[PATCH v2 3/4] lei/store: stop shard workers + cat-file on idle

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

Schedule a timer to stop shard workers and the git-cat-file
process after a `barrier' command.  This allows us to save some
memory again when the lei-daemon is idle but preserves the fork
overhead reduction when issuing many commands in parallel or in
quick succession.
---
  v2 fixes an incorrect call to add_uniq_timer.  Sometimes I wish Perl
  could have more static type||arg checking, but it's probably still
  better than other scripting languages...

Interdiff against v1:
  diff --git a/lib/PublicInbox/LeiStore.pm b/lib/PublicInbox/LeiStore.pm
  index a054f649..b2da2bc3 100644
  --- a/lib/PublicInbox/LeiStore.pm
  +++ b/lib/PublicInbox/LeiStore.pm
  @@ -574,7 +574,7 @@ sub set_xvmd {
   sub check_done {
   	my ($self) = @_;
   	$self->git->_active ?
  -		add_uniq_timer("$self-check_done", \&check_done, $self) :
  +		add_uniq_timer("$self-check_done", 5, \&check_done, $self) :
   		done($self);
   }
   

 lib/PublicInbox/LeiStore.pm | 46 ++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/lib/PublicInbox/LeiStore.pm b/lib/PublicInbox/LeiStore.pm
index 162c915f..b2da2bc3 100644
--- a/lib/PublicInbox/LeiStore.pm
+++ b/lib/PublicInbox/LeiStore.pm
@@ -571,21 +571,11 @@ sub set_xvmd {
 	sto_export_kw($self, $smsg->{num}, $vmd);
 }
 
-sub barrier {
+sub check_done {
 	my ($self) = @_;
-	my ($errfh, $lei_sock) = @$self{0, 1}; # via sto_barrier_request
-	my @err;
-	if ($self->{im}) {
-		eval { $self->{im}->barrier };
-		push(@err, "E: import barrier: $@\n") if $@;
-	}
-	delete $self->{lms};
-	eval { $self->{priv_eidx}->barrier };
-	push(@err, "E: priv_eidx barrier: $@\n") if $@;
-	print { $errfh // \*STDERR } @err;
-	send($lei_sock, 'child_error 256', 0) if @err && $lei_sock;
-	xchg_stderr($self);
-	die @err if @err;
+	$self->git->_active ?
+		add_uniq_timer("$self-check_done", 5, \&check_done, $self) :
+		done($self);
 }
 
 sub xchg_stderr {
@@ -602,23 +592,33 @@ sub xchg_stderr {
 	undef;
 }
 
-sub done {
-	my ($self) = @_;
-	my ($errfh, $lei_sock) = @$self{0, 1};
+sub _commit ($$) {
+	my ($self, $cmd) = @_; # cmd is 'done' or 'barrier'
+	my ($errfh, $lei_sock) = @$self{0, 1}; # via sto_barrier_request
 	my @err;
-	if (my $im = delete($self->{im})) {
-		eval { $im->done };
-		push(@err, "E: import done: $@\n") if $@;
+	if ($self->{im}) {
+		eval { $self->{im}->$cmd };
+		push(@err, "E: import $cmd: $@\n") if $@;
 	}
 	delete $self->{lms};
-	eval { $self->{priv_eidx}->done }; # V2Writable::done
-	push(@err, "E: priv_eidx done: $@\n") if $@;
-	print { $errfh // *STDERR{GLOB} } @err;
+	eval { $self->{priv_eidx}->$cmd };
+	push(@err, "E: priv_eidx $cmd: $@\n") if $@;
+	print { $errfh // \*STDERR } @err;
 	send($lei_sock, 'child_error 256', 0) if @err && $lei_sock;
 	xchg_stderr($self);
 	die @err if @err;
+	# $lei_sock goes out-of-scope and script/lei can terminate
+}
+
+sub barrier {
+	my ($self) = @_;
+	_commit $self, 'barrier';
+	add_uniq_timer("$self-check_done", 5, \&check_done, $self);
+	undef;
 }
 
+sub done { _commit $_[0], 'done' }
+
 sub ipc_atfork_child {
 	my ($self) = @_;
 	my $lei = $self->{lei};