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pool.hpp
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#ifndef OSMIUM_THREAD_POOL_HPP
#define OSMIUM_THREAD_POOL_HPP
/*
This file is part of Osmium (https://osmcode.org/libosmium).
Copyright 2013-2025 Jochen Topf <jochen@topf.org> and others (see README).
Boost Software License - Version 1.0 - August 17th, 2003
Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:
The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/
#include <osmium/thread/function_wrapper.hpp>
#include <osmium/thread/queue.hpp>
#include <osmium/thread/util.hpp>
#include <osmium/util/config.hpp>
#include <cstddef>
#include <future>
#include <thread>
#include <type_traits>
#include <utility>
#include <vector>
namespace osmium {
namespace thread {
namespace detail {
// Maximum number of allowed pool threads (just to keep the user
// from setting something silly).
enum {
max_pool_threads = 32
};
inline int get_pool_size(int num_threads, int user_setting, unsigned hardware_concurrency) {
if (num_threads == 0) {
num_threads = user_setting ? user_setting : -2;
}
if (num_threads < 0) {
num_threads += static_cast<int>(hardware_concurrency);
}
if (num_threads < 1) {
num_threads = 1;
} else if (num_threads > max_pool_threads) {
num_threads = max_pool_threads;
}
return num_threads;
}
inline std::size_t get_work_queue_size() noexcept {
return osmium::config::get_max_queue_size("WORK", 10);
}
} // namespace detail
class Pool {
class thread_joiner {
std::vector<std::thread>& m_threads;
public:
explicit thread_joiner(std::vector<std::thread>& threads) :
m_threads(threads) {
}
thread_joiner(const thread_joiner&) = delete;
thread_joiner& operator=(const thread_joiner&) = delete;
thread_joiner(thread_joiner&&) = delete;
thread_joiner& operator=(thread_joiner&&) = delete;
~thread_joiner() {
for (auto& thread : m_threads) {
if (thread.joinable()) {
thread.join();
}
}
}
}; // class thread_joiner
osmium::thread::Queue<function_wrapper> m_work_queue;
std::vector<std::thread> m_threads;
thread_joiner m_joiner;
int m_num_threads;
void worker_thread() {
osmium::thread::set_thread_name("_osmium_worker");
while (true) {
function_wrapper task;
m_work_queue.wait_and_pop(task);
if (task && task()) {
// The called tasks returns true only when the
// worker thread should shut down.
return;
}
}
}
public:
enum {
default_num_threads = 0
};
enum {
default_queue_size = 0U
};
explicit Pool(int num_threads = default_num_threads, std::size_t max_queue_size = default_queue_size) :
m_work_queue(max_queue_size > 0 ? max_queue_size : detail::get_work_queue_size(), "work"),
m_joiner(m_threads),
m_num_threads(detail::get_pool_size(num_threads, osmium::config::get_pool_threads(), std::thread::hardware_concurrency())) {
try {
for (int i = 0; i < m_num_threads; ++i) {
m_threads.emplace_back(&Pool::worker_thread, this);
}
} catch (...) {
shutdown_all_workers();
throw;
}
}
static Pool& default_instance() {
static Pool pool{};
return pool;
}
void shutdown_all_workers() {
for (int i = 0; i < m_num_threads; ++i) {
// The special function wrapper makes a worker shut down.
m_work_queue.push(function_wrapper{0});
}
}
Pool(const Pool&) = delete;
Pool& operator=(const Pool&) = delete;
Pool(Pool&&) = delete;
Pool& operator=(Pool&&) = delete;
~Pool() {
shutdown_all_workers();
}
int num_threads() const noexcept {
return m_num_threads;
}
std::size_t queue_size() const {
return m_work_queue.size();
}
bool queue_empty() const {
return m_work_queue.empty();
}
#if defined(__cpp_lib_is_invocable) && __cpp_lib_is_invocable >= 201703
// std::result_of is deprecated in C++17 and removed in C++20,
// so we use std::invoke_result_t.
template <typename TFunction>
using submit_func_result_type = std::invoke_result_t<TFunction>;
#else
// For C++11 and C++14
template <typename TFunction>
using submit_func_result_type = std::result_of_t<TFunction()>;
#endif
template <typename TFunction>
std::future<submit_func_result_type<TFunction>> submit(TFunction&& func) {
std::packaged_task<submit_func_result_type<TFunction>()> task{std::forward<TFunction>(func)};
std::future<submit_func_result_type<TFunction>> future_result{task.get_future()};
m_work_queue.push(std::move(task));
return future_result;
}
}; // class Pool
} // namespace thread
} // namespace osmium
#endif // OSMIUM_THREAD_POOL_HPP
osmium::thread::Pool::thread_joiner
Definition pool.hpp:96
osmium::thread::Pool::thread_joiner::thread_joiner
thread_joiner(std::vector< std::thread > &threads)
Definition pool.hpp:102
osmium::thread::Pool::thread_joiner::thread_joiner
thread_joiner(thread_joiner &&)=delete
osmium::thread::Pool::thread_joiner::m_threads
std::vector< std::thread > & m_threads
Definition pool.hpp:98
osmium::thread::Pool::thread_joiner::thread_joiner
thread_joiner(const thread_joiner &)=delete
osmium::thread::Pool::thread_joiner::operator=
thread_joiner & operator=(thread_joiner &&)=delete
osmium::thread::Pool::thread_joiner::operator=
thread_joiner & operator=(const thread_joiner &)=delete
osmium::thread::Pool::thread_joiner::~thread_joiner
~thread_joiner()
Definition pool.hpp:112
osmium::thread::Pool::submit_func_result_type
std::result_of_t< TFunction()> submit_func_result_type
Definition pool.hpp:228
osmium::thread::Pool::shutdown_all_workers
void shutdown_all_workers()
Definition pool.hpp:191
osmium::thread::Pool::m_threads
std::vector< std::thread > m_threads
Definition pool.hpp:123
osmium::thread::Pool::~Pool
~Pool()
Definition pool.hpp:204
osmium::thread::Pool::Pool
Pool(int num_threads=default_num_threads, std::size_t max_queue_size=default_queue_size)
Definition pool.hpp:165
osmium::thread::Pool::Pool
Pool(Pool &&)=delete
osmium::thread::Pool::queue_size
std::size_t queue_size() const
Definition pool.hpp:212
osmium::thread::Pool::default_queue_size
@ default_queue_size
Definition pool.hpp:147
osmium::thread::Pool::submit
std::future< submit_func_result_type< TFunction > > submit(TFunction &&func)
Definition pool.hpp:232
osmium::thread::Pool::default_instance
static Pool & default_instance()
Definition pool.hpp:186
osmium::thread::Pool::Pool
Pool(const Pool &)=delete
osmium::thread::Pool::operator=
Pool & operator=(Pool &&)=delete
osmium::thread::Pool::m_work_queue
osmium::thread::Queue< function_wrapper > m_work_queue
Definition pool.hpp:122
osmium::thread::Pool::default_num_threads
@ default_num_threads
Definition pool.hpp:143
osmium::thread::Pool::m_joiner
thread_joiner m_joiner
Definition pool.hpp:124
osmium::thread::Pool::queue_empty
bool queue_empty() const
Definition pool.hpp:216
osmium::thread::Pool::worker_thread
void worker_thread()
Definition pool.hpp:127
osmium::thread::Pool::m_num_threads
int m_num_threads
Definition pool.hpp:125
osmium::thread::Pool::operator=
Pool & operator=(const Pool &)=delete
osmium::thread::Pool::num_threads
int num_threads() const noexcept
Definition pool.hpp:208
osmium::thread::Queue
Definition queue.hpp:57
osmium::thread::function_wrapper
Definition function_wrapper.hpp:48
config.hpp
function_wrapper.hpp
detail
Definition attr.hpp:342
osmium::config
Definition config.hpp:60
osmium::config::get_max_queue_size
std::size_t get_max_queue_size(const char *queue_name, const std::size_t default_value) noexcept
Definition config.hpp:83
osmium::thread
Threading-related low-level code.
Definition function_wrapper.hpp:41
osmium::thread::set_thread_name
void set_thread_name(const char *name) noexcept
Definition util.hpp:78
osmium
Namespace for everything in the Osmium library.
Definition assembler.hpp:53
std
Definition location.hpp:555
queue.hpp
util.hpp