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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "base/metrics/field_trial.h" | 5 #include "base/metrics/field_trial.h" |
6 | 6 |
7 #include <algorithm> | 7 #include <algorithm> |
8 #include <utility> | 8 #include <utility> |
9 | 9 |
10 #include "base/base_switches.h" | 10 #include "base/base_switches.h" |
11 #include "base/build_time.h" | 11 #include "base/build_time.h" |
12 #include "base/command_line.h" | 12 #include "base/command_line.h" |
13 #include "base/debug/alias.h" | 13 #include "base/debug/alias.h" |
14 #include "base/feature_list.h" | 14 #include "base/feature_list.h" |
15 #include "base/logging.h" | 15 #include "base/logging.h" |
16 #include "base/pickle.h" | 16 #include "base/pickle.h" |
17 #include "base/process/memory.h" | 17 #include "base/process/memory.h" |
18 #include "base/rand_util.h" | 18 #include "base/rand_util.h" |
19 #include "base/strings/string_number_conversions.h" | 19 #include "base/strings/string_number_conversions.h" |
20 #include "base/strings/string_util.h" | 20 #include "base/strings/string_util.h" |
21 #include "base/strings/stringprintf.h" | 21 #include "base/strings/stringprintf.h" |
22 #include "base/strings/utf_string_conversions.h" | 22 #include "base/strings/utf_string_conversions.h" |
23 | 23 |
24 // On systems that use the zygote process to spawn child processes, we must | |
25 // retrieve the correct fd using the mapping in GlobalDescriptors. | |
26 #if defined(OS_POSIX) && !defined(OS_NACL) && !defined(OS_MACOSX) && \ | |
27 !defined(OS_ANDROID) | |
28 #define POSIX_WITH_ZYGOTE 1 | |
29 #endif | |
30 | |
31 #if defined(POSIX_WITH_ZYGOTE) | |
32 #include "base/posix/global_descriptors.h" | |
33 #endif | |
34 | |
24 namespace base { | 35 namespace base { |
25 | 36 |
26 namespace { | 37 namespace { |
27 | 38 |
28 // Define a separator character to use when creating a persistent form of an | 39 // Define a separator character to use when creating a persistent form of an |
29 // instance. This is intended for use as a command line argument, passed to a | 40 // instance. This is intended for use as a command line argument, passed to a |
30 // second process to mimic our state (i.e., provide the same group name). | 41 // second process to mimic our state (i.e., provide the same group name). |
31 const char kPersistentStringSeparator = '/'; // Currently a slash. | 42 const char kPersistentStringSeparator = '/'; // Currently a slash. |
32 | 43 |
33 // Define a marker character to be used as a prefix to a trial name on the | 44 // Define a marker character to be used as a prefix to a trial name on the |
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225 } | 236 } |
226 } | 237 } |
227 | 238 |
228 #if defined(OS_WIN) | 239 #if defined(OS_WIN) |
229 HANDLE CreateReadOnlyHandle(FieldTrialList::FieldTrialAllocator* allocator) { | 240 HANDLE CreateReadOnlyHandle(FieldTrialList::FieldTrialAllocator* allocator) { |
230 HANDLE src = allocator->shared_memory()->handle().GetHandle(); | 241 HANDLE src = allocator->shared_memory()->handle().GetHandle(); |
231 ProcessHandle process = GetCurrentProcess(); | 242 ProcessHandle process = GetCurrentProcess(); |
232 DWORD access = SECTION_MAP_READ | SECTION_QUERY; | 243 DWORD access = SECTION_MAP_READ | SECTION_QUERY; |
233 HANDLE dst; | 244 HANDLE dst; |
234 if (!::DuplicateHandle(process, src, process, &dst, access, true, 0)) | 245 if (!::DuplicateHandle(process, src, process, &dst, access, true, 0)) |
235 return nullptr; | 246 return kInvalidPlatformFile; |
236 return dst; | 247 return dst; |
237 } | 248 } |
238 #endif | 249 #endif |
239 | 250 |
251 #if defined(POSIX_WITH_ZYGOTE) | |
252 int CreateReadOnlyHandle(FieldTrialList::FieldTrialAllocator* allocator) { | |
253 SharedMemoryHandle new_handle; | |
254 allocator->shared_memory()->ShareReadOnlyToProcess(GetCurrentProcessHandle(), | |
255 &new_handle); | |
256 return SharedMemory::GetFdFromSharedMemoryHandle(new_handle); | |
257 } | |
258 #endif | |
259 | |
240 } // namespace | 260 } // namespace |
241 | 261 |
242 // statics | 262 // statics |
243 const int FieldTrial::kNotFinalized = -1; | 263 const int FieldTrial::kNotFinalized = -1; |
244 const int FieldTrial::kDefaultGroupNumber = 0; | 264 const int FieldTrial::kDefaultGroupNumber = 0; |
245 bool FieldTrial::enable_benchmarking_ = false; | 265 bool FieldTrial::enable_benchmarking_ = false; |
246 | 266 |
247 int FieldTrialList::kNoExpirationYear = 0; | 267 int FieldTrialList::kNoExpirationYear = 0; |
248 | 268 |
249 //------------------------------------------------------------------------------ | 269 //------------------------------------------------------------------------------ |
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732 } | 752 } |
733 return true; | 753 return true; |
734 } | 754 } |
735 | 755 |
736 // static | 756 // static |
737 void FieldTrialList::CreateTrialsFromCommandLine( | 757 void FieldTrialList::CreateTrialsFromCommandLine( |
738 const CommandLine& cmd_line, | 758 const CommandLine& cmd_line, |
739 const char* field_trial_handle_switch) { | 759 const char* field_trial_handle_switch) { |
740 global_->create_trials_from_command_line_called_ = true; | 760 global_->create_trials_from_command_line_called_ = true; |
741 | 761 |
742 #if defined(OS_WIN) && !defined(OS_NACL) | |
743 if (cmd_line.HasSwitch(field_trial_handle_switch)) { | |
744 std::string arg = cmd_line.GetSwitchValueASCII(field_trial_handle_switch); | |
745 int field_trial_handle = std::stoi(arg); | |
746 HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle); | |
747 bool result = CreateTrialsFromWindowsHandle(handle); | |
748 DCHECK(result); | |
749 } | |
750 #endif | |
751 | |
752 if (cmd_line.HasSwitch(switches::kForceFieldTrials)) { | 762 if (cmd_line.HasSwitch(switches::kForceFieldTrials)) { |
753 bool result = FieldTrialList::CreateTrialsFromString( | 763 bool result = FieldTrialList::CreateTrialsFromString( |
754 cmd_line.GetSwitchValueASCII(switches::kForceFieldTrials), | 764 cmd_line.GetSwitchValueASCII(switches::kForceFieldTrials), |
755 std::set<std::string>()); | 765 std::set<std::string>()); |
756 DCHECK(result); | 766 DCHECK(result); |
757 } | 767 } |
768 | |
769 #if defined(OS_WIN) | |
770 if (cmd_line.HasSwitch(field_trial_handle_switch)) { | |
771 std::string handle_switch = | |
772 cmd_line.GetSwitchValueASCII(field_trial_handle_switch); | |
773 bool result = CreateTrialsFromHandleSwitch(handle_switch); | |
774 DCHECK(result); | |
775 } | |
776 #endif | |
758 } | 777 } |
759 | 778 |
779 #if defined(POSIX_WITH_ZYGOTE) | |
780 // static | |
781 bool FieldTrialList::CreateTrialsFromDescriptor(int field_trial_descriptor_id) { | |
782 if (!kUseSharedMemoryForFieldTrials) | |
783 return false; | |
784 | |
785 int fd = | |
786 GlobalDescriptors::GetInstance()->MaybeGet(field_trial_descriptor_id); | |
787 if (fd == -1) | |
788 return false; | |
789 | |
790 global_->create_trials_from_command_line_called_ = true; | |
791 | |
792 SharedMemoryHandle shm_handle(fd, true); | |
793 bool result = FieldTrialList::CreateTrialsFromSharedMemoryHandle(shm_handle); | |
794 DCHECK(result); | |
795 return true; | |
796 } | |
797 #endif | |
798 | |
760 #if defined(OS_WIN) | 799 #if defined(OS_WIN) |
761 // static | 800 // static |
762 void FieldTrialList::AppendFieldTrialHandleIfNeeded( | 801 void FieldTrialList::AppendFieldTrialHandleIfNeeded( |
763 HandlesToInheritVector* handles) { | 802 HandlesToInheritVector* handles) { |
764 if (!global_) | 803 if (!global_) |
765 return; | 804 return; |
766 if (kUseSharedMemoryForFieldTrials) { | 805 if (kUseSharedMemoryForFieldTrials) { |
767 InstantiateFieldTrialAllocatorIfNeeded(); | 806 InstantiateFieldTrialAllocatorIfNeeded(); |
768 if (global_->readonly_allocator_handle_) | 807 if (global_->readonly_allocator_handle_) |
769 handles->push_back(global_->readonly_allocator_handle_); | 808 handles->push_back(global_->readonly_allocator_handle_); |
770 } | 809 } |
771 } | 810 } |
772 #endif | 811 #endif |
773 | 812 |
813 #if defined(OS_POSIX) && !defined(OS_NACL) | |
814 // static | |
815 int FieldTrialList::GetFieldTrialHandle() { | |
816 if (!global_) | |
817 return kInvalidPlatformFile; | |
818 if (kUseSharedMemoryForFieldTrials) { | |
819 InstantiateFieldTrialAllocatorIfNeeded(); | |
820 // We check for an invalid handle where this gets called. | |
821 return global_->readonly_allocator_handle_; | |
822 } | |
823 return kInvalidPlatformFile; | |
824 } | |
825 #endif | |
826 | |
774 // static | 827 // static |
775 void FieldTrialList::CopyFieldTrialStateToFlags( | 828 void FieldTrialList::CopyFieldTrialStateToFlags( |
776 const char* field_trial_handle_switch, | 829 const char* field_trial_handle_switch, |
777 CommandLine* cmd_line) { | 830 CommandLine* cmd_line) { |
778 // TODO(lawrencewu): Ideally, having the global would be guaranteed. However, | 831 // TODO(lawrencewu): Ideally, having the global would be guaranteed. However, |
779 // content browser tests currently don't create a FieldTrialList because they | 832 // content browser tests currently don't create a FieldTrialList because they |
780 // don't run ChromeBrowserMainParts code where it's done for Chrome. | 833 // don't run ChromeBrowserMainParts code where it's done for Chrome. |
781 if (!global_) | 834 if (!global_) |
782 return; | 835 return; |
783 | 836 |
784 #if defined(OS_WIN) | 837 #if defined(OS_WIN) || defined(POSIX_WITH_ZYGOTE) |
785 // Use shared memory to pass the state if the feature is enabled, otherwise | 838 // Use shared memory to pass the state if the feature is enabled, otherwise |
786 // fallback to passing it via the command line as a string. | 839 // fallback to passing it via the command line as a string. |
787 if (kUseSharedMemoryForFieldTrials) { | 840 if (kUseSharedMemoryForFieldTrials) { |
788 InstantiateFieldTrialAllocatorIfNeeded(); | 841 InstantiateFieldTrialAllocatorIfNeeded(); |
789 // If the readonly handle didn't get duplicated properly, then fallback to | 842 // If the readonly handle didn't get duplicated properly, then fallback to |
790 // original behavior. | 843 // original behavior. |
791 if (!global_->readonly_allocator_handle_) { | 844 if (global_->readonly_allocator_handle_ == kInvalidPlatformFile) { |
792 AddForceFieldTrialsFlag(cmd_line); | 845 AddForceFieldTrialsFlag(cmd_line); |
793 return; | 846 return; |
794 } | 847 } |
795 | 848 |
796 // HANDLE is just typedef'd to void *. We basically cast the handle into an | 849 #if defined(OS_WIN) |
Alexei Svitkine (slow)
2016/11/29 17:38:27
Add a comment above this to mention why it's win o
lawrencewu
2016/11/29 19:11:01
Done.
| |
797 // int (uintptr_t, to be exact), stringify the int, and pass it as a | 850 // PlatformFile is typedef'd to HANDLE which is typedef'd to void *. We |
798 // command-line flag. The child process will do the reverse conversions to | 851 // basically cast the handle into an int (uintptr_t, to be exact), stringify |
799 // retrieve the handle. See http://stackoverflow.com/a/153077 | 852 // the int, and pass it as a command-line flag. The child process will do |
853 // the reverse conversions to retrieve the handle. See | |
854 // http://stackoverflow.com/a/153077 | |
800 auto uintptr_handle = | 855 auto uintptr_handle = |
801 reinterpret_cast<uintptr_t>(global_->readonly_allocator_handle_); | 856 reinterpret_cast<uintptr_t>(global_->readonly_allocator_handle_); |
802 std::string field_trial_handle = std::to_string(uintptr_handle); | 857 std::string field_trial_handle = std::to_string(uintptr_handle); |
803 cmd_line->AppendSwitchASCII(field_trial_handle_switch, field_trial_handle); | 858 cmd_line->AppendSwitchASCII(field_trial_handle_switch, field_trial_handle); |
859 #endif | |
804 global_->field_trial_allocator_->UpdateTrackingHistograms(); | 860 global_->field_trial_allocator_->UpdateTrackingHistograms(); |
805 return; | 861 return; |
806 } | 862 } |
807 #endif | 863 #endif |
808 | 864 |
809 AddForceFieldTrialsFlag(cmd_line); | 865 AddForceFieldTrialsFlag(cmd_line); |
810 } | 866 } |
811 | 867 |
812 // static | 868 // static |
813 FieldTrial* FieldTrialList::CreateFieldTrial( | 869 FieldTrial* FieldTrialList::CreateFieldTrial( |
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887 // static | 943 // static |
888 size_t FieldTrialList::GetFieldTrialCount() { | 944 size_t FieldTrialList::GetFieldTrialCount() { |
889 if (!global_) | 945 if (!global_) |
890 return 0; | 946 return 0; |
891 AutoLock auto_lock(global_->lock_); | 947 AutoLock auto_lock(global_->lock_); |
892 return global_->registered_.size(); | 948 return global_->registered_.size(); |
893 } | 949 } |
894 | 950 |
895 #if defined(OS_WIN) | 951 #if defined(OS_WIN) |
896 // static | 952 // static |
897 bool FieldTrialList::CreateTrialsFromWindowsHandle(HANDLE handle) { | 953 bool FieldTrialList::CreateTrialsFromHandleSwitch( |
954 const std::string& handle_switch) { | |
955 int field_trial_handle = std::stoi(handle_switch); | |
956 HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle); | |
898 SharedMemoryHandle shm_handle(handle, GetCurrentProcId()); | 957 SharedMemoryHandle shm_handle(handle, GetCurrentProcId()); |
958 return FieldTrialList::CreateTrialsFromSharedMemoryHandle(shm_handle); | |
959 } | |
960 #endif | |
899 | 961 |
962 #if !defined(OS_NACL) | |
963 // static | |
964 bool FieldTrialList::CreateTrialsFromSharedMemoryHandle( | |
965 SharedMemoryHandle shm_handle) { | |
900 // shm gets deleted when it gets out of scope, but that's OK because we need | 966 // shm gets deleted when it gets out of scope, but that's OK because we need |
901 // it only for the duration of this method. | 967 // it only for the duration of this method. |
902 std::unique_ptr<SharedMemory> shm(new SharedMemory(shm_handle, true)); | 968 std::unique_ptr<SharedMemory> shm(new SharedMemory(shm_handle, true)); |
903 if (!shm.get()->Map(kFieldTrialAllocationSize)) | 969 if (!shm.get()->Map(kFieldTrialAllocationSize)) |
904 TerminateBecauseOutOfMemory(kFieldTrialAllocationSize); | 970 TerminateBecauseOutOfMemory(kFieldTrialAllocationSize); |
905 | 971 |
906 return FieldTrialList::CreateTrialsFromSharedMemory(std::move(shm)); | 972 return FieldTrialList::CreateTrialsFromSharedMemory(std::move(shm)); |
907 } | 973 } |
908 #endif | 974 #endif |
909 | 975 |
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979 #if !defined(OS_NACL) | 1045 #if !defined(OS_NACL) |
980 // static | 1046 // static |
981 void FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded() { | 1047 void FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded() { |
982 if (!global_) | 1048 if (!global_) |
983 return; | 1049 return; |
984 AutoLock auto_lock(global_->lock_); | 1050 AutoLock auto_lock(global_->lock_); |
985 // Create the allocator if not already created and add all existing trials. | 1051 // Create the allocator if not already created and add all existing trials. |
986 if (global_->field_trial_allocator_ != nullptr) | 1052 if (global_->field_trial_allocator_ != nullptr) |
987 return; | 1053 return; |
988 | 1054 |
1055 SharedMemoryCreateOptions options; | |
1056 options.size = kFieldTrialAllocationSize; | |
1057 options.share_read_only = true; | |
1058 | |
989 std::unique_ptr<SharedMemory> shm(new SharedMemory()); | 1059 std::unique_ptr<SharedMemory> shm(new SharedMemory()); |
990 if (!shm->CreateAndMapAnonymous(kFieldTrialAllocationSize)) | 1060 if (!shm->Create(options)) |
1061 TerminateBecauseOutOfMemory(kFieldTrialAllocationSize); | |
1062 | |
1063 if (!shm->Map(kFieldTrialAllocationSize)) | |
991 TerminateBecauseOutOfMemory(kFieldTrialAllocationSize); | 1064 TerminateBecauseOutOfMemory(kFieldTrialAllocationSize); |
992 | 1065 |
993 global_->field_trial_allocator_.reset( | 1066 global_->field_trial_allocator_.reset( |
994 new FieldTrialAllocator(std::move(shm), 0, kAllocatorName, false)); | 1067 new FieldTrialAllocator(std::move(shm), 0, kAllocatorName, false)); |
995 global_->field_trial_allocator_->CreateTrackingHistograms(kAllocatorName); | 1068 global_->field_trial_allocator_->CreateTrackingHistograms(kAllocatorName); |
996 | 1069 |
997 // Add all existing field trials. | 1070 // Add all existing field trials. |
998 for (const auto& registered : global_->registered_) { | 1071 for (const auto& registered : global_->registered_) { |
999 AddToAllocatorWhileLocked(registered.second); | 1072 AddToAllocatorWhileLocked(registered.second); |
1000 } | 1073 } |
1001 | 1074 |
1002 #if defined(OS_WIN) | 1075 #if defined(OS_WIN) || defined(POSIX_WITH_ZYGOTE) |
1003 // Set |readonly_allocator_handle_| so we can pass it to be inherited and | 1076 // Set |readonly_allocator_handle_| so we can pass it to be inherited and |
1004 // via the command line. | 1077 // via the command line. |
1005 global_->readonly_allocator_handle_ = | 1078 global_->readonly_allocator_handle_ = |
1006 CreateReadOnlyHandle(global_->field_trial_allocator_.get()); | 1079 CreateReadOnlyHandle(global_->field_trial_allocator_.get()); |
1007 #endif | 1080 #endif |
1008 } | 1081 } |
1009 #endif | 1082 #endif |
1010 | 1083 |
1011 // static | 1084 // static |
1012 void FieldTrialList::AddToAllocatorWhileLocked(FieldTrial* field_trial) { | 1085 void FieldTrialList::AddToAllocatorWhileLocked(FieldTrial* field_trial) { |
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1107 return; | 1180 return; |
1108 } | 1181 } |
1109 AutoLock auto_lock(global_->lock_); | 1182 AutoLock auto_lock(global_->lock_); |
1110 CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name(); | 1183 CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name(); |
1111 trial->AddRef(); | 1184 trial->AddRef(); |
1112 trial->SetTrialRegistered(); | 1185 trial->SetTrialRegistered(); |
1113 global_->registered_[trial->trial_name()] = trial; | 1186 global_->registered_[trial->trial_name()] = trial; |
1114 } | 1187 } |
1115 | 1188 |
1116 } // namespace base | 1189 } // namespace base |
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