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// Copyright 2014 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 "content/child/worker_thread_registry.h"
#include "base/callback.h"
#include "base/lazy_instance.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "base/single_thread_task_runner.h"
#include "base/stl_util.h"
#include "base/thread_task_runner_handle.h"
#include "base/threading/thread_local.h"
#include "content/public/child/worker_thread.h"
namespace content {
namespace {
using WorkerThreadObservers = base::ObserverList<WorkerThread::Observer>;
using ThreadLocalWorkerThreadObservers =
base::ThreadLocalPointer<WorkerThreadObservers>;
// Stores a WorkerThreadObservers instance per thread.
base::LazyInstance<ThreadLocalWorkerThreadObservers> g_observers_tls =
LAZY_INSTANCE_INITIALIZER;
// A task-runner that refuses to run any tasks.
class DoNothingTaskRunner : public base::TaskRunner {
public:
DoNothingTaskRunner() {}
private:
~DoNothingTaskRunner() override {}
bool PostDelayedTask(const tracked_objects::Location& from_here,
const base::Closure& task,
base::TimeDelta delay) override {
return false;
}
bool RunsTasksOnCurrentThread() const override { return false; }
};
} // namespace
// WorkerThread implementation:
int WorkerThread::GetCurrentId() {
if (!g_observers_tls.Pointer()->Get())
return 0;
return base::PlatformThread::CurrentId();
}
void WorkerThread::PostTask(int id, const base::Closure& task) {
WorkerThreadRegistry::Instance()->PostTask(id, task);
}
void WorkerThread::AddObserver(Observer* observer) {
DCHECK(GetCurrentId() > 0);
WorkerThreadObservers* observers = g_observers_tls.Pointer()->Get();
DCHECK(observers);
observers->AddObserver(observer);
}
void WorkerThread::RemoveObserver(Observer* observer) {
DCHECK(GetCurrentId() > 0);
WorkerThreadObservers* observers = g_observers_tls.Pointer()->Get();
DCHECK(observers);
observers->RemoveObserver(observer);
}
// WorkerThreadRegistry implementation:
WorkerThreadRegistry::WorkerThreadRegistry()
: task_runner_for_dead_worker_(new DoNothingTaskRunner()) {}
int WorkerThreadRegistry::PostTaskToAllThreads(const base::Closure& 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::LazyInstance<WorkerThreadRegistry>::Leaky worker_task_runner =
LAZY_INSTANCE_INITIALIZER;
return worker_task_runner.Pointer();
}
WorkerThreadRegistry::~WorkerThreadRegistry() {}
void WorkerThreadRegistry::DidStartCurrentWorkerThread() {
DCHECK(!g_observers_tls.Pointer()->Get());
DCHECK(!base::PlatformThread::CurrentRef().is_null());
g_observers_tls.Pointer()->Set(new WorkerThreadObservers());
int id = base::PlatformThread::CurrentId();
base::AutoLock locker_(task_runner_map_lock_);
task_runner_map_[id] = base::ThreadTaskRunnerHandle::Get().get();
CHECK(task_runner_map_[id]);
}
void WorkerThreadRegistry::WillStopCurrentWorkerThread() {
WorkerThreadObservers* observers = g_observers_tls.Pointer()->Get();
DCHECK(observers);
FOR_EACH_OBSERVER(WorkerThread::Observer, *observers,
WillStopCurrentWorkerThread());
{
base::AutoLock locker(task_runner_map_lock_);
task_runner_map_.erase(WorkerThread::GetCurrentId());
}
delete observers;
g_observers_tls.Pointer()->Set(nullptr);
}
base::TaskRunner* WorkerThreadRegistry::GetTaskRunnerFor(int worker_id) {
base::AutoLock locker(task_runner_map_lock_);
return ContainsKey(task_runner_map_, worker_id)
? task_runner_map_[worker_id]
: task_runner_for_dead_worker_.get();
}
bool WorkerThreadRegistry::PostTask(int id, const base::Closure& closure) {
DCHECK(id > 0);
base::AutoLock locker(task_runner_map_lock_);
IDToTaskRunnerMap::iterator found = task_runner_map_.find(id);
if (found == task_runner_map_.end())
return false;
return found->second->PostTask(FROM_HERE, closure);
}
} // namespace content
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