NAME

IPC::PidStat - Process ID existence test

SYNOPSIS

  use IPC::PidStat;

  my $exister = new IPC::PidStat(
    port=>1234,
    );
  $exister->pid_request(host=>'foo', pid=>$pid)
  while (1) {  # Poll receiving callbacks
     my ($epid, $eexists, $ehostname) = $exister->recv_stat();
     print "Pid $epid ",($eexists?'exists':'dead'),"\n" if $ehostname;
  }

DESCRIPTION

IPC::PidStat allows remote requests to be made to the pidstatd, to determine if a PID is running on the daemon's machine.

PidStat uses UDP, and as such results are fast but may be unreliable. Furthermore, the pidstatd may not even be running on the remote machine, so responses should never be required before an application program makes progress.

METHODS

new ([parameter=>value ...]);

Creates a new object for later use. See the PARAMETERS section.

pid_request (host=>$host, pid=>$pid);

Sends a request to the specified host's server to see if the specified PID exists.

The optional parameters return_exist=>0, return_doesnt=>0 and return_unknown=>0 improve performance by suppressing return messages if the specified pid exists, doesn't exist, or has unknown state respectively. Pidstatd versions before 1.480 ignore this flag, so the return code from recv_stat should not assume the undesired return types will be suppressed.

pid_request_recv (host=>$host, pid=>$pid);

Calls pid_request and returns the recv_stat reply. If the response fails to return in one second, it is retried up to 5 times, then undef is returned.

recv_stat()

Blocks waiting for any return from the server. Returns undef if none is found, or a 2 element array with the PID and existence flag. Generally this would be called inside a IO::Poll loop.

STATIC METHODS

local_pid_doesnt_exist(<pid>)

Static call, not a method call. Return 0 if a pid exists, 1 if not. Return undef if it can't be determined.

local_pid_exists(<pid>)

Static call, not a method call. Return 1 if a pid exists, 0 if not. Return undef if it can't be determined.

PARAMETERS

port

The port number (INET) of the pidstatd server. Defaults to 'pidstatd' looked up via /etc/services, else 1752.

DISTRIBUTION

The latest version is available from CPAN and from http://www.veripool.org/.

Copyright 2002-2013 by Wilson Snyder. This package is free software; you can redistribute it and/or modify it under the terms of either the GNU Lesser General Public License Version 3 or the Perl Artistic License Version 2.0.

AUTHORS

Wilson Snyder <wsnyder@wsnyder.org>

SEE ALSO

IPC::Locker, pidstat, pidstatd, pidwatch

IPC::PidStat::Server