[PATCH 0/4] qspawn|awaitpid error handling improvements

[PATCH 0/4] qspawn|awaitpid error handling improvements

[Eric Wong]

Nothing major, but it makes future work easier and more robust.

Eric Wong (4):
  qspawn: {quiet} only affects normal command exit
  qspawn: psgi_qx: do not call async_pass on errors
  ds: improve error handling of synchronous awaitpid
  qspawn: drop unnecessary awaitpid import

 lib/PublicInbox/DS.pm     | 12 +++++++++---
 lib/PublicInbox/Qspawn.pm | 25 ++++++++++++-------------
 2 files changed, 21 insertions(+), 16 deletions(-)

[PATCH 1/4] qspawn: {quiet} only affects normal command exit

[Eric Wong]

{quiet} is nice for quieting normal/expected errors (e.g `git diff'),
but we still want to show the command in case there's errors in
our own code.
---
 lib/PublicInbox/Qspawn.pm | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 78afe718..c4708c0f 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -57,7 +57,8 @@ sub _do_spawn {
 			$o{$k} = $rlimit;
 		}
 	}
-	$self->{cmd} = $o{quiet} ? undef : $cmd;
+	$self->{cmd} = $cmd;
+	$self->{-quiet} = 1 if $o{quiet};
 	$o{cb_arg} = [ \&waitpid_err, $self ];
 	eval {
 		# popen_rd may die on EMFILE, ENFILE
@@ -85,7 +86,7 @@ sub finalize ($) {
 		if (my $dst = $self->{qsp_err}) {
 			$$dst .= $$dst ? " $err" : "; $err";
 		}
-		warn "@{$self->{cmd}}: $err" if $self->{cmd};
+		warn "@{$self->{cmd}}: $err" if !$self->{-quiet};
 	}
 
 	my ($env, $qx_cb, $qx_arg, $qx_buf) =
@@ -216,9 +217,8 @@ sub rd_hdr ($) {
 				warn "parse_hdr: $@";
 				$ret = [ 500, [], [ "Internal error\n" ] ];
 			} elsif (!defined($ret) && !$r) {
-				my $cmd = $self->{cmd} // [ '(?)' ];
 				warn <<EOM;
-EOF parsing headers from @$cmd ($self->{psgi_env}->{REQUEST_URI})
+EOF parsing headers from @{$self->{cmd}} ($self->{psgi_env}->{REQUEST_URI})
 EOM
 				$ret = [ 500, [], [ "Internal error\n" ] ];
 			}

[PATCH 2/4] qspawn: psgi_qx: do not call async_pass on errors

[Eric Wong]

This makes control flow slightly less confusing.
---
 lib/PublicInbox/Qspawn.pm | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index c4708c0f..de74b174 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -142,20 +142,20 @@ sub start ($$$) {
 
 sub psgi_qx_init_cb { # this may be PublicInbox::HTTPD::Async {cb}
 	my ($self) = @_;
-	my $async = delete $self->{async}; # PublicInbox::HTTPD::Async
 	my ($r, $buf);
-	my $qx_fh = $self->{qx_fh};
 reread:
 	$r = sysread($self->{rpipe}, $buf, 65536);
-	if ($async) {
-		$async->async_pass($self->{psgi_env}->{'psgix.io'},
-					$qx_fh, \$buf);
-	} elsif (defined $r) {
-		$r ? (print $qx_fh $buf) : event_step($self, undef);
-	} else {
+	if (!defined($r)) {
 		return if $! == EAGAIN; # try again when notified
 		goto reread if $! == EINTR;
 		event_step($self, $!);
+	} elsif (my $as = delete $self->{async}) { # PublicInbox::HTTPD::Async
+		$as->async_pass($self->{psgi_env}->{'psgix.io'},
+				$self->{qx_fh}, \$buf);
+	} elsif ($r) { # generic PSGI:
+		print { $self->{qx_fh} } $buf;
+	} else { # EOF
+		event_step($self, undef);
 	}
 }
 

[PATCH 3/4] ds: improve error handling of synchronous awaitpid

[Eric Wong]

EINTR needs to be retried for non-kqueue|signalfd users,
and ECHILD indicates a bug in our code.
---
 lib/PublicInbox/DS.pm | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index c849f515..523d47e4 100644
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -30,7 +30,7 @@ use Time::HiRes qw(clock_gettime CLOCK_MONOTONIC);
 use Scalar::Util qw(blessed);
 use PublicInbox::Syscall qw(:epoll);
 use PublicInbox::Tmpfile;
-use Errno qw(EAGAIN EINVAL);
+use Errno qw(EAGAIN EINVAL ECHILD EINTR);
 use Carp qw(carp croak);
 our @EXPORT_OK = qw(now msg_more awaitpid add_timer add_uniq_timer);
 
@@ -703,13 +703,19 @@ sub awaitpid {
 	$AWAIT_PIDS->{$pid} //= @cb_args ? \@cb_args : 0;
 	# provide synchronous API
 	if (defined(wantarray) || (!$in_loop && !@cb_args)) {
-		my $ret = waitpid($pid, 0) // -2;
+		my $ret;
+again:
+		$ret = waitpid($pid, 0) // -2;
 		if ($ret == $pid) {
 			my $cb_args = delete $AWAIT_PIDS->{$pid};
 			@cb_args = @$cb_args if !@cb_args && $cb_args;
 			await_cb($pid, @cb_args);
-			return $ret;
+		} else {
+			goto again if $! == EINTR;
+			carp "waitpid($pid): $!";
+			delete $AWAIT_PIDS->{$pid};
 		}
+		return $ret;
 	}
 	# We could've just missed our SIGCHLD, cover it, here:
 	enqueue_reap() if $in_loop;

[PATCH 4/4] qspawn: drop unnecessary awaitpid import

[Eric Wong]

We don't actually need to call awaitpid here, ProcessPipe
will take care of that.
---
 lib/PublicInbox/Qspawn.pm | 1 -
 1 file changed, 1 deletion(-)

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index de74b174..cc81a4cd 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -28,7 +28,6 @@ package PublicInbox::Qspawn;
 use v5.12;
 use PublicInbox::Spawn qw(popen_rd);
 use PublicInbox::GzipFilter;
-use PublicInbox::DS qw(awaitpid);
 use Scalar::Util qw(blessed);
 
 # n.b.: we get EAGAIN with public-inbox-httpd, and EINTR on other PSGI servers