IPC::Run::Debug - debugging routines for IPC::Run

IPC-Run documentation Contained in the IPC-Run distribution.

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NAME

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IPC::Run::Debug - debugging routines for IPC::Run

SYNOPSIS

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   ##
   ## Environment variable usage
   ##
   ## To force debugging off and shave a bit of CPU and memory
   ## by compile-time optimizing away all debugging code in IPC::Run
   ## (debug => ...) options to IPC::Run will be ignored.
   export IPCRUNDEBUG=none

   ## To force debugging on (levels are from 0..10)
   export IPCRUNDEBUG=basic

   ## Leave unset or set to "" to compile in debugging support and
   ## allow runtime control of it using the debug option.

DESCRIPTION

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Controls IPC::Run debugging. Debugging levels are now set by using words, but the numbers shown are still supported for backwards compatibility:

   0  none         disabled (special, see below)
   1  basic        what's running
   2  data         what's being sent/recieved
   3  details      what's going on in more detail
   4  gory         way too much detail for most uses
   10 all          use this when submitting bug reports
      noopts       optimizations forbidden due to inherited STDIN

The none level is special when the environment variable IPCRUNDEBUG is set to this the first time IPC::Run::Debug is loaded: it prevents the debugging code from being compiled in to the remaining IPC::Run modules, saving a bit of cpu.

To do this in a script, here's a way that allows it to be overridden:

   BEGIN {
      unless ( defined $ENV{IPCRUNDEBUG} ) {
	 eval 'local $ENV{IPCRUNDEBUG} = "none"; require IPC::Run::Debug"'
	    or die $@;
      }
   }

This should force IPC::Run to not be debuggable unless somebody sets the IPCRUNDEBUG flag; modify this formula to grep @ARGV if need be:

   BEGIN {
      unless ( grep /^--debug/, @ARGV ) {
	 eval 'local $ENV{IPCRUNDEBUG} = "none"; require IPC::Run::Debug"'
	 or die $@;
   }

Both of those are untested.

AUTHOR

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Barrie Slaymaker <barries@slaysys.com>, with numerous suggestions by p5p.

IPC-Run documentation Contained in the IPC-Run distribution. 
package IPC::Run::Debug;


## We use @EXPORT for the end user's convenience: there's only one function
## exported, it's homonymous with the module, it's an unusual name, and
## it can be suppressed by "use IPC::Run ();".

use strict;
use Exporter;
use vars qw{$VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS};
BEGIN {
	$VERSION = '0.89';
	@ISA     = qw( Exporter );
	@EXPORT  = qw(
		_debug
		_debug_desc_fd
		_debugging
		_debugging_data
		_debugging_details
		_debugging_gory_details
		_debugging_not_optimized
		_set_child_debug_name
	);
	
	@EXPORT_OK = qw(
		_debug_init
		_debugging_level
		_map_fds
	);
	%EXPORT_TAGS = (
		default => \@EXPORT,
		all     => [ @EXPORT, @EXPORT_OK ],
	);
}

my $disable_debugging =
   defined $ENV{IPCRUNDEBUG}
   && (
      ! $ENV{IPCRUNDEBUG}
      || lc $ENV{IPCRUNDEBUG} eq "none"
   );

eval( $disable_debugging ? <<'STUBS' : <<'SUBS' ) or die $@;
sub _map_fds()                 { "" }
sub _debug                     {}
sub _debug_desc_fd             {}
sub _debug_init                {}
sub _set_child_debug_name      {}
sub _debugging()               { 0 }
sub _debugging_level()         { 0 }
sub _debugging_data()          { 0 }
sub _debugging_details()       { 0 }
sub _debugging_gory_details()  { 0 }
sub _debugging_not_optimized() { 0 }

1;
STUBS

use POSIX;

sub _map_fds {
   my $map = '';
   my $digit = 0;
   my $in_use;
   my $dummy;
   for my $fd (0..63) {
      ## I'd like a quicker way (less user, cpu & expecially sys and kernal
      ## calls) to detect open file descriptors.  Let me know...
      ## Hmmm, could do a 0 length read and check for bad file descriptor...
      ## but that segfaults on Win32
      my $test_fd = POSIX::dup( $fd );
      $in_use = defined $test_fd;
      POSIX::close $test_fd if $in_use;
      $map .= $in_use ? $digit : '-';
      $digit = 0 if ++$digit > 9;
   }
   warn "No fds open???" unless $map =~ /\d/;
   $map =~ s/(.{1,12})-*$/$1/;
   return $map;
}

use vars qw( $parent_pid );

$parent_pid = $$;

## TODO: move debugging to it's own module and make it compile-time
## optimizable.

## Give kid process debugging nice names
my $debug_name;

sub _set_child_debug_name {
   $debug_name = shift;
}

## There's a bit of hackery going on here.
##
## We want to have any code anywhere be able to emit
## debugging statements without knowing what harness the code is
## being called in/from, since we'd need to pass a harness around to
## everything.
##
## Thus, $cur_self was born.
#
my %debug_levels = (
   none    => 0,
   basic   => 1,
   data    => 2,
   details => 3,
   gore           => 4,
   gory_details   => 4,
   "gory details" => 4,
   gory           => 4,
   gorydetails    => 4,
   all     => 10,
   notopt  => 0,
);

my $warned;

sub _debugging_level() {
   my $level = 0;

   $level = $IPC::Run::cur_self->{debug} || 0
      if $IPC::Run::cur_self
         && ( $IPC::Run::cur_self->{debug} || 0 ) >= $level;

   if ( defined $ENV{IPCRUNDEBUG} ) {
      my $v = $ENV{IPCRUNDEBUG};
      $v = $debug_levels{lc $v} if $v =~ /[a-zA-Z]/;
      unless ( defined $v ) {
	 $warned ||= warn "Unknown debug level $ENV{IPCRUNDEBUG}, assuming 'basic' (1)\n";
	 $v = 1;
      }
      $level = $v if $v > $level;
   }
   return $level;
}

sub _debugging_atleast($) {
   my $min_level = shift || 1;

   my $level = _debugging_level;
   
   return $level >= $min_level ? $level : 0;
}

sub _debugging()               { _debugging_atleast 1 }
sub _debugging_data()          { _debugging_atleast 2 }
sub _debugging_details()       { _debugging_atleast 3 }
sub _debugging_gory_details()  { _debugging_atleast 4 }
sub _debugging_not_optimized() { ( $ENV{IPCRUNDEBUG} || "" ) eq "notopt" }

sub _debug_init {
   ## This routine is called only in spawned children to fake out the
   ## debug routines so they'll emit debugging info.
   $IPC::Run::cur_self = {};
   (  $parent_pid,
      $^T, 
      $IPC::Run::cur_self->{debug}, 
      $IPC::Run::cur_self->{DEBUG_FD}, 
      $debug_name 
   ) = @_;
}


sub _debug {
#   return unless _debugging || _debugging_not_optimized;

   my $fd = defined &IPC::Run::_debug_fd
      ? IPC::Run::_debug_fd()
      : fileno STDERR;

   my $s;
   my $debug_id;
   $debug_id = join( 
      " ",
      join(
         "",
         defined $IPC::Run::cur_self ? "#$IPC::Run::cur_self->{ID}" : (),
         "($$)",
      ),
      defined $debug_name && length $debug_name ? $debug_name        : (),
   );
   my $prefix = join(
      "",
      "IPC::Run",
      sprintf( " %04d", time - $^T ),
      ( _debugging_details ? ( " ", _map_fds ) : () ),
      length $debug_id ? ( " [", $debug_id, "]" ) : (),
      ": ",
   );

   my $msg = join( '', map defined $_ ? $_ : "<undef>", @_ );
   chomp $msg;
   $msg =~ s{^}{$prefix}gm;
   $msg .= "\n";
   POSIX::write( $fd, $msg, length $msg );
}


my @fd_descs = ( 'stdin', 'stdout', 'stderr' );

sub _debug_desc_fd {
   return unless _debugging;
   my $text = shift;
   my $op = pop;
   my $kid = $_[0];

Carp::carp join " ", caller(0), $text, $op  if defined $op  && UNIVERSAL::isa( $op, "IO::Pty" );

   _debug(
      $text,
      ' ',
      ( defined $op->{FD}
         ? $op->{FD} < 3
            ? ( $fd_descs[$op->{FD}] )
            : ( 'fd ', $op->{FD} )
         : $op->{FD}
      ),
      ( defined $op->{KFD}
         ? (
            ' (kid',
            ( defined $kid ? ( ' ', $kid->{NUM}, ) : () ),
            "'s ",
            ( $op->{KFD} < 3
               ? $fd_descs[$op->{KFD}]
               : defined $kid
                  && defined $kid->{DEBUG_FD}
                  && $op->{KFD} == $kid->{DEBUG_FD}
                  ? ( 'debug (', $op->{KFD}, ')' )
                  : ( 'fd ', $op->{KFD} )
            ),
            ')',
         )
         : ()
      ),
   );
}

1;

SUBS