Thread::Detach - fix broken threads->detach on Windows

Thread-Detach documentation

Contained in the Thread-Detach distribution.

Index

NAME
SYNOPSIS
DESCRIPTION
THEORY OF OPERATION
REQUIRED MODULES
TODO
AUTHOR
COPYRIGHT
SEE ALSO

Code Index:

package Thread::Detach
__END__
EOF

NAME

Thread::Detach - fix broken threads->detach on Windows

SYNOPSIS

    use Thread::Detach ();   # apply the fix

DESCRIPTION

                  *** A note of CAUTION ***

 This module only functions on Perl versions 5.8.0 and later.
 And then only when threads are enabled with -Dusethreads.  It
 is of no use with any version of Perl before 5.8.0 or without
 threads enabled.

                  *************************

Perl versions before 5.8.4 don't support the "detach" method of the threads module on Windows!. This module provides a temporary fix for this problem if it is running under Windows and with a version of Perl that has the problem. In any other situation, this module does nothing.

THEORY OF OPERATION

All of this happens on Windows only and if the version of the Perl executor is known to have the problem.

This module replaces the standard threads-detach> method with another subroutine that just sets an internal flag to mark the thread as "detached".

Futhermore it uses Thread::Exit to register a subroutine that is executed after each thread is finished executing: this subroutine marks the thread as "done" if the thread was marked as "detached" earlier.

Lastly, it uses Thread::Exit to register a subroutine that is executed at the beginning of each thread: this subroutine reaps all the threads that were marked "done", hence providing the necessary cleanup.

REQUIRED MODULES

 Thread::Exit (0.08)

TODO

Maybe the reliance on Thread::Exit should be replaced by some more direct magic. Using Thread::Exit made this module all the more simple, though.

Examples should be added.

AUTHOR

Elizabeth Mattijsen, <liz@dijkmat.nl>.

Please report bugs to <perlbugs@dijkmat.nl>.

COPYRIGHT

Copyright (c) 2004 Elizabeth Mattijsen <liz@dijkmat.nl>. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

threads, Thread::Exit.

Thread-Detach documentation

Contained in the Thread-Detach distribution.

package Thread::Detach;

# Make sure we have version info for this module

$VERSION = '0.01';

# Make sure we do this before anything else
#  If we're on a Windows system, or we fake it to be a Win32 system
#   If we have a crippled detach
#    Make sure we do everything by the book from now on
#    Make sure we can do threads
#    Make sure we can do shared variables
#    Create the hash that keeps detached information
#    Create the hash that keeps threads that are done information

BEGIN {
    if ($^O =~ m#Win32# or $ENV{THIS_IS_WIN32}) {
        if ($] < 5.008004) {  # not sure what to do about blead...
            use strict;
            require threads;
            require threads::shared;
            my %detached : shared;
            my %done : shared;

#    Get Thread::Exit
#    Set up the necessary Thread::Exit capabilities
#     Make sure that all subsequent threads get the same

            require Thread::Exit;
            Thread::Exit->import( 
             inherit => 1,

#     Begin each thread with
#      Lock the detached threads hash
#      For each detached thread
#       Reap the thread if it was detached and is now done

             begin => sub {
                 lock( %done );
                 while (my $tid = each %done) {
                     threads->object( $tid )->join if delete $done{$tid};
                 }
             },

#     End this thread with
#      Mark this thread as done

             end => sub { $done{threads->tid} = 1 }
            );

#    Allow for dirty tricks
#    Replace the detach method with one that just sets the detached flag

            no warnings 'redefine';
            *threads::detach = sub { $detached{threads->tid} = 1 };
        }
    }
} #BEGIN

# Satisfy -require-

1;

#---------------------------------------------------------------------------

__END__