lei: prefer IO::FDPass over our Inline::C recv_3fds

While our recv_3fds() implementation is more efficient
syscall-wise, loading Inline takes nearly 50ms on my machine
even after Inline::C memoizes the build.  The current ~20ms in
the fast path is barely acceptable to me, and 50ms would be
unusable.

Eventually, script/lei may invoke tcc(1) or cc(1) directly in
the fast path, but it needs @INC for the slow path, at least.

We'll encode the number of FDs into the socket name allow
parallel installations, for now.

2 files changed, 9 insertions, 14 deletions

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 6f21da35..f41f63ed 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -660,7 +660,7 @@ sub noop {}
 
 # lei(1) calls this when it can't connect
 sub lazy_start {
-        my ($path, $errno) = @_;
+        my ($path, $errno, $nfd) = @_;
         if ($errno == ECONNREFUSED) {
                 unlink($path) or die "unlink($path): $!";
         } elsif ($errno != ENOENT) {
@@ -675,8 +675,14 @@ sub lazy_start {
         my $dev_ino_expect = pack('dd', $st[0], $st[1]); # dev+ino
         pipe(my ($eof_r, $eof_w)) or die "pipe: $!";
         my $oldset = PublicInbox::Sigfd::block_signals();
-        $recv_3fds = PublicInbox::Spawn->can('recv_3fds') or die
-                "Inline::C not installed/configured or IO::FDPass missing\n";
+        if ($nfd == 1) {
+                require IO::FDPass;
+                $recv_3fds = sub { map { IO::FDPass::recv($_[0]) } (0..2) };
+        } elsif ($nfd == 3) {
+                $recv_3fds = PublicInbox::Spawn->can('recv_3fds');
+        }
+        $recv_3fds or die
+                "IO::FDPass missing or Inline::C not installed/configured\n";
         require PublicInbox::Listener;
         require PublicInbox::EOFpipe;
         (-p STDOUT) or die "E: stdout must be a pipe\n";
diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 61e95433..cd94ba96 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -315,17 +315,6 @@ unless ($set_nodatacow) {
         *nodatacow_fd = \&PublicInbox::NDC_PP::nodatacow_fd;
         *nodatacow_dir = \&PublicInbox::NDC_PP::nodatacow_dir;
 }
-unless (__PACKAGE__->can('recv_3fds')) {
-        eval { # try the XS IO::FDPass package
-                require IO::FDPass;
-                no warnings 'once';
-                *recv_3fds = sub { map { IO::FDPass::recv($_[0]) } (0..2) };
-                *send_3fds = sub ($$$$) {
-                        my $sockfd = shift;
-                        IO::FDPass::send($sockfd, shift) for (0..2);
-                };
-        };
-}
 
 undef $set_nodatacow;
 undef $vfork_spawn;