void operator()( tbb::blocked_range<size_t>& range ) const {
     typename M::scoped_lock lock2;
     for( size_t i=range.begin(); i!=range.end(); ++i ) {
         if( i&1 ) {
             typename M::scoped_lock lock1(my_mutex, true) ;
             if( lock1.downgrade_to_reader()==false )
                 REPORT("ERROR for %s: downgrade should always succeed\n", name);
         } else {
             lock2.acquire( my_mutex, false );
             if( lock2.upgrade_to_writer()==false )
                 REPORT("ERROR for %s: upgrade should always succeed\n", name);
             lock2.release();
         }
     }
 }
void TestTryAcquireReader_OneThread( const char * mutex_name ) {
    M tested_mutex;
    typename M::scoped_lock lock1;
    if( M::is_rw_mutex ) {
        if( lock1.try_acquire(tested_mutex, false) )
            lock1.release();
        else
            REPORT("ERROR for %s: try_acquire failed though it should not\n", mutex_name);
        {
            typename M::scoped_lock lock2(tested_mutex, false);
            if( lock1.try_acquire(tested_mutex) )
                REPORT("ERROR for %s: try_acquire succeeded though it should not\n", mutex_name);
            lock2.release();
            lock2.acquire(tested_mutex, true);
            if( lock1.try_acquire(tested_mutex, false) )
                REPORT("ERROR for %s: try_acquire succeeded though it should not\n", mutex_name);
        }
        if( lock1.try_acquire(tested_mutex, false) )
            lock1.release();
        else
            REPORT("ERROR for %s: try_acquire failed though it should not\n", mutex_name);
    }
}