1 | package Devel::FindRef; |
1 | package Devel::FindRef; |
2 | |
2 | |
3 | use strict; |
3 | use common::sense; |
4 | |
4 | |
5 | use XSLoader; |
5 | use XSLoader; |
6 | |
6 | use Scalar::Util; |
7 | |
7 | |
8 | BEGIN { |
8 | BEGIN { |
9 | our $VERSION = '0.1'; |
9 | our $VERSION = 1.45; |
10 | XSLoader::load __PACKAGE__, $VERSION; |
10 | XSLoader::load __PACKAGE__, $VERSION; |
11 | } |
11 | } |
12 | |
12 | |
13 | =head1 NAME |
13 | =head1 NAME |
14 | |
14 | |
15 | Devel::FindRef - where is that reference to my scalar hiding? |
15 | Devel::FindRef - where is that reference to my variable hiding? |
16 | |
16 | |
17 | =head1 SYNOPSIS |
17 | =head1 SYNOPSIS |
18 | |
18 | |
19 | use Devel::FindRef; |
19 | use Devel::FindRef; |
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20 | |
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21 | print Devel::FindRef::track \$some_variable; |
20 | |
22 | |
21 | =head1 DESCRIPTION |
23 | =head1 DESCRIPTION |
22 | |
24 | |
23 | Tracking down reference problems (e.g. you expect some object to be |
25 | 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 be |
26 | destroyed, but there are still references to it that keep it alive) can be |
… | |
… | |
28 | The C<track> function can help track down some of those references back to |
30 | The C<track> function can help track down some of those references back to |
29 | the variables containing them. |
31 | the variables containing them. |
30 | |
32 | |
31 | For example, for this fragment: |
33 | For example, for this fragment: |
32 | |
34 | |
33 | package Test; |
35 | package Test; |
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36 | |
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37 | use Devel::FindRef; |
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38 | use Scalar::Util; |
34 | |
39 | |
35 | our $var = "hi\n"; |
40 | our $var = "hi\n"; |
36 | my $x = \$var; |
41 | my $global_my = \$var; |
37 | our %hash = (ukukey => \$var); |
42 | our %global_hash = (ukukey => \$var); |
38 | our $hash2 = {ukukey2 => \$var}; |
43 | our $global_hashref = { ukukey2 => \$var }; |
39 | |
44 | |
40 | sub testsub { |
45 | sub testsub { |
41 | my $local = $hash2; |
46 | my $testsub_local = $global_hashref; |
42 | print Devel::FindRef::track \$var; |
47 | print Devel::FindRef::track \$var; |
43 | } |
48 | } |
44 | |
49 | |
45 | testsub; |
50 | my $closure = sub { |
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51 | my $closure_var = \$_[0]; |
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52 | Scalar::Util::weaken (my $weak_ref = \$var); |
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53 | testsub; |
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54 | }; |
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55 | |
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56 | $closure->($var); |
46 | |
57 | |
47 | The output is as follows (or similar to this, in case I forget to update |
58 | The output is as follows (or similar to this, in case I forget to update |
48 | the manpage after some changes): |
59 | the manpage after some changes): |
49 | |
60 | |
50 | SCALAR(0x676fa0) is |
61 | SCALAR(0x7cc888) [refcount 6] is |
51 | referenced by REF(0x676fb0), which is |
62 | +- referenced by REF(0x8abcc8) [refcount 1], which is |
52 | in the lexical '$x' in CODE(0x676370), which is |
63 | | the lexical '$closure_var' in CODE(0x8abc50) [refcount 4], which is |
53 | not found anywhere I looked :( |
64 | | +- the closure created at tst:18. |
54 | referenced by REF(0x676360), which is |
65 | | +- referenced by REF(0x7d3c58) [refcount 1], which is |
55 | in the member 'ukukey' of HASH(0x756660), which is |
66 | | | the lexical '$closure' in CODE(0x7ae530) [refcount 2], which is |
56 | in the global %Test::hash. |
67 | | | +- the containing scope for CODE(0x8ab430) [refcount 3], which is |
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68 | | | | the global &Test::testsub. |
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69 | | | +- the main body of the program. |
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70 | | +- the lexical '&' in CODE(0x7ae530) [refcount 2], which was seen before. |
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71 | +- referenced by REF(0x7cc7c8) [refcount 1], which is |
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72 | | the lexical '$global_my' in CODE(0x7ae530) [refcount 2], which was seen before. |
57 | in the global $Test::var. |
73 | +- the global $Test::var. |
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74 | +- referenced by REF(0x7cc558) [refcount 1], which is |
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75 | | the member 'ukukey2' of HASH(0x7ae140) [refcount 2], which is |
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76 | | +- referenced by REF(0x8abad0) [refcount 1], which is |
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77 | | | the lexical '$testsub_local' in CODE(0x8ab430) [refcount 3], which was seen before. |
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78 | | +- referenced by REF(0x8ab4f0) [refcount 1], which is |
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79 | | the global $Test::global_hashref. |
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80 | +- referenced by REF(0x7ae518) [refcount 1], which is |
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81 | | the member 'ukukey' of HASH(0x7d3bb0) [refcount 1], which is |
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82 | | the global %Test::global_hash. |
58 | referenced by REF(0x6760e0), which is |
83 | +- referenced by REF(0x7ae2f0) [refcount 1], which is |
59 | in the member 'ukukey2' of HASH(0x676f30), which is |
84 | a temporary on the stack. |
60 | referenced by REF(0x77bcf0), which is |
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61 | in the lexical '$local' in CODE(0x77bcb0), which is |
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62 | in the global &Test::testsub. |
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63 | referenced by REF(0x77bc80), which is |
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64 | in the global $Test::hash2. |
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65 | |
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66 | |
85 | |
67 | It is a bit convoluted to read, but basically it says that the value |
86 | It is a bit convoluted to read, but basically it says that the value |
68 | stored in C<$var> can be found: |
87 | stored in C<$var> is referenced by: |
69 | |
88 | |
70 | =over 4 |
89 | =over 4 |
71 | |
90 | |
72 | =item - in some variable C<$x> whose origin is not known (I frankly have no |
91 | =item - the lexical C<$closure_var> (0x8abcc8), which is inside an instantiated |
73 | idea why, hints accepted). |
92 | closure, which in turn is used quite a bit. |
74 | |
93 | |
75 | =item - in the hash element with key C<ukukey> in the hash stored in C<%Test::hash>. |
94 | =item - the package-level lexical C<$global_my>. |
76 | |
95 | |
77 | =item - in the global variable named C<$Test::var>. |
96 | =item - the global package variable named C<$Test::var>. |
78 | |
97 | |
79 | =item - in the hash element C<ukukey2>, in the hash in the my variable |
98 | =item - the hash element C<ukukey2>, in the hash in the my variable |
80 | C<$local> in the sub C<Test::testsub> and also in the hash referenced by |
99 | C<$testsub_local> in the sub C<Test::testsub> and also in the hash |
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100 | C<$referenced by Test::hash2>. |
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101 | |
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102 | =item - the hash element with key C<ukukey> in the hash stored in |
81 | C<$Test::hash2>. |
103 | C<%Test::hash>. |
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104 | |
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105 | =item - some anonymous mortalised reference on the stack (which is caused |
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106 | by calling C<track> with the expression C<\$var>, which creates the |
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107 | reference). |
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108 | |
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109 | =back |
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110 | |
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111 | And all these account for six reference counts. |
82 | |
112 | |
83 | =head1 EXPORTS |
113 | =head1 EXPORTS |
84 | |
114 | |
85 | None. |
115 | None. |
86 | |
116 | |
… | |
… | |
92 | |
122 | |
93 | Track the perl value pointed to by C<$ref> up to a depth of C<$depth> and |
123 | Track the perl value pointed to by C<$ref> up to a depth of C<$depth> and |
94 | return a descriptive string. C<$ref> can point at any perl value, be it |
124 | return a descriptive string. C<$ref> can point at any perl value, be it |
95 | anonymous sub, hash, array, scalar etc. |
125 | anonymous sub, hash, array, scalar etc. |
96 | |
126 | |
97 | This is the function you most often use. |
127 | This is the function you most likely want to use when tracking down |
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128 | references. |
98 | |
129 | |
99 | =cut |
130 | =cut |
100 | |
131 | |
101 | sub find($); |
132 | sub find($); |
102 | |
133 | |
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134 | sub _f($) { |
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135 | "$_[0] [refcount " . (_refcnt $_[0]) . "]" |
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136 | } |
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137 | |
103 | sub track { |
138 | sub track { |
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139 | my ($ref, $depth) = @_; |
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140 | @_ = (); |
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141 | |
104 | my $buf = ""; |
142 | my $buf = ""; |
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143 | my %seen; |
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144 | |
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145 | Scalar::Util::weaken $ref; |
105 | |
146 | |
106 | my $track; $track = sub { |
147 | my $track; $track = sub { |
107 | my (undef, $depth, $indent) = @_; |
148 | my ($refref, $depth, $indent) = @_; |
108 | |
149 | |
109 | if ($depth) { |
150 | if ($depth) { |
110 | my (@about) = find $_[0]; |
151 | my (@about) = find $$refref; |
111 | if (@about) { |
152 | if (@about) { |
112 | for my $about (@about) { |
153 | for my $about (@about) { |
113 | $buf .= (" ") x $indent; |
154 | $about->[0] =~ s/([^\x20-\x7e])/sprintf "\\{%02x}", ord $1/ge; |
114 | $buf .= $about->[0]; |
155 | $buf .= "$indent" . (@about > 1 ? "+- " : "") . $about->[0]; |
115 | if (@$about > 1) { |
156 | if (@$about > 1) { |
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157 | if ($seen{ref2ptr $about->[1]}++) { |
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158 | $buf .= " " . (_f $about->[1]) . ", which was seen before.\n"; |
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159 | } else { |
116 | $buf .= " $about->[1], which is\n"; |
160 | $buf .= " " . (_f $about->[1]) . ", which is\n"; |
117 | $track->($about->[1], $depth - 1, $indent + 1); |
161 | $track->(\$about->[1], $depth - 1, $about == $about[-1] ? "$indent " : "$indent| "); |
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162 | } |
118 | } else { |
163 | } else { |
119 | $buf .= ".\n"; |
164 | $buf .= ".\n"; |
120 | } |
165 | } |
121 | } |
166 | } |
122 | } else { |
167 | } else { |
123 | $buf .= (" ") x $indent; |
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124 | $buf .= "not found anywhere I looked :(\n"; |
168 | $buf .= "$indent not found anywhere I looked :(\n"; |
125 | } |
169 | } |
126 | } else { |
170 | } else { |
127 | $buf .= (" ") x $indent; |
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128 | $buf .= "not referenced within the search depth.\n"; |
171 | $buf .= "$indent not referenced within the search depth.\n"; |
129 | } |
172 | } |
130 | }; |
173 | }; |
131 | |
174 | |
132 | $buf .= "$_[0] is\n"; |
175 | $buf .= (_f $ref) . " is\n"; |
133 | $track->($_[0], $_[1] || 10, 1); |
176 | |
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177 | $track->(\$ref, $depth || $ENV{PERL_DEVEL_FINDREF_DEPTH} || 10, ""); |
134 | $buf |
178 | $buf |
135 | } |
179 | } |
136 | |
180 | |
137 | =item @references = Devel::FindRef::find $ref |
181 | =item @references = Devel::FindRef::find $ref |
138 | |
182 | |
139 | Return arrayrefs that contain [$message, $ref] pairs. The message |
183 | Return arrayrefs that contain [$message, $ref] pairs. The message |
140 | describes what kind of reference was found and the C<$ref> is the |
184 | describes what kind of reference was found and the C<$ref> is the |
141 | reference itself, which cna be omitted if C<find> decided to end the |
185 | reference itself, which can be omitted if C<find> decided to end the |
142 | search. |
186 | search. The returned references are all weak references. |
143 | |
187 | |
144 | The C<track> function uses this to find references to the value you are |
188 | The C<track> function uses this to find references to the value you are |
145 | interested in and recurses on the returned references. |
189 | interested in and recurses on the returned references. |
146 | |
190 | |
147 | =cut |
191 | =cut |
148 | |
192 | |
149 | sub find($) { |
193 | sub find($) { |
150 | my ($about, $excl) = &find_; |
194 | my ($about, $excl) = &find_; |
151 | my %excl = map +($_ => 1), @$excl; |
195 | my %excl = map +($_ => undef), @$excl; |
152 | grep !$excl{$_->[1] + 0}, @$about |
196 | grep !($#$_ && exists $excl{ref2ptr $_->[1]}), @$about |
153 | } |
197 | } |
154 | |
198 | |
155 | =item $ref = Devel::FindRef::ref2ptr $ptr |
199 | =item $ref = Devel::FindRef::ptr2ref $integer |
156 | |
200 | |
157 | Sometimes you know (from debugging output) the address of a perl scalar |
201 | Sometimes you know (from debugging output) the address of a perl value you |
158 | you are interested in. This function can be used to turn the address into |
202 | are interested in (e.g. C<HASH(0x176ff70)>). This function can be used to |
159 | a reference to that scalar. It is quite safe to call on valid addresses, |
203 | turn the address into a reference to that value. It is quite safe to call |
160 | but extremely dangerous to call on invalid ones. |
204 | on valid addresses, but extremely dangerous to call on invalid ones. I<No |
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205 | checks whatsoever will be done>, so don't use this unless you really know |
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206 | the value is the address of a valid perl value. |
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207 | |
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208 | # we know that HASH(0x176ff70) exists, so turn it into a hashref: |
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209 | my $ref_to_hash = Devel::FindRef::ptr2ref 0x176ff70; |
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210 | |
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211 | =item $ptr = Devel::FindRef::ref2ptr $reference |
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212 | |
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213 | The opposite of C<ptr2ref>, above: returns the internal address of the |
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214 | value pointed to by the passed reference. This function is safe to call on |
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215 | anything, and returns the same value that a normal reference would if used |
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216 | in a numeric context. |
161 | |
217 | |
162 | =back |
218 | =back |
163 | |
219 | |
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220 | =head1 ENVIRONMENT VARIABLES |
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221 | |
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222 | You can set the environment variable C<PERL_DEVEL_FINDREF_DEPTH> to an |
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223 | integer to override the default depth in C<track>. If a call explicitly |
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224 | specifies a depth, it is not overridden. |
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225 | |
164 | =head1 AUTHOR |
226 | =head1 AUTHOR |
165 | |
227 | |
166 | Marc Lehmann <pcg@goof.com>. |
228 | Marc Lehmann <pcg@goof.com>. |
167 | |
229 | |
168 | =head1 BUGS |
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169 | |
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170 | Only code values, arrays, hashes, scalars and magic are being looked at. |
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171 | |
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172 | This is a quick hack only. |
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173 | |
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174 | =head1 COPYRIGHT AND LICENSE |
230 | =head1 COPYRIGHT AND LICENSE |
175 | |
231 | |
176 | Copyright (C) 2007 by Marc Lehmann. |
232 | Copyright (C) 2007, 2008, 2009, 2013 by Marc Lehmann. |
177 | |
233 | |
178 | This library is free software; you can redistribute it and/or modify |
234 | This library is free software; you can redistribute it and/or modify |
179 | it under the same terms as Perl itself, either Perl version 5.8.8 or, |
235 | it under the same terms as Perl itself, either Perl version 5.8.8 or, |
180 | at your option, any later version of Perl 5 you may have available. |
236 | at your option, any later version of Perl 5 you may have available. |
181 | |
237 | |