Wow.. that makes everything so much clearer. That is exactly what I have
been trying to do. Instead I spent countless hours writing a queue program
only to find out it is not async. Something like this should be included in
the examples.
-Ryan
----- Original Message -----
From: "Al Tobey" <[EMAIL PROTECTED]>
To: "Ryan White" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Thursday, March 14, 2002 7:55 PM
Subject: Re: Multithreaded Forking. Wheel::Run
> I think Wheel Run is one of the best parts of POE for what I do!
> Especially useful can be the coderef executions. With this example, you
> should be able to do any of the following:
>
> # in some routine in my session ...
> $kernel->yield( 'run_something_async', "/usr/sbin/sendmail" );
> # or
> $kernel->yield( 'run_something_async', sub { print "I'm running in child
> process $$ ! } );
> # or
> $kernel->yield( 'run_something_async' [ '/usr/local/bin/my_program',
> '-a', $argument_1, '-b', $argument2 ] );
>
> sub run_something_async {
> my( $heap, $kernel, $what ) = @_[ HEAP, KERNEL, ARG0 ];
>
> # this isn't necessary if you put the event in inline_states
> # at POE::Session creation time
> $kernel->state('my_input_event', \&handle_input_event );
> $kernel->state('whine_about_error', \&error_handler );
>
> # create a new wheel, storing a reference to it in my heap
> $heap->{run_wheel} = POE::Wheel::Run->new(
> Program => $what,
> ErrorEvent => 'whine_about_error',
> StdoutEvent => 'my_input_event',
> StderrEvent => 'my_input_event', # or its own handler
> Filter => POE::Filter::Line->new()
> );
>
> # send SOME DATA to the child process's STDIN
> $heap->{run_wheel}->put( "SOME DATA" );
> }
>
> # this is input from the child process
> sub handle_input_event {
> my( $heap, $buffer, $wheel_id ) = @_[ HEAP, ARG0, ARG1 ];
> print "I got this: '$buffer' from wheel $wheel_id\n";
>
> # Send SOME MORE DATA to the child's standard in
> $heap->{run_wheel}->put( "SOME MORE DATA" );
> }
>
> sub error_handler {
> my($heap,$buffer,$error,$wheel_id) = @_[HEAP,ARG0,ARG1,ARG2];
> # do something ...
> }
>
> -Al Tobey
> Unix Administrator
>
> On Thu, 2002-03-14 at 17:01, Ryan White wrote:
> > I have tried a number of different things. Immediately after I sent my
post
> > I noticed the missing LF. I have added that and I still get no return
value.
> > Inline comments...
> >
> > From: "Rocco Caputo" <[EMAIL PROTECTED]>
> > > On Thu, Mar 14, 2002 at 01:45:28AM -0800, Ryan White wrote:
> > > > I am looking for an example using Wheel::Run within a child process.
I
> > need
> > > > to know how to read the output of a Wheel after using put.
> > [..]
> > > >
> > > > sub child_start {
> > > > my ($kernel, $session, $parent, $heap, $email) = @_[KERNEL,
SESSION,
> > > > SENDER, HEAP, ARG0];
> > > >
> > > > # Remember the parent.
> > > > $heap->{parent} = $parent;
> > > >
> > > > warn "Child ", $session->ID, " will validate $email.\n";
> > > >
> > > > # Check the passed email address.
> > > >
> > > > my $program = [ "./check_addr.pl" ];
> > > > my $wheel = POE::Wheel::Run->new(
> > > > Program => $program,
> > > > StdoutEvent => &stdout, # Event to emit with child
> > stdout
> >
> > I have also tried using 'stdout' but it never calls the stdout method..
> > Where should the stdout method be defined. I had the following in my
creat
> > child function:
> > sub create_a_child {
> > my $email = shift;
> > POE::Session->create
> > ( inline_states =>
> > { _start => \&child_start,
> > _stop => \&child_stop,
> > stdout => \&child_stdout,
> > },
> > args => [$email],
> > );
> > }
> >
> > Is this not the correct method? When I used this code it would never
call te
> > child_stdout method. Which session does it need to be in?
> >
> > [..]
> > > > }
> > >
> > > I see two problems here:
> > >
> > > First, you are not storing the new POE::Wheel::Run instance in $heap,
> > > so it's destructing as soon as child_start() returns.
> >
> > I didn't see anything in the POE::Wheel::Run docs about putting the
instance
> > in $heap. What is the convention for that
> >
> > > Second, your StdoutEvent should be an event name, not a code
> > > reference.
> > >
> > > [...]
> > >
> > > > And the check_addr.pl program simply looks like this
> > > > #!/usr/bin/perl
> > > > my $email = <>;
> > > > chomp($email);
> > > > print 1;
> > > >
> > > > It doesn't seem to ever be able to read the data that check_addr
sends
> > back.
> > > > Should I be doing this another way?
> >
> > Ok the script now looks like this
> > #!/usr/bin/perl
> > use strict;
> > $| = 1;
> > my $email = <>;
> > chomp($email);
> > print "1\n";
> >
> > I over simplified the script so that it only test the wheel processes. I
am
> > attaching the scripts so that you can see if I'm missing something
easier.
> > What I think it happening (not sure if it make sense) is the child it
> > calling the wheel but has nothing else to do so it then exits before
getting
> > stdout.
> >
>
>
>
>
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