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.

4 files changed, 27 insertions, 24 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;
diff --git a/script/lei b/script/lei
index 029881f8..2ea98da4 100755
--- a/script/lei
+++ b/script/lei
@@ -4,11 +4,17 @@
 use strict;
 use v5.10.1;
 use Socket qw(AF_UNIX SOCK_STREAM pack_sockaddr_un);
-my $send_3fds;
+my ($send_3fds, $nfd);
 if (my ($sock, $pwd) = eval {
-        require PublicInbox::Spawn;
-        $send_3fds = PublicInbox::Spawn->can('send_3fds') or die
-                "Inline::C not installed/configured or IO::FDPass missing\n";
+        $send_3fds = eval {
+                require IO::FDPass;
+                $nfd = 1; # 1 FD per-sendmsg
+                sub { IO::FDPass::send($_[0], $_[$_]) for (1..3) }
+        } // do {
+                require PublicInbox::Spawn; # takes ~50ms even if built *sigh*
+                $nfd = 3; # 3 FDs per-sendmsg(2)
+                PublicInbox::Spawn->can('send_3fds');
+        } // die "IO::FDPass missing or Inline::C not installed/configured\n";
         my $path = do {
                 my $runtime_dir = ($ENV{XDG_RUNTIME_DIR} // '') . '/lei';
                 if ($runtime_dir eq '/lei') {
@@ -19,7 +25,7 @@ if (my ($sock, $pwd) = eval {
                         require File::Path;
                         File::Path::mkpath($runtime_dir, 0, 0700);
                 }
-                "$runtime_dir/sock";
+                "$runtime_dir/$nfd.sock";
         };
         my $addr = pack_sockaddr_un($path);
         socket(my $sock, AF_UNIX, SOCK_STREAM, 0) or die "socket: $!";
@@ -27,7 +33,7 @@ if (my ($sock, $pwd) = eval {
                 local $ENV{PERL5LIB} = join(':', @INC);
                 open(my $daemon, '-|', $^X, qw[-MPublicInbox::LEI
                         -E PublicInbox::LEI::lazy_start(@ARGV)],
-                        $path, $! + 0) or die "popen: $!";
+                        $path, $! + 0, $nfd) or die "popen: $!";
                 while (<$daemon>) { warn $_ } # EOF when STDERR is redirected
                 close($daemon) or warn <<"";
 lei-daemon could not start, exited with \$?=$?
diff --git a/t/lei.t b/t/lei.t
index 42c0eb8f..5afb8351 100644
--- a/t/lei.t
+++ b/t/lei.t
@@ -193,12 +193,14 @@ if ($ENV{TEST_LEI_ONESHOT}) {
 
 SKIP: { # real socket
         require_mods(qw(Cwd), my $nr = 46);
-        require PublicInbox::Spawn;
-        skip "Inline::C not installed/configured or IO::FDPass missing", $nr
-                unless PublicInbox::Spawn->can('send_3fds');
+        my $nfd = eval { require IO::FDPass; 1 } // do {
+                require PublicInbox::Spawn;
+                PublicInbox::Spawn->can('send_3fds') ? 3 : undef;
+        } //
+        skip 'IO::FDPass missing or Inline::C not installed/configured', $nr;
 
         local $ENV{XDG_RUNTIME_DIR} = "$home/xdg_run";
-        my $sock = "$ENV{XDG_RUNTIME_DIR}/lei/sock";
+        my $sock = "$ENV{XDG_RUNTIME_DIR}/lei/$nfd.sock";
 
         ok($lei->('daemon-pid'), 'daemon-pid');
         is($err, '', 'no error from daemon-pid');