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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/build_time.h" | 11 #include "base/build_time.h" |
| 12 #include "base/command_line.h" |
| 13 #include "base/feature_list.h" |
11 #include "base/logging.h" | 14 #include "base/logging.h" |
12 #include "base/rand_util.h" | 15 #include "base/rand_util.h" |
13 #include "base/strings/string_number_conversions.h" | 16 #include "base/strings/string_number_conversions.h" |
14 #include "base/strings/string_util.h" | 17 #include "base/strings/string_util.h" |
15 #include "base/strings/stringprintf.h" | 18 #include "base/strings/stringprintf.h" |
16 #include "base/strings/utf_string_conversions.h" | 19 #include "base/strings/utf_string_conversions.h" |
17 | 20 |
18 namespace base { | 21 namespace base { |
19 | 22 |
20 namespace { | 23 namespace { |
21 | 24 |
22 // Define a separator character to use when creating a persistent form of an | 25 // Define a separator character to use when creating a persistent form of an |
23 // instance. This is intended for use as a command line argument, passed to a | 26 // instance. This is intended for use as a command line argument, passed to a |
24 // second process to mimic our state (i.e., provide the same group name). | 27 // second process to mimic our state (i.e., provide the same group name). |
25 const char kPersistentStringSeparator = '/'; // Currently a slash. | 28 const char kPersistentStringSeparator = '/'; // Currently a slash. |
26 | 29 |
27 // 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 |
28 // command line which forces its activation. | 31 // command line which forces its activation. |
29 const char kActivationMarker = '*'; | 32 const char kActivationMarker = '*'; |
30 | 33 |
| 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 |
| 36 // shared memory segment). See https://codereview.chromium.org/2365273004/ and |
| 37 // crbug.com/653874 |
| 38 #if defined(OS_WIN) |
| 39 const bool kUseSharedMemoryForFieldTrials = false; |
| 40 #endif |
| 41 |
31 // Created a time value based on |year|, |month| and |day_of_month| parameters. | 42 // Created a time value based on |year|, |month| and |day_of_month| parameters. |
32 Time CreateTimeFromParams(int year, int month, int day_of_month) { | 43 Time CreateTimeFromParams(int year, int month, int day_of_month) { |
33 DCHECK_GT(year, 1970); | 44 DCHECK_GT(year, 1970); |
34 DCHECK_GT(month, 0); | 45 DCHECK_GT(month, 0); |
35 DCHECK_LT(month, 13); | 46 DCHECK_LT(month, 13); |
36 DCHECK_GT(day_of_month, 0); | 47 DCHECK_GT(day_of_month, 0); |
37 DCHECK_LT(day_of_month, 32); | 48 DCHECK_LT(day_of_month, 32); |
38 | 49 |
39 Time::Exploded exploded; | 50 Time::Exploded exploded; |
40 exploded.year = year; | 51 exploded.year = year; |
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551 // Call |group()| to mark the trial as "used" and notify observers, if | 562 // Call |group()| to mark the trial as "used" and notify observers, if |
552 // any. This is useful to ensure that field trials created in child | 563 // any. This is useful to ensure that field trials created in child |
553 // processes are properly reported in crash reports. | 564 // processes are properly reported in crash reports. |
554 trial->group(); | 565 trial->group(); |
555 } | 566 } |
556 } | 567 } |
557 return true; | 568 return true; |
558 } | 569 } |
559 | 570 |
560 // static | 571 // static |
| 572 void FieldTrialList::CreateTrialsFromCommandLine( |
| 573 const base::CommandLine& cmd_line, |
| 574 const char* field_trial_handle_switch) { |
| 575 DCHECK(global_); |
| 576 |
| 577 #if defined(OS_WIN) |
| 578 if (cmd_line.HasSwitch(field_trial_handle_switch)) { |
| 579 std::string arg = cmd_line.GetSwitchValueASCII(field_trial_handle_switch); |
| 580 size_t token = arg.find(","); |
| 581 int field_trial_handle = std::stoi(arg.substr(0, token)); |
| 582 int field_trial_length = std::stoi(arg.substr(token + 1, arg.length())); |
| 583 |
| 584 HANDLE handle = reinterpret_cast<HANDLE>(field_trial_handle); |
| 585 base::SharedMemoryHandle shm_handle = |
| 586 base::SharedMemoryHandle(handle, base::GetCurrentProcId()); |
| 587 |
| 588 // 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. |
| 590 base::SharedMemory shared_memory(shm_handle, false); |
| 591 shared_memory.Map(field_trial_length); |
| 592 |
| 593 char* field_trial_state = static_cast<char*>(shared_memory.memory()); |
| 594 bool result = FieldTrialList::CreateTrialsFromString( |
| 595 std::string(field_trial_state), std::set<std::string>()); |
| 596 DCHECK(result); |
| 597 return; |
| 598 } |
| 599 #endif |
| 600 |
| 601 if (cmd_line.HasSwitch(switches::kForceFieldTrials)) { |
| 602 bool result = FieldTrialList::CreateTrialsFromString( |
| 603 cmd_line.GetSwitchValueASCII(switches::kForceFieldTrials), |
| 604 std::set<std::string>()); |
| 605 DCHECK(result); |
| 606 } |
| 607 } |
| 608 |
| 609 // static |
| 610 std::unique_ptr<base::SharedMemory> FieldTrialList::CopyFieldTrialStateToFlags( |
| 611 const char* field_trial_handle_switch, |
| 612 base::CommandLine* cmd_line) { |
| 613 std::string field_trial_states; |
| 614 base::FieldTrialList::AllStatesToString(&field_trial_states); |
| 615 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, |
| 637 field_trial_states); |
| 638 } |
| 639 return std::unique_ptr<base::SharedMemory>(nullptr); |
| 640 } |
| 641 |
| 642 // static |
561 FieldTrial* FieldTrialList::CreateFieldTrial( | 643 FieldTrial* FieldTrialList::CreateFieldTrial( |
562 const std::string& name, | 644 const std::string& name, |
563 const std::string& group_name) { | 645 const std::string& group_name) { |
564 DCHECK(global_); | 646 DCHECK(global_); |
565 DCHECK_GE(name.size(), 0u); | 647 DCHECK_GE(name.size(), 0u); |
566 DCHECK_GE(group_name.size(), 0u); | 648 DCHECK_GE(group_name.size(), 0u); |
567 if (name.empty() || group_name.empty() || !global_) | 649 if (name.empty() || group_name.empty() || !global_) |
568 return NULL; | 650 return NULL; |
569 | 651 |
570 FieldTrial* field_trial = FieldTrialList::Find(name); | 652 FieldTrial* field_trial = FieldTrialList::Find(name); |
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650 return; | 732 return; |
651 } | 733 } |
652 AutoLock auto_lock(global_->lock_); | 734 AutoLock auto_lock(global_->lock_); |
653 CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name(); | 735 CHECK(!global_->PreLockedFind(trial->trial_name())) << trial->trial_name(); |
654 trial->AddRef(); | 736 trial->AddRef(); |
655 trial->SetTrialRegistered(); | 737 trial->SetTrialRegistered(); |
656 global_->registered_[trial->trial_name()] = trial; | 738 global_->registered_[trial->trial_name()] = trial; |
657 } | 739 } |
658 | 740 |
659 } // namespace base | 741 } // namespace base |
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