[PATCH 3/3] xap_client: spawn C++ xap_helper directly

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

No need to suffer through slow Perl load times when we can build
in the parent Perl process and get the executable path name to
pass to spawn directly.
---
 lib/PublicInbox/XapClient.pm    | 28 ++++++++++++++--------------
 lib/PublicInbox/XapHelperCxx.pm |  9 ++++-----
 t/xap_helper.t                  | 22 +++++++++-------------
 3 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/lib/PublicInbox/XapClient.pm b/lib/PublicInbox/XapClient.pm
index 21c89265..dda5e044 100644
--- a/lib/PublicInbox/XapClient.pm
+++ b/lib/PublicInbox/XapClient.pm
@@ -11,7 +11,7 @@ use v5.12;
 use PublicInbox::Spawn qw(spawn);
 use Socket qw(AF_UNIX SOCK_SEQPACKET);
 use PublicInbox::IPC;
-use autodie qw(pipe socketpair);
+use autodie qw(fork pipe socketpair);
 
 sub mkreq {
 	my ($self, $ios, @arg) = @_;
@@ -28,19 +28,19 @@ sub mkreq {
 sub start_helper {
 	my @argv = @_;
 	socketpair(my $sock, my $in, AF_UNIX, SOCK_SEQPACKET, 0);
-	my $cls = ($ENV{PI_NO_CXX} ? undef : eval {
-			require PublicInbox::XapHelperCxx;
-			PublicInbox::XapHelperCxx::check_build();
-			'PublicInbox::XapHelperCxx';
-		}) // do {
-			require PublicInbox::XapHelper;
-			'PublicInbox::XapHelper';
-		};
-	# ensure the child process has the same @INC we do:
-	my $env = { PERL5LIB => join(':', @INC) };
-	my $pid = spawn([$^X, ($^W ? ('-w') : ()), "-M$cls", '-e',
-				$cls.'::start(@ARGV)', '--', @argv],
-			$env, { 0 => $in });
+	require PublicInbox::XapHelperCxx;
+	my $cls = 'PublicInbox::XapHelperCxx';
+	my $env;
+	my $cmd = eval { PublicInbox::XapHelperCxx::cmd() };
+	if ($@) { # fall back to Perl + XS|SWIG
+		require PublicInbox::XapHelper;
+		$cls = 'PublicInbox::XapHelper';
+		# ensure the child process has the same @INC we do:
+		$env = { PERL5LIB => join(':', @INC) };
+		$cmd = [$^X, ($^W ? ('-w') : ()), "-M$cls", '-e',
+			$cls.'::start(@ARGV)', '--' ];
+	}
+	my $pid = spawn($cmd, $env, { 0 => $in });
 	((bless { io => $sock, impl => $cls }, __PACKAGE__), $pid);
 }
 
diff --git a/lib/PublicInbox/XapHelperCxx.pm b/lib/PublicInbox/XapHelperCxx.pm
index 88a83438..e257fb6e 100644
--- a/lib/PublicInbox/XapHelperCxx.pm
+++ b/lib/PublicInbox/XapHelperCxx.pm
@@ -113,17 +113,16 @@ sub check_build () {
 	needs_rebuild() ? build() : 0;
 }
 
-sub start (@) {
+# returns spawn arg
+sub cmd {
 	check_build();
 	my @cmd;
 	if (my $v = $ENV{VALGRIND}) {
 		$v = 'valgrind -v' if $v eq '1';
 		@cmd = split(/\s+/, $v);
 	}
-	push @cmd, $bin, @_;
-	my $prog = $cmd[0];
-	$cmd[0] =~ s!\A.*?/([^/]+)\z!$1!;
-	exec { $prog } @cmd;
+	push @cmd, $bin;
+	\@cmd;
 }
 
 1;
diff --git a/t/xap_helper.t b/t/xap_helper.t
index 7890392d..83f59d7d 100644
--- a/t/xap_helper.t
+++ b/t/xap_helper.t
@@ -61,11 +61,11 @@ my $doreq = sub {
 
 my $env = { PERL5LIB => join(':', @INC) };
 my $test = sub {
-	my (@arg) = @_;
+	my (@cmd) = @_;
 	socketpair(my $s, my $y, AF_UNIX, SOCK_SEQPACKET, 0);
-	my $pid = spawn([$^X, '-w', @arg], $env, { 0 => $y });
+	my $pid = spawn(\@cmd, $env, { 0 => $y });
 	my $ar = PublicInbox::AutoReap->new($pid);
-	diag "$arg[-1] running pid=$pid";
+	diag "$cmd[-1] running pid=$pid";
 	close $y;
 	my $r = $doreq->($s, qw(test_inspect -d), $ibx_idx[0]);
 	my %info = map { split(/=/, $_, 2) } split(/ /, do { local $/; <$r> });
@@ -141,24 +141,20 @@ my $test = sub {
 
 my @NO_CXX = (1);
 unless ($ENV{TEST_XH_CXX_ONLY}) {
-	my $ar = $test->(qw[-MPublicInbox::XapHelper -e
+	my $ar = $test->($^X, qw[-w -MPublicInbox::XapHelper -e
 			PublicInbox::XapHelper::start('-j0')]);
-	($ar, my $s) = $test->(qw[-MPublicInbox::XapHelper -e
+	($ar, my $s) = $test->($^X, qw[-w -MPublicInbox::XapHelper -e
 			PublicInbox::XapHelper::start('-j1')]);
 	no_pollerfd($ar->{pid});
 }
 SKIP: {
-	eval {
-		require PublicInbox::XapHelperCxx;
-		PublicInbox::XapHelperCxx::check_build();
-	};
+	require PublicInbox::XapHelperCxx;
+	my $cmd = eval { PublicInbox::XapHelperCxx::cmd() };
 	skip "XapHelperCxx build: $@", 1 if $@ || $ENV{PI_NO_CXX};
 
 	@NO_CXX = $ENV{TEST_XH_CXX_ONLY} ? (0) : (0, 1);
-	my $ar = $test->(qw[-MPublicInbox::XapHelperCxx -e
-			PublicInbox::XapHelperCxx::start('-j0')]);
-	$ar = $test->(qw[-MPublicInbox::XapHelperCxx -e
-			PublicInbox::XapHelperCxx::start('-j1')]);
+	my $ar = $test->(@$cmd, '-j0');
+	$ar = $test->(@$cmd, '-j1');
 };
 
 require PublicInbox::CodeSearch;