lei: fork + FD cleanup

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.

1 files changed, 38 insertions, 19 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;