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.

1 files changed, 10 insertions, 13 deletions

diff --git a/lib/PublicInbox/Mbox.pm b/lib/PublicInbox/Mbox.pm
index 63ec605f..1c97f959 100644
--- 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