From 7aa53210c8a1d396b5295551b9122b8690698894 Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <m.bunkus@linet-services.de>
Date: Wed, 1 Mar 2017 16:54:59 +0100
Subject: [PATCH] =?utf8?q?LXDebug::dump:=20Unterst=C3=BCtzung=20f=C3=BCr?=
 =?utf8?q?=20zirkul=C3=A4re=20Strukturen?=
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Durch die Umstellung auf vorheriges Reduzieren auf essenzielle
Informationen muss dump() sicherstellen, dass es bei zirkulären
Strukturen nicht in eine Endlosschleife gerät.

Weiterhin müssen alle Rückwärtsreferenzen aufgeweicht
werden (Scalar::Util::weaken), damit sie von der garbage collection
normal aufgeräumt werden.
---
 SL/LXDebug.pm | 55 ++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 12 deletions(-)

diff --git a/SL/LXDebug.pm b/SL/LXDebug.pm
index cedd5baec..e22dc0f5e 100644
--- a/SL/LXDebug.pm
+++ b/SL/LXDebug.pm
@@ -20,7 +20,7 @@ use constant STDERR_TARGET => 1;
 
 use Data::Dumper;
 use POSIX qw(strftime getpid);
-use Scalar::Util qw(blessed reftype);
+use Scalar::Util qw(blessed refaddr reftype weaken);
 use Time::HiRes qw(gettimeofday tv_interval);
 use YAML;
 use SL::Request ();
@@ -157,20 +157,51 @@ sub warn {
   $self->message(WARN, $message);
 }
 
-sub _clone_for_dump {
-  my ($src) = @_;
-
-  return undef unless defined($src);
-  return $src->as_debug_info                                            if blessed($src) && $src->can('as_debug_info');
-  return [ map { _clone_for_dump($_) } @{ $src } ]                      if reftype($src) eq 'ARRAY';
-  return { map { ($_ => _clone_for_dump($src->{$_})) } keys %{ $src } } if reftype($src) eq 'HASH';
-  return "$src";
-}
-
 sub dump {
   my ($self, $level, $name, $variable, %options) = @_;
 
-  $variable  = _clone_for_dump($variable);
+  my %dumped;
+
+  my $clone_for_dump;
+  $clone_for_dump = sub {
+    my ($src) = @_;
+
+    return undef if !defined($src);
+
+    my $addr = refaddr($src);
+
+    return $dumped{$addr} if $dumped{$addr // ''};
+
+
+    if (blessed($src) && $src->can('as_debug_info')) {
+      $dumped{$addr} = $src->as_debug_info;
+
+    } elsif (reftype($src) eq 'ARRAY') {
+      $dumped{$addr} = [];
+
+      foreach my $entry (@{ $src }) {
+        my $exists = !!$dumped{refaddr($entry) // ''};
+        push @{ $dumped{$addr} }, $clone_for_dump->($entry);
+
+        weaken($dumped{$addr}->[-1]) if $exists;
+
+      }
+
+    } elsif (reftype($src) eq 'HASH') {
+      $dumped{$addr} = {};
+
+      foreach my $key (keys %{ $src }) {
+        my $exists             = !!$dumped{refaddr($src->{$key}) // ''};
+        $dumped{$addr}->{$key} = $clone_for_dump->($src->{$key});
+
+        weaken($dumped{$addr}->{$key}) if $exists;
+      }
+    }
+
+    return $dumped{$addr} // "$src";
+  };
+
+  $variable  = $clone_for_dump->($variable);
   my $dumper = Data::Dumper->new([$variable]);
   $dumper->Sortkeys(1);
   $dumper->Indent(2);
-- 
2.20.1