lei_store_err: use level-trigger for error pipe

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

diff --git a/lib/PublicInbox/LeiStoreErr.pm b/lib/PublicInbox/LeiStoreErr.pm
index cc085fdca1b852315341244956caa4fad4828e7a..47fa2277f2548310b0d4f7d7eab97b895cc77d86 100644 (file)
--- 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
        }
 }