[PATCH 06/14] qspawn: implement psgi_qx

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

This new asynchronous API, will allow us to take
advantage of non-blocking I/O from even small commands;
as those may still need to wait for slow operations.
---
 lib/PublicInbox/Qspawn.pm | 89 ++++++++++++++++++++++++++++++++-------
 1 file changed, 74 insertions(+), 15 deletions(-)

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 96fbf38..6859a8a 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -61,6 +61,48 @@ sub start {
 	}
 }
 
+sub _psgi_finish ($$) {
+	my ($self, $env) = @_;
+	my $err = $self->finish;
+	if ($err && !$env->{'qspawn.quiet'}) {
+		$err = join(' ', @{$self->{args}->[0]}).": $err\n";
+		$env->{'psgi.errors'}->print($err);
+	}
+}
+
+sub psgi_qx {
+	my ($self, $env, $limiter, $qx_cb) = @_;
+	my $qx = PublicInbox::Qspawn::Qx->new;
+	my $end = sub {
+		_psgi_finish($self, $env);
+		eval { $qx_cb->($qx) };
+		$qx = undef;
+	};
+	my $rpipe;
+	my $async = $env->{'pi-httpd.async'};
+	my $cb = sub {
+		my $r = sysread($rpipe, my $buf, 8192);
+		if ($async) {
+			$async->async_pass($env->{'psgix.io'}, $qx, \$buf);
+		} elsif (defined $r) {
+			$r ? $qx->write($buf) : $end->();
+		} else {
+			return if $!{EAGAIN} || $!{EINTR}; # loop again
+			$end->();
+		}
+	};
+	$limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
+	$self->start($limiter, sub { # may run later, much later...
+		($rpipe) = @_;
+		if ($async) {
+		# PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
+			$async = $async->($rpipe, $cb, $end);
+		} else { # generic PSGI
+			$cb->() while $qx;
+		}
+	});
+}
+
 # create a filter for "push"-based streaming PSGI writes used by HTTPD::Async
 sub filter_fh ($$) {
 	my ($fh, $filter) = @_;
@@ -78,11 +120,7 @@ sub psgi_return {
 	my ($self, $env, $limiter, $parse_hdr) = @_;
 	my ($fh, $rpipe);
 	my $end = sub {
-		my $err = $self->finish;
-		if ($err && !$env->{'qspawn.quiet'}) {
-			$err = join(' ', @{$self->{args}->[0]}).": $err\n";
-			$env->{'psgi.errors'}->print($err);
-		}
+		_psgi_finish($self, $env);
 		$fh->close if $fh; # async-only
 	};
 
@@ -92,7 +130,7 @@ sub psgi_return {
 		return if !defined($r) && ($!{EINTR} || $!{EAGAIN});
 		$parse_hdr->($r, \$buf);
 	};
-	my $res;
+	my $res = delete $env->{'qspawn.response'};
 	my $async = $env->{'pi-httpd.async'};
 	my $cb = sub {
 		my $r = $rd_hdr->() or return;
@@ -118,17 +156,21 @@ sub psgi_return {
 		}
 	};
 	$limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
+	my $start_cb = sub { # may run later, much later...
+		($rpipe) = @_;
+		if ($async) {
+			# PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
+			$async = $async->($rpipe, $cb, $end);
+		} else { # generic PSGI
+			$cb->() while $rd_hdr;
+		}
+	};
+
+	return $self->start($limiter, $start_cb) if $res;
+
 	sub {
 		($res) = @_;
-		$self->start($limiter, sub { # may run later, much later...
-			($rpipe) = @_;
-			if ($async) {
-			# PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
-				$async = $async->($rpipe, $cb, $end);
-			} else { # generic PSGI
-				$cb->() while $rd_hdr;
-			}
-		});
+		$self->start($limiter, $start_cb);
 	};
 }
 
@@ -146,4 +188,21 @@ sub new {
 	}, $class;
 }
 
+# captures everything into a buffer and executes a callback when done
+package PublicInbox::Qspawn::Qx;
+use strict;
+use warnings;
+
+sub new {
+	my ($class) = @_;
+	my $buf = '';
+	bless \$buf, $class;
+}
+
+# called by PublicInbox::HTTPD::Async ($fh->write)
+sub write {
+	${$_[0]} .= $_[1];
+	undef;
+}
+
 1;
-- 
EW