[PATCH 1/2] eml: avoid anonymous __WARN__ sub for encode/decode

[Eric Wong]

Repeatedly allocating an anonymous sub is an expensive operation
and a potential source of leaks in older Perl.  Instead,
`local'-ize a global and use a permanent sub to workaround the
old Encode 2.87..3.12 leak.
---
 lib/PublicInbox/Eml.pm | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/lib/PublicInbox/Eml.pm b/lib/PublicInbox/Eml.pm
index 24060ec8..56aec1e5 100644
--- a/lib/PublicInbox/Eml.pm
+++ b/lib/PublicInbox/Eml.pm
@@ -334,6 +334,11 @@ sub body_set {
        undef;
 }
 
+# workaround https://rt.cpan.org/Public/Bug/Display.html?id=139622
+# Encode 2.87..3.12 leaks on croak, so we defer and croak ourselves
+our @enc_warn;
+my $enc_warn = sub { push @enc_warn, @_ };
+
 sub body_str_set {
        my ($self, $str) = @_;
        my $cs = ct($self)->{attributes}->{charset} //
@@ -341,10 +346,10 @@ sub body_str_set {
        my $enc = find_encoding($cs) // croak "unknown encoding `$cs'";
        my $tmp;
        {
-               my @w;
-               local $SIG{__WARN__} = sub { push @w, @_ };
+               local @enc_warn;
+               local $SIG{__WARN__} = $enc_warn;
                $tmp = $enc->encode($str, Encode::FB_WARN);
-               croak(@w) if @w;
+               croak(@enc_warn) if @enc_warn;
        };
        body_set($self, \$tmp);
 }
@@ -471,11 +476,10 @@ sub body_str {
        };
        my $enc = find_encoding($cs) or croak "unknown encoding `$cs'";
        my $tmp = body($self);
-       # workaround https://rt.cpan.org/Public/Bug/Display.html?id=139622
-       my @w;
-       local $SIG{__WARN__} = sub { push @w, @_ };
+       local @enc_warn;
+       local $SIG{__WARN__} = $enc_warn;
        my $ret = $enc->decode($tmp, Encode::FB_WARN);
-       croak(@w) if @w;
+       croak(@enc_warn) if @enc_warn;
        $ret;
 }