qspawn: clarify and improve error handling

[public-inbox.git] / lib / PublicInbox / Qspawn.pm

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 73fd3225f7f2e7d2f2d1579af3ed4ae9c6f3444c..4b9bca5a075cc50ef0ca76e39fcd611606350c56 100644 (file)
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -73,6 +73,11 @@ sub child_err ($) {
        $msg;
 }
 
+sub log_err ($$) {
+       my ($env, $msg) = @_;
+       $env->{'psgi.errors'}->print($msg, "\n");
+}
+
 # callback for dwaitpid
 sub waitpid_err ($$) {
        my ($self, $pid) = @_;
@@ -99,8 +104,7 @@ sub waitpid_err ($$) {
        $self->{err} = $err;
        my $env = $self->{env} or return;
        if (!$env->{'qspawn.quiet'}) {
-               $err = join(' ', @{$self->{args}->[0]}).": $err\n";
-               $env->{'psgi.errors'}->print($err);
+               log_err($env, join(' ', @{$self->{args}->[0]}) . ": $err");
        }
 }
 
@@ -155,6 +159,8 @@ sub psgi_qx {
        my $scalar = '';
        open(my $qx, '+>', \$scalar) or die; # PerlIO::scalar
        my $end = sub {
+               my $err = $_[0]; # $!
+               log_err($env, "psgi_qx: $err") if defined($err);
                finish($self, $env);
                eval { $qx_cb->(\$scalar) };
                $qx = $scalar = undef;
@@ -162,14 +168,17 @@ sub psgi_qx {
        my $rpipe; # comes from popen_rd
        my $async = $env->{'pi-httpd.async'};
        my $cb = sub {
-               my $r = sysread($rpipe, my $buf, 65536);
+               my ($r, $buf);
+reread:
+               $r = sysread($rpipe, $buf, 65536);
                if ($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->();
+                       return if $! == EAGAIN; # try again when notified
+                       goto reread if $! == EINTR;
+                       $end->($!);
                }
        };
        $limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
@@ -223,6 +232,8 @@ sub psgi_return {
        my ($self, $env, $limiter, $parse_hdr) = @_;
        my ($fh, $rpipe);
        my $end = sub {
+               my $err = $_[0]; # $!
+               log_err($env, "psgi_return: $err") if defined($err);
                finish($self, $env);
                $fh->close if $fh; # async-only
        };
@@ -233,14 +244,19 @@ sub psgi_return {
                # we must loop until EAGAIN for EPOLLET in HTTPD/Async.pm
                # We also need to check EINTR for generic PSGI servers.
                my $ret;
-               my $n = 0;
+               my $total_rd = 0;
                do {
                        my $r = sysread($rpipe, $buf, 4096, length($buf));
-                       return if !defined($r) && $! == EAGAIN || $! == EINTR;
-
-                       # $r may be undef, here:
-                       $n += $r if $r;
-                       $ret = $parse_hdr->($r ? $n : $r, \$buf);
+                       if (defined($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;
        };