lei: use ->barrier to commit to lei/store

barrier (synchronous checkpoint) is better than ->done with
parallel lei commands being issued (via '&' or different
terminals), since repeatedly stopping and restarting processes
doesn't play nicely with expensive tasks like `lei reindex'.

This introduces a slight regression in maintaining more
processes (and thus resource use) when lei is idle, but that'll
be fixed in the next commit.

8 files changed, 30 insertions, 18 deletions

diff --git a/lib/PublicInbox/ExtSearchIdx.pm b/lib/PublicInbox/ExtSearchIdx.pm
index ebbffffc..763a124c 100644
--- a/lib/PublicInbox/ExtSearchIdx.pm
+++ b/lib/PublicInbox/ExtSearchIdx.pm
@@ -1424,5 +1424,6 @@ no warnings 'once';
 *idx_shard = \&PublicInbox::V2Writable::idx_shard;
 *reindex_checkpoint = \&PublicInbox::V2Writable::reindex_checkpoint;
 *checkpoint = \&PublicInbox::V2Writable::checkpoint;
+*barrier = \&PublicInbox::V2Writable::barrier;
 
 1;
diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 5b46686a..e9a0de6c 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -1443,7 +1443,7 @@ sub wq_eof { # EOF callback for main daemon
         my ($lei, $wq_fld) = @_;
         local $current_lei = $lei;
         my $wq = delete $lei->{$wq_fld // 'wq1'};
-        $lei->sto_done_request($wq);
+        $lei->sto_barrier_request($wq);
         $wq // $lei->fail; # already failed
 }
 
@@ -1548,7 +1548,7 @@ sub lms {
         (-f $f || $creat) ? PublicInbox::LeiMailSync->new($f) : undef;
 }
 
-sub sto_done_request {
+sub sto_barrier_request {
         my ($lei, $wq) = @_;
         return unless $lei->{sto} && $lei->{sto}->{-wq_s1};
         local $current_lei = $lei;
@@ -1558,7 +1558,7 @@ sub sto_done_request {
                 my $s = ($wq ? $wq->{lei_sock} : undef) // $lei->{sock};
                 my $errfh = $lei->{2} // *STDERR{GLOB};
                 my @io = $s ? ($errfh, $s) : ($errfh);
-                eval { $lei->{sto}->wq_io_do('done', \@io) };
+                eval { $lei->{sto}->wq_io_do('barrier', \@io, 1) };
         }
         warn($@) if $@;
 }
diff --git a/lib/PublicInbox/LeiInput.pm b/lib/PublicInbox/LeiInput.pm
index d003d983..c388f7dc 100644
--- a/lib/PublicInbox/LeiInput.pm
+++ b/lib/PublicInbox/LeiInput.pm
@@ -499,7 +499,7 @@ sub process_inputs {
         }
         # always commit first, even on error partial work is acceptable for
         # lei <import|tag|convert>
-        $self->{lei}->sto_done_request;
+        $self->{lei}->sto_barrier_request;
         $self->{lei}->fail($err) if $err;
 }
 
diff --git a/lib/PublicInbox/LeiRefreshMailSync.pm b/lib/PublicInbox/LeiRefreshMailSync.pm
index a60a9a5e..dde23274 100644
--- a/lib/PublicInbox/LeiRefreshMailSync.pm
+++ b/lib/PublicInbox/LeiRefreshMailSync.pm
@@ -60,7 +60,7 @@ sub input_path_url { # overrides PublicInbox::LeiInput::input_path_url
                         $self->folder_missing($$uri);
                 }
         } else { die "BUG: $input not supported" }
-        $self->{lei}->sto_done_request;
+        $self->{lei}->sto_barrier_request;
 }
 
 sub lei_refresh_mail_sync {
diff --git a/lib/PublicInbox/LeiRemote.pm b/lib/PublicInbox/LeiRemote.pm
index ddcaf2c9..d6fc40a4 100644
--- a/lib/PublicInbox/LeiRemote.pm
+++ b/lib/PublicInbox/LeiRemote.pm
@@ -1,4 +1,4 @@
-# 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>
 
 # Make remote externals HTTP(S) inboxes behave like
@@ -51,7 +51,7 @@ sub mset {
         $fh = IO::Uncompress::Gunzip->new($fh, MultiStream=>1, AutoClose=>1);
         eval { PublicInbox::MboxReader->mboxrd($fh, \&each_mboxrd_eml, $self) };
         my $err = $@ ? ": $@" : '';
-        my $wait = $self->{lei}->{sto}->wq_do('done');
+        my $wait = $self->{lei}->{sto}->wq_do('barrier');
         $lei->child_error($?, "@$cmd failed$err") if $err || $?;
         $self; # we are the mset (and $ibx, and $self)
 }
diff --git a/lib/PublicInbox/LeiStore.pm b/lib/PublicInbox/LeiStore.pm
index 0df2352c..162c915f 100644
--- a/lib/PublicInbox/LeiStore.pm
+++ b/lib/PublicInbox/LeiStore.pm
@@ -81,7 +81,7 @@ sub importer {
                 delete $self->{im};
                 $im->done;
                 undef $im;
-                $self->checkpoint;
+                $self->barrier;
                 $max = $self->{priv_eidx}->{mg}->git_epochs + 1;
         }
         my (undef, $tl) = eidx_init($self); # acquire lock
@@ -118,7 +118,7 @@ sub cat_blob {
 
 sub schedule_commit {
         my ($self, $sec) = @_;
-        add_uniq_timer($self->{priv_eidx}->{topdir}, $sec, \&done, $self);
+        add_uniq_timer($self->{priv_eidx}->{topdir}, $sec, \&barrier, $self);
 }
 
 # follows the stderr file
@@ -391,7 +391,7 @@ sub reindex_done {
         my ($self) = @_;
         my ($eidx, $tl) = eidx_init($self);
         $eidx->git->async_wait_all;
-        # ->done to be called via sto_done_request
+        # ->done to be called via sto_barrier_request
 }
 
 sub add_eml {
@@ -571,11 +571,21 @@ sub set_xvmd {
         sto_export_kw($self, $smsg->{num}, $vmd);
 }
 
-sub checkpoint {
-        my ($self, $wait) = @_;
-        $self->{im}->barrier if $self->{im};
+sub barrier {
+        my ($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};
-        $self->{priv_eidx}->checkpoint($wait);
+        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;
 }
 
 sub xchg_stderr {
@@ -594,7 +604,7 @@ sub xchg_stderr {
 
 sub done {
         my ($self) = @_;
-        my ($errfh, $lei_sock) = @$self{0, 1}; # via sto_done_request
+        my ($errfh, $lei_sock) = @$self{0, 1};
         my @err;
         if (my $im = delete($self->{im})) {
                 eval { $im->done };
diff --git a/lib/PublicInbox/LeiToMail.pm b/lib/PublicInbox/LeiToMail.pm
index dfae29e9..593547f6 100644
--- a/lib/PublicInbox/LeiToMail.pm
+++ b/lib/PublicInbox/LeiToMail.pm
@@ -724,8 +724,9 @@ sub post_augment {
         my ($self, $lei, @args) = @_;
         $self->{-au_noted}++ and $lei->qerr("# writing to $self->{dst} ...");
 
+        # FIXME: this synchronous wait can be slow w/ parallel callers
         my $wait = $lei->{opt}->{'import-before'} ?
-                        $lei->{sto}->wq_do('checkpoint', 1) : 0;
+                        $lei->{sto}->wq_do('barrier') : 0;
         # _post_augment_mbox
         my $m = $self->can("_post_augment_$self->{base_type}") or return;
         $m->($self, $lei, @args);
diff --git a/lib/PublicInbox/LeiXSearch.pm b/lib/PublicInbox/LeiXSearch.pm
index d4f34733..5a5a1adc 100644
--- a/lib/PublicInbox/LeiXSearch.pm
+++ b/lib/PublicInbox/LeiXSearch.pm
@@ -363,7 +363,7 @@ print STDERR $_;
                                                 $self, $lei, $each_smsg);
                 };
                 my ($exc, $code) = ($@, $?);
-                $lei->sto_done_request if delete($self->{-sto_imported});
+                $lei->sto_barrier_request if delete($self->{-sto_imported});
                 die "E: $exc" if $exc && !$code;
                 my $nr = delete $lei->{-nr_remote_eml} // 0;
                 if (!$code) { # don't update if no results, maybe MTA is down
@@ -399,7 +399,7 @@ sub query_done { # EOF callback for main daemon
         delete $lei->{lxs};
         ($lei->{opt}->{'mail-sync'} && !$lei->{sto}) and
                 warn "BUG: {sto} missing with --mail-sync";
-        $lei->sto_done_request;
+        $lei->sto_barrier_request;
         $lei->{ovv}->ovv_end($lei);
         if ($l2m) { # close() calls LeiToMail reap_compress
                 $l2m->finish_output($lei);