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// Copyright (c) 2012 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 "chrome/browser/chrome_browser_field_trials.h"
#include <string>
#include "base/command_line.h"
#include "base/feature_list.h"
#include "base/files/file_util.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_base.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/persistent_histogram_allocator.h"
#include "base/path_service.h"
#include "base/strings/string_util.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "chrome/browser/metrics/chrome_metrics_service_client.h"
#include "chrome/browser/metrics/chrome_metrics_services_manager_client.h"
#include "chrome/browser/tracing/background_tracing_field_trial.h"
#include "chrome/common/channel_info.h"
#include "chrome/common/chrome_paths.h"
#include "chrome/common/chrome_switches.h"
#include "components/metrics/metrics_pref_names.h"
#include "components/variations/variations_associated_data.h"
#if defined(OS_ANDROID)
#include "chrome/browser/chrome_browser_field_trials_mobile.h"
#else
#include "chrome/browser/chrome_browser_field_trials_desktop.h"
#endif
namespace {
// Check for feature enabling the use of persistent histogram storage and
// enable the global allocator if so.
// TODO(bcwhite): Move this and CreateInstallerFileMetricsProvider into a new
// file and make kBrowserMetricsName local to that file.
void InstantiatePersistentHistograms() {
base::FilePath metrics_dir;
if (!base::PathService::Get(chrome::DIR_USER_DATA, &metrics_dir))
return;
base::FilePath metrics_file, active_file;
base::GlobalHistogramAllocator::ConstructFilePaths(
metrics_dir, ChromeMetricsServiceClient::kBrowserMetricsName,
&metrics_file, &active_file);
// Move any existing "active" file to the final name from which it will be
// read when reporting initial stability metrics. If there is no file to
// move, remove any old, existing file from before the previous session.
if (!base::ReplaceFile(active_file, metrics_file, nullptr))
base::DeleteFile(metrics_file, /*recursive=*/false);
// This is used to report results to an UMA histogram.
enum InitResult {
LOCAL_MEMORY_SUCCESS,
LOCAL_MEMORY_FAILED,
MAPPED_FILE_SUCCESS,
MAPPED_FILE_FAILED,
MAPPED_FILE_EXISTS,
INIT_RESULT_MAX
};
InitResult result;
// Create persistent/shared memory and allow histograms to be stored in
// it. Memory that is not actualy used won't be physically mapped by the
// system. BrowserMetrics usage, as reported in UMA, peaked around 3.0MiB
// as of 2016-12-20.
const size_t kAllocSize = 5 << 20; // 5 MiB
const uint32_t kAllocId = 0x935DDD43; // SHA1(BrowserMetrics)
std::string storage = variations::GetVariationParamValueByFeature(
base::kPersistentHistogramsFeature, "storage");
if (storage == "MappedFile") {
// If for some reason the existing "active" file could not be moved above
// then it is essential it be scheduled for deletion when possible and the
// contents ignored. Because this shouldn't happen but can on an OS like
// Windows where another process reading the file (backup, AV, etc.) can
// prevent its alteration, it's necessary to handle this case by switching
// to the equivalent of "LocalMemory" for this run.
if (base::PathExists(active_file)) {
base::File file(active_file, base::File::FLAG_OPEN |
base::File::FLAG_READ |
base::File::FLAG_DELETE_ON_CLOSE);
result = MAPPED_FILE_EXISTS;
base::GlobalHistogramAllocator::CreateWithLocalMemory(
kAllocSize, kAllocId,
ChromeMetricsServiceClient::kBrowserMetricsName);
} else {
// Create global allocator with the "active" file.
if (base::GlobalHistogramAllocator::CreateWithFile(
active_file, kAllocSize, kAllocId,
ChromeMetricsServiceClient::kBrowserMetricsName)) {
result = MAPPED_FILE_SUCCESS;
} else {
result = MAPPED_FILE_FAILED;
}
}
} else if (storage == "LocalMemory") {
// Use local memory for storage even though it will not persist across
// an unclean shutdown.
base::GlobalHistogramAllocator::CreateWithLocalMemory(
kAllocSize, kAllocId, ChromeMetricsServiceClient::kBrowserMetricsName);
result = LOCAL_MEMORY_SUCCESS;
} else {
// Persistent metric storage is disabled.
return;
}
// Get the allocator that was just created and report result. Exit if the
// allocator could not be created.
UMA_HISTOGRAM_ENUMERATION("UMA.PersistentHistograms.InitResult", result,
INIT_RESULT_MAX);
base::GlobalHistogramAllocator* allocator =
base::GlobalHistogramAllocator::Get();
if (!allocator)
return;
// Create tracking histograms for the allocator and record storage file.
allocator->CreateTrackingHistograms(
ChromeMetricsServiceClient::kBrowserMetricsName);
}
// Create a field trial to control metrics/crash sampling for Stable on
// Windows/Android if no variations seed was applied.
void CreateFallbackSamplingTrialIfNeeded(bool has_seed,
base::FeatureList* feature_list) {
#if defined(OS_WIN) || defined(OS_ANDROID)
// Only create the fallback trial if there isn't already a variations seed
// being applied. This should occur during first run when first-run variations
// isn't supported. It's assumed that, if there is a seed, then it either
// contains the relavent study, or is intentionally omitted, so no fallback is
// needed.
if (has_seed)
return;
ChromeMetricsServicesManagerClient::CreateFallbackSamplingTrial(
chrome::GetChannel(), feature_list);
#endif // defined(OS_WIN) || defined(OS_ANDROID)
}
} // namespace
ChromeBrowserFieldTrials::ChromeBrowserFieldTrials() {}
ChromeBrowserFieldTrials::~ChromeBrowserFieldTrials() {
}
void ChromeBrowserFieldTrials::SetupFieldTrials() {
// Field trials that are shared by all platforms.
InstantiateDynamicTrials();
#if defined(OS_ANDROID)
chrome::SetupMobileFieldTrials();
#else
chrome::SetupDesktopFieldTrials();
#endif
}
void ChromeBrowserFieldTrials::SetupFeatureControllingFieldTrials(
bool has_seed,
base::FeatureList* feature_list) {
CreateFallbackSamplingTrialIfNeeded(has_seed, feature_list);
}
void ChromeBrowserFieldTrials::InstantiateDynamicTrials() {
// Persistent histograms must be enabled as soon as possible.
InstantiatePersistentHistograms();
tracing::SetupBackgroundTracingFieldTrial();
}
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