--- /dev/null
+# Copyright (C) 2021 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# WQ worker for dealing with parallel Maildir reads;
+# this does NOT use the {shard_info} field of LeiToMail
+# (and we may remove {shard_info})
+# WQ key: {pmd}
+package PublicInbox::LeiPmdir;
+use strict;
+use v5.10.1;
+use parent qw(PublicInbox::IPC);
+
+sub new {
+ my ($cls, $lei, $ipt) = @_;
+ my $self = bless { -wq_ident => 'lei Maildir worker' }, $cls;
+ my $jobs = $lei->{opt}->{jobs};
+ $jobs =~ /\A[0-9]+,([0-9]+)\z/ and $jobs = $1;
+ my $nproc = $jobs // do {
+ # untested with >=4 CPUs, though I suspect I/O latency
+ # of SATA SSD storage will make >=4 processes unnecessary,
+ # here. NVMe users may wish to use '-j'
+ my $n = $self->detect_nproc;
+ $n = 4 if $n > 4;
+ };
+ my ($op_c, $ops) = $lei->workers_start($self, $nproc,
+ undef, { ipt => $ipt }); # LeiInput subclass
+ $op_c->{ops} = $ops; # for PktOp->event_step
+ $lei->{pmd} = $self;
+}
+
+sub ipc_atfork_child {
+ my ($self) = @_;
+ my $lei = $self->{lei};
+ $lei->_lei_atfork_child;
+ my $ipt = $self->{ipt} // die 'BUG: no self->{ipt}';
+ $ipt->{lei} = $lei;
+ $ipt->{sto} = $lei->{sto} // die 'BUG: no lei->{sto}';
+ $ipt->{lse} = $ipt->{sto}->search;
+ $ipt->{over} = $ipt->{lse}->over;
+ $ipt->{-lms_ro} //= $ipt->{lse}->lms; # may be undef or '0'
+ $self->SUPER::ipc_atfork_child;
+}
+
+sub each_mdir_fn { # maildir_each_file callback
+ my ($f, $self, @args) = @_;
+ $self->wq_io_do('mdir_iter', [], $f, @args);
+}
+
+sub mdir_iter { # via wq_io_do
+ my ($self, $f, @args) = @_;
+ $self->{ipt}->pmdir_cb($f, @args);
+}
+
+sub pmd_done_wait {
+ my ($arg, $pid) = @_;
+ my ($self, $lei) = @$arg;
+ my $wait = $lei->{sto}->ipc_do('done');
+ $lei->can('wq_done_wait')->($arg, $pid);
+}
+
+sub _lei_wq_eof { # EOF callback for main lei daemon
+ my ($lei) = @_;
+ my $pmd = delete $lei->{pmd} or return $lei->fail;
+ $pmd->wq_wait_old(\&pmd_done_wait, $lei);
+}
+
+1;