[PATCH 19/22] lei: fork + FD cleanup

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

Do a better job of closing FDs that we don't want shared with
the work queue workers.  We'll also fix naming and use
"atfork_prepare" instead of "atfork_parent" to match
pthread_atfork(3) naming.
---
 lib/PublicInbox/IPC.pm        | 57 +++++++++++++++++++++++------------
 lib/PublicInbox/LEI.pm        | 18 +++++++++--
 lib/PublicInbox/LeiQuery.pm   |  7 +++--
 lib/PublicInbox/LeiXSearch.pm | 11 +++++--
 4 files changed, 68 insertions(+), 25 deletions(-)

diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index 4db4b8ea..88f81e47 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -126,7 +126,7 @@ sub ipc_worker_spawn {
 	pipe(my ($r_res, $w_res)) or die "pipe: $!";
 	my $sigset = $oldset // PublicInbox::DS::block_signals();
 	my $parent = $$;
-	$self->ipc_atfork_parent;
+	$self->ipc_atfork_prepare;
 	defined(my $pid = fork) or die "fork: $!";
 	if ($pid == 0) {
 		eval { PublicInbox::DS->Reset };
@@ -155,8 +155,14 @@ sub ipc_worker_reap { # dwaitpid callback
 }
 
 # for base class, override in sub classes
-sub ipc_atfork_parent {}
-sub ipc_atfork_child {}
+sub ipc_atfork_prepare {}
+
+sub ipc_atfork_child {
+	my ($self) = @_;
+	my $io = delete($self->{-ipc_atfork_child_close}) or return;
+	close($_) for @$io;
+	undef;
+}
 
 # idempotent, can be called regardless of whether worker is active or not
 sub ipc_worker_stop {
@@ -251,14 +257,21 @@ sub ipc_sibling_atfork_child {
 	$pid == $$ and die "BUG: $$ ipc_atfork_child called on itself";
 }
 
+sub _close_recvd ($) {
+	my ($self) = @_;
+	close($_) for (grep { defined } (delete @$self{0..2}));
+}
+
 sub wq_worker_loop ($) {
 	my ($self) = @_;
 	my $buf;
 	my $len = $self->{wq_req_len} // (4096 * 33);
-	my ($rec, $sub, @args);
+	my ($sub, $args);
 	my $s2 = $self->{-wq_s2} // die 'BUG: no -wq_s2';
 	local $SIG{PIPE} = sub {
-		die(bless(\"$_[0]", __PACKAGE__.'::PIPE')) if $sub;
+		my $cur_sub = $sub;
+		_close_recvd($self);
+		die(bless(\$cur_sub, __PACKAGE__.'::PIPE')) if $cur_sub;
 	};
 	my $rcv = $self->{-wq_recv_cmd} // $recv_cmd;
 	while (1) {
@@ -267,22 +280,25 @@ sub wq_worker_loop ($) {
 		my @m = @{$self->{wq_open_modes} // [qw( +<&= >&= >&= )]};
 		for my $fd (@fds) {
 			my $mode = shift(@m);
-			if (open(my $fh, $mode, $fd)) {
-				$self->{$i++} = $fh;
-				$fh->autoflush(1);
+			if (open(my $cmdfh, $mode, $fd)) {
+				$self->{$i++} = $cmdfh;
+				$cmdfh->autoflush(1);
 			} else {
 				die "$$ open($mode$fd) (FD:$i): $!";
 			}
 		}
-		# Sereal dies, Storable returns undef
-		$rec = thaw($buf) //
+		# Sereal dies on truncated data, Storable returns undef
+		$args = thaw($buf) //
 			die "thaw error on buffer of size:".length($buf);
-		($sub, @args) = @$rec;
-		eval { $self->$sub(@args) };
+		eval {
+			$sub = shift @$args;
+			eval { $self->$sub(@$args) };
+			undef $sub; # quiet SIG{PIPE} handler
+			die $@ if $@;
+		};
 		warn "$$ wq_worker: $@" if $@ && ref $@ ne __PACKAGE__.'::PIPE';
-		undef $sub; # quiet SIG{PIPE} handler
 		# need to close explicitly to avoid warnings after SIGPIPE
-		close($_) for (delete(@$self{0..2}));
+		_close_recvd($self);
 	}
 }
 
@@ -306,14 +322,17 @@ sub _wq_worker_start ($$) {
 		eval { PublicInbox::DS->Reset };
 		close(delete $self->{-wq_s1});
 		delete $self->{qw(-wq_workers -wq_ppid)};
-		$SIG{$_} = 'IGNORE' for (qw(TTOU TTIN));
-		$SIG{$_} = 'DEFAULT' for (qw(TERM QUIT INT));
+		$SIG{$_} = 'IGNORE' for (qw(PIPE TTOU TTIN));
+		$SIG{$_} = 'DEFAULT' for (qw(TERM QUIT INT CHLD));
 		local $0 = $self->{-wq_ident};
 		PublicInbox::DS::sig_setmask($oldset);
+		# ensure we properly exit even if warn() dies:
+		my $end = PublicInbox::OnDestroy->new($$, sub { exit(!!$@) });
 		my $on_destroy = $self->ipc_atfork_child;
 		eval { wq_worker_loop($self) };
 		warn "worker $self->{-wq_ident} PID:$$ died: $@" if $@;
-		exit($@ ? 1 : 0);
+		undef $on_destroy;
+		undef $end; # trigger exit
 	} else {
 		$self->{-wq_workers}->{$pid} = \undef;
 	}
@@ -326,7 +345,7 @@ sub wq_workers_start {
 	return if $self->{-wq_s1}; # idempotent
 	my ($s1, $s2);
 	socketpair($s1, $s2, AF_UNIX, $SEQPACKET, 0) or die "socketpair: $!";
-	$self->ipc_atfork_parent;
+	$self->ipc_atfork_prepare;
 	$nr_workers //= 4;
 	$nr_workers = $WQ_MAX_WORKERS if $nr_workers > $WQ_MAX_WORKERS;
 	my $sigset = $oldset // PublicInbox::DS::block_signals();
@@ -343,7 +362,7 @@ sub wq_worker_incr { # SIGTTIN handler
 	my ($self, $oldset) = @_;
 	$self->{-wq_s2} or return;
 	return if wq_workers($self) >= $WQ_MAX_WORKERS;
-	$self->ipc_atfork_parent;
+	$self->ipc_atfork_prepare;
 	my $sigset = $oldset // PublicInbox::DS::block_signals();
 	_wq_worker_start($self, $sigset);
 	PublicInbox::DS::sig_setmask($sigset) unless $oldset;
diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 0cbf342c..1ef0cbec 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -33,6 +33,7 @@ my $GLP_PASS = Getopt::Long::Parser->new;
 $GLP_PASS->configure(qw(gnu_getopt no_ignore_case auto_abbrev pass_through));
 
 our %PATH2CFG; # persistent for socket daemon
+our @TO_CLOSE_ATFORK_CHILD;
 
 # TBD: this is a documentation mechanism to show a subcommand
 # (may) pass options through to another command:
@@ -266,12 +267,20 @@ sub fail ($$;$) {
 	undef;
 }
 
+sub atfork_prepare_wq {
+	my ($self, $wq) = @_;
+	push @{$wq->{-ipc_atfork_child_close}}, @TO_CLOSE_ATFORK_CHILD,
+				grep { defined } @$self{qw(0 1 2 sock)}
+}
+
 # usage: local %SIG = (%SIG, $lei->atfork_child_wq($wq));
 sub atfork_child_wq {
 	my ($self, $wq) = @_;
 	$self->{sock} //= $wq->{0};
 	$self->{$_} //= $wq->{$_} for (0..2);
 	my $oldpipe = $SIG{PIPE};
+	%PATH2CFG = ();
+	@TO_CLOSE_ATFORK_CHILD = ();
 	(
 		__WARN__ => sub { err($self, @_) },
 		PIPE => sub {
@@ -281,11 +290,14 @@ sub atfork_child_wq {
 	);
 }
 
-# usage: ($lei, @io) = $lei->atfork_prepare_wq($wq);
-sub atfork_prepare_wq {
+# usage: ($lei, @io) = $lei->atfork_parent_wq($wq);
+sub atfork_parent_wq {
 	my ($self, $wq) = @_;
 	if ($wq->wq_workers) {
+		my $env = delete $self->{env}; # env is inherited at fork
 		my $ret = bless { %$self }, ref($self);
+		$self->{env} = $env;
+		delete @$ret{qw(-lei_store cfg)};
 		my $in = delete $ret->{0};
 		($ret, delete($ret->{sock}) // $in, delete @$ret{1, 2});
 	} else {
@@ -738,6 +750,7 @@ sub lazy_start {
 	return if $pid;
 	$0 = "lei-daemon $path";
 	local %PATH2CFG;
+	local @TO_CLOSE_ATFORK_CHILD = ($l, $eof_r, $eof_w);
 	$_->blocking(0) for ($l, $eof_r, $eof_w);
 	$l = PublicInbox::Listener->new($l, \&accept_dispatch, $l);
 	my $exit_code;
@@ -764,6 +777,7 @@ sub lazy_start {
 	local %SIG = (%SIG, %$sig) if !$sigfd;
 	local $SIG{PIPE} = 'IGNORE';
 	if ($sigfd) { # TODO: use inotify/kqueue to detect unlinked sockets
+		push @TO_CLOSE_ATFORK_CHILD, $sigfd->{sock};
 		PublicInbox::DS->SetLoopTimeout(5000);
 	} else {
 		# wake up every second to accept signals if we don't
diff --git a/lib/PublicInbox/LeiQuery.pm b/lib/PublicInbox/LeiQuery.pm
index d5376be5..9a383cef 100644
--- a/lib/PublicInbox/LeiQuery.pm
+++ b/lib/PublicInbox/LeiQuery.pm
@@ -66,7 +66,7 @@ sub lei_q {
 
 	# --local is enabled by default
 	# src: LeiXSearch || LeiSearch || Inbox
-	my @srcs = $opt->{'local'} ? ($sto->search) : ();
+	my @srcs;
 	require PublicInbox::LeiXSearch;
 	my $lxs = PublicInbox::LeiXSearch->new;
 
@@ -74,12 +74,15 @@ sub lei_q {
 	if ($opt->{external} // 1) {
 		$self->_externals_each(\&_vivify_external, \@srcs);
 	}
-	my $j = $opt->{jobs} // scalar(@srcs) > 4 ? 4 : scalar(@srcs);
+	my $j = $opt->{jobs} // scalar(@srcs) > 3 ? 3 : scalar(@srcs);
 	$j = 1 if !$opt->{thread};
+	$j++ if $opt->{'local'}; # for sto->search below
 	if ($self->{sock}) {
+		$self->atfork_prepare_wq($lxs);
 		$lxs->wq_workers_start('lei_xsearch', $j, $self->oldset)
 			// $self->wq_workers($j);
 	}
+	unshift(@srcs, $sto->search) if $opt->{'local'};
 	my $out = $opt->{output} // '-';
 	$out = 'json:/dev/stdout' if $out eq '-';
 	my $isatty = -t $self->{1};
diff --git a/lib/PublicInbox/LeiXSearch.pm b/lib/PublicInbox/LeiXSearch.pm
index c0df21a8..b4172734 100644
--- a/lib/PublicInbox/LeiXSearch.pm
+++ b/lib/PublicInbox/LeiXSearch.pm
@@ -9,6 +9,7 @@ use strict;
 use v5.10.1;
 use parent qw(PublicInbox::LeiSearch PublicInbox::IPC);
 use PublicInbox::Search qw(get_pct);
+use Sys::Syslog qw(syslog);
 
 sub new {
 	my ($class) = @_;
@@ -92,13 +93,13 @@ sub _mset_more ($$) {
 
 sub query_thread_mset { # for --thread
 	my ($self, $lei, $ibxish) = @_;
+	local %SIG = (%SIG, $lei->atfork_child_wq($self));
 	my ($srch, $over) = ($ibxish->search, $ibxish->over);
 	unless ($srch && $over) {
 		my $desc = $ibxish->{inboxdir} // $ibxish->{topdir};
 		warn "$desc not indexed by Xapian\n";
 		return;
 	}
-	local %SIG = (%SIG, $lei->atfork_child_wq($self));
 	my $mo = { %{$lei->{mset_opt}} };
 	my $mset;
 	do {
@@ -145,7 +146,7 @@ sub query_mset { # non-parallel for non-"--thread" users
 
 sub do_query {
 	my ($self, $lei_orig, $srcs) = @_;
-	my ($lei, @io) = $lei_orig->atfork_prepare_wq($self);
+	my ($lei, @io) = $lei_orig->atfork_parent_wq($self);
 	$io[1]->autoflush(1);
 	$io[2]->autoflush(1);
 	if ($lei->{opt}->{thread}) {
@@ -161,4 +162,10 @@ sub do_query {
 	}
 }
 
+sub ipc_atfork_child {
+	my ($self) = @_;
+	$SIG{__WARN__} = sub { syslog('warning', "@_") };
+	$self->SUPER::ipc_atfork_child; # PublicInbox::IPC
+}
+
 1;