base/android/field_trial_list.cc

   1 // Copyright 2014 The Chromium Authors
   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 <jni.h>
   6
   7 #include <map>
   8 #include <string>
   9
  10 #include "base/android/jni_string.h"
  11 #include "base/base_jni/FieldTrialList_jni.h"
  12 #include "base/lazy_instance.h"
  13 #include "base/metrics/field_trial.h"
  14 #include "base/metrics/field_trial_list_including_low_anonymity.h"
  15 #include "base/metrics/field_trial_params.h"
  16
  17 using base::android::ConvertJavaStringToUTF8;
  18 using base::android::ConvertUTF8ToJavaString;
  19 using base::android::JavaParamRef;
  20 using base::android::ScopedJavaLocalRef;
  21
  22 namespace {
  23
  24 // Log trials and their groups on activation, for debugging purposes.
  25 class TrialLogger : public base::FieldTrialList::Observer {
  26  public:
  27   TrialLogger() {}
  28
  29   TrialLogger(const TrialLogger&) = delete;
  30   TrialLogger& operator=(const TrialLogger&) = delete;
  31
  32   void OnFieldTrialGroupFinalized(const std::string& trial_name,
  33                                   const std::string& group_name) override {
  34     Log(trial_name, group_name);
  35   }
  36
  37   static void Log(const std::string& trial_name,
  38                   const std::string& group_name) {
  39     // Changes to format of the log message below must be accompanied by
  40     // changes to finch smoke tests since they look for this log message
  41     // in the logcat.
  42     LOG(INFO) << "Active field trial \"" << trial_name
  43               << "\" in group \"" << group_name<< '"';
  44   }
  45
  46  protected:
  47   ~TrialLogger() override {}
  48 };
  49
  50 base::LazyInstance<TrialLogger>::Leaky g_trial_logger =
  51     LAZY_INSTANCE_INITIALIZER;
  52
  53 }  // namespace
  54
  55 static ScopedJavaLocalRef<jstring> JNI_FieldTrialList_FindFullName(
  56     JNIEnv* env,
  57     const JavaParamRef<jstring>& jtrial_name) {
  58   std::string trial_name(ConvertJavaStringToUTF8(env, jtrial_name));
  59   return ConvertUTF8ToJavaString(
  60       env, base::FieldTrialList::FindFullName(trial_name));
  61 }
  62
  63 static jboolean JNI_FieldTrialList_TrialExists(
  64     JNIEnv* env,
  65     const JavaParamRef<jstring>& jtrial_name) {
  66   std::string trial_name(ConvertJavaStringToUTF8(env, jtrial_name));
  67   return base::FieldTrialList::TrialExists(trial_name);
  68 }
  69
  70 static ScopedJavaLocalRef<jstring> JNI_FieldTrialList_GetVariationParameter(
  71     JNIEnv* env,
  72     const JavaParamRef<jstring>& jtrial_name,
  73     const JavaParamRef<jstring>& jparameter_key) {
  74   std::map<std::string, std::string> parameters;
  75   base::GetFieldTrialParams(ConvertJavaStringToUTF8(env, jtrial_name),
  76                             &parameters);
  77   return ConvertUTF8ToJavaString(
  78       env, parameters[ConvertJavaStringToUTF8(env, jparameter_key)]);
  79 }
  80
  81 // JNI_FieldTrialList_LogActiveTrials() is static function, this makes friending
  82 // it a hassle because it must be declared in the file that the friend
  83 // declaration is in, but its declaration can't be included in multiple places
  84 // or things get messy and the linker gets mad. This helper class exists only to
  85 // friend the JNI function and is, in turn, friended by
  86 // FieldTrialListIncludingLowAnonymity which allows for the private
  87 // GetActiveFieldTrialGroups() to be reached.
  88 class AndroidFieldTrialListLogActiveTrialsFriendHelper {
  89  private:
  90   friend void ::JNI_FieldTrialList_LogActiveTrials(JNIEnv* env);
  91
  92   static bool AddObserver(base::FieldTrialList::Observer* observer) {
  93     return base::FieldTrialListIncludingLowAnonymity::AddObserver(observer);
  94   }
  95
  96   static void GetActiveFieldTrialGroups(
  97       base::FieldTrial::ActiveGroups* active_groups) {
  98     base::FieldTrialListIncludingLowAnonymity::GetActiveFieldTrialGroups(
  99         active_groups);
 100   }
 101 };
 102
 103 static void JNI_FieldTrialList_LogActiveTrials(JNIEnv* env) {
 104   DCHECK(!g_trial_logger.IsCreated()); // This need only be called once.
 105
 106   LOG(INFO) << "Logging active field trials...";
 107   AndroidFieldTrialListLogActiveTrialsFriendHelper::AddObserver(
 108       &g_trial_logger.Get());
 109
 110   // Log any trials that were already active before adding the observer.
 111   std::vector<base::FieldTrial::ActiveGroup> active_groups;
 112   AndroidFieldTrialListLogActiveTrialsFriendHelper::GetActiveFieldTrialGroups(
 113       &active_groups);
 114   for (const base::FieldTrial::ActiveGroup& group : active_groups) {
 115     TrialLogger::Log(group.trial_name, group.group_name);
 116   }
 117 }
 118
 119 static jboolean JNI_FieldTrialList_CreateFieldTrial(
 120     JNIEnv* env,
 121     const JavaParamRef<jstring>& jtrial_name,
 122     const JavaParamRef<jstring>& jgroup_name) {
 123   return base::FieldTrialList::CreateFieldTrial(
 124              ConvertJavaStringToUTF8(env, jtrial_name),
 125              ConvertJavaStringToUTF8(env, jgroup_name)) != nullptr;
 126 }