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

[Eric Wong]

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};