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/*
* Copyright (c) 2016-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
*/
#pragma once
#include "utils/WorkQueue.h"
#include <cstddef>
#include <functional>
#include <thread>
#include <vector>
namespace pzstd {
/// A simple thread pool that pulls tasks off its queue in FIFO order.
class ThreadPool {
std::vector<std::thread> threads_;
WorkQueue<std::function<void()>> tasks_;
public:
/// Constructs a thread pool with `numThreads` threads.
explicit ThreadPool(std::size_t numThreads) {
threads_.reserve(numThreads);
for (std::size_t i = 0; i < numThreads; ++i) {
threads_.emplace_back([this] {
std::function<void()> task;
while (tasks_.pop(task)) {
task();
}
});
}
}
/// Finishes all tasks currently in the queue.
~ThreadPool() {
tasks_.finish();
for (auto& thread : threads_) {
thread.join();
}
}
/**
* Adds `task` to the queue of tasks to execute. Since `task` is a
* `std::function<>`, it cannot be a move only type. So any lambda passed must
* not capture move only types (like `std::unique_ptr`).
*
* @param task The task to execute.
*/
void add(std::function<void()> task) {
tasks_.push(std::move(task));
}
};
}
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