/ 
System-Command-1.02
River stage two • 8 direct dependents • 90 total dependents
/ System::Command::Reaper

NAME

System::Command::Reaper - Reap processes started by System::Command

SYNOPSIS

This class is used for internal purposes. Move along, nothing to see here.

DESCRIPTION

The System::Command objects delegate the reaping of child processes to System::Command::Reaper objects. This allows a user to create a System::Command and discard it after having obtained one or more references to its handles connected to the child process.

The typical use case looks like this:

my $fh = System::Command->new( @cmd )->stdout();

The child process is reaped either through a direct call to close() or when the command object and all its handles have been destroyed, thus avoiding zombies (which would be reaped by the system at the end of the main program).

This is possible thanks to the following reference graph:

    System::Command
     |   |   |  ^|
     v   v   v  !|
    in out err  !|
    ^|  ^|  ^|  !|
    !v  !v  !v  !v
System::Command::Reaper

Legend: | normal ref ! weak ref

The System::Command::Reaper object acts as a sentinel, that takes care of reaping the child process when the original System::Command and its filehandles have been destroyed (or when System::Command close() method is being called).

METHODS

System::Command::Reaper supports the following methods:

new( $command )

Create a new System::Command::Reaper object attached to the System::Command object passed as a parameter.

reap()

Close all the opened filehandles of the main System::Command object, reaps the child process, and updates the main object with the status information of the child process.

DESTROY calls reap() when the sentinel is being destroyed.

AUTHOR

Philippe Bruhat (BooK), <book at cpan.org>

ACKNOWLEDGEMENTS

This scheme owes a lot to Vincent Pit who on #perlfr provided the general idea (use a proxy to delay object destruction and child process reaping) with code examples, which I then adapted to my needs.

COPYRIGHT

Copyright 2010-2011 Philippe Bruhat (BooK), all rights reserved.

LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.