prerender_field_trial.cc revision dc0f95d653279beabeb9817299e2902918ba123e 
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 kPrerenderExperimentProbability = 0;
61      const base::FieldTrial::Probability kPrerenderControlProbability = 0;
62
63      scoped_refptr<base::FieldTrial> trial(
64          new base::FieldTrial("Prefetch", kPrefetchDivisor,
65                               "ContentPrefetchDisabled", 2011, 6, 30));
66
67      const int kNoPrefetchGroup = trial->kDefaultGroupNumber;
68      const int kYesPrefetchGroup =
69          trial->AppendGroup("ContentPrefetchEnabled", kYesPrefetchProbability);
70      const int kPrerenderExperimentGroup =
71          trial->AppendGroup("ContentPrefetchPrerender",
72                             kPrerenderExperimentProbability);
73      const int kPrerenderControlGroup =
74          trial->AppendGroup("ContentPrefetchPrerenderControl",
75                             kPrerenderControlProbability);
76      const int trial_group = trial->group();
77      if (trial_group == kYesPrefetchGroup) {
78        ResourceDispatcherHost::set_is_prefetch_enabled(true);
79        PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
80      } else if (trial_group == kNoPrefetchGroup) {
81        ResourceDispatcherHost::set_is_prefetch_enabled(false);
82        PrerenderManager::SetMode(
83            PrerenderManager::PRERENDER_MODE_DISABLED);
84      } else if (trial_group == kPrerenderExperimentGroup) {
85        ResourceDispatcherHost::set_is_prefetch_enabled(true);
86        PrerenderManager::SetMode(
87            PrerenderManager::PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP);
88      } else if (trial_group == kPrerenderControlGroup) {
89        ResourceDispatcherHost::set_is_prefetch_enabled(false);
90        PrerenderManager::SetMode(
91            PrerenderManager::PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP);
92      } else {
93        NOTREACHED();
94      }
95      break;
96    }
97    case PRERENDER_OPTION_DISABLED:
98      ResourceDispatcherHost::set_is_prefetch_enabled(false);
99      PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
100      break;
101    case PRERENDER_OPTION_ENABLED:
102      ResourceDispatcherHost::set_is_prefetch_enabled(true);
103      PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_ENABLED);
104      break;
105    case PRERENDER_OPTION_PREFETCH_ONLY:
106      ResourceDispatcherHost::set_is_prefetch_enabled(true);
107      PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
108      break;
109    default:
110      NOTREACHED();
111  }
112
113  UMA_HISTOGRAM_ENUMERATION("Prerender.Sessions",
114                            PrerenderManager::GetMode(),
115                            PrerenderManager::PRERENDER_MODE_MAX);
116}
117
118}  // namespace prerender
119