[PATCH 6/7] lei up: avoid excessively parallel --all

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

We shouldn't dispatch all outputs right away since they
can be expensive CPU-wise.  Instead, rely on DESTROY to
trigger further redispatches.

This also fixes a circular reference bug for the single-output
case that could lead to a leftover script/lei after MUA exit.

I'm not sure how --jobs/-j should work when the actual xsearch
and lei2mail has it's own parallelism ("--jobs=$X,$M"), but
it's better than having thousands of subtasks running.

Fixes: b34a267efff7b831 ("lei up: fix --mua with single output")
---
 lib/PublicInbox/LEI.pm   |  2 +-
 lib/PublicInbox/LeiUp.pm | 86 +++++++++++++++++++++++++---------------
 2 files changed, 56 insertions(+), 32 deletions(-)

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index a1cab55a..1305dfb8 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -1384,7 +1384,7 @@ sub fchdir {
 sub wq_eof { # EOF callback for main daemon
 	my ($lei) = @_;
 	my $wq1 = delete $lei->{wq1} // return $lei->fail; # already failed
-	$wq1->wq_wait_old(\&wq_done_wait, $lei);
+	$wq1->wq_wait_old($wq1->can('_wq_done_wait') // \&wq_done_wait, $lei);
 }
 
 sub watch_state_ok ($) {
diff --git a/lib/PublicInbox/LeiUp.pm b/lib/PublicInbox/LeiUp.pm
index 89cf0112..377a720e 100644
--- a/lib/PublicInbox/LeiUp.pm
+++ b/lib/PublicInbox/LeiUp.pm
@@ -36,7 +36,7 @@ sub up1 ($$) {
 		$lei->{opt}->{$k} //= $v;
 	}
 	my $o = $lei->{opt}->{output} // '';
-	return $lei->fail("lei.q.output unset in $f") if $o eq '';
+	return $lei->fail("lei.q.output unset in $f (out=$out)") if $o eq '';
 	$lss->translate_dedupe($lei) or return;
 	$lei->{lss} = $lss; # for LeiOverview->new and query_remote_mboxrd
 	my $lxs = $lei->lxs_prepare or return;
@@ -44,39 +44,30 @@ sub up1 ($$) {
 	$lei->_start_query;
 }
 
-sub up1_redispatch {
-	my ($lei, $out, $op_p) = @_;
-	my $l;
-	if (defined($lei->{opt}->{mua})) { # single output
-		$l = $lei;
-	} else { # multiple outputs
-		$l = bless { %$lei }, ref($lei);
-		$l->{opt} = { %{$l->{opt}} }; # deep copy
-		delete $l->{opt}->{all};
-		delete $l->{sock}; # do not close
-		# make close($l->{1}) happy in lei->dclose
-		open my $fh, '>&', $l->{1} or
-			return $l->child_error(0, "dup: $!");
-		$l->{1} = $fh;
-		$l->qerr("# updating $out");
-	}
-	$l->{''} = $op_p; # daemon only ($l => $lei => script/lei)
-	eval { $l->dispatch('up', $out) };
-	$lei->child_error(0, $@) if $@ || $l->{failed}; # lei->fail()
-}
-
 sub redispatch_all ($$) {
 	my ($self, $lei) = @_;
+	my $upq = [ (@{$self->{local} // []}, @{$self->{remote} // []}) ];
+	return up1($lei, $upq->[0]) if @$upq == 1; # just one, may start MUA
+
+	# FIXME: this is also used per-query, see lei->_start_query
+	my $j = $lei->{opt}->{jobs} || do {
+		my $n = $self->detect_nproc // 1;
+		$n > 4 ? 4 : $n;
+	};
+	$j = ($j =~ /\A([0-9]+)/) ? $1 + 0 : 1; # may be --jobs=$x,$m on CLI
 	# re-dispatch into our event loop w/o creating an extra fork-level
+	# $upq will be drained via DESTROY as each query finishes
 	$lei->{fmsg} = PublicInbox::LeiFinmsg->new($lei);
 	my ($op_c, $op_p) = PublicInbox::PktOp->pair;
-	for my $o (@{$self->{local} // []}, @{$self->{remote} // []}) {
-		PublicInbox::DS::requeue(sub {
-			up1_redispatch($lei, $o, $op_p);
-		});
+	# call lei->dclose when upq is done processing:
+	$op_c->{ops} = { '' => [ $lei->can('dclose'), $lei ] };
+	my @first_batch = splice(@$upq, 0, $j); # initial parallelism
+	$lei->{-upq} = $upq;
+	$lei->event_step_init; # wait for client disconnects
+	for my $out (@first_batch) {
+		PublicInbox::DS::requeue(
+			PublicInbox::LeiUp1::nxt($lei, $out, $op_p));
 	}
-	$lei->event_step_init;
-	$lei->pkt_ops($op_c->{ops} = { '' => [$lei->can('dclose'), $lei] });
 }
 
 sub lei_up {
@@ -98,7 +89,7 @@ sub lei_up {
 		} else {
 			$lei->fail("only --all=$all not understood");
 		}
-	} elsif ($lei->{lse}) {
+	} elsif ($lei->{lse}) { # redispatched
 		scalar(@outs) == 1 or die "BUG: lse set w/ >1 out[@outs]";
 		return up1($lei, $outs[0]);
 	} else {
@@ -131,16 +122,49 @@ sub net_merge_all_done {
 	my ($self, $lei) = @_;
 	$lei->{net} = delete($self->{-net_new}) if $self->{-net_new};
 	$self->wq_close(1);
-	redispatch_all($self, $lei);
+	eval { redispatch_all($self, $lei) };
+	warn "E: $@" if $@;
 }
 
-sub _complete_up {
+sub _complete_up { # lei__complete hook
 	my ($lei, @argv) = @_;
 	my $match_cb = $lei->complete_url_prepare(\@argv);
 	map { $match_cb->($_) } PublicInbox::LeiSavedSearch::list($lei);
 }
 
+sub _wq_done_wait { # dwaitpid callback
+	my ($arg, $pid) = @_;
+	my ($wq, $lei) = @$arg;
+	$lei->child_error($?, 'auth failure') if $?
+}
+
 no warnings 'once';
 *ipc_atfork_child = \&PublicInbox::LeiInput::input_only_atfork_child;
 
+package PublicInbox::LeiUp1; # for redispatch_all
+use strict;
+use v5.10.1;
+
+sub nxt ($$$) {
+	my ($lei, $out, $op_p) = @_;
+	bless { lei => $lei, out => $out, op_p => $op_p }, __PACKAGE__;
+}
+
+sub event_step { # runs via PublicInbox::DS::requeue
+	my ($self) = @_;
+	my $lei = $self->{lei}; # the original, from lei_up
+	my $l = bless { %$lei }, ref($lei); # per-output copy
+	delete($l->{sock}) or return; # client disconnected if {sock} is gone
+	$l->{opt} = { %{$l->{opt}} }; # deep copy
+	delete $l->{opt}->{all};
+	$l->qerr("# updating $self->{out}");
+	$l->{up_op_p} = $self->{op_p}; # ($l => $lei => script/lei)
+	eval { $l->dispatch('up', $self->{out}) };
+	$lei->child_error(0, $@) if $@ || $l->{failed}; # lei->fail()
+
+	# onto the next:
+	my $out = shift(@{$lei->{-upq}}) or return;
+	PublicInbox::DS::requeue(nxt($lei, $out, $self->{op_p}));
+}
+
 1;