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- // Copyright 2018 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "components/variations/variations_crash_keys.h"
- #include <string>
- #include "base/debug/leak_annotations.h"
- #include "base/sequence_checker.h"
- #include "base/strings/string_number_conversions.h"
- #include "base/strings/string_piece.h"
- #include "base/strings/stringprintf.h"
- #include "base/task/sequenced_task_runner.h"
- #include "base/threading/sequenced_task_runner_handle.h"
- #include "build/buildflag.h"
- #include "build/chromeos_buildflags.h"
- #include "components/crash/core/common/crash_key.h"
- #include "components/variations/active_field_trials.h"
- #include "components/variations/buildflags.h"
- #include "components/variations/synthetic_trials.h"
- #if BUILDFLAG(IS_CHROMEOS_ASH)
- #include "base/task/thread_pool.h"
- #include "components/variations/variations_crash_keys_chromeos.h"
- #endif
- namespace variations {
- namespace {
- // Size of the "num-experiments" crash key in bytes. 4096 bytes should be able
- // to hold about 227 entries, given each entry is 18 bytes long (due to being
- // of the form "8e7abfb0-c16397b7,").
- #if BUILDFLAG(LARGE_VARIATION_KEY_SIZE)
- constexpr size_t kVariationsKeySize = 8192;
- #else
- constexpr size_t kVariationsKeySize = 4096;
- #endif
- // Crash key reporting the number of experiments. 8 is the size of the crash key
- // in bytes, which is used to hold an int as a string.
- crash_reporter::CrashKeyString<8> g_num_variations_crash_key(
- kNumExperimentsKey);
- // Crash key reporting the variations state.
- crash_reporter::CrashKeyString<kVariationsKeySize> g_variations_crash_key(
- kExperimentListKey);
- std::string ActiveGroupToString(const ActiveGroupId& active_group) {
- return base::StringPrintf("%x-%x,", active_group.name, active_group.group);
- }
- class VariationsCrashKeys final : public base::FieldTrialList::Observer {
- public:
- VariationsCrashKeys();
- VariationsCrashKeys(const VariationsCrashKeys&) = delete;
- VariationsCrashKeys& operator=(const VariationsCrashKeys&) = delete;
- ~VariationsCrashKeys() override;
- // base::FieldTrialList::Observer:
- void OnFieldTrialGroupFinalized(const std::string& trial_name,
- const std::string& group_name) override;
- // Notifies the object that the list of synthetic field trial groups has
- // changed. Note: This matches the SyntheticTrialObserver interface, but this
- // object isn't a direct observer, so doesn't implement it.
- void OnSyntheticTrialsChanged(const std::vector<SyntheticTrialGroup>& groups);
- // Gets the list of experiments and number of experiments in the format we
- // want to place it in the crash keys.
- ExperimentListInfo GetExperimentListInfo();
- private:
- // Adds an entry for the specified field trial to internal state, without
- // updating crash keys.
- void AppendFieldTrial(const std::string& trial_name,
- const std::string& group_name);
- // Updates crash keys based on internal state.
- void UpdateCrashKeys();
- // Task runner corresponding to the UI thread, used to reschedule synchronous
- // observer calls that happen on a different thread.
- scoped_refptr<base::SequencedTaskRunner> ui_thread_task_runner_;
- #if BUILDFLAG(IS_CHROMEOS_ASH)
- // Task runner corresponding to a background thread, used for tasks that may
- // block.
- scoped_refptr<base::SequencedTaskRunner> background_thread_task_runner_;
- #endif // IS_CHROMEOS_ASH
- // A serialized string containing the variations state.
- std::string variations_string_;
- // Number of entries in |variations_string_|.
- size_t num_variations_ = 0;
- // A serialized string containing the synthetic trials state.
- std::string synthetic_trials_string_;
- // Number of entries in |synthetic_trials_string_|.
- size_t num_synthetic_trials_ = 0;
- SEQUENCE_CHECKER(sequence_checker_);
- };
- VariationsCrashKeys::VariationsCrashKeys() {
- base::FieldTrial::ActiveGroups active_groups;
- base::FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
- for (const auto& entry : active_groups) {
- AppendFieldTrial(entry.trial_name, entry.group_name);
- }
- #if BUILDFLAG(IS_CHROMEOS_ASH)
- background_thread_task_runner_ = base::ThreadPool::CreateSequencedTaskRunner(
- {base::TaskPriority::BEST_EFFORT, base::MayBlock()});
- #endif // IS_CHROMEOS_ASH
- UpdateCrashKeys();
- ui_thread_task_runner_ = base::SequencedTaskRunnerHandle::Get();
- base::FieldTrialList::AddObserver(this);
- }
- VariationsCrashKeys::~VariationsCrashKeys() {
- base::FieldTrialList::RemoveObserver(this);
- g_num_variations_crash_key.Clear();
- g_variations_crash_key.Clear();
- }
- void VariationsCrashKeys::OnFieldTrialGroupFinalized(
- const std::string& trial_name,
- const std::string& group_name) {
- // If this is called on a different thread, post it back to the UI thread.
- // Note: This is safe to do because in production, this object is never
- // deleted and if this is called, it means the constructor has already run,
- // which is the only place that |ui_thread_task_runner_| is set.
- if (!ui_thread_task_runner_->RunsTasksInCurrentSequence()) {
- ui_thread_task_runner_->PostTask(
- FROM_HERE,
- BindOnce(&VariationsCrashKeys::OnFieldTrialGroupFinalized,
- // base::Unretained() is safe here because this object is
- // never deleted in production.
- base::Unretained(this), trial_name, group_name));
- return;
- }
- DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
- AppendFieldTrial(trial_name, group_name);
- UpdateCrashKeys();
- }
- void VariationsCrashKeys::AppendFieldTrial(const std::string& trial_name,
- const std::string& group_name) {
- DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
- auto active_group_id = MakeActiveGroupId(trial_name, group_name);
- auto variation = ActiveGroupToString(active_group_id);
- variations_string_ += variation;
- ++num_variations_;
- }
- ExperimentListInfo VariationsCrashKeys::GetExperimentListInfo() {
- DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
- ExperimentListInfo result;
- result.num_experiments = num_variations_ + num_synthetic_trials_;
- result.experiment_list.reserve(variations_string_.size() +
- synthetic_trials_string_.size());
- result.experiment_list.append(variations_string_);
- result.experiment_list.append(synthetic_trials_string_);
- return result;
- }
- void VariationsCrashKeys::UpdateCrashKeys() {
- DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
- ExperimentListInfo info = GetExperimentListInfo();
- g_num_variations_crash_key.Set(base::NumberToString(info.num_experiments));
- if (info.experiment_list.size() > kVariationsKeySize) {
- // If size exceeded, truncate to the last full entry.
- int comma_index =
- info.experiment_list.substr(0, kVariationsKeySize).rfind(',');
- info.experiment_list.resize(comma_index + 1);
- // NOTREACHED() will let us know of the problem and adjust the limit.
- NOTREACHED();
- }
- g_variations_crash_key.Set(info.experiment_list);
- #if BUILDFLAG(IS_CHROMEOS_ASH)
- ReportVariationsToChromeOs(background_thread_task_runner_, info);
- #endif // IS_CHROMEOS_ASH
- }
- void VariationsCrashKeys::OnSyntheticTrialsChanged(
- const std::vector<SyntheticTrialGroup>& synthetic_trials) {
- DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
- // Note: This part is inefficient as each time synthetic trials change, this
- // code recomputes all their name hashes. However, given that there should
- // not be too many synthetic trials, this is not too big of an issue.
- synthetic_trials_string_.clear();
- for (const auto& synthetic_trial : synthetic_trials) {
- synthetic_trials_string_ += ActiveGroupToString(synthetic_trial.id());
- }
- num_synthetic_trials_ = synthetic_trials.size();
- UpdateCrashKeys();
- }
- // Singletone crash key manager. Allocated once at process start up and
- // intentionally leaked since it needs to live for the duration of the process
- // there's no benefit in cleaning it up at exit.
- VariationsCrashKeys* g_variations_crash_keys = nullptr;
- } // namespace
- const char kNumExperimentsKey[] = "num-experiments";
- const char kExperimentListKey[] = "variations";
- void InitCrashKeys() {
- DCHECK(!g_variations_crash_keys);
- g_variations_crash_keys = new VariationsCrashKeys();
- ANNOTATE_LEAKING_OBJECT_PTR(g_variations_crash_keys);
- }
- void UpdateCrashKeysWithSyntheticTrials(
- const std::vector<SyntheticTrialGroup>& synthetic_trials) {
- DCHECK(g_variations_crash_keys);
- g_variations_crash_keys->OnSyntheticTrialsChanged(synthetic_trials);
- }
- void ClearCrashKeysInstanceForTesting() {
- DCHECK(g_variations_crash_keys);
- delete g_variations_crash_keys;
- g_variations_crash_keys = nullptr;
- }
- ExperimentListInfo GetExperimentListInfo() {
- DCHECK(g_variations_crash_keys);
- return g_variations_crash_keys->GetExperimentListInfo();
- }
- } // namespace variations
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