Devel-FindRef/FindRef.pm

package Devel::FindRef;

use strict;

use XSLoader;


BEGIN {
   our $VERSION = '0.1';
   XSLoader::load __PACKAGE__, $VERSION;
}

=head1 NAME

Devel::FindRef - where is that reference to my scalar hiding?

=head1 SYNOPSIS

  use Devel::FindRef;

=head1 DESCRIPTION

Tracking down reference problems (e.g. you expect some object to be
destroyed, but there are still references to it that keep it alive). can
be very hard, although perl keeps track of all values.

The C<track> function can hlep track down some of those refernces back to
the variables containing them.

For example, for this fragment:

   package Test;           
                         
   our $var = "hi\n";
   my $x = \$var;      
   our %hash = (ukukey => \$var);
   our $hash2 = {ukukey2 => \$var};
                           
   sub testsub {             
      my $local = $hash2;      
      print Devel::FindRef::track \$var;
   }                             
                                   
   testsub;                        

The output is as follows (or similar to htis, in case I forget to update
the manpage after some changes):

   SCALAR(0x676fa0) is
      referenced by REF(0x676fb0), which is
         in the lexical '$x' in CODE(0x676370), which is
            not found anywhere I looked :(
      referenced by REF(0x676360), which is
         in the member 'ukukey' of HASH(0x756660), which is
            in the global %Test::hash.
      in the global $Test::var.
      referenced by REF(0x6760e0), which is
         in the member 'ukukey2' of HASH(0x676f30), which is
            referenced by REF(0x77bcf0), which is
               in the lexical '$local' in CODE(0x77bcb0), which is
                  in the global &Test::testsub.
            referenced by REF(0x77bc80), which is
               in the global $Test::hash2.


It is a bit convoluted to read, but basically it says that the value stored in C<$var>
can be found:

=over 4

=item - in some variable C<$x> whose origin is not known (I frankly have no
idea why, hints accepted).

=item - in the hash element with key C<ukukey> in the hash stored in C<%Test::hash>.

=item - in the global variable named C<$Test::var>.

=item - in the hash element C<ukukey2>, in the hash in the my variable
C<$local> in the sub C<Test::testsub> and also in the hash referenced by
C<$Test::hash2>.

=head1 EXPORTS

None.

=head1 FUNCTIONS

=over 4

=item $string = Devel::FindRef::track $ref[, $depth]

Track the perl value pointed to by C<$ref> up to a depth of C<$depth> and
return a descriptive string. C<$ref> can point at any perl value, be it
anonymous sub, hash, array, scalar etc.

This is the function you most often use.

=cut

sub find($);

sub track {
   my $buf = "";

   my $track; $track = sub {
      my (undef, $depth, $indent) = @_;

      if ($depth) {
         my (@about) = find $_[0];
         if (@about) {
            for my $about (@about) {
               $buf .= ("   ") x $indent;
               $buf .= $about->[0];
               if (@$about > 1) {
                  $buf .= " $about->[1], which is\n";
                  $track->($about->[1], $depth - 1, $indent + 1);
               } else {
                  $buf .= ".\n";
               }
            }
         } else {
            $buf .= ("   ") x $indent;
            $buf .= "not found anywhere I looked :(\n";
         }
      } else {
         $buf .= ("   ") x $indent;
         $buf .= "not referenced within the search depth.\n";
      }
   };

   $buf .= "$_[0] is\n";
   $track->($_[0], $_[1] || 10, 1);
   $buf
}

=item @references = Devel::FindRef::find $ref

Return arrayrefs that contain [$message, $ref] pairs. The message
describes what kind of reference was found and the C<$ref> is the
reference itself, which cna be omitted if C<find> decided to end the
search.

The C<track> function uses this to find references to the value you are
interested in and recurses on the returned references.

=cut

sub find($) {
   my ($about, $excl) = &find_;
   my %excl = map +($_ => 1), @$excl;
   grep !$excl{$_->[1] + 0}, @$about
}

=item $ref = Devel::FindRef::ref2ptr $ptr

Sometimes you know (from debugging output) the address of a perl scalar
you are interested in. This function can be used to turn the address into
a reference to that scalar. It is quite safe to call on valid addresses,
but extremely dangerous to call on invalid ones.

=back

=head1 AUTHOR

Marc Lehmann <pcg@goof.com>.

=head1 BUGS

Only code values, arrays, hashes, scalars and magic are being looked at.

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2007 by Marc Lehmann.

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.8.8 or,
at your option, any later version of Perl 5 you may have available.

=cut

1

Revision:	1.3
Committed:	Thu Jan 11 23:13:37 2007 UTC (19 years, 8 months ago) by root
Branch:	MAIN
Changes since 1.2:	+1 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	package Devel::FindRef;
2
3			use strict;
4
5			use XSLoader;
6
7
8			BEGIN {
9			our $VERSION = '0.1';
10			XSLoader::load __PACKAGE__, $VERSION;
11			}
12
13			=head1 NAME
14
15			Devel::FindRef - where is that reference to my scalar hiding?
16
17			=head1 SYNOPSIS
18
19			use Devel::FindRef;
20
21			=head1 DESCRIPTION
22
23			Tracking down reference problems (e.g. you expect some object to be
24			destroyed, but there are still references to it that keep it alive). can
25			be very hard, although perl keeps track of all values.
26
27			The C<track> function can hlep track down some of those refernces back to
28			the variables containing them.
29
30			For example, for this fragment:
31
32			package Test;
33
34			our $var = "hi\n";
35			my $x = \$var;
36			our %hash = (ukukey => \$var);
37			our $hash2 = {ukukey2 => \$var};
38
39			sub testsub {
40			my $local = $hash2;
41			print Devel::FindRef::track \$var;
42			}
43
44			testsub;
45
46			The output is as follows (or similar to htis, in case I forget to update
47	root	1.3	the manpage after some changes):
48	root	1.1
49			SCALAR(0x676fa0) is
50			referenced by REF(0x676fb0), which is
51			in the lexical '$x' in CODE(0x676370), which is
52			not found anywhere I looked :(
53			referenced by REF(0x676360), which is
54			in the member 'ukukey' of HASH(0x756660), which is
55			in the global %Test::hash.
56			in the global $Test::var.
57			referenced by REF(0x6760e0), which is
58			in the member 'ukukey2' of HASH(0x676f30), which is
59			referenced by REF(0x77bcf0), which is
60			in the lexical '$local' in CODE(0x77bcb0), which is
61			in the global &Test::testsub.
62			referenced by REF(0x77bc80), which is
63			in the global $Test::hash2.
64
65
66			It is a bit convoluted to read, but basically it says that the value stored in C<$var>
67			can be found:
68
69			=over 4
70
71			=item - in some variable C<$x> whose origin is not known (I frankly have no
72			idea why, hints accepted).
73
74			=item - in the hash element with key C<ukukey> in the hash stored in C<%Test::hash>.
75
76			=item - in the global variable named C<$Test::var>.
77
78			=item - in the hash element C<ukukey2>, in the hash in the my variable
79			C<$local> in the sub C<Test::testsub> and also in the hash referenced by
80			C<$Test::hash2>.
81
82			=head1 EXPORTS
83
84			None.
85
86			=head1 FUNCTIONS
87
88			=over 4
89
90			=item $string = Devel::FindRef::track $ref[, $depth]
91
92			Track the perl value pointed to by C<$ref> up to a depth of C<$depth> and
93			return a descriptive string. C<$ref> can point at any perl value, be it
94			anonymous sub, hash, array, scalar etc.
95
96			This is the function you most often use.
97
98			=cut
99
100			sub find($);
101
102			sub track {
103			my $buf = "";
104
105			my $track; $track = sub {
106			my (undef, $depth, $indent) = @_;
107
108			if ($depth) {
109			my (@about) = find $_[0];
110			if (@about) {
111			for my $about (@about) {
112			$buf .= (" ") x $indent;
113			$buf .= $about->[0];
114			if (@$about > 1) {
115			$buf .= " $about->[1], which is\n";
116			$track->($about->[1], $depth - 1, $indent + 1);
117			} else {
118			$buf .= ".\n";
119			}
120			}
121			} else {
122			$buf .= (" ") x $indent;
123			$buf .= "not found anywhere I looked :(\n";
124			}
125			} else {
126			$buf .= (" ") x $indent;
127			$buf .= "not referenced within the search depth.\n";
128			}
129			};
130
131			$buf .= "$_[0] is\n";
132			$track->($_[0], $_[1] \|\| 10, 1);
133			$buf
134			}
135
136			=item @references = Devel::FindRef::find $ref
137
138			Return arrayrefs that contain [$message, $ref] pairs. The message
139			describes what kind of reference was found and the C<$ref> is the
140			reference itself, which cna be omitted if C<find> decided to end the
141			search.
142
143			The C<track> function uses this to find references to the value you are
144			interested in and recurses on the returned references.
145
146			=cut
147
148			sub find($) {
149			my ($about, $excl) = &find_;
150			my %excl = map +($_ => 1), @$excl;
151			grep !$excl{$_->[1] + 0}, @$about
152			}
153
154			=item $ref = Devel::FindRef::ref2ptr $ptr
155
156			Sometimes you know (from debugging output) the address of a perl scalar
157			you are interested in. This function can be used to turn the address into
158			a reference to that scalar. It is quite safe to call on valid addresses,
159			but extremely dangerous to call on invalid ones.
160
161			=back
162
163			=head1 AUTHOR
164
165			Marc Lehmann <pcg@goof.com>.
166
167			=head1 BUGS
168
169	root	1.2	Only code values, arrays, hashes, scalars and magic are being looked at.
170	root	1.1
171			=head1 COPYRIGHT AND LICENSE
172
173			Copyright (C) 2007 by Marc Lehmann.
174
175			This library is free software; you can redistribute it and/or modify
176			it under the same terms as Perl itself, either Perl version 5.8.8 or,
177			at your option, any later version of Perl 5 you may have available.
178
179			=cut
180
181			1
182