net/socket/stream_socket.cc

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/socket/stream_socket.h"
   6
   7 #include "base/metrics/field_trial.h"
   8 #include "base/metrics/histogram.h"
   9 #include "base/strings/string_number_conversions.h"
  10 #include "base/values.h"
  11
  12 namespace net {
  13
  14 StreamSocket::UseHistory::UseHistory()
  15     : was_ever_connected_(false),
  16       was_used_to_convey_data_(false),
  17       omnibox_speculation_(false),
  18       subresource_speculation_(false) {
  19 }
  20
  21 StreamSocket::UseHistory::~UseHistory() {
  22   EmitPreconnectionHistograms();
  23 }
  24
  25 void StreamSocket::UseHistory::Reset() {
  26   EmitPreconnectionHistograms();
  27   was_ever_connected_ = false;
  28   was_used_to_convey_data_ = false;
  29   // omnibox_speculation_ and subresource_speculation_ values
  30   // are intentionally preserved.
  31 }
  32
  33 void StreamSocket::UseHistory::set_was_ever_connected() {
  34   DCHECK(!was_used_to_convey_data_);
  35   was_ever_connected_ = true;
  36 }
  37
  38 void StreamSocket::UseHistory::set_was_used_to_convey_data() {
  39   DCHECK(was_ever_connected_);
  40   was_used_to_convey_data_ = true;
  41 }
  42
  43
  44 void StreamSocket::UseHistory::set_subresource_speculation() {
  45   DCHECK(was_ever_connected_);
  46   // TODO(jar): We should transition to marking a socket (or stream) at
  47   // construction time as being created for speculative reasons.  This current
  48   // approach of trying to track use of a socket to convey data can make
  49   // mistakes when other sockets (such as ones sitting in the pool for a long
  50   // time) are issued.  Unused sockets can be left over when a when a set of
  51   // connections to a host are made, and one is "unlucky" and takes so long to
  52   // complete a connection, that another socket is used, and recycled before a
  53   // second connection comes available.  Similarly, re-try connections can leave
  54   // an original (slow to connect socket) in the pool, and that can be issued
  55   // to a speculative requester. In any cases such old sockets will fail when an
  56   // attempt is made to used them!... and then it will look like a speculative
  57   // socket was discarded without any user!?!?!
  58   if (was_used_to_convey_data_)
  59     return;
  60   subresource_speculation_ = true;
  61 }
  62
  63 void StreamSocket::UseHistory::set_omnibox_speculation() {
  64   DCHECK(was_ever_connected_);
  65   if (was_used_to_convey_data_)
  66     return;
  67   omnibox_speculation_ = true;
  68 }
  69
  70 bool StreamSocket::UseHistory::was_used_to_convey_data() const {
  71   DCHECK(!was_used_to_convey_data_ || was_ever_connected_);
  72   return was_used_to_convey_data_;
  73 }
  74
  75 void StreamSocket::UseHistory::EmitPreconnectionHistograms() const {
  76   DCHECK(!subresource_speculation_ || !omnibox_speculation_);
  77   // 0 ==> non-speculative, never connected.
  78   // 1 ==> non-speculative never used (but connected).
  79   // 2 ==> non-speculative and used.
  80   // 3 ==> omnibox_speculative never connected.
  81   // 4 ==> omnibox_speculative never used (but connected).
  82   // 5 ==> omnibox_speculative and used.
  83   // 6 ==> subresource_speculative never connected.
  84   // 7 ==> subresource_speculative never used (but connected).
  85   // 8 ==> subresource_speculative and used.
  86   int result;
  87   if (was_used_to_convey_data_)
  88     result = 2;
  89   else if (was_ever_connected_)
  90     result = 1;
  91   else
  92     result = 0;  // Never used, and not really connected.
  93
  94   if (omnibox_speculation_)
  95     result += 3;
  96   else if (subresource_speculation_)
  97     result += 6;
  98   UMA_HISTOGRAM_ENUMERATION("Net.PreconnectUtilization2", result, 9);
  99 }
 100
 101 }  // namespace net