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ThreadPool.hpp
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ThreadPool.hpp
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/**
*
* @author Matthew R. Supernaw
*
* Public Domain Notice
* National Oceanic And Atmospheric Administration
*
* This software is a "United States Government Work" under the terms of the
* United States Copyright Act. It was written as part of the author's official
* duties as a United States Government employee and thus cannot be copyrighted.
* This software is freely available to the public for use. The National Oceanic
* And Atmospheric Administration and the U.S. Government have not placed any
* restriction on its use or reproduction. Although all reasonable efforts have
* been taken to ensure the accuracy and reliability of the software and data,
* the National Oceanic And Atmospheric Administration and the U.S. Government
* do not and cannot warrant the performance or results that may be obtained
* by using this software or data. The National Oceanic And Atmospheric
* Administration and the U.S. Government disclaim all warranties, express
* or implied, including warranties of performance, merchantability or fitness
* for any particular purpose.
*
* Please cite the author(s) in any work or product based on this material.
*
*/
/*
* File: ThreadPool.hpp
* Author: matthewsupernaw
*
* Created on November 3, 2016, 1:58 PM
*/
#ifndef THREADPOOL_HPP
#define THREADPOOL_HPP
#include <thread>
#include <atomic>
#include <condition_variable>
#include <queue>
#include <vector>
#include <future>
#include <cstdlib>
#include <functional>
#if defined(linux) || defined(__linux) || defined(__linux__)
#define NOAA_TP_LINUX
#elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
#define NOAA_TP_BSD
#elif defined(sun) || defined(__sun)
#define NOAA_TP_SOLARIS
#elif defined(__sgi)
#define NOAA_TP_IRIX
#elif defined(__hpux)
#define NOAA_TP_HPUX
#elif defined(__CYGWIN__)
#define NOAA_TP_CYGWIN
#elif defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
#define NOAA_TP_WIN32
#elif defined(_WIN64) || defined(__WIN64__) || defined(WIN64)
#define NOAA_TP_WIN64
#elif defined(__BEOS__)
#define NOAA_TP_BEOS
#elif defined(macintosh) || defined(__APPLE__) || defined(__APPLE_CC__)
#define NOAA_TP_MACOS
#elif defined(__IBMCPP__) || defined(_AIX)
#define NOAA_TP_AIX
#elif defined(__amigaos__)
#define NOAA_TP_AMIGAOS
#elif defined(__QNXNTO__)
#define NOAA_TP_QNXNTO
#endif
#if defined(NOAA_TP_WIN32) || defined(NOAA_TP_WIN64)
#define NOAA_TP_WINDOWS
#endif
#if defined(NOAA_TP_WINDOWS)
#undef max
#undef min
#endif
namespace atl {
class ThreadPool;
struct WaitableFunction;
/**
*
* WaitVariable is used in conjunction with ThreadPool runs where it is
* desired to wait for threads to complete before continuing.
*
*/
class WaitVariable {
friend class ThreadPool;
std::atomic<int> wait;
inline std::atomic<int>& operator++(int i) {
wait++;
return wait;
}
inline std::atomic<int>& operator--(int i) {
wait--;
return wait;
}
public:
WaitVariable() : wait(0) {
}
};
/**
*
*Thread pool.
*
*/
class ThreadPool {
template<class InputIt, typename Function>
struct ForEachFunctor {
InputIt start;
InputIt end;
Function f;
ForEachFunctor(InputIt start, InputIt end, Function f) :
start(start), end(end), f(f) {
}
void operator()(void) {
for (InputIt it = start; it != end; it++) {
f((*it));
}
}
};
/**
*/
struct WaitableFunction {
std::function<void(void) > f;
std::atomic<int>& wait;
WaitableFunction(const WaitableFunction& other) :
f(other.f), wait(other.wait) {
}
WaitableFunction(const std::function<void(void) >& f, std::atomic<int>& wait) :
f(f), wait(wait) {
}
WaitableFunction(std::function<void(void) >&& f, std::atomic<int>&& wait) :
f(f), wait(wait) {
}
void operator()(void) {
f.operator()();
wait--;
}
};
public:
/**
* Constructor. Sets the number of threads in this thread pool.
*
* @param threads
*/
ThreadPool(int threads = std::thread::hardware_concurrency()) : shutdown_(false), started_(true) {
// Create the specified number of threads
threads_.reserve(threads);
for (int i = 0; i < threads; ++i)
threads_.emplace_back(std::bind(&ThreadPool::threadEntry, this, i));
this->thread_count = threads;
#ifndef NOAA_TP_WINDOWS
sched_param sch;
sch.sched_priority = 70;
for (int i = 0; i < threads_.size(); i++) {
pthread_setschedparam(threads_[i].native_handle(), SCHED_FIFO, &sch);
}
#else
for (int i = 0; i < threads_.size(); i++) {
// SetThreadPriority(threads_[i].native_handle(), 50);
}
#endif
}
/**
* Destructor. Shuts down all threads.
*/
~ThreadPool() {
{
// Unblock any threads and tell them to stop
std::unique_lock <std::mutex> l(lock_);
shutdown_ = true;
condVar_.notify_all();
}
// Wait for all threads to stop
for (auto& thread : threads_)
thread.join();
}
void Start(int threads = std::thread::hardware_concurrency()) {
if (!started_) {
threads_.reserve(threads);
for (int i = 0; i < threads; ++i)
threads_.emplace_back(std::bind(&ThreadPool::threadEntry, this, i));
started_ = true;
}
}
/**
* Returns the number of threads in this thread pool.
* @return
*/
size_t Size() {
return threads_.size();
}
/**
* Do a job that doesn't require wait.
*
* @param func
*/
void DoJob(std::function <void (void) > func) {
// Place a job on the queue and unblock a thread
std::unique_lock <std::mutex> l(lock_);
jobs_.emplace(std::move(func));
condVar_.notify_one();
}
/**
* Do a job that requires wait. The wait variable is incremented.
* @param func
* @param wait
*/
void DoJob(std::function <void (void) > func, WaitVariable& wait) {
wait.wait++;
// Place a job on the queue and unblock a thread
std::unique_lock <std::mutex> l(lock_);
std::function<void(void) > f = WaitableFunction(func, wait.wait);
jobs_.emplace(std::move(f));
condVar_.notify_one();
}
/**
* For each job.
*
* @param first
* @param elements
* @param function
*/
template<class InputIt, typename Function>
void ForEach(InputIt first, const size_t& elements, const Function &function) {
if (!elements)return;
size_t max_threads = std::max(1ul, (unsigned long int)std::min((elements), this->thread_count));
size_t inc = elements / max_threads;
auto siter = first;
size_t end;
size_t start;
for (int t = 0; t < max_threads; t++) {
start = inc*t;
siter = first + start;
t == (max_threads - 1) ? end = elements : end = inc * (t + 1);
auto eiter = first + end;
std::function<void(void) > func = ForEachFunctor<InputIt, Function>(siter, eiter, std::move(function)); //std::bind(std::for_each<InputIt, Function>, siter, eiter, std::move(function));
std::unique_lock <std::mutex> l(lock_);
jobs_.emplace(
std::move(func)
);
condVar_.notify_one();
}
}
/**
* For each job with wait.
*
* @param first
* @param elements
* @param function
* @param wait
*/
template<class InputIt, typename Function>
void ForEach(InputIt first, const size_t& elements, const Function &function, WaitVariable& wait) {
if (!elements)return;
size_t max_threads = std::max(1ul, (unsigned long int)std::min((elements), this->thread_count));
wait.wait += max_threads;
size_t inc = elements / max_threads;
auto siter = first;
size_t end;
size_t start;
for (int t = 0; t < max_threads; t++) {
start = inc*t;
siter = first + start;
t == (max_threads - 1) ? end = elements : end = inc * (t + 1);
auto eiter = first + end;
std::function<void(void) > func = ForEachFunctor<InputIt, Function>(siter, eiter, (function));
std::function<void(void) > f = WaitableFunction(std::move(func), std::move(wait.wait));
std::unique_lock <std::mutex> l(lock_);
jobs_.emplace(
std::move(f)
);
condVar_.notify_one();
}
}
/**
* Wait for this wait variable to signal completion.
*
* @param wait
*/
void Wait(WaitVariable& wait) {
while (wait.wait > 0) {
}
}
protected:
void threadEntry(int i) {
std::function <void (void) > job_;
while (1) {
{
std::unique_lock <std::mutex> l(lock_);
while (!shutdown_ && jobs_.empty())
condVar_.wait(l);
if (jobs_.empty()) {
// No jobs to do and we are shutting down
return;
}
job_ = std::move(jobs_.front());
jobs_.pop();
}
// Do the job without holding any locks
std::function <void (void) > task = job_;
task();
}
}
std::mutex lock_;
std::condition_variable condVar_;
bool shutdown_;
bool started_;
size_t thread_count;
std::queue <std::function <void (void) > > jobs_;
std::vector <std::thread> threads_;
};
#ifdef ATL_USE_THREAD_POOL
//global thread pool
atl::ThreadPool thread_pool_g;
#endif
}
#endif /* THREADPOOL_HPP */