadersHOLBlockedTime",
       base::TimeDelta::FromMicroseconds(delta.ToMicroseconds()));
 }
 
 void QuicChromiumClientSession::OnStreamFrame(const QuicStreamFrame& frame) {
   // Record total number of stream frames.
   UMA_HISTOGRAM_COUNTS("Net.QuicNumStreamFramesInPacket", 1);
@@ skipping 796 matching lines @@
 }
 
 void QuicChromiumClientSession::DeletePromised(
     QuicClientPromisedInfo* promised) {
   if (IsOpenStream(promised->id()))
     streams_pushed_and_claimed_count_++;
   QuicClientSessionBase::DeletePromised(promised);
 }
 
 }  // namespace net