void swap( promise< R > & l, promise< R > & r) noexcept {
l.swap( r);
}
task< R > t( f, ctx1);
callable ca( fn, boost::move( prom), ctx2);
shared_ptr< thread > thrd( new thread( ca), detail::joiner() );
ctx1.reset( thrd);
return t;
}
template< typename Fn >
task< typename result_of< Fn() >::result_type >
operator()( BOOST_RV_REF( Fn) fn)
{
typedef typename result_of< Fn() >::result_type R;
BOOST_ASSERT( ! this_task::runs_in_pool() );
promise< R > prom;
unique_future< R > f( prom.get_future() );
context ctx1, ctx2;
task< R > t( f, ctx1);
callable ca( boost::move( fn), boost::move( prom), ctx2);
shared_ptr< thread > thrd( new thread( ca), detail::joiner() );
ctx1.reset( thrd);
return t;
}
};
}}
#ifdef BOOST_HAS_ABI_HEADERS
# include BOOST_ABI_SUFFIX
#endif
void swap(promise<T>& lhs, promise<T>& rhs)
{
lhs.swap(rhs);
}
void foo(promise<unsigned int> p)
{
sleep(1);
p.set_value(42);
}
void work2(promise<int> prom) {
printf("this is thread2\n"); //C++11的线程输出cout没有boost的好，还是会出现乱序，所以采用printf，有点不爽
flag=2;
prom.set_value(10); //线程2设置了共享状态后，线程1才会被唤醒
printf("thread2 exit\n");
}