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      1 /*
      2  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #include "webrtc/test/field_trial.h"
     12 
     13 #include <algorithm>
     14 #include <cassert>
     15 #include <cstdio>
     16 #include <cstdlib>
     17 #include <map>
     18 #include <string>
     19 
     20 #include "webrtc/system_wrappers/interface/field_trial.h"
     21 
     22 namespace webrtc {
     23 namespace {
     24 // Clients of this library have show a clear intent to setup field trials by
     25 // linking with it. As so try to crash if they forget to call
     26 // InitFieldTrialsFromString before webrtc tries to access a field trial.
     27 bool field_trials_initiated_ = false;
     28 std::map<std::string, std::string> field_trials_;
     29 }  // namespace
     30 
     31 namespace field_trial {
     32 std::string FindFullName(const std::string& trial_name) {
     33   assert(field_trials_initiated_);
     34   std::map<std::string, std::string>::const_iterator it =
     35       field_trials_.find(trial_name);
     36   if (it == field_trials_.end())
     37     return std::string();
     38   return it->second;
     39 }
     40 }  // namespace field_trial
     41 
     42 namespace test {
     43 // Note: this code is copied from src/base/metrics/field_trial.cc since the aim
     44 // is to mimic chromium --force-fieldtrials.
     45 void InitFieldTrialsFromString(const std::string& trials_string) {
     46   static const char kPersistentStringSeparator = '/';
     47 
     48   // Catch an error if this is called more than once.
     49   assert(field_trials_initiated_ == false);
     50   field_trials_initiated_ = true;
     51 
     52   if (trials_string.empty()) return;
     53 
     54   size_t next_item = 0;
     55   while (next_item < trials_string.length()) {
     56     size_t name_end = trials_string.find(kPersistentStringSeparator, next_item);
     57     if (name_end == trials_string.npos || next_item == name_end)
     58       break;
     59     size_t group_name_end = trials_string.find(kPersistentStringSeparator,
     60                                                name_end + 1);
     61     if (group_name_end == trials_string.npos || name_end + 1 == group_name_end)
     62       break;
     63     std::string name(trials_string, next_item, name_end - next_item);
     64     std::string group_name(trials_string, name_end + 1,
     65                            group_name_end - name_end - 1);
     66     next_item = group_name_end + 1;
     67 
     68     // Fail if duplicate with different group name.
     69     if (field_trials_.find(name) != field_trials_.end() &&
     70         field_trials_.find(name)->second != group_name)
     71       break;
     72 
     73     field_trials_[name] = group_name;
     74 
     75     // Successfully parsed all field trials from the string.
     76     if (next_item == trials_string.length())
     77       return;
     78   }
     79   // LOG does not prints when this is called early on main.
     80   fprintf(stderr, "Invalid field trials string.\n");
     81 
     82   // Using abort so it crashs both in debug and release mode.
     83   abort();
     84 }
     85 }  // namespace test
     86 }  // namespace webrtc
     87