[PATCH 15/21] lei_to_mail: reduce spew on Maildir removal

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

At most, we'll only warn once per worker when a Maildir
disappears from under us.  We'll also use the '!' OpPipe
to note the exceptional condition, and use '|' to SIGPIPE
so it'll be a bit easier for hackers to remember.
---
 lib/PublicInbox/LEI.pm        |  8 ++++----
 lib/PublicInbox/LeiToMail.pm  | 12 +++++++-----
 lib/PublicInbox/LeiXSearch.pm | 20 ++++++++++++--------
 3 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index e2f22a75..17ad18b9 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -305,7 +305,8 @@ sub qerr ($;@) { $_[0]->{opt}->{quiet} or err(shift, @_) }
 
 sub fail ($$;$) {
 	my ($self, $buf, $exit_code) = @_;
-	err($self, $buf);
+	err($self, $buf) if defined $buf;
+	syswrite($self->{op_pipe}, '!') if $self->{op_pipe}; # fail_handler
 	x_it($self, ($exit_code // 1) << 8);
 	undef;
 }
@@ -365,11 +366,10 @@ sub io_restore ($$) {
 	}
 }
 
-# triggers sigpipe_handler
-sub note_sigpipe {
+sub note_sigpipe { # triggers sigpipe_handler
 	my ($self, $fd) = @_;
 	close(delete($self->{$fd})); # explicit close silences Perl warning
-	syswrite($self->{op_pipe}, '!') if $self->{op_pipe};
+	syswrite($self->{op_pipe}, '|') if $self->{op_pipe};
 	x_it($self, 13);
 }
 
diff --git a/lib/PublicInbox/LeiToMail.pm b/lib/PublicInbox/LeiToMail.pm
index 01e7cec5..c6c5f84b 100644
--- a/lib/PublicInbox/LeiToMail.pm
+++ b/lib/PublicInbox/LeiToMail.pm
@@ -296,14 +296,14 @@ sub _buf2maildir {
 	my $kw = $smsg->{kw} // [];
 	my $sfx = join('', sort(map { $kw2char{$_} // () } @$kw));
 	my $rand = ''; # chosen by die roll :P
-	my ($tmp, $fh, $final);
+	my ($tmp, $fh, $final, $ok);
 	my $common = $smsg->{blob} // _rand;
 	if (defined(my $pct = $smsg->{pct})) { $common .= "=$pct" }
 	do {
 		$tmp = $dst.'tmp/'.$rand.$common;
-	} while (!sysopen($fh, $tmp, O_CREAT|O_EXCL|O_WRONLY) &&
+	} while (!($ok = sysopen($fh, $tmp, O_CREAT|O_EXCL|O_WRONLY)) &&
 		$! == EEXIST && ($rand = _rand.','));
-	if (print $fh $$buf and close($fh)) {
+	if ($ok && print $fh $$buf and close($fh)) {
 		# ignore new/ and write only to cur/, otherwise MUAs
 		# with R/W access to the Maildir will end up doing
 		# a mass rename which can take a while with thousands
@@ -316,9 +316,10 @@ sub _buf2maildir {
 			($rand = _rand.','));
 		unlink($tmp) or warn "W: failed to unlink $tmp: $!\n";
 	} else {
-		my $err = $!;
+		my $err = "Error writing $smsg->{blob} to $dst: $!\n";
+		$_[0] = undef; # clobber dst
 		unlink($tmp);
-		die "Error writing $smsg->{blob} to $dst: $err";
+		die $err;
 	}
 }
 
@@ -329,6 +330,7 @@ sub _maildir_write_cb ($$) {
 	my $dst = $lei->{ovv}->{dst};
 	sub { # for git_to_mail
 		my ($buf, $smsg, $eml) = @_;
+		$dst // return $lei->fail; # dst may be undef-ed in last run
 		$buf //= \($eml->as_string);
 		return _buf2maildir($dst, $buf, $smsg) if !$dedupe;
 		$eml //= PublicInbox::Eml->new($$buf); # copy buf
diff --git a/lib/PublicInbox/LeiXSearch.pm b/lib/PublicInbox/LeiXSearch.pm
index 4d390ee4..f630e79a 100644
--- a/lib/PublicInbox/LeiXSearch.pm
+++ b/lib/PublicInbox/LeiXSearch.pm
@@ -356,14 +356,17 @@ sub query_prepare { # called by wq_do
 	syswrite($lei->{op_pipe}, '.') == 1 or die "do_post_augment trigger: $!"
 }
 
-sub sigpipe_handler { # handles SIGPIPE from l2m/lxs workers
-	my ($lei) = @_;
-	my $lxs = delete $lei->{lxs};
-	if ($lxs && $lxs->wq_kill_old) { # is this the daemon?
-		$lxs->wq_wait_old($lei);
+sub fail_handler ($;$$) {
+	my ($lei, $code, $io) = @_;
+	if (my $lxs = delete $lei->{lxs}) {
+		$lxs->wq_wait_old($lei) if $lxs->wq_kill_old; # lei-daemon
 	}
-	close(delete $lei->{1}) if $lei->{1};
-	$lei->x_it(13);
+	close($io) if $io; # needed to avoid warnings on SIGPIPE
+	$lei->x_it($code // (1 >> 8));
+}
+
+sub sigpipe_handler { # handles SIGPIPE from l2m/lxs workers
+	fail_handler($_[0], 13, delete $_[0]->{1});
 }
 
 sub do_query {
@@ -384,7 +387,8 @@ sub do_query {
 	$lei->event_step_init; # wait for shutdowns
 	my $done_op = {
 		'' => [ \&query_done, $lei ],
-		'!' => [ \&sigpipe_handler, $lei ]
+		'|' => [ \&sigpipe_handler, $lei ],
+		'!' => [ \&fail_handler, $lei ]
 	};
 	my $in_loop = exists $lei->{sock};
 	$done = PublicInbox::OpPipe->new($done, $done_op, $in_loop);