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pip/lib/main/thread/piexecutor.h

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3.9 KiB
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/*
PIP - Platform Independent Primitives
Stephan Fomenko
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef PIEXECUTOR_H
#define PIEXECUTOR_H
#include "piblockingdequeue.h"
#include <atomic>
template <typename Thread_, typename Dequeue_>
class PIThreadPoolExecutorTemplate {
public:
NO_COPY_CLASS(PIThreadPoolExecutorTemplate)
explicit PIThreadPoolExecutorTemplate(size_t corePoolSize = 1) : isShutdown_(false) { makePool(corePoolSize); }
virtual ~PIThreadPoolExecutorTemplate() {
shutdownNow();
while (threadPool.size() > 0) delete threadPool.take_back();
}
void execute(const std::function<void()> & runnable) {
if (!isShutdown_) taskQueue.offer(runnable);
}
void shutdown() {
isShutdown_ = true;
}
void shutdownNow() {
isShutdown_ = true;
for (size_t i = 0; i < threadPool.size(); ++i) threadPool[i]->stop();
}
bool isShutdown() const {
return isShutdown_;
}
bool awaitTermination(int timeoutMs) {
PITimeMeasurer measurer;
for (size_t i = 0; i < threadPool.size(); ++i) {
int dif = timeoutMs - (int)measurer.elapsed_m();
if (dif < 0) return false;
if (!threadPool[i]->waitForFinish(dif)) return false;
}
return true;
}
protected:
std::atomic_bool isShutdown_;
Dequeue_ taskQueue;
PIVector<Thread_*> threadPool;
template<typename Function>
PIThreadPoolExecutorTemplate(size_t corePoolSize, Function onBeforeStart) : isShutdown_(false) {
makePool(corePoolSize, onBeforeStart);
}
void makePool(size_t corePoolSize, std::function<void(Thread_*)> onBeforeStart = [](Thread_*){}) {
for (size_t i = 0; i < corePoolSize; ++i) {
auto* thread = new Thread_([&, i](){
auto runnable = taskQueue.poll(100);
if (runnable) {
runnable();
}
if (isShutdown_ && taskQueue.size() == 0) threadPool[i]->stop();
});
threadPool.push_back(thread);
onBeforeStart(thread);
thread->start();
}
}
};
typedef PIThreadPoolExecutorTemplate<PIThread, PIBlockingDequeue<std::function<void()> > > PIThreadPoolExecutor;
#ifdef DOXYGEN
/**
* @brief Thread pools address two different problems: they usually provide improved performance when executing large
* numbers of asynchronous tasks, due to reduced per-task invocation overhead, and they provide a means of bounding and
* managing the resources, including threads, consumed when executing a collection of tasks.
*
* TODO adapt documentation to template
*/
class PIThreadPoolExecutor {
public:
explicit PIThreadPoolExecutor(size_t corePoolSize);
virtual ~PIThreadPoolExecutor();
/**
* @brief Executes the given task sometime in the future. The task execute in an existing pooled thread. If the task
* cannot be submitted for execution, either because this executor has been shutdown or because its capacity has been
* reached.
*
* @param runnable not empty function for thread pool execution
*/
void execute(const std::function<void()> & runnable);
/**
* @brief Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be
* accepted. Invocation has no additional effect if already shut down. This method does not wait for previously
* submitted tasks to complete execution. Use awaitTermination to do that.
*/
void shutdown();
void shutdownNow();
bool isShutdown() const;
bool awaitTermination(int timeoutMs);
};
#endif //DOXYGEN
#endif //PIEXECUTOR_H