NAME¶

MCE::Signal - Temporary directory creation/cleanup and signal handling

VERSION¶

This document describes MCE::Signal version 1.898

SYNOPSIS¶

 ## Creates tmp_dir under $ENV{TEMP} if defined, otherwise /tmp.
 use MCE::Signal;
 ## Attempts to create tmp_dir under /dev/shm if writable.
 use MCE::Signal qw( -use_dev_shm );
 ## Keeps tmp_dir after the script terminates.
 use MCE::Signal qw( -keep_tmp_dir );
 use MCE::Signal qw( -use_dev_shm -keep_tmp_dir );
 ## MCE loads MCE::Signal by default when not present.
 ## Therefore, load MCE::Signal first for options to take effect.
 use MCE::Signal qw( -keep_tmp_dir -use_dev_shm );
 use MCE;

DESCRIPTION¶

This package configures $SIG{ ABRT, HUP, INT, PIPE, QUIT, and TERM } to point to stop_and_exit and creates a temporary directory. The main process and workers receiving said signals call stop_and_exit, which signals all workers to terminate, removes the temporary directory unless -keep_tmp_dir is specified, and terminates itself.

The location of the temp directory resides under $ENV{TEMP} if defined, otherwise /dev/shm if writeable and -use_dev_shm is specified, or /tmp. On Windows, the temp directory is made under $ENV{TEMP}/Perl-MCE/.

As of MCE 1.405, MCE::Signal no longer calls setpgrp by default. Pass the -setpgrp option to MCE::Signal to call setpgrp.

 ## Running MCE through Daemon::Control requires setpgrp to be called
 ## for MCE releases 1.511 and below.
 use MCE::Signal qw(-setpgrp);   ## Not necessary for MCE 1.512 and above
 use MCE;

The following are available options and their meanings.

 -keep_tmp_dir     - The temporary directory is not removed during exiting
                     A message is displayed with the location afterwards
 -use_dev_shm      - Create the temporary directory under /dev/shm
 -no_kill9         - Do not kill -9 after receiving a signal to terminate
 -setpgrp          - Calls setpgrp to set the process group for the process
                     This option ensures all workers terminate when reading
                     STDIN for MCE releases 1.511 and below.
                        cat big_input_file | ./mce_script.pl | head -10
                     This works fine without the -setpgrp option:
                        ./mce_script.pl < big_input_file | head -10

Nothing is exported by default. Exportable are 1 variable and 2 subroutines.

 use MCE::Signal qw( $tmp_dir stop_and_exit sys_cmd );
 use MCE::Signal qw( :all );
 $tmp_dir          - Path to the temporary directory.
 stop_and_exit     - Described below
 sys_cmd           - Described below

 MCE::Signal::stop_and_exit(1);
 MCE::Signal::stop_and_exit('INT');

 ## Execute command and return the actual exit status. The perl script
 ## is also signaled if command caught SIGINT or SIGQUIT.
 use MCE::Signal qw(sys_cmd);   ## Include before MCE
 use MCE;
 my $exit_status = sys_cmd($command);

DEFER SIGNAL¶

 sub sig_handler {
    return MCE::Signal::defer($_[0]) if $MCE::Signal::IPC;
    ...
 }

 use strict;
 use warnings;
 use MCE::Hobo;
 use MCE::Shared;
 use Time::HiRes 'sleep';
 my $count = MCE::Shared->scalar(0);
 my $winch = MCE::Shared->scalar(0);
 my $done  = MCE::Shared->scalar(0);
 $SIG{WINCH} = sub {
    # defer signal if signaled during IPC
    return MCE::Signal::defer($_[0]) if $MCE::Signal::IPC;
    # mask signal handler
    local $SIG{$_[0]} = 'IGNORE';
    printf "inside winch handler %d\n", $winch->incr;
 };
 $SIG{INT} = sub {
    # defer signal if signaled during IPC
    return MCE::Signal::defer($_[0]) if $MCE::Signal::IPC;
    # set flag for workers to leave loop
    $done->set(1);
 };
 sub task {
    while ( ! $done->get ) {
       $count->incr;
       sleep 0.03;
    };
 }
 print "Resize the terminal window continuously.\n";
 print "Press Ctrl-C to stop.\n";
 MCE::Hobo->create('task') for 1..8;
 sleep 0.015 until $done->get;
 MCE::Hobo->wait_all;
 printf "\ncount incremented %d times\n\n", $count->get;

INDEX¶

MCE, MCE::Core

AUTHOR¶

Mario E. Roy, <marioeroy AT gmail DOT com>