http: reduce over-buffering for getline responses

By switching to a "pull"-based I/O model for reading
application responses, we should be able to throttle
buffering to slow clients more effectively and avoid
wasting precious RAM.

This will also allow us to more Danga::Socket-specific
knowledge out of the PSGI application and keep it
confined to PublicInbox::HTTP.

diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index 1ef3fb31d8d6f8a61a1482860e33ddf5becc2b65..f69056f87932980cb8dffe2d41ae9d1c3be4297b 100644 (file)
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -205,7 +205,7 @@ sub response_write {
                if ($alive) {
                        $self->event_write; # watch for readability if done
                } else {
-                       $self->write(sub { $self->close });
+                       Danga::Socket::write($self, sub { $self->close });
                }
                if (my $obj = $env->{'pi-httpd.inbox'}) {
                        # grace period for reaping resources
@@ -215,9 +215,27 @@ sub response_write {
                $self->{env} = undef;
        };
 
-       if (defined $res->[2]) {
-               Plack::Util::foreach($res->[2], $write);
-               $close->();
+       if (defined(my $body = $res->[2])) {
+               if (ref $body eq 'ARRAY') {
+                       $write->($_) foreach @$body;
+                       $close->();
+               } else {
+                       my $pull;
+                       $pull = sub {
+                               local $/ = \8192;
+                               while (defined(my $buf = $body->getline)) {
+                                       $write->($buf);
+                                       if ($self->{write_buf}) {
+                                               $self->write($pull);
+                                               return;
+                                       }
+                               }
+                               $pull = undef;
+                               $body->close();
+                               $close->();
+                       };
+                       $pull->();
+               }
        } else {
                # this is returned to the calling application:
                Plack::Util::inline_object(write => $write, close => $close);