[PATCH 07/30] qspawn: reduce local vars, de-anonymize rd_hdr

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

rd_hdr() now becomes a named subroutine instead of a per-call
local variable, so kilobytes of memory will not have to be
allocated for it on every ->psgi_return call.
---
 lib/PublicInbox/Qspawn.pm | 79 ++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 39 deletions(-)

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 6cb28b9a..1985dccd 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -162,12 +162,11 @@ sub psgi_qx {
 	$self->{qx_arg} = $qx_arg;
 	$self->{qx_fh} = $qx_fh;
 	$self->{qx_buf} = \$qx_buf;
-	my $rpipe; # comes from popen_rd
 	my $async = $env->{'pi-httpd.async'};
 	my $cb = sub {
 		my ($r, $buf);
 reread:
-		$r = sysread($rpipe, $buf, 65536);
+		$r = sysread($self->{rpipe}, $buf, 65536);
 		if ($async) {
 			$async->async_pass($env->{'psgix.io'}, $qx_fh, \$buf);
 		} elsif (defined $r) {
@@ -180,10 +179,9 @@ reread:
 	};
 	$limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
 	$self->start($limiter, sub { # start_cb, may run later, much later...
-		($rpipe) = @_; # popen_rd result
 		if ($async) {
-		# PublicInbox::HTTPD::Async->new($rpipe, $cb, $end_obj)
-			$async = $async->($rpipe, $cb, undef, $self);
+		# PublicInbox::HTTPD::Async->new(rpipe, $cb, $end_obj)
+			$async = $async->($self->{rpipe}, $cb, undef, $self);
 			# $cb will call ->async_pass or ->close
 		} else { # generic PSGI
 			$cb->() while $self->{qx_fh};
@@ -215,6 +213,32 @@ sub event_step {
 	$fh->close if $fh; # async-only (psgi_return)
 }
 
+sub rd_hdr ($) {
+	my ($self) = @_;
+	# typically used for reading CGI headers
+	# we must loop until EAGAIN for EPOLLET in HTTPD/Async.pm
+	# We also need to check EINTR for generic PSGI servers.
+	my $ret;
+	my $total_rd = 0;
+	my $hdr_buf = $self->{hdr_buf};
+	do {
+		my $r = sysread($self->{rpipe}, $$hdr_buf, 4096,
+				length($$hdr_buf));
+		if (defined($r)) {
+			$total_rd += $r;
+			$ret = $self->{parse_hdr}->($total_rd, $hdr_buf);
+		} else {
+			# caller should notify us when it's ready:
+			return if $! == EAGAIN;
+			next if $! == EINTR; # immediate retry
+			log_err($self->{psgi_env}, "error reading header: $!");
+			$ret = [ 500, [], [ "Internal error\n" ] ];
+		}
+	} until (defined $ret);
+	delete $self->{parse_hdr}; # done parsing headers
+	$ret;
+}
+
 # Used for streaming the stdout of one process as a PSGI response.
 #
 # $env is the PSGI env.
@@ -240,43 +264,20 @@ sub event_step {
 sub psgi_return {
 	my ($self, $env, $limiter, $parse_hdr) = @_;
 	$self->{psgi_env} = $env;
-	my $rpipe;
-	my $buf = '';
-	my $rd_hdr = sub {
-		# typically used for reading CGI headers
-		# we must loop until EAGAIN for EPOLLET in HTTPD/Async.pm
-		# We also need to check EINTR for generic PSGI servers.
-		my $ret;
-		my $total_rd = 0;
-		do {
-			my $r = sysread($rpipe, $buf, 4096, length($buf));
-			if (defined($r)) {
-				$total_rd += $r;
-				$ret = $parse_hdr->($r ? $total_rd : 0, \$buf);
-			} else {
-				# caller should notify us when it's ready:
-				return if $! == EAGAIN;
-				next if $! == EINTR; # immediate retry
-				log_err($env, "error reading header: $!");
-				$ret = [ 500, [], [ "Internal error\n" ] ];
-			}
-		} until (defined $ret);
-		$ret;
-	};
-
+	$self->{hdr_buf} = \(my $hdr_buf = '');
+	$self->{parse_hdr} = $parse_hdr;
 	my $wcb = delete $env->{'qspawn.wcb'}; # or PSGI server supplies it
 	my $async = $env->{'pi-httpd.async'};
 
 	my $cb = sub {
-		my $r = $rd_hdr->() or return;
-		$rd_hdr = undef; # done reading headers
+		my $r = rd_hdr($self) or return;
 		my $filter = delete $env->{'qspawn.filter'};
 		if (scalar(@$r) == 3) { # error
 			if ($async) {
 				# calls rpipe->close && ->event_step
 				$async->close;
 			} else {
-				$rpipe->close;
+				$self->{rpipe}->close;
 				event_step($self);
 			}
 			$wcb->($r);
@@ -285,12 +286,13 @@ sub psgi_return {
 			my $fh = $wcb->($r); # scalar @$r == 2
 			$fh = filter_fh($fh, $filter) if $filter;
 			$self->{fh} = $fh;
-			$async->async_pass($env->{'psgix.io'}, $fh, \$buf);
+			$async->async_pass($env->{'psgix.io'}, $fh,
+						delete($self->{hdr_buf}));
 		} else { # for synchronous PSGI servers
 			require PublicInbox::GetlineBody;
-			$r->[2] = PublicInbox::GetlineBody->new($rpipe,
+			$r->[2] = PublicInbox::GetlineBody->new($self->{rpipe},
 						\&event_step, $self,
-						$buf, $filter);
+						${$self->{hdr_buf}}, $filter);
 			$wcb->($r);
 		}
 
@@ -300,14 +302,13 @@ 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, $cb_arg,
+			# PublicInbox::HTTPD::Async->new(rpipe, $cb, $cb_arg,
 			#				 $end_obj)
-			$async = $async->($rpipe, $cb, undef, $self);
+			$async = $async->($self->{rpipe}, $cb, undef, $self);
 			# $cb will call ->async_pass or ->close
 		} else { # generic PSGI
-			$cb->() while $rd_hdr;
+			$cb->() while $self->{parse_hdr};
 		}
 	};