From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-10-13T22:21:54+09:00
Subject: Re: threading in win32

On Thu, 13 Oct 2005, Shea Martin wrote:

> I have a TK app.  On a button presses, I call a windows copy command which 
> can take up to 10 minutes to run. In order to not freeze the GUI, so that the 
> gui can be doing other stuff, I launch the command in a thread.
>
> Running the command with system, does not let me get the output of the 
> command, thought it does not lock gui up at all.  So, I tried two other 
> versions.  I had the most success with version 3. I believe version 3 is what 
> the TkTextIo example uses in ruby 1.8.3. See below.
>
> # callback for tk button press
> def buttonPress
>  Thread.new do
>    Button.state( "disable" );
>    runCommand( "copy /Y bigfile1 dest1" );
>    runCommand( "copy /Y bigfile2 dest2" );
>    runCommand( "copy /Y bigfile3 dest3" );
>    Button.state( "active" );
>  end
> end
>
> #version 1
> def runCommand( cmd )
>  system( cmd )
> end
>
> #version 2
> def runCommand( cmd )
>  IO.popen( cmd ) do | cmd_out |
>    cmd_out.each_line do | line |
>      MyTextArea.insert( 'end', line, 'normal' )
>    end
>  end
> end
>
> #version 3
> def runCommand( cmd )
>  cmd_pipe = IO.popen( cmd )
>  t = Thread.new { cmd_pipe.each{ | line | addText( line ) } }
>  t.join
> end
>
> Only version 1 allows teh gui to remain responsive.  Unfortunately it does 
> not capture the output of the copy command.  I would like to something with a 
> fork, though win32 ruby does not seem to support it.
>
> Any ideas.

i think reading from pipes should not block the whole process in windows, at
least this works fine on my win system:

   Thread::abort_on_exception = true
   t = Thread::new{ IO::popen("tree c:").read }
   (4 << 2).times{ p 42; sleep 0.42 }
   puts t.value

does it work on yours?

perhaps you need something like

   #version 4
   def runCommand( cmd )
     Thread::new do
       IO::popen("#{ cmd 2>&1 }"){|pipe| pipe.each{|line| addText line}}
     end
   end

which is to say spawn the thread and let it go.  you'll need to prevent two
commands being run at once too...

hth.

-a
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