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这个问题是跟进的this问题。总之，这是动机 - 从原来的问题的评论有点C/P的：升压ASIO旗语般的解决方案
我希望能够发布关于多线程（CalcFib功能）工作一组，然后将作业时已经结束，另一基团的作业（CalcFib2功能），还对多个线程。这个周期循环多次（这里是二），所以我认为做的最好的事情就是创建boost::asio::io_service，并在循环的开始创建线程，所以我没有创建&销毁线程每次循环开始时间/结束。
我已经创建了两个int乏错误信号_ **命名，并在上面提到的功能递减他们。等待工作组完成的代码如下所示为while。至少在我看来，解决方案是有效的。
是使用while真的很长的路要走等待？我错过了什么？有一个更好的方法吗？
我的代码如下所示：
#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/thread.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/bind.hpp>
#include <iostream>
boost::mutex global_stream_lock;
int semaphore_fib = 0;
int semaphore_fib2 = 0;
void WorkerThread(boost::shared_ptr<boost::asio::io_service> io_service)
{
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] Thread Start" << std::endl;
global_stream_lock.unlock();
io_service->run();
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] Thread Finish" << std::endl;
global_stream_lock.unlock();
}
size_t fib(size_t n)
{
if (n <= 1)
{
return n;
}
boost::this_thread::sleep(boost::posix_time::milliseconds(1000));
return fib(n - 1) + fib(n - 2);
}
void CalcFib(size_t n)
{
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] Now calculating fib(" << n << ") " << std::endl;
global_stream_lock.unlock();
size_t f = fib(n);
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] fib(" << n << ") = " << f << std::endl;
semaphore_fib = semaphore_fib-1;
global_stream_lock.unlock();
}
void CalcFib2(size_t n)
{
global_stream_lock.lock();
std::cout << "\t\t[" << boost::this_thread::get_id()
<< "] Now calculating fib2(" << n << ") " << std::endl;
global_stream_lock.unlock();
size_t f = fib(n);
global_stream_lock.lock();
std::cout << "\t\t[" << boost::this_thread::get_id()
<< "] fib2(" << n << ") = " << f << std::endl;
semaphore_fib2=semaphore_fib2-1;
global_stream_lock.unlock();
}
int main(int argc, char * argv[])
{
boost::shared_ptr<boost::asio::io_service> io_service(
new boost::asio::io_service
);
boost::shared_ptr<boost::asio::io_service::work> work(
new boost::asio::io_service::work(*io_service)
);
boost::asio::io_service::strand strand(*io_service);
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] The program will exit when all work has finished."
<< std::endl;
global_stream_lock.unlock();
boost::thread_group worker_threads;
for(int x = 0; x < 2; ++x)
{
worker_threads.create_thread(
boost::bind(&WorkerThread, io_service)
);
}
for(int loop_no=0; loop_no<2; ++loop_no)
{
semaphore_fib=3;
io_service->post(boost::bind(CalcFib, 5));
io_service->post(boost::bind(CalcFib, 4));
io_service->post(boost::bind(CalcFib, 3));
while(semaphore_fib>0)
{
// waiting
}
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] ******* CalcFib group finished ********" << std::endl;
global_stream_lock.unlock();
semaphore_fib2=3;
io_service->post(boost::bind(CalcFib2, 2));
io_service->post(boost::bind(CalcFib2, 1));
io_service->post(boost::bind(CalcFib2, 1));
while(semaphore_fib2>0)
{
// waiting
}
global_stream_lock.lock();
std::cout << "[" << boost::this_thread::get_id()
<< "] ******* CalcFib2 group finished ********" << std::endl;
global_stream_lock.unlock();
}
work.reset();
worker_threads.join_all();
return 0;
}