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 "chrome/browser/prerender/prerender_field_trial.h"
6
7#include "base/command_line.h"
8#include "base/logging.h"
9#include "base/metrics/field_trial.h"
10#include "base/metrics/histogram.h"
11#include "content/browser/renderer_host/resource_dispatcher_host.h"
12#include "chrome/browser/prerender/prerender_manager.h"
13#include "chrome/common/chrome_switches.h"
14
15
16namespace prerender {
17
18void ConfigurePrefetchAndPrerender(const CommandLine& command_line) {
19  enum PrerenderOption {
20    PRERENDER_OPTION_AUTO,
21    PRERENDER_OPTION_DISABLED,
22    PRERENDER_OPTION_ENABLED,
23    PRERENDER_OPTION_PREFETCH_ONLY,
24  };
25
26  PrerenderOption prerender_option = PRERENDER_OPTION_AUTO;
27  if (command_line.HasSwitch(switches::kPrerender)) {
28    const std::string switch_value =
29        command_line.GetSwitchValueASCII(switches::kPrerender);
30
31    if (switch_value == switches::kPrerenderSwitchValueAuto) {
32#if defined(OS_CHROMEOS)
33      // Prerender is temporarily disabled on CrOS.
34      // http://crosbug.com/12483
35      prerender_option = PRERENDER_OPTION_DISABLED;
36#else
37      prerender_option = PRERENDER_OPTION_AUTO;
38#endif
39    } else if (switch_value == switches::kPrerenderSwitchValueDisabled) {
40      prerender_option = PRERENDER_OPTION_DISABLED;
41    } else if (switch_value.empty() ||
42               switch_value == switches::kPrerenderSwitchValueEnabled) {
43      // The empty string means the option was provided with no value, and that
44      // means enable.
45      prerender_option = PRERENDER_OPTION_ENABLED;
46    } else if (switch_value == switches::kPrerenderSwitchValuePrefetchOnly) {
47      prerender_option = PRERENDER_OPTION_PREFETCH_ONLY;
48    } else {
49      prerender_option = PRERENDER_OPTION_DISABLED;
50      LOG(ERROR) << "Invalid --prerender option received on command line: "
51                 << switch_value;
52      LOG(ERROR) << "Disabling prerendering!";
53    }
54  }
55
56  switch (prerender_option) {
57    case PRERENDER_OPTION_AUTO: {
58      const base::FieldTrial::Probability kPrefetchDivisor = 1000;
59      const base::FieldTrial::Probability kYesPrefetchProbability = 0;
60      const base::FieldTrial::Probability kPrerenderExp1Probability = 0;
61      const base::FieldTrial::Probability kPrerenderControl1Probability = 0;
62      const base::FieldTrial::Probability kPrerenderExp2Probability = 0;
63      const base::FieldTrial::Probability kPrerenderControl2Probability = 0;
64
65      scoped_refptr<base::FieldTrial> trial(
66          new base::FieldTrial("Prefetch", kPrefetchDivisor,
67                               "ContentPrefetchDisabled", 2011, 6, 30));
68
69      const int kNoPrefetchGroup = trial->kDefaultGroupNumber;
70      const int kYesPrefetchGroup =
71          trial->AppendGroup("ContentPrefetchEnabled", kYesPrefetchProbability);
72      const int kPrerenderExperiment1Group =
73          trial->AppendGroup("ContentPrefetchPrerender1",
74                             kPrerenderExp1Probability);
75      const int kPrerenderControl1Group =
76          trial->AppendGroup("ContentPrefetchPrerenderControl1",
77                             kPrerenderControl1Probability);
78      const int kPrerenderExperiment2Group =
79          trial->AppendGroup("ContentPrefetchPrerender2",
80                             kPrerenderExp2Probability);
81      const int kPrerenderControl2Group =
82          trial->AppendGroup("ContentPrefetchPrerenderControl2",
83                             kPrerenderControl2Probability);
84      const int trial_group = trial->group();
85      if (trial_group == kYesPrefetchGroup) {
86        ResourceDispatcherHost::set_is_prefetch_enabled(true);
87        PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
88      } else if (trial_group == kNoPrefetchGroup) {
89        ResourceDispatcherHost::set_is_prefetch_enabled(false);
90        PrerenderManager::SetMode(
91            PrerenderManager::PRERENDER_MODE_DISABLED);
92      } else if (trial_group == kPrerenderExperiment1Group ||
93                 trial_group == kPrerenderExperiment2Group) {
94        ResourceDispatcherHost::set_is_prefetch_enabled(true);
95        PrerenderManager::SetMode(
96            PrerenderManager::PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP);
97      } else if (trial_group == kPrerenderControl1Group ||
98                 trial_group == kPrerenderControl2Group) {
99        ResourceDispatcherHost::set_is_prefetch_enabled(true);
100        PrerenderManager::SetMode(
101            PrerenderManager::PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP);
102      } else {
103        NOTREACHED();
104      }
105      break;
106    }
107    case PRERENDER_OPTION_DISABLED:
108      ResourceDispatcherHost::set_is_prefetch_enabled(false);
109      PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
110      break;
111    case PRERENDER_OPTION_ENABLED:
112      ResourceDispatcherHost::set_is_prefetch_enabled(true);
113      PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_ENABLED);
114      break;
115    case PRERENDER_OPTION_PREFETCH_ONLY:
116      ResourceDispatcherHost::set_is_prefetch_enabled(true);
117      PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
118      break;
119    default:
120      NOTREACHED();
121  }
122
123  UMA_HISTOGRAM_ENUMERATION("Prerender.Sessions",
124                            PrerenderManager::GetMode(),
125                            PrerenderManager::PRERENDER_MODE_MAX);
126}
127
128}  // namespace prerender
129