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
12namespace net {
13
14StreamSocket::UseHistory::UseHistory()
15    : was_ever_connected_(false),
16      was_used_to_convey_data_(false),
17      omnibox_speculation_(false),
18      subresource_speculation_(false) {
19}
20
21StreamSocket::UseHistory::~UseHistory() {
22  EmitPreconnectionHistograms();
23}
24
25void 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
33void StreamSocket::UseHistory::set_was_ever_connected() {
34  DCHECK(!was_used_to_convey_data_);
35  was_ever_connected_ = true;
36}
37
38void StreamSocket::UseHistory::set_was_used_to_convey_data() {
39  DCHECK(was_ever_connected_);
40  was_used_to_convey_data_ = true;
41}
42
43
44void 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
63void 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
70bool 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
75void 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
102