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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 "chrome/browser/metrics/persistent_histograms.h"
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/files/file_path.h"
#include "base/files/file_util.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/persistent_histogram_allocator.h"
#include "base/path_service.h"
#include "base/system/sys_info.h"
#include "base/task/post_task.h"
#include "build/build_config.h"
#include "chrome/common/chrome_paths.h"
#include "components/metrics/persistent_system_profile.h"
#include "components/variations/variations_associated_data.h"
namespace {
// Creating a "spare" file for persistent metrics involves a lot of I/O and
// isn't important so delay the operation for a while after startup.
#if defined(OS_ANDROID)
// Android needs the spare file and also launches faster.
constexpr bool kSpareFileRequired = true;
constexpr int kSpareFileCreateDelaySeconds = 10;
#else
// Desktop may have to restore a lot of tabs so give it more time before doing
// non-essential work. The spare file is still a performance boost but not as
// significant of one so it's not required.
constexpr bool kSpareFileRequired = false;
constexpr int kSpareFileCreateDelaySeconds = 90;
#endif
} // namespace
const char kBrowserMetricsName[] = "BrowserMetrics";
// Check for feature enabling the use of persistent histogram storage and
// enable the global allocator if so.
void InstantiatePersistentHistograms() {
base::FilePath metrics_dir;
if (!base::PathService::Get(chrome::DIR_USER_DATA, &metrics_dir))
return;
// Create a directory for storing completed metrics files. Files in this
// directory must have embedded system profiles. If the directory can't be
// created, the file will just be deleted below.
base::FilePath upload_dir = metrics_dir.AppendASCII(kBrowserMetricsName);
base::CreateDirectory(upload_dir);
// Metrics files are typically created as a |spare_file| in the profile
// directory (e.g. "BrowserMetrics-spare.pma") and are then rotated into
// a subdirectory as a stamped file for upload when no longer in use.
// (e.g. "BrowserMetrics/BrowserMetrics-1234ABCD-12345.pma")
base::FilePath upload_file;
base::FilePath active_file;
base::FilePath spare_file;
base::GlobalHistogramAllocator::ConstructFilePathsForUploadDir(
metrics_dir, upload_dir, kBrowserMetricsName, &upload_file, &active_file,
&spare_file);
// This is used to report results to an UMA histogram.
enum InitResult {
kLocalMemorySuccess,
kLocalMemoryFailed,
kMappedFileSuccess,
kMappedFileFailed,
kMappedFileExists,
kNoSpareFile,
kNoUploadDir,
kMaxValue = kNoUploadDir
};
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, has the 99.99
// percentile around 3MiB as of 2018-10-22.
const size_t kAllocSize = 4 << 20; // 4 MiB
const uint32_t kAllocId = 0x935DDD43; // SHA1(BrowserMetrics)
std::string storage = variations::GetVariationParamValueByFeature(
base::kPersistentHistogramsFeature, "storage");
static const char kMappedFile[] = "MappedFile";
static const char kLocalMemory[] = "LocalMemory";
#if defined(OS_LINUX) && !defined(OS_CHROMEOS)
// Linux kernel 4.4.0.* shows a huge number of SIGBUS crashes with persistent
// histograms enabled using a mapped file. Change this to use local memory.
// https://bugs.chromium.org/p/chromium/issues/detail?id=753741
if (storage.empty() || storage == kMappedFile) {
int major, minor, bugfix;
base::SysInfo::OperatingSystemVersionNumbers(&major, &minor, &bugfix);
if (major == 4 && minor == 4 && bugfix == 0)
storage = kLocalMemory;
}
#endif
// Don't use mapped-file memory by default on low-end devices, especially
// Android. The extra disk consumption and/or extra disk access could have
// a significant performance impact. https://crbug.com/896394
if (storage.empty() && base::SysInfo::IsLowEndDevice())
storage = kLocalMemory;
// Create a global histogram allocator using the desired storage type.
if (storage.empty() || storage == kMappedFile) {
if (!base::PathExists(upload_dir)) {
// Handle failure to create the directory.
result = kNoUploadDir;
} else if (base::PathExists(upload_file)) {
// "upload" filename is supposed to be unique so this shouldn't happen.
result = kMappedFileExists;
} else {
// Move any sparse file into the upload position.
base::ReplaceFile(spare_file, upload_file, nullptr);
// Create global allocator using the "upload" file.
if (kSpareFileRequired && !base::PathExists(upload_file)) {
result = kNoSpareFile;
} else if (base::GlobalHistogramAllocator::CreateWithFile(
upload_file, kAllocSize, kAllocId, kBrowserMetricsName)) {
result = kMappedFileSuccess;
} else {
result = kMappedFileFailed;
}
}
// Schedule the creation of a "spare" file for use on the next run.
base::PostDelayedTaskWithTraits(
FROM_HERE,
{base::MayBlock(), base::TaskPriority::LOWEST,
base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN},
base::BindOnce(base::IgnoreResult(
&base::GlobalHistogramAllocator::CreateSpareFile),
std::move(spare_file), kAllocSize),
base::TimeDelta::FromSeconds(kSpareFileCreateDelaySeconds));
} else if (storage == kLocalMemory) {
// Use local memory for storage even though it will not persist across
// an unclean shutdown. This sets the result but the actual creation is
// done below.
result = kLocalMemorySuccess;
} else {
// Persistent metric storage is disabled. Must return here.
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);
base::GlobalHistogramAllocator* allocator =
base::GlobalHistogramAllocator::Get();
if (!allocator) {
// If no allocator was created above, try to create a LocalMemomory one
// here. This avoids repeating the call many times above. In the case where
// persistence is disabled, an early return is done above.
base::GlobalHistogramAllocator::CreateWithLocalMemory(kAllocSize, kAllocId,
kBrowserMetricsName);
allocator = base::GlobalHistogramAllocator::Get();
if (!allocator)
return;
}
// Store a copy of the system profile in this allocator.
metrics::GlobalPersistentSystemProfile::GetInstance()
->RegisterPersistentAllocator(allocator->memory_allocator());
// Create tracking histograms for the allocator and record storage file.
allocator->CreateTrackingHistograms(kBrowserMetricsName);
}