[PATCH] qspawn: more generic command chaining

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

Move the chaining logic into qspawn so we can gracefully
try other commands when cgit or git-http-backend refuses
to service a request for us.
---
 lib/PublicInbox/GitHTTPBackend.pm | 9 +++------
 lib/PublicInbox/Qspawn.pm         | 7 ++++++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/lib/PublicInbox/GitHTTPBackend.pm b/lib/PublicInbox/GitHTTPBackend.pm
index 974a1831..e84d4ff8 100644
--- a/lib/PublicInbox/GitHTTPBackend.pm
+++ b/lib/PublicInbox/GitHTTPBackend.pm
@@ -154,12 +154,9 @@ sub parse_cgi_headers { # {parse_hdr} for Qspawn
 		delete $ctx->{env}->{'qspawn.wcb'};
 		$ctx->{env}->{'plack.skip-deflater'} = 1; # prevent 2x gzip
 		my $res = $ctx->{www}->coderepo->srv(\%ctx);
-		if (ref($res) eq 'CODE') {
-			$res->(delete $ctx{env}->{'qspawn.wcb'});
-		} else { # ref($res) eq 'ARRAY'
-			$ctx->{env}->{'qspawn.wcb'} = $ctx{env}->{'qspawn.wcb'};
-		}
-		$res; # non ARRAY ref for ->psgi_return_init_cb
+		# for ->psgi_return_init_cb:
+		$ctx->{env}->{'qspawn.wcb'} = $ctx{env}->{'qspawn.wcb'};
+		$res; # CODE or ARRAY ref
 	} else {
 		[ $code, \@h ]
 	}
diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 6e245389..9ca6b3db 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -237,7 +237,12 @@ sub psgi_return_init_cb {
 			$self->{rpipe}->close;
 			event_step($self);
 		}
-		$wcb->($r) if ref($r) eq 'ARRAY';
+		if (ref($r) eq 'ARRAY') { # error
+			$wcb->($r)
+		} elsif (ref($r) eq 'CODE') { # chain another command
+			$r->($wcb)
+		}
+		# else do nothing
 	} elsif ($async) {
 		# done reading headers, handoff to read body
 		my $fh = $wcb->($r); # scalar @$r == 2