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