+# Copyright (C) all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# internal command for dealing with inotify, kqueue vnodes, etc
+package PublicInbox::LeiNoteEvent;
+use strict;
+use v5.10.1;
+use parent qw(PublicInbox::IPC);
+
+my $flush_timer;
+our $to_flush; # { cfgpath => $lei }
+
+sub flush_lei ($) {
+ my ($lei) = @_;
+ if (my $lne = delete $lei->{cfg}->{-lei_note_event}) {
+ $lne->wq_close(1, undef, $lei); # runs _lei_wq_eof;
+ } else { # lms_clear_src calls only:
+ my $wait = $lei->{sto}->ipc_do('done');
+ }
+}
+
+# we batch up writes and flush every 5s (matching Linux default
+# writeback behavior) since MUAs can trigger a storm of inotify events
+sub flush_task { # PublicInbox::DS timer callback
+ undef $flush_timer;
+ my $todo = $to_flush // return;
+ $to_flush = undef;
+ for my $lei (values %$todo) { flush_lei($lei) }
+}
+
+# sets a timer to flush
+sub note_event_arm_done ($) {
+ my ($lei) = @_;
+ $flush_timer //= PublicInbox::DS::add_timer(5, \&flush_task);
+ $to_flush->{$lei->{cfg}->{'-f'}} //= $lei;
+}
+
+sub eml_event ($$$$) {
+ my ($self, $eml, $kw, $state) = @_;
+ my $sto = $self->{lei}->{sto};
+ my $lse = $self->{lse} //= $sto->search;
+ my $vmd = { kw => $kw };
+ if ($state =~ /\Aimport-(?:rw|ro)\z/) {
+ $sto->ipc_do('set_eml', $eml, $vmd);
+ } elsif ($state =~ /\Aindex-(?:rw|ro)\z/) {
+ my $xoids = $self->{lei}->ale->xoids_for($eml);
+ $sto->ipc_do('index_eml_only', $eml, $vmd, $xoids);
+ } elsif ($state =~ /\Atag-(?:rw|ro)\z/) {
+ my $c = $lse->kw_changed($eml, $kw, my $docids = []);
+ if (scalar @$docids) { # already in lei/store
+ $sto->ipc_do('set_eml_vmd', undef, $vmd, $docids) if $c;
+ } elsif (my $xoids = $self->{lei}->ale->xoids_for($eml)) {
+ # it's in an external, only set kw, here
+ $sto->ipc_do('set_xvmd', $xoids, $eml, $vmd);
+ } # else { totally unknown
+ } else {
+ warn "unknown state: $state (in $self->{lei}->{cfg}->{'-f'})\n";
+ }
+}
+
+sub maildir_event { # via wq_io_do
+ my ($self, $fn, $kw, $state) = @_;
+ my $eml = PublicInbox::InboxWritable::eml_from_path($fn) // return;
+ eml_event($self, $eml, $kw, $state);
+}
+
+sub lei_note_event {
+ my ($lei, $folder, $new_cur, $bn, $fn, @rest) = @_;
+ die "BUG: unexpected: @rest" if @rest;
+ my $cfg = $lei->_lei_cfg or return; # gone (race)
+ my $sto = $lei->_lei_store or return; # gone
+ return flush_lei($lei) if $folder eq 'done'; # special case
+ my $lms = $sto->search->lms or return;
+ my $err = $lms->arg2folder($lei, [ $folder ]);
+ return if $err->{fail};
+ undef $lms;
+ my $state = $cfg->get_1("watch.$folder", 'state') // 'pause';
+ return if $state eq 'pause';
+ $lei->ale; # prepare
+ $sto->write_prepare($lei);
+ if ($new_cur eq '') {
+ $sto->ipc_do('lms_clear_src', $folder, \$bn);
+ return note_event_arm_done($lei);
+ }
+ require PublicInbox::MdirReader;
+ my $self = $cfg->{-lei_note_event} //= do {
+ my $wq = bless {}, __PACKAGE__;
+ # MUAs such as mutt can trigger massive rename() storms so
+ # use all CPU power available:
+ my $jobs = $wq->detect_nproc // 1;
+ my ($op_c, $ops) = $lei->workers_start($wq, $jobs);
+ $lei->wait_wq_events($op_c, $ops);
+ note_event_arm_done($lei);
+ $lei->{lne} = $wq;
+ };
+ if ($folder =~ /\Amaildir:/i) {
+ my $fl = PublicInbox::MdirReader::maildir_basename_flags($bn)
+ // return;
+ return if index($fl, 'T') >= 0;
+ my $kw = PublicInbox::MdirReader::flags2kw($fl);
+ $self->wq_io_do('maildir_event', [], $fn, $kw, $state);
+ } # else: TODO: imap
+}
+
+sub ipc_atfork_child {
+ my ($self) = @_;
+ $self->{lei}->_lei_atfork_child(1); # persistent, for a while
+ $self->SUPER::ipc_atfork_child;
+}
+
+sub lne_done_wait {
+ my ($arg, $pid) = @_;
+ my ($self, $lei) = @$arg;
+ $lei->can('wq_done_wait')->($arg, $pid);
+}
+
+sub _lei_wq_eof { # EOF callback for main lei daemon
+ my ($lei) = @_;
+ my $lne = delete $lei->{lne} or return $lei->fail;
+ my $wait = $lei->{sto}->ipc_do('done');
+ $lne->wq_wait_old(\&lne_done_wait, $lei);
+}
+
+1;