ci: make sure that only one copy of native_test.v is executed at once, when run through v test vlib (fix #24505)

Author: spytheman

vlib/v/gen/native/macho_test.v

@@ -1,12 +1,18 @@
 import os
 import v.gen.native
 import v.pref
+import log
 
 fn test_macho() {
-	os.chdir(os.temp_dir()) or {}
+	log.info('start')
+	os.chdir(os.vtmp_dir()) or {}
+	log.info('chdir')
 	mut g := native.macho_test_new_gen(&pref.Preferences{
 		arch: .amd64
 	}, 'test.bin')
+	log.info('native.macho_test_new_gen')
 	g.generate_macho_header()
+	log.info('g.generate_macho_header')
 	g.generate_macho_footer()
+	log.info('g.generate_macho_footer')
 }

vlib/v/gen/native/tests/native_test.v

@@ -1,20 +1,36 @@
 // vtest build: (amd64 || arm64) && !self_sandboxed_packaging? && !gcc-windows
+@[has_globals]
+module main
+
 import os
 import time
 import benchmark
 import term
+import log
+import os.filelock
 
 const is_verbose = os.getenv('VTEST_SHOW_CMD') != ''
 const user_os = os.user_os()
 const wrkdir = os.join_path(os.vtmp_dir(), 'native_tests')
 
+const flock_path = os.join_path(os.vtmp_dir(), 'native_tests.lock')
+
+__global flock_singleton = filelock.new(flock_path)
+
 fn testsuite_begin() {
+	log.info(@FN)
+	if !flock_singleton.try_acquire() {
+		log.info('>>>> skipping ${@FILE}, since it has been already started and ${flock_path} is present...')
+		exit(0)
+	}
 	os.mkdir_all(wrkdir) or {}
 	os.chdir(wrkdir) or {}
 }
 
 fn testsuite_end() {
 	os.rmdir_all(wrkdir) or {}
+	flock_singleton.release()
+	log.info(@FN)
 }
 
 // TODO: some logic copy pasted from valgrind_test.v and compiler_test.v, move to a module