thread/example/mutex.cpp at develop · boostorg/thread · GitHub

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// William E. Kempf

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <boost/thread/mutex.hpp>

#include <boost/thread/thread.hpp>

#include <iostream>

boost::mutex g_io_mutex; // The iostreams are not guaranteed to be thread-safe!

class counter

{

public:

counter() : count(0) { }

int increment() {

boost::unique_lock<boost::mutex> scoped_lock(mutex);

return ++count;

}

private:

boost::mutex mutex;

int count;

};

counter g_counter;

void change_count()

{

int i = g_counter.increment();

boost::unique_lock<boost::mutex> scoped_lock(g_io_mutex);

std::cout << "count == " << i << std::endl;

}

int main(int, char*[])

{

const int num_threads = 4;

boost::thread_group thrds;

for (int i=0; i < num_threads; ++i)

thrds.create_thread(&change_count);

thrds.join_all();

return 0;

}

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