From: Chris Hulan <chris.hulan@...>
Date: 2013-01-16T13:41:45+09:00
Subject: Re: Ruby Threads and Shoes

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Did you see this?
http://stackoverflow.com/questions/958662/shoes-and-heavy-operation-in-separate-thread

It uses an .append method, maybe that has built in smarts to allow the GUI
to update
Tried to have a look but th docs are as funky as _why's manual ;)

BTW, having a rescue that just re-raises is redundant


On Tue, Jan 15, 2013 at 9:26 PM, Steve L. <lists@ruby-forum.com> wrote:

> TL;DR: How do you pass execution from within a PTY.spawn block back to
> the calling thread long enough to allow the caller to update GUI
> elements?
>
>
> I have a situation that I doubt is particularly unique, but Google
> hasn't been a lot of help, so I thought I'd try you guys as a last
> resort.  So...to jump right in to it:
>
> I've built a front-end GUI for running Cucumber tests using Shoes. All
> the app really does is take user selections from the GUI and use them to
> string together a command line that I'm then passing in to it's own
> process through a PTY.spawn call.
>
> The point of using the PTY library was to be able to grab the STDOUT
> stream of the child process in real time, as per this stack-overflow:
>
> http://stackoverflow.com/questions/1154846/continuously-read-from-stdout-of-external-process-in-ruby
>
> When testing the bare-bones of my code in a terminal, it works
> beautifully...the external process is spawned, and I'm able to pull the
> stdout of the external process and see it in real time.  However, my
> situation has the added layer of a GUI.  Despite the fact that I'm sure
> that the IO pipes are flowing properly, I'm still not getting an update
> on my GUI until after the child process terminates.
>
> I've done enough reading to understand that this has something to do
> with the way Ruby handles thread priority, but I'm having a little bit
> of trouble groking a potential solution to my problem.  In short, what
> I'm looking for is a way to 'give back' execution to my GUI process long
> enough to let it update itself from the STDOUT output of the child
> process.
>
> I hope I was clear enough, but feel free to ask clarifying questions,
> and I appreciate any insight!
>
> My code, for reference:
>
> def spawn_command_in_pty(cmd, env, outwindow)
>       env.each do |k, v|
>         ENV[k] = v
>       end
>       PTY.spawn(cmd) do |r, w, pid|
>         begin
>           r.each{|line| outwindow.text = outwindow.text + line }
>         rescue Errno::EIO => e
>           raise e
>         end
>       end
>
>     end
>
> Steve
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

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<div dir=3D"ltr">Did you see this?=A0<a href=3D"http://stackoverflow.com/qu=
estions/958662/shoes-and-heavy-operation-in-separate-thread">http://stackov=
erflow.com/questions/958662/shoes-and-heavy-operation-in-separate-thread</a=
><div>

<br></div><div style>It uses an .append method, maybe that has built in sma=
rts to=A0allow=A0the GUI to update</div><div style>Tried to have a look but=
 th docs are as funky as _why&#39;s manual ;)</div><div style><br></div><di=
v style>

BTW, having a rescue that just re-raises is redundant</div></div><div class=
=3D"gmail_extra"><br><br><div class=3D"gmail_quote">On Tue, Jan 15, 2013 at=
 9:26 PM, Steve L. <span dir=3D"ltr">&lt;<a href=3D"mailto:lists@ruby-forum=
.com" target=3D"_blank">lists@ruby-forum.com</a>&gt;</span> wrote:<br>

<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">TL;DR: How do you pass execution from within=
 a PTY.spawn block back to<br>
the calling thread long enough to allow the caller to update GUI<br>
elements?<br>
<br>
<br>
I have a situation that I doubt is particularly unique, but Google<br>
hasn&#39;t been a lot of help, so I thought I&#39;d try you guys as a last<=
br>
resort. =A0So...to jump right in to it:<br>
<br>
I&#39;ve built a front-end GUI for running Cucumber tests using Shoes. All<=
br>
the app really does is take user selections from the GUI and use them to<br=
>
string together a command line that I&#39;m then passing in to it&#39;s own=
<br>
process through a PTY.spawn call.<br>
<br>
The point of using the PTY library was to be able to grab the STDOUT<br>
stream of the child process in real time, as per this stack-overflow:<br>
<a href=3D"http://stackoverflow.com/questions/1154846/continuously-read-fro=
m-stdout-of-external-process-in-ruby" target=3D"_blank">http://stackoverflo=
w.com/questions/1154846/continuously-read-from-stdout-of-external-process-i=
n-ruby</a><br>


<br>
When testing the bare-bones of my code in a terminal, it works<br>
beautifully...the external process is spawned, and I&#39;m able to pull the=
<br>
stdout of the external process and see it in real time. =A0However, my<br>
situation has the added layer of a GUI. =A0Despite the fact that I&#39;m su=
re<br>
that the IO pipes are flowing properly, I&#39;m still not getting an update=
<br>
on my GUI until after the child process terminates.<br>
<br>
I&#39;ve done enough reading to understand that this has something to do<br=
>
with the way Ruby handles thread priority, but I&#39;m having a little bit<=
br>
of trouble groking a potential solution to my problem. =A0In short, what<br=
>
I&#39;m looking for is a way to &#39;give back&#39; execution to my GUI pro=
cess long<br>
enough to let it update itself from the STDOUT output of the child<br>
process.<br>
<br>
I hope I was clear enough, but feel free to ask clarifying questions,<br>
and I appreciate any insight!<br>
<br>
My code, for reference:<br>
<br>
def spawn_command_in_pty(cmd, env, outwindow)<br>
=A0 =A0 =A0 env.each do |k, v|<br>
=A0 =A0 =A0 =A0 ENV[k] =3D v<br>
=A0 =A0 =A0 end<br>
=A0 =A0 =A0 PTY.spawn(cmd) do |r, w, pid|<br>
=A0 =A0 =A0 =A0 begin<br>
=A0 =A0 =A0 =A0 =A0 r.each{|line| outwindow.text =3D outwindow.text + line =
}<br>
=A0 =A0 =A0 =A0 rescue Errno::EIO =3D&gt; e<br>
=A0 =A0 =A0 =A0 =A0 raise e<br>
=A0 =A0 =A0 =A0 end<br>
=A0 =A0 =A0 end<br>
<br>
=A0 =A0 end<br>
<span class=3D"HOEnZb"><font color=3D"#888888"><br>
Steve<br>
<br>
--<br>
Posted via <a href=3D"http://www.ruby-forum.com/" target=3D"_blank">http://=
www.ruby-forum.com/</a>.<br>
<br>
</font></span></blockquote></div><br></div>

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