mbox: reduce small packets for gzipped mboxes

We want to avoid sending 10 or 20-byte gzip headers as
separate TCP packets to reduce syscalls and avoid wasting
bandwidth.

diff --git a/lib/PublicInbox/Mbox.pm b/lib/PublicInbox/Mbox.pm
index 63ec605f6b1ecf0dd47534352335d3c423f36e4b..1c97f959c84502f6529310af2b5f6704f4858c30 100644 (file)
--- a/lib/PublicInbox/Mbox.pm
+++ b/lib/PublicInbox/Mbox.pm
@@ -110,7 +110,7 @@ use warnings;
 
 sub new {
        my ($class, $ctx, $cb) = @_;
-       my $buf;
+       my $buf = '';
        bless {
                buf => \$buf,
                gz => IO::Compress::Gzip->new(\$buf, Time => 0),
@@ -121,19 +121,11 @@ sub new {
        }, $class;
 }
 
-sub _flush_buf {
-       my ($self) = @_;
-       my $ret = $self->{buf};
-       $ret = $$ret;
-       ${$self->{buf}} = undef;
-       $ret;
-}
-
 # called by Plack::Util::foreach or similar
 sub getline {
        my ($self) = @_;
+       my $ctx = $self->{ctx} or return;
        my $res;
-       my $ctx = $self->{ctx};
        my $ibx = $ctx->{-inbox};
        my $gz = $self->{gz};
        do {
@@ -141,8 +133,12 @@ sub getline {
                        my $msg = eval { $ibx->msg_by_mid($smsg->mid) } or next;
                        $msg = Email::Simple->new($msg);
                        $gz->write(PublicInbox::Mbox::msg_str($ctx, $msg));
-                       my $ret = _flush_buf($self);
-                       return $ret if $ret;
+                       my $bref = $self->{buf};
+                       if (length($$bref) >= 8192) {
+                               my $ret = $$bref; # copy :<
+                               ${$self->{buf}} = '';
+                               return $ret;
+                       }
                }
                $res = $self->{cb}->($self->{opts});
                $self->{msgs} = $res->{msgs};
@@ -150,7 +146,8 @@ sub getline {
                $self->{opts}->{offset} += $res;
        } while ($res);
        $gz->close;
-       _flush_buf($self);
+       delete $self->{ctx};
+       ${delete $self->{buf}};
 }
 
 sub close {} # noop