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#include "threadpool.h"
/**
* Stolen from some guy.
*/
// Constructor.
ThreadPool::ThreadPool(int threads) :
terminate(false),
stopped(false)
{
// Create number of required threads and add them to the thread pool vector.
for(int i = 0; i < threads; i++)
{
threadPool.emplace_back(thread(&ThreadPool::Invoke, this));
}
}
void ThreadPool::Enqueue(function<void()> f)
{
// Scope based locking.
{
// Put unique lock on task mutex.
unique_lock<mutex> lock(tasksMutex);
// Push task into queue.
tasks.push(f);
}
// Wake up one thread.
condition.notify_one();
}
void ThreadPool::Invoke() {
function<void()> task;
while(true)
{
// Scope based locking.
{
// Put unique lock on task mutex.
unique_lock<mutex> lock(tasksMutex);
// Wait until queue is not empty or termination signal is sent.
condition.wait(lock, [this]{ return !tasks.empty() || terminate; });
// If termination signal received and queue is empty then exit else continue clearing the queue.
if (terminate && tasks.empty())
{
return;
}
// Get next task in the queue.
task = tasks.front();
// Remove it from the queue.
tasks.pop();
}
// Execute the task.
task();
}
}
void ThreadPool::ShutDown()
{
// Scope based locking.
{
// Put unique lock on task mutex.
unique_lock<mutex> lock(tasksMutex);
// Set termination flag to true.
terminate = true;
}
// Wake up all threads.
condition.notify_all();
// Join all threads.
for(thread &thread : threadPool)
{
thread.join();
}
// Empty workers vector.
threadPool.empty();
// Indicate that the pool has been shut down.
stopped = true;
}
// Destructor.
ThreadPool::~ThreadPool()
{
if (!stopped)
{
ShutDown();
}
}
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