[PATCH 21/43] wwwatomstream: support async blob fetch

[Eric Wong <e@yhbt.net>]

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
---
 Documentation/mknews.perl        |  7 +--
 lib/PublicInbox/WwwAtomStream.pm | 74 +++++++++++++++++++++++----
 t/psgi_v2.t                      | 86 ++++++++++++++++++++------------
 3 files changed, 123 insertions(+), 44 deletions(-)

diff --git a/Documentation/mknews.perl b/Documentation/mknews.perl
index ba049d9e6..2d22d147e 100755
--- a/Documentation/mknews.perl
+++ b/Documentation/mknews.perl
@@ -147,9 +147,10 @@ EOF
 }
 
 sub mime2atom  {
-	my ($out, $astream, $mime, $ctx) = @_;
-	my $smsg = bless { mime => $mime }, 'PublicInbox::Smsg';
-	if (defined(my $str = $astream->feed_entry($smsg))) {
+	my ($out, $astream, $eml, $ctx) = @_;
+	my $smsg = bless {}, 'PublicInbox::Smsg';
+	$smsg->populate($eml);
+	if (defined(my $str = $astream->feed_entry($smsg, $eml))) {
 		print $out $str or die;
 	}
 }
diff --git a/lib/PublicInbox/WwwAtomStream.pm b/lib/PublicInbox/WwwAtomStream.pm
index 9f322d38f..583309228 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);
diff --git a/t/psgi_v2.t b/t/psgi_v2.t
index 90a710a44..4ab9601c0 100644
--- a/t/psgi_v2.t
+++ b/t/psgi_v2.t
@@ -14,6 +14,36 @@ use_ok($_) for (qw(HTTP::Request::Common Plack::Test));
 use_ok 'PublicInbox::WWW';
 use_ok 'PublicInbox::V2Writable';
 my ($inboxdir, $for_destroy) = tmpdir();
+my $cfgpath = "$inboxdir/$$.config";
+SKIP: {
+	require_mods(qw(Plack::Test::ExternalServer), 1);
+	open my $fh, '>', $cfgpath or BAIL_OUT $!;
+	print $fh <<EOF or BAIL_OUT $!;
+[publicinbox "v2test"]
+	inboxdir = $inboxdir
+	address = test\@example.com
+EOF
+	close $fh or BAIL_OUT $!;
+}
+
+my $run_httpd = sub {
+	my ($client, $skip) = @_;
+	SKIP: {
+		require_mods(qw(Plack::Test::ExternalServer), $skip);
+		my $env = { PI_CONFIG => $cfgpath };
+		my $sock = tcp_server() or die;
+		my ($out, $err) = map { "$inboxdir/std$_.log" } qw(out err);
+		my $cmd = [ qw(-httpd -W0), "--stdout=$out", "--stderr=$err" ];
+		my $td = start_script($cmd, $env, { 3 => $sock });
+		my ($h, $p) = ($sock->sockhost, $sock->sockport);
+		local $ENV{PLACK_TEST_EXTERNALSERVER_URI} = "http://$h:$p";
+		Plack::Test::ExternalServer::test_psgi(client => $client);
+		$td->join('TERM');
+		open my $fh, '<', $err or BAIL_OUT $!;
+		is(do { local $/; <$fh> }, '', 'no errors');
+	}
+};
+
 my $ibx = {
 	inboxdir => $inboxdir,
 	name => 'test-v2writable',
@@ -60,7 +90,7 @@ EOF
 my $config = PublicInbox::Config->new(\$cfg);
 my $www = PublicInbox::WWW->new($config);
 my ($res, $raw, @from_);
-test_psgi(sub { $www->call(@_) }, sub {
+my $client0 = sub {
 	my ($cb) = @_;
 	$res = $cb->(GET('/v2test/description'));
 	like($res->content, qr!\$INBOX_DIR/description missing!,
@@ -90,7 +120,9 @@ test_psgi(sub { $www->call(@_) }, sub {
 	@bodies = ($res->content =~ /^(hello [^<]+)$/mg);
 	is_deeply(\@bodies, [ "hello world!\n", "hello world\n" ],
 		'new.html ordering is chronological');
-});
+};
+test_psgi(sub { $www->call(@_) }, $client0);
+$run_httpd->($client0, 9);
 
 $mime->header_set('Message-Id', 'a-mid@b');
 $mime->body_set("hello ghosts\n");
@@ -103,7 +135,7 @@ $mids = mids($mime->header_obj);
 my $third = $mids->[-1];
 $im->done;
 
-my $client = sub {
+my $client1 = sub {
 	my ($cb) = @_;
 	$res = $cb->(GET("/v2test/$third/raw"));
 	$raw = $res->content;
@@ -196,32 +228,10 @@ my $client = sub {
 	like($raw, qr/\b3\+ messages\b/, 'thread overview shown');
 };
 
-test_psgi(sub { $www->call(@_) }, $client);
-SKIP: {
-	require_mods(qw(Plack::Test::ExternalServer), 37);
-	my $cfgpath = "$inboxdir/$$.config";
-	open my $fh, '>', $cfgpath or BAIL_OUT $!;
-	print $fh <<EOF or BAIL_OUT $!;
-[publicinbox "v2test"]
-	inboxdir = $inboxdir
-	address = test\@example.com
-EOF
-	close $fh or BAIL_OUT $!;
-	my $env = { PI_CONFIG => $cfgpath };
-	my $sock = tcp_server() or die;
-	my ($out, $err) = map { "$inboxdir/std$_.log" } qw(out err);
-	my $cmd = [ qw(-httpd -W0), "--stdout=$out", "--stderr=$err" ];
-	my $td = start_script($cmd, $env, { 3 => $sock });
-	my ($h, $p) = ($sock->sockhost, $sock->sockport);
-	local $ENV{PLACK_TEST_EXTERNALSERVER_URI} = "http://$h:$p";
-	Plack::Test::ExternalServer::test_psgi(client => $client);
-	$td->join('TERM');
-	open $fh, '<', $err or BAIL_OUT $!;
-	is(do { local $/; <$fh> }, '', 'no errors');
-};
+test_psgi(sub { $www->call(@_) }, $client1);
+$run_httpd->($client1, 38);
 
-test_psgi(sub { $www->call(@_) }, sub {
-	my ($cb) = @_;
+{
 	my $exp = [ qw(<a-mid@b> <reuse@mid>) ];
 	$mime->header_set('Message-Id', @$exp);
 	$mime->header_set('Subject', '4th dupe');
@@ -230,10 +240,12 @@ test_psgi(sub { $www->call(@_) }, sub {
 	$im->done;
 	my @h = $mime->header('Message-ID');
 	is_deeply($exp, \@h, 'reused existing Message-ID');
-
 	$config->each_inbox(sub { $_[0]->search->reopen });
+}
 
-	$res = $cb->(GET('/v2test/new.atom'));
+my $client2 = sub {
+	my ($cb) = @_;
+	my $res = $cb->(GET('/v2test/new.atom'));
 	my @ids = ($res->content =~ m!<id>urn:uuid:([^<]+)</id>!sg);
 	my %ids;
 	$ids{$_}++ for @ids;
@@ -256,7 +268,11 @@ test_psgi(sub { $www->call(@_) }, sub {
 	is($res->code, 200, 'got info refs for dumb clones w/ .git suffix');
 	$res = $cb->(GET('/v2test/info/refs'));
 	is($res->code, 404, 'v2 git URL w/o shard fails');
+};
 
+test_psgi(sub { $www->call(@_) }, $client2);
+$run_httpd->($client2, 8);
+{
 	# ensure conflicted attachments can be resolved
 	foreach my $body (qw(old new)) {
 		$mime = eml_load "t/psgi_v2-$body.eml";
@@ -264,7 +280,11 @@ test_psgi(sub { $www->call(@_) }, sub {
 	}
 	$im->done;
 	$config->each_inbox(sub { $_[0]->search->reopen });
-	$res = $cb->(GET('/v2test/a@dup/'));
+}
+
+my $client3 = sub {
+	my ($cb) = @_;
+	my $res = $cb->(GET('/v2test/a@dup/'));
 	my @links = ($res->content =~ m!"\.\./([^/]+/2-attach\.txt)\"!g);
 	is(scalar(@links), 2, 'both attachment links exist');
 	isnt($links[0], $links[1], 'attachment links are different');
@@ -276,7 +296,9 @@ test_psgi(sub { $www->call(@_) }, sub {
 	}
 	$res = $cb->(GET('/v2test/?t=1970'.'01'.'01'.'000000'));
 	is($res->code, 404, '404 for out-of-range t= param');
-});
+};
+test_psgi(sub { $www->call(@_) }, $client3);
+$run_httpd->($client3, 4);
 
 done_testing();