OpenEuphoria

Re: Non Blocking Support

• Posted by Jonas Temple <jtemple at yhti.net> Feb 15, 2007
• 615 views

CChris wrote:
> > <a href="http://www.innovativesys.net">http://www.innovativesys.net</a>
> 
> Did you plainly insert a task_yield() call at line 33376 or is it
> anything subtler?
> 
> CChris

Actually, looking at what I did, I insert this into two places.  And, of course,
I can't remember why I did the first!  :)

The first is in eventLoop() procedure:

-- Gather some entropy for the random integer routine
        w32Seed = remainder((w32Seed * peek4u(msg+16))
                            + 1 + peek4u(msg+20) * peek4u(msg+24),
                            #FFFFFFFF)

        w32Proc( xTranslateMessage, { msg } )
        w32Proc( xDispatchMessage, { msg } )
        task_yield()

The second is in doEvents():

global procedure doEvents(integer id)
    atom msg, hWnd

    if vWinMainState != kStarted then
    return
    end if

    if id = 0 then
    hWnd = 0
    else
    if validId(id) = w32False then
        return
    end if
    hWnd = getHandle(id)
    end if

    -- Allocate a message buffer
    msg = w32acquire_mem(0, SIZEOF_MSG)

    if w32Func( xPeekMessage, { msg, hWnd, 0, 0, PM_REMOVE } ) then
        w32Proc( xTranslateMessage, { msg } )
        w32Proc( xDispatchMessage, { msg } )
        task_yield()
    end if
    w32release_mem(msg)

end procedure

And to be honest, I haven't noticed any performance depreciation using
task_yield() in these routines.

Sorry I can't give you the exact line numbers, my copy of Win32lib has some
"tweaks".

Just in case you're curious, here's how I modified my code (which was not a
lot!)

* included tdll.e (of course)
* changed my open_dll() call to open_tdll()
* For functions that I wanted non-blocking, I replaced the define_c_func() calls
with define_t_func() calls.  In my case the only change was replacing the "c" in
define_c_func with "t".  The parameters to the define_t_func were identical to
define_c_func.  I then replaced the c_func() calls with t_func().  Again, the
only change was the "c" to "t".  I even left all the rest of the C functions with
the standard define_c_func/c_func Euphoria routines and they worked fine!

In my main program I coded a routine to kick off the task and then wait until it
was complete:

task = task_create(routine_id("execute_task"), {invoked_from, ctl_index})
    task_schedule(task,1)
    -- Process message loop until end of task
    while find(task, task_list()) do
        doEvents(0)
        task_yield()                    
    end while

Carefully placed task_yield() calls, both in the main program and in Win32Lib
seemed to keep things in order.

I did have to rework a HUGE portion of my code to eliminate my over-use of
globals.  But that was my issue, not tdll.  I just had to ensure that one task
would not interfere with the values in another task.

I was having some problems at first before I figured out how to place calls to
task_yield() and Daniel suggested his APC DLL which he said was better than TDLL
but I could not figure out how to use the library and never got a response back
from him on a request for documentation.  I just found the TDLL calls easier to
understand.

HTH,

Jonas Temple
http://www.innovativesys.net