Re: [boost] [thread] RFC standard proposed mutex, read-write mutex, condition

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-08-21 17:14:05

Howard Hinnant wrote:

> Did I make more sense this time?  I often complain when people use too
> much English and not enough C++ in their arguments, and then I find
> myself being guilty of the same thing. :-)

Hmmm. Maybe I need to heed this advice as well.

template<class M> class condition
{
public:

    explicit condition( M * pm = 0 )
    {
        __cndcheck_init( this, pm );
    }

    wait( Lock & lk )
    {
        __cndcheck_wait( this, lk.mutex() );
        // ...
    }
};

// Release mode (duh)

void __cndcheck_init( void * pc, void * pm )
{
}

void __cndcheck_wait( void * pc, void * pm2 )
{
}

// Debug mode

map< void*, void* > __cndcheck_state; // must be synchronized

void __cndcheck_init( void * pc, void * pm )
{
    __cndcheck_state[ pc ] = pm;
}

void __cndcheck_wait( void * pc, void * pm2 )
{
    assert( __cndcheck_state.count( pc ) );
    assert( __cndcheck_state[ pc ] == 0 || __cndcheck_state[ pc ] == pm2 );
}

// Checked release mode

struct __cndcheck_item // must be atomic
{
    void * pc_;
    void * pm_;
};

__cndcheck_item __cndcheck_state[ 17041 ];

void __cndcheck_init( void * pc, void * pm )
{
    __cndcheck_state[ (size_t)pc % 17041 ] = { pc, pm }; // atomic store
}

void __cndcheck_wait( void * pc, void * pm2 )
{
    __cndcheck_item it = __cndcheck_state[ (size_t)pc % 17041 ]; // atomic 
load

    if( it.pc_ == pc )
    {
        assert( it.pm_ == 0 || it.pm_ == pm2 );
    }
}

Or something along those lines. :-)