The Create command is used to create a new condition variable.  It returns a positive integer that is used as an identifier.

The Create command takes no arguments.

Once a condition variable is no longer needed it should be destroyed by calling the Destroy function.

For more information on using condition variables, see the Condition Variable help page.

Producer := proc( m, cp, cc, max, mindiff )
    global tab, e;
    local i,j,n;

    Threads[Mutex][Lock]( m );
    j := 0;

    tab[ "maxjob" ] := mindiff;
    tab[ "curjob" ] := 1;

    for j from 1 to mindiff
    do
        tab[ j ] := 2*j;
    end do;

    Threads[ConditionVariable][Signal]( cp );

    n := false;
    while ( e )
    do
        j := tab[ "maxjob" ];
        if ( j - tab[ "curjob" ] > mindiff/2 ) then
            n := true;
            Threads[ConditionVariable][Wait]( cp, m );
        end if;

        for i from j to tab[ "curjob" ] + mindiff
        do
            tab[ i ] := 2*i;
        end do;

        tab[ "maxjob" ] := tab[ "curjob" ] + mindiff;

        if ( n ) then
            Threads[ConditionVariable][Broadcast]( cc );
            n := false;
        end if;

    end do;
    Threads[Mutex][Unlock]( m );

end proc:
Consumer := proc( m, cp, cc, max )
    global tab, e;
    local n, i, j, num;

    num := 0;
    Threads[Mutex][Lock]( m );
    while ( num < max )
    do
        while ( tab[ "curjob" ] = tab[ "maxjob" ] )
        do
            Threads[ConditionVariable][Signal]( cp );
            Threads[ConditionVariable][Wait]( cc, m );
        end do;

        n := tab[ "curjob" ];
        j := tab[ n ];
        tab[ "curjob" ] := n + 1;

        Threads[Mutex][Unlock]( m );

        j := add( i, i=1..j );
        num := num+1;

        Threads[Mutex][Lock]( m );
        tab[ n ] := j;
    end do;
    Threads[Mutex][Unlock]( m );
end proc:

$\mathrm{tab}≔\mathrm{table}\left(\right)\&colon;$

$m≔\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Create}\right]\left(\right)$

$m≔2$

$\mathrm{cc}≔\mathrm{Threads}\left[\mathrm{ConditionVariable}\right]\left[\mathrm{Create}\right]\left(\right)$

$\mathrm{cc}≔1$

$\mathrm{cp}≔\mathrm{Threads}\left[\mathrm{ConditionVariable}\right]\left[\mathrm{Create}\right]\left(\right)$

$\mathrm{cp}≔2$

$e≔\mathrm{true}\&colon;$

$\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Lock}\right]\left(m\right)$

$\mathrm{id1}≔\mathrm{Threads}\left[\mathrm{Create}\right]\left(\mathrm{Producer}\left(m\&comma;\mathrm{cp}\&comma;\mathrm{cc}\&comma;31\&comma;10\right)\right)$

$\mathrm{id1}≔1$

$\mathrm{Threads}\left[\mathrm{ConditionVariable}\right]\left[\mathrm{Wait}\right]\left(\mathrm{cp}\&comma;m\right)$

$\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Unlock}\right]\left(m\right)$

$\mathrm{id2}≔\left[\mathrm{seq}\left(\mathrm{Threads}\left[\mathrm{Create}\right]\left(\mathrm{Consumer}\left(m\&comma;\mathrm{cp}\&comma;\mathrm{cc}\&comma;100\right)\right)\&comma;i=1..5\right)\right]$

$\mathrm{id2}≔\left[2\&comma;3\&comma;4\&comma;5\&comma;6\right]$

$\mathrm{Threads}\left[\mathrm{Wait}\right]\left(\mathrm{op}\left(\mathrm{id2}\right)\right)$

$\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Lock}\right]\left(m\right)$

$e≔\mathrm{false}\&colon;$

$\mathrm{Threads}\left[\mathrm{ConditionVariable}\right]\left[\mathrm{Signal}\right]\left(\mathrm{cp}\right)$

$\mathrm{Threads}\left[\mathrm{Mutex}\right]\left[\mathrm{Unlock}\right]\left(m\right)$

$\mathrm{Threads}\left[\mathrm{Wait}\right]\left(\mathrm{id1}\right)$

$\mathrm{print}\left(\mathrm{tab}\left[''curjob''\right]\right)$

$501$

$\mathrm{print}\left(\mathrm{tab}\left[233\right]\right)$

$108811$

$\mathrm{print}\left(\mathrm{add}\left(i\&comma;i=1..2\cdot 233\right)\right)$

$108811$