thread/tutorial/once.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/thread.hpp>

#include <boost/thread/once.hpp>

#include <cassert>

int value=0;

boost::once_flag once = BOOST_ONCE_INIT;

void init()

{

++value;

}

void thread_proc()

{

boost::call_once(&init, once);

}

int main(int argc, char* argv[])

{

boost::thread_group threads;

for (int i=0; i<5; ++i)

threads.create_thread(&thread_proc);

threads.join_all();

assert(value == 1);

}

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