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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 "content/renderer/worker/worker_thread_registry.h"
#include <atomic>
#include <utility>
#include "base/check.h"
#include "base/containers/contains.h"
#include "base/location.h"
#include "base/memory/ptr_util.h"
#include "base/no_destructor.h"
#include "base/observer_list.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/single_thread_task_runner.h"
#include "content/public/renderer/worker_thread.h"
namespace content {
namespace {
using WorkerThreadObservers =
base::ObserverList<WorkerThread::Observer>::Unchecked;
struct WorkerThreadData {
WorkerThreadData() {
// Worker thread ID starts with 1 (0 is reserved for the main thread).
static std::atomic_int seq{1};
thread_id = seq++;
}
int thread_id = 0;
WorkerThreadObservers observers;
};
constinit thread_local WorkerThreadData* worker_data = nullptr;
// A task-runner that refuses to run any tasks.
class DoNothingTaskRunner : public base::SequencedTaskRunner {
public:
DoNothingTaskRunner() {}
private:
~DoNothingTaskRunner() override {}
bool PostDelayedTask(const base::Location& from_here,
base::OnceClosure task,
base::TimeDelta delay) override {
return false;
}
bool PostNonNestableDelayedTask(const base::Location& from_here,
base::OnceClosure task,
base::TimeDelta delay) override {
return false;
}
bool RunsTasksInCurrentSequence() const override { return false; }
};
} // namespace
// WorkerThread implementation:
int WorkerThread::GetCurrentId() {
return worker_data ? worker_data->thread_id : 0;
}
void WorkerThread::PostTask(int id, base::OnceClosure task) {
WorkerThreadRegistry::Instance()->PostTask(id, std::move(task));
}
void WorkerThread::AddObserver(Observer* observer) {
DCHECK(worker_data);
worker_data->observers.AddObserver(observer);
}
void WorkerThread::RemoveObserver(Observer* observer) {
DCHECK(worker_data);
worker_data->observers.RemoveObserver(observer);
}
// WorkerThreadRegistry implementation:
WorkerThreadRegistry::WorkerThreadRegistry()
: task_runner_for_dead_worker_(new DoNothingTaskRunner()) {}
int WorkerThreadRegistry::PostTaskToAllThreads(
const base::RepeatingClosure& closure) {
base::AutoLock locker(task_runner_map_lock_);
for (const auto& it : task_runner_map_)
it.second->PostTask(FROM_HERE, closure);
return static_cast<int>(task_runner_map_.size());
}
WorkerThreadRegistry* WorkerThreadRegistry::Instance() {
static base::NoDestructor<WorkerThreadRegistry> worker_thread_registry;
return worker_thread_registry.get();
}
WorkerThreadRegistry::~WorkerThreadRegistry() = default;
void WorkerThreadRegistry::DidStartCurrentWorkerThread() {
DCHECK(!worker_data);
DCHECK(!base::PlatformThread::CurrentRef().is_null());
worker_data = new WorkerThreadData();
base::AutoLock locker_(task_runner_map_lock_);
task_runner_map_[worker_data->thread_id] =
base::SingleThreadTaskRunner::GetCurrentDefault().get();
CHECK(task_runner_map_[worker_data->thread_id]);
}
void WorkerThreadRegistry::WillStopCurrentWorkerThread() {
DCHECK(worker_data);
for (auto& observer : worker_data->observers)
observer.WillStopCurrentWorkerThread();
{
base::AutoLock locker(task_runner_map_lock_);
task_runner_map_.erase(worker_data->thread_id);
}
delete worker_data;
worker_data = nullptr;
}
base::SequencedTaskRunner* WorkerThreadRegistry::GetTaskRunnerFor(
int worker_id) {
base::AutoLock locker(task_runner_map_lock_);
return base::Contains(task_runner_map_, worker_id)
? task_runner_map_[worker_id]
: task_runner_for_dead_worker_.get();
}
bool WorkerThreadRegistry::PostTask(int id, base::OnceClosure closure) {
DCHECK(id > 0);
base::AutoLock locker(task_runner_map_lock_);
auto found = task_runner_map_.find(id);
if (found == task_runner_map_.end())
return false;
return found->second->PostTask(FROM_HERE, std::move(closure));
}
} // namespace content
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