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#include "common.hh"
#include <algorithm>
#include <condition_variable>
#include <deque>
#include <mutex>
#include <thread>
#include "task_runner.hh"
namespace {
class TaskRunnerThread : public TaskRunner {
public:
explicit TaskRunnerThread(size_t threads)
: threads_(std::max<size_t>(1, threads)) {
thread_ = std::make_unique<std::thread[]>(threads_);
for (size_t i = 0; i < threads_; ++i)
thread_[i] = std::thread(&TaskRunnerThread::thread, this);
}
~TaskRunnerThread() override {
{
std::lock_guard<std::mutex> lock(mutex_);
quit_ = true;
}
cond_.notify_all();
for (size_t i = 0; i < threads_; ++i)
thread_[i].join();
}
void post(std::function<void()> callback) override {
{
std::lock_guard<std::mutex> lock(mutex_);
queue_.push_back(std::move(callback));
}
cond_.notify_one();
}
private:
void thread() {
while (true) {
std::function<void()> callback;
while (true) {
std::unique_lock<std::mutex> lock(mutex_);
if (queue_.empty()) {
if (quit_)
return;
cond_.wait(lock);
} else {
callback = std::move(queue_.front());
queue_.pop_front();
break;
}
}
callback();
}
}
size_t const threads_;
bool quit_{false};
std::condition_variable cond_;
std::mutex mutex_;
std::deque<std::function<void()>> queue_;
std::unique_ptr<std::thread[]> thread_;
};
} // namespace
std::unique_ptr<TaskRunner> TaskRunner::create(size_t threads) {
return std::make_unique<TaskRunnerThread>(threads);
}
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