131 lines
3.3 KiB
C++
131 lines
3.3 KiB
C++
/*
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PIP - Platform Independent Primitives
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Thread pool loop
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Ivan Pelipenko peri4ko@yandex.ru
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "pithreadpoolloop.h"
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#include "pisysteminfo.h"
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#include "pithread.h"
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/*! \class PIThreadPoolLoop
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* @brief Thread class
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* \details This class allow you parallelize loop.
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*
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* \section PIThreadPoolLoop_sec0 Usage
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* This class designed to replace "for(;;)" statement in very simple way.
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* In constructor several threads created, then by "setFunction()" method
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* you should pass body of your loop, and then call "start()" or "exec()".
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* Every thread take loop counter and execute your function until all
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* counter range is passed.
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*
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* Example:
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\code{.cpp}
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PIVector<int> data(10, [](int i)->int{return i;});
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piCout << data; // {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
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PIThreadPoolLoop pool;
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pool.exec(0, data.size(), [&](int i){ // parallel analogue "for (int i = 0; i < data.size(); i++)"
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data[i] = data[i] + 10;
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});
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piCout << data; // {10, 11, 12, 13, 14, 15, 16, 17, 18, 19}
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\endcode
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*
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* Equivalent to:
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\code{.cpp}
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PIVector<int> data(10, [](int i)->int{return i;});
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piCout << data; // {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
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pool.setFunction([&](int i){
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data[i] = data[i] + 10;
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});
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pool.exec(0, data.size());
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piCout << data; // {10, 11, 12, 13, 14, 15, 16, 17, 18, 19}
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\endcode
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*
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* \section PIThreadPoolLoop_sec1 Important
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* Due to multithreading it`s very important to protect output data of loop body, use mutex.
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* Also remember that execution order is undefined and you shouldn`t use global variables in
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* your function. Use local variables and lambda capture.
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*
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*/
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PIThreadPoolLoop::PIThreadPoolLoop(int thread_cnt) {
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if (thread_cnt <= 0)
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thread_cnt = piMaxi(1, PISystemInfo::instance()->processorsCount);
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piForTimes (thread_cnt) {
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auto * t = new PIThread();
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threads << t;
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}
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//piCout << "PIThreadPoolLoop" << proc_cnt << "threads";
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}
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PIThreadPoolLoop::~PIThreadPoolLoop() {
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for (auto * t: threads) {
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t->stop(false);
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if (!t->waitForFinish(100))
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t->terminate();
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delete t;
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}
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}
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void PIThreadPoolLoop::setFunction(std::function<void (int)> f) {
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func = f;
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}
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void PIThreadPoolLoop::start(int index_start, int index_count) {
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counter = index_start;
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int end = index_start + index_count;
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for (auto * t: threads)
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t->start([this,end,t](){
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while (1) {
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int cc = counter.fetch_add(1);
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if (cc >= end) {
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t->stop(false);
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return;
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}
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func(cc);
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}
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});
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}
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void PIThreadPoolLoop::exec(int index_start, int index_count) {
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start(index_start, index_count);
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wait();
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}
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void PIThreadPoolLoop::exec(int index_start, int index_count, std::function<void (int)> f) {
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setFunction(f);
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exec(index_start, index_count);
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}
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void PIThreadPoolLoop::wait() {
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for (auto * t: threads)
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t->waitForFinish();
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}
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