[PATCH] http: support async_pass for Danga::Socket

[Eric Wong <e@80x24.org>]

This will allow us to minimize buffering after we wait
(possibly a long time) for readability.  This also greatly
reduces the amount of Danga::Socket-specific knowledge we
have in our PSGI code, making it easier for others to
understand.
---
 lib/PublicInbox/HTTP.pm        | 18 ++++++++++++++++++
 lib/PublicInbox/HTTPD/Async.pm |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index f69056f..d523bd4 100644
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -219,6 +219,24 @@ sub response_write {
 		if (ref $body eq 'ARRAY') {
 			$write->($_) foreach @$body;
 			$close->();
+		} elsif ($body->can('async_pass')) { # HTTPD::Async
+			# prevent us from reading the body faster than we
+			# can write to the client
+			my $restart_read = sub { $body->watch_read(1) };
+			$body->async_pass(sub {
+				local $/ = \8192;
+				my $buf = $body->getline;
+				if (defined $buf) {
+					$write->($buf);
+					if ($self->{write_buf}) {
+						$body->watch_read(0);
+						$self->write($restart_read);
+					}
+					return; # continue waiting
+				}
+				$body->close;
+				$close->();
+			});
 		} else {
 			my $pull;
 			$pull = sub {
diff --git a/lib/PublicInbox/HTTPD/Async.pm b/lib/PublicInbox/HTTPD/Async.pm
index bedb397..ceba738 100644
--- a/lib/PublicInbox/HTTPD/Async.pm
+++ b/lib/PublicInbox/HTTPD/Async.pm
@@ -21,10 +21,12 @@ sub new {
 	$self;
 }
 
+sub async_pass { $_[0]->{cb} = $_[1] }
 sub event_read { $_[0]->{cb}->() }
 sub event_hup { $_[0]->{cb}->() }
 sub event_err { $_[0]->{cb}->() }
 sub sysread { shift->{sock}->sysread(@_) }
+sub getline { $_[0]->{sock}->getline };
 
 sub close {
 	my $self = shift;
-- 
2.8.0.rc2.38.gfdf5e7f