OLD | NEW |
---|---|
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" |
(...skipping 17 matching lines...) Expand all Loading... | |
28 const char kPersistentStringSeparator = '/'; // Currently a slash. | 28 const char kPersistentStringSeparator = '/'; // Currently a slash. |
29 | 29 |
30 // Define a marker character to be used as a prefix to a trial name on the | 30 // Define a marker character to be used as a prefix to a trial name on the |
31 // command line which forces its activation. | 31 // command line which forces its activation. |
32 const char kActivationMarker = '*'; | 32 const char kActivationMarker = '*'; |
33 | 33 |
34 // Use shared memory to communicate field trial (experiment) state. Set to false | 34 // Use shared memory to communicate field trial (experiment) state. Set to false |
35 // for now while the implementation is fleshed out (e.g. data format, single | 35 // for now while the implementation is fleshed out (e.g. data format, single |
36 // shared memory segment). See https://codereview.chromium.org/2365273004/ and | 36 // shared memory segment). See https://codereview.chromium.org/2365273004/ and |
37 // crbug.com/653874 | 37 // crbug.com/653874 |
38 const bool kUseSharedMemoryForFieldTrials = false; | |
39 | |
40 // Allocator used to instantiate field trial in child processes. In the | |
41 // future, we may want to move this to a more generic place if we want to | |
42 // start passing more data other than field trials. | |
43 base::SharedPersistentMemoryAllocator* g_field_trial_allocator = nullptr; | |
38 #if defined(OS_WIN) | 44 #if defined(OS_WIN) |
39 const bool kUseSharedMemoryForFieldTrials = false; | 45 HANDLE g_readonly_allocator_handle = 0; |
40 #endif | 46 #endif |
41 | 47 |
48 // Constants for the field trial allocator. | |
49 const char kAllocatorName[] = "FieldTrialAllocator"; | |
50 const uint32_t kFieldTrialType = 0xABA17E13 + 1; // SHA1(FieldTrialEntry) v1 | |
51 | |
52 // We create one FieldTrialEntry struct per field trial in shared memory (via | |
53 // g_field_trial_allocator). It contains whether or not it's activated, and the | |
54 // offset from the start of the allocated memory to the group name. We don't | |
55 // need the offset into the trial name because that's always a fixed position | |
56 // from the start of the struct. Two strings will be appended to the end of this | |
57 // structure in allocated memory, so the result will look like this: | |
58 // --------------------------------- | |
59 // | fte | trial_name | group_name | | |
60 // --------------------------------- | |
61 struct FieldTrialEntry { | |
62 bool activated; | |
63 uint32_t group_name_offset; | |
64 | |
65 const char* GetTrialName() const { | |
66 const char* src = | |
67 reinterpret_cast<char*>(const_cast<FieldTrialEntry*>(this)); | |
68 return src + sizeof(FieldTrialEntry); | |
69 } | |
70 | |
71 const char* GetGroupName() const { | |
72 const char* src = | |
73 reinterpret_cast<char*>(const_cast<FieldTrialEntry*>(this)); | |
74 return src + this->group_name_offset; | |
75 } | |
76 }; | |
77 | |
42 // Created a time value based on |year|, |month| and |day_of_month| parameters. | 78 // Created a time value based on |year|, |month| and |day_of_month| parameters. |
43 Time CreateTimeFromParams(int year, int month, int day_of_month) { | 79 Time CreateTimeFromParams(int year, int month, int day_of_month) { |
44 DCHECK_GT(year, 1970); | 80 DCHECK_GT(year, 1970); |
45 DCHECK_GT(month, 0); | 81 DCHECK_GT(month, 0); |
46 DCHECK_LT(month, 13); | 82 DCHECK_LT(month, 13); |
47 DCHECK_GT(day_of_month, 0); | 83 DCHECK_GT(day_of_month, 0); |
48 DCHECK_LT(day_of_month, 32); | 84 DCHECK_LT(day_of_month, 32); |
49 | 85 |
50 Time::Exploded exploded; | 86 Time::Exploded exploded; |
51 exploded.year = year; | 87 exploded.year = year; |
(...skipping 70 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... | |
122 entries->push_back(entry); | 158 entries->push_back(entry); |
123 } | 159 } |
124 return true; | 160 return true; |
125 } | 161 } |
126 | 162 |
127 } // namespace | 163 } // namespace |
128 | 164 |
129 // statics | 165 // statics |
130 const int FieldTrial::kNotFinalized = -1; | 166 const int FieldTrial::kNotFinalized = -1; |
131 const int FieldTrial::kDefaultGroupNumber = 0; | 167 const int FieldTrial::kDefaultGroupNumber = 0; |
168 const int kFieldTrialAllocationSize = 4 << 10; // 4 KiB = one page | |
132 bool FieldTrial::enable_benchmarking_ = false; | 169 bool FieldTrial::enable_benchmarking_ = false; |
133 | 170 |
134 int FieldTrialList::kNoExpirationYear = 0; | 171 int FieldTrialList::kNoExpirationYear = 0; |
135 | 172 |
136 //------------------------------------------------------------------------------ | 173 //------------------------------------------------------------------------------ |
137 // FieldTrial methods and members. | 174 // FieldTrial methods and members. |
138 | 175 |
139 FieldTrial::EntropyProvider::~EntropyProvider() { | 176 FieldTrial::EntropyProvider::~EntropyProvider() { |
140 } | 177 } |
141 | 178 |
(...skipping 437 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... | |
579 std::string arg = cmd_line.GetSwitchValueASCII(field_trial_handle_switch); | 616 std::string arg = cmd_line.GetSwitchValueASCII(field_trial_handle_switch); |
580 size_t token = arg.find(","); | 617 size_t token = arg.find(","); |
581 int field_trial_handle = std::stoi(arg.substr(0, token)); | 618 int field_trial_handle = std::stoi(arg.substr(0, token)); |
582 int field_trial_length = std::stoi(arg.substr(token + 1, arg.length())); | 619 int field_trial_length = std::stoi(arg.substr(token + 1, arg.length())); |
583 | 620 |
584 HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle); | 621 HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle); |
585 base::SharedMemoryHandle shm_handle = | 622 base::SharedMemoryHandle shm_handle = |
586 base::SharedMemoryHandle(handle, base::GetCurrentProcId()); | 623 base::SharedMemoryHandle(handle, base::GetCurrentProcId()); |
587 | 624 |
588 // Gets deleted when it gets out of scope, but that's OK because we need it | 625 // Gets deleted when it gets out of scope, but that's OK because we need it |
589 // only for the duration of this call currently anyway. | 626 // only for the duration of this method. |
590 base::SharedMemory shared_memory(shm_handle, false); | 627 std::unique_ptr<base::SharedMemory> shm( |
591 shared_memory.Map(field_trial_length); | 628 new base::SharedMemory(shm_handle, true)); |
629 shm.get()->Map(field_trial_length); | |
bcwhite
2016/10/20 21:14:06
Map() will return false if it fails which can happ
lawrencewu
2016/10/21 16:41:58
Done.
| |
592 | 630 |
593 char* field_trial_state = static_cast<char*>(shared_memory.memory()); | 631 FieldTrialList::CreateTrialsFromSharedMemory(std::move(shm)); |
594 bool result = FieldTrialList::CreateTrialsFromString( | |
595 std::string(field_trial_state), std::set<std::string>()); | |
596 DCHECK(result); | |
597 return; | 632 return; |
598 } | 633 } |
599 #endif | 634 #endif |
600 | 635 |
601 if (cmd_line.HasSwitch(switches::kForceFieldTrials)) { | 636 if (cmd_line.HasSwitch(switches::kForceFieldTrials)) { |
602 bool result = FieldTrialList::CreateTrialsFromString( | 637 bool result = FieldTrialList::CreateTrialsFromString( |
603 cmd_line.GetSwitchValueASCII(switches::kForceFieldTrials), | 638 cmd_line.GetSwitchValueASCII(switches::kForceFieldTrials), |
604 std::set<std::string>()); | 639 std::set<std::string>()); |
605 DCHECK(result); | 640 DCHECK(result); |
606 } | 641 } |
607 } | 642 } |
608 | 643 |
644 #if defined(OS_WIN) | |
645 // static | |
646 void FieldTrialList::AppendFieldTrialHandleIfNeeded( | |
647 base::HandlesToInheritVector* handles) { | |
648 FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded(); | |
649 | |
650 // Need to get a new, read-only handle to share to the child. | |
651 handles->push_back(g_readonly_allocator_handle); | |
652 } | |
653 #endif | |
654 | |
655 // static | |
656 void FieldTrialList::CreateTrialsFromSharedMemory( | |
657 std::unique_ptr<base::SharedMemory> shm) { | |
658 const base::SharedPersistentMemoryAllocator shalloc(std::move(shm), 0, | |
659 kAllocatorName, true); | |
660 base::PersistentMemoryAllocator::Iterator iter(&shalloc); | |
661 | |
662 base::SharedPersistentMemoryAllocator::Reference ref; | |
663 while ((ref = iter.GetNextOfType(kFieldTrialType)) != | |
664 base::SharedPersistentMemoryAllocator::kReferenceNull) { | |
665 const FieldTrialEntry* entry = | |
666 shalloc.GetAsObject<const FieldTrialEntry>(ref, kFieldTrialType); | |
667 FieldTrial* trial = | |
668 CreateFieldTrial(entry->GetTrialName(), entry->GetGroupName()); | |
669 | |
670 if (entry->activated) { | |
671 // Call |group()| to mark the trial as "used" and notify observers, if | |
672 // any. This is useful to ensure that field trials created in child | |
673 // processes are properly reported in crash reports. | |
674 trial->group(); | |
675 } | |
676 } | |
677 } | |
678 | |
609 // static | 679 // static |
610 std::unique_ptr<base::SharedMemory> FieldTrialList::CopyFieldTrialStateToFlags( | 680 void FieldTrialList::CopyFieldTrialStateToFlags( |
611 const char* field_trial_handle_switch, | 681 const char* field_trial_handle_switch, |
612 base::CommandLine* cmd_line) { | 682 base::CommandLine* cmd_line) { |
683 #if defined(OS_WIN) | |
684 // Use shared memory to pass the state if the feature is enabled, otherwise | |
685 // fallback to passing it via the command line as a string. | |
686 if (kUseSharedMemoryForFieldTrials) { | |
687 FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded(); | |
688 // HANDLE is just typedef'd to void *. We basically cast the handle into an | |
689 // int (uintptr_t, to be exact), stringify the int, and pass it as a | |
690 // command-line flag. The child process will do the reverse conversions to | |
691 // retrieve the handle. See http://stackoverflow.com/a/153077 | |
692 auto uintptr_handle = | |
693 reinterpret_cast<uintptr_t>(g_readonly_allocator_handle); | |
694 size_t field_trial_length = | |
695 g_field_trial_allocator->shared_memory()->mapped_size(); | |
bcwhite
2016/10/20 21:14:06
Instead of UpdateTrackingHistograms you could also
lawrencewu
2016/10/23 20:01:56
Ack, will do later.
| |
696 std::string field_trial_handle = std::to_string(uintptr_handle) + "," + | |
697 std::to_string(field_trial_length); | |
698 | |
699 cmd_line->AppendSwitchASCII(field_trial_handle_switch, field_trial_handle); | |
700 return; | |
701 } | |
702 #endif | |
703 | |
613 std::string field_trial_states; | 704 std::string field_trial_states; |
614 base::FieldTrialList::AllStatesToString(&field_trial_states); | 705 base::FieldTrialList::AllStatesToString(&field_trial_states); |
615 if (!field_trial_states.empty()) { | 706 if (!field_trial_states.empty()) { |
616 // Use shared memory to pass the state if the feature is enabled, otherwise | |
617 // fallback to passing it via the command line as a string. | |
618 #if defined(OS_WIN) | |
619 if (kUseSharedMemoryForFieldTrials) { | |
620 std::unique_ptr<base::SharedMemory> shm(new base::SharedMemory()); | |
621 size_t length = field_trial_states.size() + 1; | |
622 shm->CreateAndMapAnonymous(length); | |
623 memcpy(shm->memory(), field_trial_states.c_str(), length); | |
624 | |
625 // HANDLE is just typedef'd to void * | |
626 auto uintptr_handle = | |
627 reinterpret_cast<std::uintptr_t>(shm->handle().GetHandle()); | |
628 std::string field_trial_handle = | |
629 std::to_string(uintptr_handle) + "," + std::to_string(length); | |
630 | |
631 cmd_line->AppendSwitchASCII(field_trial_handle_switch, | |
632 field_trial_handle); | |
633 return shm; | |
634 } | |
635 #endif | |
636 cmd_line->AppendSwitchASCII(switches::kForceFieldTrials, | 707 cmd_line->AppendSwitchASCII(switches::kForceFieldTrials, |
637 field_trial_states); | 708 field_trial_states); |
638 } | 709 } |
639 return std::unique_ptr<base::SharedMemory>(nullptr); | |
640 } | 710 } |
641 | 711 |
642 // static | 712 // static |
713 base::SharedPersistentMemoryAllocator* | |
714 FieldTrialList::GetFieldTrialAllocatorForTesting() { | |
715 return g_field_trial_allocator; | |
716 } | |
717 | |
718 // static | |
643 FieldTrial* FieldTrialList::CreateFieldTrial( | 719 FieldTrial* FieldTrialList::CreateFieldTrial( |
644 const std::string& name, | 720 const std::string& name, |
645 const std::string& group_name) { | 721 const std::string& group_name) { |
646 DCHECK(global_); | 722 DCHECK(global_); |
647 DCHECK_GE(name.size(), 0u); | 723 DCHECK_GE(name.size(), 0u); |
648 DCHECK_GE(group_name.size(), 0u); | 724 DCHECK_GE(group_name.size(), 0u); |
649 if (name.empty() || group_name.empty() || !global_) | 725 if (name.empty() || group_name.empty() || !global_) |
650 return NULL; | 726 return NULL; |
651 | 727 |
652 FieldTrial* field_trial = FieldTrialList::Find(name); | 728 FieldTrial* field_trial = FieldTrialList::Find(name); |
(...skipping 34 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... | |
687 { | 763 { |
688 AutoLock auto_lock(global_->lock_); | 764 AutoLock auto_lock(global_->lock_); |
689 if (field_trial->group_reported_) | 765 if (field_trial->group_reported_) |
690 return; | 766 return; |
691 field_trial->group_reported_ = true; | 767 field_trial->group_reported_ = true; |
692 } | 768 } |
693 | 769 |
694 if (!field_trial->enable_field_trial_) | 770 if (!field_trial->enable_field_trial_) |
695 return; | 771 return; |
696 | 772 |
773 if (kUseSharedMemoryForFieldTrials) { | |
774 FieldTrialList::UpdateFieldTrialAllocator(field_trial); | |
775 } | |
776 | |
697 global_->observer_list_->Notify( | 777 global_->observer_list_->Notify( |
698 FROM_HERE, &FieldTrialList::Observer::OnFieldTrialGroupFinalized, | 778 FROM_HERE, &FieldTrialList::Observer::OnFieldTrialGroupFinalized, |
699 field_trial->trial_name(), field_trial->group_name_internal()); | 779 field_trial->trial_name(), field_trial->group_name_internal()); |
700 } | 780 } |
701 | 781 |
702 // static | 782 // static |
783 void FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded() { | |
784 AutoLock auto_lock(global_->lock_); | |
785 // Create the allocator if not already created and add all existing trials. | |
786 if (g_field_trial_allocator == nullptr) { | |
787 std::unique_ptr<base::SharedMemory> shm(new base::SharedMemory()); | |
788 shm->CreateAndMapAnonymous(kFieldTrialAllocationSize); | |
789 | |
790 // TODO(lawrencewu): call UpdateTrackingHistograms() when all field trials | |
791 // have been registered (perhaps in the destructor?) | |
792 g_field_trial_allocator = new base::SharedPersistentMemoryAllocator( | |
793 std::move(shm), 0, kAllocatorName, false); | |
794 g_field_trial_allocator->CreateTrackingHistograms(kAllocatorName); | |
795 | |
796 // Add all existing field trials. | |
797 for (const auto& registered : global_->registered_) { | |
798 FieldTrialList::UpdateFieldTrialAllocator(registered.second); | |
799 } | |
800 | |
801 #if defined(OS_WIN) | |
802 // Duplicate and set |g_readonly_allocator_handle| so we can pass it to be | |
803 // inherited and via the command line. | |
804 HANDLE src = g_field_trial_allocator->shared_memory()->handle().GetHandle(); | |
805 ProcessHandle process = GetCurrentProcess(); | |
806 DWORD access = SECTION_MAP_READ | SECTION_QUERY; | |
807 ::DuplicateHandle(process, src, process, &g_readonly_allocator_handle, | |
808 access, true, 0); | |
809 #endif | |
810 } | |
811 } | |
812 | |
813 // static | |
814 void FieldTrialList::UpdateFieldTrialAllocator(FieldTrial* field_trial) { | |
815 // Don't do anything if the allocator hasn't been instantiated yet. | |
816 if (g_field_trial_allocator == nullptr) | |
bcwhite
2016/10/21 13:48:29
Since we've established that there could be parall
lawrencewu
2016/10/23 20:01:56
Done.
| |
817 return; | |
818 | |
819 // We allocate just enough memory to fit the FTE struct, trial name, and group | |
820 // name. If there's no more memory available, quit early. | |
821 FieldTrial::State trial_state; | |
822 field_trial->GetState(&trial_state); | |
823 | |
824 std::string trial_name; | |
825 trial_state.trial_name.CopyToString(&trial_name); | |
826 size_t trial_name_size = trial_name.size() + 1; | |
827 | |
828 std::string group_name; | |
829 trial_state.group_name.CopyToString(&group_name); | |
830 size_t group_name_size = group_name.size() + 1; | |
831 | |
832 uint32_t trial_name_offset = sizeof(FieldTrialEntry); | |
833 uint32_t group_name_offset = trial_name_offset + trial_name_size; | |
834 size_t size = sizeof(FieldTrialEntry) + trial_name_size + group_name_size; | |
835 | |
836 base::SharedPersistentMemoryAllocator::Reference ref = | |
837 g_field_trial_allocator->Allocate(size, kFieldTrialType); | |
838 if (ref == base::SharedPersistentMemoryAllocator::kReferenceNull) | |
839 return; | |
840 | |
841 FieldTrialEntry* dst = g_field_trial_allocator->GetAsObject<FieldTrialEntry>( | |
842 ref, kFieldTrialType); | |
843 FieldTrialEntry entry = {trial_state.activated, group_name_offset}; | |
844 *dst = entry; | |
845 memcpy(reinterpret_cast<char*>(dst) + trial_name_offset, trial_name.c_str(), | |
846 trial_name_size); | |
847 memcpy(reinterpret_cast<char*>(dst) + group_name_offset, group_name.c_str(), | |
848 group_name_size); | |
849 | |
850 g_field_trial_allocator->MakeIterable(ref); | |
851 } | |
852 | |
853 // static | |
703 size_t FieldTrialList::GetFieldTrialCount() { | 854 size_t FieldTrialList::GetFieldTrialCount() { |
704 if (!global_) | 855 if (!global_) |
705 return 0; | 856 return 0; |
706 AutoLock auto_lock(global_->lock_); | 857 AutoLock auto_lock(global_->lock_); |
707 return global_->registered_.size(); | 858 return global_->registered_.size(); |
708 } | 859 } |
709 | 860 |
710 // static | 861 // static |
711 const FieldTrial::EntropyProvider* | 862 const FieldTrial::EntropyProvider* |
712 FieldTrialList::GetEntropyProviderForOneTimeRandomization() { | 863 FieldTrialList::GetEntropyProviderForOneTimeRandomization() { |
(...skipping 19 matching lines...) Expand all Loading... | |
732 return; | 883 return; |
733 } | 884 } |
734 AutoLock auto_lock(global_->lock_); | 885 AutoLock auto_lock(global_->lock_); |
735 CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name(); | 886 CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name(); |
736 trial->AddRef(); | 887 trial->AddRef(); |
737 trial->SetTrialRegistered(); | 888 trial->SetTrialRegistered(); |
738 global_->registered_[trial->trial_name()] = trial; | 889 global_->registered_[trial->trial_name()] = trial; |
739 } | 890 } |
740 | 891 |
741 } // namespace base | 892 } // namespace base |
OLD | NEW |