ds: introduce awaitpid, switch ProcessPipe users

[public-inbox.git] / lib / PublicInbox / DS.pm

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index e4629e97acc461aaa2debbe1687db8f0aecab796..9563a1cbbbb5795fc724c9b3d19b8e76dd66a7ab 100644 (file)
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -32,11 +32,12 @@ use PublicInbox::Syscall qw(:epoll);
 use PublicInbox::Tmpfile;
 use Errno qw(EAGAIN EINVAL);
 use Carp qw(carp croak);
-our @EXPORT_OK = qw(now msg_more dwaitpid add_timer add_uniq_timer);
+our @EXPORT_OK = qw(now msg_more dwaitpid awaitpid add_timer add_uniq_timer);
 
 my %Stack;
 my $nextq; # queue for next_tick
 my $wait_pids; # list of [ pid, callback, callback_arg ]
+my $AWAIT_PIDS; # pid => [ $callback, @args ]
 my $reap_armed;
 my $ToClose; # sockets to close when event loop is done
 our (
@@ -74,11 +75,11 @@ sub Reset {
                # we may be iterating inside one of these on our stack
                my @q = delete @Stack{keys %Stack};
                for my $q (@q) { @$q = () }
-               $wait_pids = $nextq = $ToClose = undef;
+               $AWAIT_PIDS = $wait_pids = $nextq = $ToClose = undef;
                $ep_io = undef; # closes real $Epoll FD
                $Epoll = undef; # may call DSKQXS::DESTROY
        } while (@Timers || keys(%Stack) || $nextq || $wait_pids ||
-               $ToClose || keys(%DescriptorMap) ||
+               $ToClose || keys(%DescriptorMap) || $AWAIT_PIDS ||
                $PostLoopCallback || keys(%UniqTimer));
 
        $reap_armed = undef;
@@ -201,6 +202,13 @@ sub block_signals () {
        $oldset;
 }
 
+sub await_cb ($;@) {
+       my ($pid, @cb_args) = @_;
+       my $cb = shift @cb_args or return;
+       eval { $cb->($pid, @cb_args) };
+       warn "E: awaitpid($pid): $@" if $@;
+}
+
 # We can't use waitpid(-1) safely here since it can hit ``, system(),
 # and other things.  So we scan the $wait_pids list, which is hopefully
 # not too big.  We keep $wait_pids small by not calling dwaitpid()
@@ -208,10 +216,12 @@ sub block_signals () {
 
 sub reap_pids {
        $reap_armed = undef;
-       my $tmp = $wait_pids or return;
+       my $tmp = $wait_pids // [];
        $wait_pids = undef;
        $Stack{reap_runq} = $tmp;
        my $oldset = block_signals();
+
+       # old API
        foreach my $ary (@$tmp) {
                my ($pid, $cb, $arg) = @$ary;
                my $ret = waitpid($pid, WNOHANG);
@@ -226,6 +236,14 @@ sub reap_pids {
                        warn "waitpid($pid, WNOHANG) = $ret, \$!=$!, \$?=$?";
                }
        }
+
+       # new API TODO: convert to waitpid(-1) in the future as long
+       # as we don't use threads
+       for my $pid (keys %$AWAIT_PIDS) {
+               my $wpid = waitpid($pid, WNOHANG) // next;
+               my $cb_args = delete $AWAIT_PIDS->{$wpid} or next;
+               await_cb($pid, @$cb_args);
+       }
        sig_setmask($oldset);
        delete $Stack{reap_runq};
 }
@@ -720,6 +738,23 @@ sub dwaitpid ($;$$) {
        }
 }
 
+sub awaitpid {
+       my ($pid, @cb_args) = @_;
+       $AWAIT_PIDS->{$pid} //= @cb_args ? \@cb_args : 0;
+       # provide synchronous API
+       if (defined(wantarray) || (!$in_loop && !@cb_args)) {
+               my $ret = waitpid($pid, 0) // -2;
+               if ($ret == $pid) {
+                       my $cb_args = delete $AWAIT_PIDS->{$pid};
+                       @cb_args = @$cb_args if !@cb_args && $cb_args;
+                       await_cb($pid, @cb_args);
+                       return $ret;
+               }
+       }
+       # We could've just missed our SIGCHLD, cover it, here:
+       enqueue_reap() if $in_loop;
+}
+
 1;
 
 =head1 AUTHORS (Danga::Socket)