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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/ash/power/freezer_cgroup_process_manager.h"
#include <string>
#include "base/files/file_util.h"
#include "base/functional/bind.h"
#include "base/functional/callback_helpers.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/system/sys_info.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/thread_pool.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
namespace ash {
namespace {
const char kFreezerPath[] = "/sys/fs/cgroup/freezer/ui/chrome_renderers";
const char kToBeFrozen[] = "to_be_frozen";
const char kFreezerState[] = "freezer.state";
const char kCgroupProcs[] = "cgroup.procs";
const char kFreezeCommand[] = "FROZEN";
const char kThawCommand[] = "THAWED";
} // namespace
class FreezerCgroupProcessManager::FileWorker {
public:
// Called on UI thread.
explicit FileWorker(scoped_refptr<base::SequencedTaskRunner> file_thread)
: ui_thread_(content::GetUIThreadTaskRunner({})),
file_thread_(file_thread),
enabled_(false),
froze_successfully_(false) {
DCHECK(ui_thread_->RunsTasksInCurrentSequence());
}
FileWorker(const FileWorker&) = delete;
FileWorker& operator=(const FileWorker&) = delete;
// Called on FILE thread.
virtual ~FileWorker() { DCHECK(file_thread_->RunsTasksInCurrentSequence()); }
void Start() {
DCHECK(file_thread_->RunsTasksInCurrentSequence());
default_control_path_ = base::FilePath(kFreezerPath).Append(kCgroupProcs);
to_be_frozen_control_path_ = base::FilePath(kFreezerPath)
.AppendASCII(kToBeFrozen)
.AppendASCII(kCgroupProcs);
to_be_frozen_state_path_ = base::FilePath(kFreezerPath)
.AppendASCII(kToBeFrozen)
.AppendASCII(kFreezerState);
enabled_ = base::PathIsWritable(default_control_path_) &&
base::PathIsWritable(to_be_frozen_control_path_) &&
base::PathIsWritable(to_be_frozen_state_path_);
if (!enabled_) {
LOG_IF(WARNING, base::SysInfo::IsRunningOnChromeOS())
<< "Cgroup freezer does not exist or is not writable. "
<< "Unable to freeze renderer processes.";
return;
}
// Thaw renderers on startup. This helps robustness for the case where we
// start up with renderers in frozen state, for example after the previous
// Chrome process crashed at a point in time after suspend where it still
// hadn't thawed renderers yet.
ThawRenderers(base::DoNothing());
}
void SetShouldFreezeRenderer(base::ProcessHandle handle, bool frozen) {
DCHECK(file_thread_->RunsTasksInCurrentSequence());
WriteCommandToFile(
base::NumberToString(handle),
frozen ? to_be_frozen_control_path_ : default_control_path_);
}
void FreezeRenderers() {
DCHECK(file_thread_->RunsTasksInCurrentSequence());
if (!enabled_) {
LOG(ERROR) << "Attempting to freeze renderers when the freezer cgroup is "
<< "not available.";
return;
}
froze_successfully_ =
WriteCommandToFile(kFreezeCommand, to_be_frozen_state_path_);
}
void ThawRenderers(ResultCallback callback) {
DCHECK(file_thread_->RunsTasksInCurrentSequence());
if (!enabled_) {
LOG(ERROR) << "Attempting to thaw renderers when the freezer cgroup is "
<< "not available.";
return;
}
bool result = WriteCommandToFile(kThawCommand, to_be_frozen_state_path_);
// TODO(derat): For now, lie and report success if thawing failed but
// freezing also failed previously. Remove after weird EBADF and ENOENT
// problems tracked at http://crbug.com/661310 are fixed.
if (!result && !froze_successfully_)
result = true;
ui_thread_->PostTask(FROM_HERE,
base::BindOnce(std::move(callback), result));
}
void CheckCanFreezeRenderers(ResultCallback callback) {
DCHECK(file_thread_->RunsTasksInCurrentSequence());
ui_thread_->PostTask(FROM_HERE,
base::BindOnce(std::move(callback), enabled_));
}
private:
bool WriteCommandToFile(const std::string& command,
const base::FilePath& file) {
if (!base::WriteFile(file, command)) {
PLOG(ERROR) << "Writing " << command << " to " << file.value()
<< " failed";
return false;
}
return true;
}
scoped_refptr<base::SequencedTaskRunner> ui_thread_;
scoped_refptr<base::SequencedTaskRunner> file_thread_;
// Control path for the cgroup that is not frozen.
base::FilePath default_control_path_;
// Control and state paths for the cgroup whose processes will be frozen.
base::FilePath to_be_frozen_control_path_;
base::FilePath to_be_frozen_state_path_;
bool enabled_;
// True iff FreezeRenderers() wrote its command successfully the last time it
// was called.
bool froze_successfully_;
};
FreezerCgroupProcessManager::FreezerCgroupProcessManager()
: file_thread_(base::ThreadPool::CreateSequencedTaskRunner(
{base::TaskPriority::BEST_EFFORT, base::MayBlock()})),
file_worker_(new FileWorker(file_thread_)) {
file_thread_->PostTask(
FROM_HERE,
base::BindOnce(&FileWorker::Start, base::Unretained(file_worker_.get())));
}
FreezerCgroupProcessManager::~FreezerCgroupProcessManager() {
file_thread_->DeleteSoon(FROM_HERE, file_worker_.release());
}
void FreezerCgroupProcessManager::SetShouldFreezeRenderer(
base::ProcessHandle handle,
bool frozen) {
file_thread_->PostTask(
FROM_HERE,
base::BindOnce(&FileWorker::SetShouldFreezeRenderer,
base::Unretained(file_worker_.get()), handle, frozen));
}
void FreezerCgroupProcessManager::FreezeRenderers() {
file_thread_->PostTask(FROM_HERE,
base::BindOnce(&FileWorker::FreezeRenderers,
base::Unretained(file_worker_.get())));
}
void FreezerCgroupProcessManager::ThawRenderers(ResultCallback callback) {
file_thread_->PostTask(FROM_HERE,
base::BindOnce(&FileWorker::ThawRenderers,
base::Unretained(file_worker_.get()),
std::move(callback)));
}
void FreezerCgroupProcessManager::CheckCanFreezeRenderers(
ResultCallback callback) {
file_thread_->PostTask(FROM_HERE,
base::BindOnce(&FileWorker::CheckCanFreezeRenderers,
base::Unretained(file_worker_.get()),
std::move(callback)));
}
} // namespace ash
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