From 9eac193c72e1380972f3589cb6b4f36b79183233 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@yhbt.net>
Date: Sun, 5 Jul 2020 23:27:37 +0000
Subject: wwwatomstream: support async blob fetch

This allows -httpd to handle other requests while waiting
for git to retrieve and decode blobs.  We'll also break
apart t/psgi_v2.t further to ensure tests run against
-httpd in addition to generic PSGI testing.

Using xt/httpd-async-stream.t to test against clones of meta@public-inbox.org
shows a 10-12% performance improvement with the following env:
TEST_JOBS=1000 TEST_CURL_OPT=--compressed TEST_ENDPOINT=new.atom
---
 lib/PublicInbox/WwwAtomStream.pm | 74 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 65 insertions(+), 9 deletions(-)

(limited to 'lib')

diff --git a/lib/PublicInbox/WwwAtomStream.pm b/lib/PublicInbox/WwwAtomStream.pm
index 9f322d38..58330922 100644
--- a/lib/PublicInbox/WwwAtomStream.pm
+++ b/lib/PublicInbox/WwwAtomStream.pm
@@ -15,9 +15,11 @@ use PublicInbox::Address;
 use PublicInbox::Hval qw(ascii_html mid_href);
 use PublicInbox::MsgTime qw(msg_timestamp);
 use PublicInbox::GzipFilter qw(gzf_maybe);
+use PublicInbox::GitAsyncCat;
 
-# called by PSGI server after getline:
-sub close {}
+# called by generic PSGI server after getline,
+# and also by PublicInbox::HTTP::close
+sub close { !!delete($_[0]->{http_out}) }
 
 sub new {
 	my ($class, $ctx, $cb) = @_;
@@ -27,12 +29,62 @@ sub new {
 	bless $ctx, $class;
 }
 
+# called by PublicInbox::DS::write
+sub atom_async_next {
+	my ($http) = @_; # PublicInbox::HTTP
+	atom_async_step($http->{forward});
+}
+
+# this is public-inbox-httpd-specific
+sub atom_blob_cb { # git->cat_async callback
+	my ($bref, $oid, $type, $size, $ctx) = @_;
+	my $http = $ctx->{env}->{'psgix.io'} or return; # client abort
+	my $smsg = delete $ctx->{smsg} or die 'BUG: no smsg';
+	if (!defined($oid)) {
+		# it's possible to have TOCTOU if an admin runs
+		# public-inbox-(edit|purge), just move onto the next message
+		return $http->next_step(\&atom_async_next);
+	} else {
+		$smsg->{blob} eq $oid or die "BUG: $smsg->{blob} != $oid";
+	}
+	my $buf = feed_entry($ctx, $smsg, PublicInbox::Eml->new($bref));
+	if (my $gzf = $ctx->{gzf}) {
+		$buf = $gzf->translate($buf);
+	}
+	# PublicInbox::HTTP::{Chunked,Identity}::write
+	$ctx->{http_out}->write($buf);
+
+	$http->next_step(\&atom_async_next);
+}
+
+sub atom_async_step { # this is public-inbox-httpd-specific
+	my ($ctx) = @_;
+	if (my $smsg = $ctx->{smsg} = $ctx->{cb}->($ctx)) {
+		git_async_cat($ctx->{-inbox}->git, $smsg->{blob},
+				\&atom_blob_cb, $ctx);
+	} elsif (my $out = delete $ctx->{http_out}) {
+		if (my $gzf = delete $ctx->{gzf}) {
+			$out->write($gzf->zflush);
+		}
+		$out->close;
+	}
+}
+
 sub response {
 	my ($class, $ctx, $code, $cb) = @_;
-	my $h = [ 'Content-Type' => 'application/atom+xml' ];
+	my $res_hdr = [ 'Content-Type' => 'application/atom+xml' ];
 	$class->new($ctx, $cb);
-	$ctx->{gzf} = gzf_maybe($h, $ctx->{env});
-	[ $code, $h, $ctx ]
+	$ctx->{gzf} = gzf_maybe($res_hdr, $ctx->{env});
+	if ($ctx->{env}->{'pi-httpd.async'}) {
+		sub {
+			my ($wcb) = @_; # -httpd provided write callback
+			$ctx->{http_out} = $wcb->([200, $res_hdr]);
+			$ctx->{env}->{'psgix.io'}->{forward} = $ctx;
+			atom_async_step($ctx); # start stepping
+		};
+	} else {
+		[ $code, $res_hdr, $ctx ];
+	}
 }
 
 # called once for each message by PSGI server
@@ -40,8 +92,13 @@ sub getline {
 	my ($self) = @_;
 	my $buf = do {
 		if (my $middle = $self->{cb}) {
-			my $smsg = $middle->($self);
-			feed_entry($self, $smsg) if $smsg;
+			if (my $smsg = $middle->($self)) {
+				my $eml = $self->{-inbox}->smsg_eml($smsg) or
+						return '';
+				feed_entry($self, $smsg, $eml);
+			} else {
+				undef;
+			}
 		}
 	} // (delete($self->{cb}) ? '</feed>' : undef);
 
@@ -108,8 +165,7 @@ sub atom_header {
 
 # returns undef or string
 sub feed_entry {
-	my ($ctx, $smsg) = @_;
-	my $eml = $ctx->{-inbox}->smsg_eml($smsg) or return '';
+	my ($ctx, $smsg, $eml) = @_;
 	my $hdr = $eml->header_obj;
 	my $mid = $smsg->{mid};
 	my $irt = PublicInbox::View::in_reply_to($hdr);
-- 
cgit v1.2.3-24-ge0c7