1 files changed, 40 insertions, 0 deletions
diff --git a/lib/PublicInbox/GetlineResponse.pm b/lib/PublicInbox/GetlineResponse.pm
new file mode 100644
index 00000000..290cce74
--- /dev/null
+++ b/lib/PublicInbox/GetlineResponse.pm
@@ -0,0 +1,40 @@
+# Copyright (C) all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# For generic PSGI servers (not public-inbox-httpd/netd) which assumes their
+# getline response bodies can be backpressure-aware for slow clients
+# This depends on rpipe being _blocking_ on getline.
+package PublicInbox::GetlineResponse;
+use v5.12;
+
+sub response {
+        my ($qsp) = @_;
+        my ($res, $rbuf);
+        do { # read header synchronously
+                sysread($qsp->{rpipe}, $rbuf, 65536);
+                $res = $qsp->parse_hdr_done($rbuf); # fills $bref
+        } until defined($res);
+        my ($wcb, $filter) = $qsp->yield_pass(undef, $res) or return;
+        my $self = $res->[2] = bless {
+                qsp => $qsp,
+                filter => $filter,
+        }, __PACKAGE__;
+        my ($bref) = @{delete $qsp->{yield_parse_hdr}};
+        $self->{rbuf} = $$bref if $$bref ne '';
+        $wcb->($res);
+}
+
+sub getline {
+        my ($self) = @_;
+        my $rpipe = $self->{qsp}->{rpipe} // do {
+                delete($self->{qsp})->finish;
+                return; # EOF was set on previous call
+        };
+        my $buf = delete($self->{rbuf}) // $rpipe->getline;
+        $buf // delete($self->{qsp}->{rpipe}); # set EOF for next call
+        $self->{filter} ? $self->{filter}->translate($buf) : $buf;
+}
+
+sub close {}
+
+1;