lei_store_err: use level-trigger for error pipe

This fixes deadlocks from errors inside lei/store when multiple
errors are spewed.

1 files changed, 10 insertions, 11 deletions

diff --git a/lib/PublicInbox/LeiStoreErr.pm b/lib/PublicInbox/LeiStoreErr.pm
index cc085fdc..47fa2277 100644
--- a/lib/PublicInbox/LeiStoreErr.pm
+++ b/lib/PublicInbox/LeiStoreErr.pm
@@ -1,13 +1,12 @@
-# Copyright (C) 2021 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 
 # forwards stderr from lei/store process to any lei clients using
 # the same store, falls back to syslog if no matching clients exist.
 package PublicInbox::LeiStoreErr;
-use strict;
-use v5.10.1;
+use v5.12;
 use parent qw(PublicInbox::DS);
-use PublicInbox::Syscall qw(EPOLLIN EPOLLONESHOT);
+use PublicInbox::Syscall qw(EPOLLIN);
 use Sys::Syslog qw(openlog syslog closelog);
 use IO::Handle (); # ->blocking
 
@@ -15,24 +14,24 @@ sub new {
         my ($cls, $rd, $lei) = @_;
         my $self = bless { sock => $rd, store_path => $lei->store_path }, $cls;
         $rd->blocking(0);
-        $self->SUPER::new($rd, EPOLLIN | EPOLLONESHOT);
+        $self->SUPER::new($rd, EPOLLIN); # level-trigger
 }
 
 sub event_step {
         my ($self) = @_;
-        my $rbuf = $self->{rbuf} // \(my $x = '');
-        $self->do_read($rbuf, 8192, length($$rbuf)) or return;
-        my $cb;
+        my $n = sysread($self->{sock}, my $buf, 8192);
+        return ($!{EAGAIN} ? 0 : $self->close) if !defined($n);
+        return $self->close if !$n;
         my $printed;
         for my $lei (values %PublicInbox::DS::DescriptorMap) {
-                $cb = $lei->can('store_path') // next;
+                my $cb = $lei->can('store_path') // next;
                 next if $cb->($lei) ne $self->{store_path};
                 my $err = $lei->{2} // next;
-                print $err $$rbuf and $printed = 1;
+                print $err $buf and $printed = 1;
         }
         if (!$printed) {
                 openlog('lei/store', 'pid,nowait,nofatal,ndelay', 'user');
-                for my $l (split(/\n/, $$rbuf)) { syslog('warning', '%s', $l) }
+                for my $l (split(/\n/, $buf)) { syslog('warning', '%s', $l) }
                 closelog(); # don't share across fork
         }
 }