in reply to Alternative for Select for pipes in Windows?

One way: 

use threads       qw( async );
use Thread::Queue qw( );

my $q = Threads::Queue->new();

async { 
   while (<STDIN>) {
      $q->enqueue(...);
   }
   $q->enqueue(...);
};

async { 
   while (<$fr_child_pipe>) {
      $q->enqueue(...);
   }
   $q->enqueue(...);
};

while (defined(my $item = $q->dequeue())) {
   ...
}

[download]

Thread::Queue

Another solution would be to create socket pairs (which are selectable), and have threads that simply convert the pipes into sockets. That would allow you to use existing code. 

use threads           qw( async );
use Win32::Socketpair qw( winsocketpair );

my ($fr_parent_sock, $fr_parent_sock_writer) = winsocketpair();
async {
   print($fr_parent_sock_writer $_) while <STDIN>;
   close($fr_parent_sock_writer);
};

my ($fr_child_sock, $fr_child_sock_writer) = winsocketpair();
async {
   print($fr_child_sock_writer $_) while <$fr_child_pipe>;
   close($fr_child_sock_writer);
};

... select $fr_parent_sock and $fr_child_sock ...

[download]

(You could avoid the second thread by tying the socket directly to the child's STDOUT.)

Win32::Socketpair

Update: Fleshed out the code for the second solution, and added a link to the module.

Replies are listed 'Best First'.
Re^2: Alternative for Select for pipes in Windows?
by matematiko (Novice) on Nov 06, 2010 at 03:58 UTC

    Unfortunately, the installation of Win32-Socketpair fails in both: ActivePerl 5.10 and Strawberry 5.12. The make Test fails... I will try to force the installation in Starwberry anyways....In ActivePerl it proved to make perl hang when trying to run the script.

[reply]

      Replace the winsocket pair sub with this: 

      sub winsocketpair {
    my $proto = getprotobyname('tcp');
    my $first = 1;

    for (1..5) {

        if ($first) {
            undef $first;
        }
        else {
            carp "winsocketpair failed: $!, retrying"
        }

        socket(my $listener, AF_INET, SOCK_STREAM, $proto)
            or return ();

        socket(my $server, AF_INET, SOCK_STREAM, $proto)
            or return ();

        socket(my $client, AF_INET, SOCK_STREAM, $proto)
            or return ();

        my $true = 1;
        ioctl($client, 0x8004667e, \$true );

        my $addr = sockaddr_in(0, INADDR_LOOPBACK);
        bind($listener, $addr) or return ();
        listen($listener, 1) or return ();
        $addr = getsockname($listener);

        connect($client, $addr) 
            or $! ==  10035 or $! == EINPROGRESS 
            or next;
        my $peer = accept($server, $listener) or next;

        my $false = 0;
        ioctl($client, 0x8004667e, \$false );

        if ($peer eq getsockname($client)) {
            return ($server, $client);
        }

    }
    return ();
}

      [download]

      And ignore make test--the tests seem to be broken. They sometime pass and sometimes fail?

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
[reply]
[d/l]

        I can not tell if the original suggestions work, because after careful consideration, I have decided to approach my needs from a different and way more easier perspective.

        What I'd like to say thou, is that the modification to the subroutine winsocketpair suggested by BrowserUk (see above), stopped making my perl interpreter to hang up.So, whoever comes behind me looking for a solution that requieres Win32::Socketpair, be aware of this needed modification.

        Additionally, in my particular case, "use threads qw( async );" complains that "async" is an unknow import, even thou I verified it is there in threads.pm, go figure.

        Many thanks to ikegami, BrowserUk and everyone else for the help provided.

        Best regards

        matematiko

[reply]
Re^2: Alternative for Select for pipes in Windows?
by BrowserUk (Patriarch) on Nov 06, 2010 at 01:39 UTC
    One way ...

    How do you combine a select loop with a blocking dequeue?

[reply]
      The dequeue loop replaces the select loop.
[reply]

        Ah! Okay.

[reply]

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