Method internal_pop_if_present

benchmarks/tbb/concurrent_queue.cpp:468–490

}

bool concurrent_queue_base_v3::internal_pop_if_present( void* dst ) {
    concurrent_queue_rep& r = *my_rep;
    ticket k;
    do {
        k = r.head_counter;
        for(;;) {
            if( (ptrdiff_t)(r.tail_counter-k)<=0 ) {
                // Queue is empty
                return false;
            }
            // Queue had item with ticket k when we looked.  Attempt to get that item.
            ticket tk=k;
            k = r.head_counter.compare_and_swap( tk+1, tk );
            if( k==tk )
                break;
            // Another thread snatched the item, retry.
        }
    } while( !r.choose( k ).pop( dst, k, *this ) );

    r.slots_avail.notify( predicate_leq(k) );

    return true;
}

bool concurrent_queue_base_v3::internal_push_if_not_full( const void* src ) {
    return internal_insert_if_not_full( src, copy );