+++ /dev/null
-/* A thread pool (C++ version). */
-
-/* Copyright (c) 2004-2021 The SimGrid Team. All rights reserved. */
-
-/* This program is free software; you can redistribute it and/or modify it
- * under the terms of the license (GNU LGPL) which comes with this package. */
-
-#ifndef XBT_PARMAP_HPP
-#define XBT_PARMAP_HPP
-
-#include "src/internal_config.h" // HAVE_FUTEX_H
-#include "src/kernel/context/Context.hpp"
-#include "src/simix/smx_private.hpp" /* simix_global */
-
-#include <boost/optional.hpp>
-#include <condition_variable>
-#include <functional>
-#include <mutex>
-#include <thread>
-
-#if HAVE_FUTEX_H
-#include <linux/futex.h>
-#include <sys/syscall.h>
-#endif
-
-#if HAVE_PTHREAD_NP_H
-#include <pthread_np.h>
-#endif
-
-XBT_LOG_EXTERNAL_CATEGORY(xbt_parmap);
-
-namespace simgrid {
-namespace xbt {
-
-/** @addtogroup XBT_parmap
- * @ingroup XBT_misc
- * @brief Parallel map class
- * @{
- */
-template <typename T> class Parmap {
-public:
- Parmap(unsigned num_workers, e_xbt_parmap_mode_t mode);
- Parmap(const Parmap&) = delete;
- Parmap& operator=(const Parmap&) = delete;
- ~Parmap();
- void apply(std::function<void(T)>&& fun, const std::vector<T>& data);
- boost::optional<T> next();
-
-private:
- /**
- * @brief Thread data transmission structure
- */
- class ThreadData {
- public:
- ThreadData(Parmap<T>& parmap, int id) : parmap(parmap), worker_id(id) {}
- Parmap<T>& parmap;
- int worker_id;
- };
-
- /**
- * @brief Synchronization object (different specializations).
- */
- class Synchro {
- public:
- explicit Synchro(Parmap<T>& parmap) : parmap(parmap) {}
- virtual ~Synchro() = default;
- /**
- * @brief Wakes all workers and waits for them to finish the tasks.
- *
- * This function is called by the controller thread.
- */
- virtual void master_signal() = 0;
- /**
- * @brief Starts the parmap: waits for all workers to be ready and returns.
- *
- * This function is called by the controller thread.
- */
- virtual void master_wait() = 0;
- /**
- * @brief Ends the parmap: wakes the controller thread when all workers terminate.
- *
- * This function is called by all worker threads when they end (not including the controller).
- */
- virtual void worker_signal() = 0;
- /**
- * @brief Waits for some work to process.
- *
- * This function is called by each worker thread (not including the controller) when it has no more work to do.
- *
- * @param round the expected round number
- */
- virtual void worker_wait(unsigned) = 0;
-
- Parmap<T>& parmap;
- };
-
- class PosixSynchro : public Synchro {
- public:
- explicit PosixSynchro(Parmap<T>& parmap) : Synchro(parmap) {}
- void master_signal() override;
- void master_wait() override;
- void worker_signal() override;
- void worker_wait(unsigned round) override;
-
- private:
- std::condition_variable ready_cond;
- std::mutex ready_mutex;
- std::condition_variable done_cond;
- std::mutex done_mutex;
- };
-
-#if HAVE_FUTEX_H
- class FutexSynchro : public Synchro {
- public:
- explicit FutexSynchro(Parmap<T>& parmap) : Synchro(parmap) {}
- void master_signal() override;
- void master_wait() override;
- void worker_signal() override;
- void worker_wait(unsigned) override;
-
- private:
- static void futex_wait(std::atomic_uint* uaddr, unsigned val);
- static void futex_wake(std::atomic_uint* uaddr, unsigned val);
- };
-#endif
-
- class BusyWaitSynchro : public Synchro {
- public:
- explicit BusyWaitSynchro(Parmap<T>& parmap) : Synchro(parmap) {}
- void master_signal() override;
- void master_wait() override;
- void worker_signal() override;
- void worker_wait(unsigned) override;
- };
-
- static void worker_main(ThreadData* data);
- Synchro* new_synchro(e_xbt_parmap_mode_t mode);
- void work();
-
- bool destroying = false; /**< is the parmap being destroyed? */
- std::atomic_uint work_round{0}; /**< index of the current round */
- std::vector<std::thread*> workers; /**< worker thread handlers */
- unsigned num_workers; /**< total number of worker threads including the controller */
- Synchro* synchro; /**< synchronization object */
-
- std::atomic_uint thread_counter{0}; /**< number of workers that have done the work */
- std::function<void(T)> fun; /**< function to run in parallel on each element of data */
- const std::vector<T>* data = nullptr; /**< parameters to pass to fun in parallel */
- std::atomic_uint index{0}; /**< index of the next element of data to pick */
-};
-
-/**
- * @brief Creates a parallel map object
- * @param num_workers number of worker threads to create
- * @param mode how to synchronize the worker threads
- */
-template <typename T> Parmap<T>::Parmap(unsigned num_workers, e_xbt_parmap_mode_t mode)
-{
- XBT_CDEBUG(xbt_parmap, "Create new parmap (%u workers)", num_workers);
-
- /* Initialize the thread pool data structure */
- this->workers.resize(num_workers);
- this->num_workers = num_workers;
- this->synchro = new_synchro(mode);
-
- /* Create the pool of worker threads (the caller of apply() will be worker[0]) */
- this->workers[0] = nullptr;
-
- for (unsigned i = 1; i < num_workers; i++) {
- auto* data = new ThreadData(*this, i);
- this->workers[i] = new std::thread(worker_main, data);
-
- /* Bind the worker to a core if possible */
-#if HAVE_PTHREAD_SETAFFINITY
-#if HAVE_PTHREAD_NP_H /* FreeBSD ? */
- cpuset_t cpuset;
- size_t size = sizeof(cpuset_t);
-#else /* Linux ? */
- cpu_set_t cpuset;
- size_t size = sizeof(cpu_set_t);
-#endif
- pthread_t pthread = this->workers[i]->native_handle();
- int core_bind = (i - 1) % std::thread::hardware_concurrency();
- CPU_ZERO(&cpuset);
- CPU_SET(core_bind, &cpuset);
- pthread_setaffinity_np(pthread, size, &cpuset);
-#endif
- }
-}
-
-/**
- * @brief Destroys a parmap
- */
-template <typename T> Parmap<T>::~Parmap()
-{
- destroying = true;
- synchro->master_signal();
-
- for (unsigned i = 1; i < num_workers; i++) {
- workers[i]->join();
- delete workers[i];
- }
- delete synchro;
-}
-
-/**
- * @brief Applies a list of tasks in parallel.
- * @param fun the function to call in parallel
- * @param data each element of this vector will be passed as an argument to fun
- */
-template <typename T> void Parmap<T>::apply(std::function<void(T)>&& fun, const std::vector<T>& data)
-{
- /* Assign resources to worker threads (we are maestro here)*/
- this->fun = std::move(fun);
- this->data = &data;
- this->index = 0;
- this->synchro->master_signal(); // maestro runs futex_wake to wake all the minions (the working threads)
- this->work(); // maestro works with its minions
- this->synchro->master_wait(); // When there is no more work to do, then maestro waits for the last minion to stop
- XBT_CDEBUG(xbt_parmap, "Job done"); // ... and proceeds
-}
-
-/**
- * @brief Returns a next task to process.
- *
- * Worker threads call this function to get more work.
- *
- * @return the next task to process, or throws a std::out_of_range exception if there is no more work
- */
-template <typename T> boost::optional<T> Parmap<T>::next()
-{
- unsigned index = this->index.fetch_add(1, std::memory_order_relaxed);
- if (index < this->data->size())
- return (*this->data)[index];
- else
- return boost::none;
-}
-
-/**
- * @brief Main work loop: applies fun to elements in turn.
- */
-template <typename T> void Parmap<T>::work()
-{
- unsigned length = this->data->size();
- unsigned index = this->index.fetch_add(1, std::memory_order_relaxed);
- while (index < length) {
- this->fun((*this->data)[index]);
- index = this->index.fetch_add(1, std::memory_order_relaxed);
- }
-}
-
-/**
- * Get a synchronization object for given mode.
- * @param mode the synchronization mode
- */
-template <typename T> typename Parmap<T>::Synchro* Parmap<T>::new_synchro(e_xbt_parmap_mode_t mode)
-{
- if (mode == XBT_PARMAP_DEFAULT) {
-#if HAVE_FUTEX_H
- mode = XBT_PARMAP_FUTEX;
-#else
- mode = XBT_PARMAP_POSIX;
-#endif
- }
- Synchro* res;
- switch (mode) {
- case XBT_PARMAP_POSIX:
- res = new PosixSynchro(*this);
- break;
- case XBT_PARMAP_FUTEX:
-#if HAVE_FUTEX_H
- res = new FutexSynchro(*this);
-#else
- xbt_die("Futex is not available on this OS.");
-#endif
- break;
- case XBT_PARMAP_BUSY_WAIT:
- res = new BusyWaitSynchro(*this);
- break;
- default:
- THROW_IMPOSSIBLE;
- }
- return res;
-}
-
-/** @brief Main function of a worker thread */
-template <typename T> void Parmap<T>::worker_main(ThreadData* data)
-{
- Parmap<T>& parmap = data->parmap;
- unsigned round = 0;
- kernel::context::Context* context = simix_global->context_factory->create_context(std::function<void()>(), nullptr);
- kernel::context::Context::set_current(context);
-
- XBT_CDEBUG(xbt_parmap, "New worker thread created");
-
- /* Worker's main loop */
- while (true) {
- round++; // New scheduling round
- parmap.synchro->worker_wait(round);
- if (parmap.destroying)
- break;
-
- XBT_CDEBUG(xbt_parmap, "Worker %d got a job", data->worker_id);
- parmap.work();
- parmap.synchro->worker_signal();
- XBT_CDEBUG(xbt_parmap, "Worker %d has finished", data->worker_id);
- }
- /* We are destroying the parmap */
- delete context;
- delete data;
-}
-
-template <typename T> void Parmap<T>::PosixSynchro::master_signal()
-{
- std::unique_lock<std::mutex> lk(ready_mutex);
- this->parmap.thread_counter = 1;
- this->parmap.work_round++;
- /* wake all workers */
- ready_cond.notify_all();
-}
-
-template <typename T> void Parmap<T>::PosixSynchro::master_wait()
-{
- std::unique_lock<std::mutex> lk(done_mutex);
- /* wait for all workers to be ready */
- done_cond.wait(lk, [this]() { return this->parmap.thread_counter >= this->parmap.num_workers; });
-}
-
-template <typename T> void Parmap<T>::PosixSynchro::worker_signal()
-{
- std::unique_lock<std::mutex> lk(done_mutex);
- this->parmap.thread_counter++;
- if (this->parmap.thread_counter == this->parmap.num_workers) {
- /* all workers have finished, wake the controller */
- done_cond.notify_one();
- }
-}
-
-template <typename T> void Parmap<T>::PosixSynchro::worker_wait(unsigned round)
-{
- std::unique_lock<std::mutex> lk(ready_mutex);
- /* wait for more work */
- ready_cond.wait(lk, [this, round]() { return this->parmap.work_round == round; });
-}
-
-#if HAVE_FUTEX_H
-template <typename T> inline void Parmap<T>::FutexSynchro::futex_wait(std::atomic_uint* uaddr, unsigned val)
-{
- XBT_CVERB(xbt_parmap, "Waiting on futex %p", uaddr);
- syscall(SYS_futex, uaddr, FUTEX_WAIT_PRIVATE, val, nullptr, nullptr, 0);
-}
-
-template <typename T> inline void Parmap<T>::FutexSynchro::futex_wake(std::atomic_uint* uaddr, unsigned val)
-{
- XBT_CVERB(xbt_parmap, "Waking futex %p", uaddr);
- syscall(SYS_futex, uaddr, FUTEX_WAKE_PRIVATE, val, nullptr, nullptr, 0);
-}
-
-template <typename T> void Parmap<T>::FutexSynchro::master_signal()
-{
- this->parmap.thread_counter.store(1);
- this->parmap.work_round.fetch_add(1);
- /* wake all workers */
- futex_wake(&this->parmap.work_round, std::numeric_limits<int>::max());
-}
-
-template <typename T> void Parmap<T>::FutexSynchro::master_wait()
-{
- unsigned count = this->parmap.thread_counter.load();
- while (count < this->parmap.num_workers) {
- /* wait for all workers to be ready */
- futex_wait(&this->parmap.thread_counter, count);
- count = this->parmap.thread_counter.load();
- }
-}
-
-template <typename T> void Parmap<T>::FutexSynchro::worker_signal()
-{
- unsigned count = this->parmap.thread_counter.fetch_add(1) + 1;
- if (count == this->parmap.num_workers) {
- /* all workers have finished, wake the controller */
- futex_wake(&this->parmap.thread_counter, std::numeric_limits<int>::max());
- }
-}
-
-template <typename T> void Parmap<T>::FutexSynchro::worker_wait(unsigned round)
-{
- unsigned work_round = this->parmap.work_round.load();
- /* wait for more work */
- while (work_round != round) {
- futex_wait(&this->parmap.work_round, work_round);
- work_round = this->parmap.work_round.load();
- }
-}
-#endif
-
-template <typename T> void Parmap<T>::BusyWaitSynchro::master_signal()
-{
- this->parmap.thread_counter.store(1);
- this->parmap.work_round.fetch_add(1);
-}
-
-template <typename T> void Parmap<T>::BusyWaitSynchro::master_wait()
-{
- while (this->parmap.thread_counter.load() < this->parmap.num_workers) {
- std::this_thread::yield();
- }
-}
-
-template <typename T> void Parmap<T>::BusyWaitSynchro::worker_signal()
-{
- this->parmap.thread_counter.fetch_add(1);
-}
-
-template <typename T> void Parmap<T>::BusyWaitSynchro::worker_wait(unsigned round)
-{
- /* wait for more work */
- while (this->parmap.work_round.load() != round) {
- std::this_thread::yield();
- }
-}
-
-/** @} */
-}
-}
-
-#endif
