tests: simplify the synchronized printing of results, using chan string

cmd/tools/modules/testing/common.v

@@ -8,14 +8,6 @@ import sync
 import v.pref
 import v.util.vtest
 
-pub struct TestMessageHandler {
-mut:
-	messages []string
-pub mut:
-	message_idx int
-	mtx &sync.Mutex
-}
-
 pub struct TestSession {
 pub mut:
 	files         []string
@@ -26,14 +18,24 @@ pub mut:
 	failed        bool
 	benchmark     benchmark.Benchmark
 	show_ok_tests bool
-	message_handler &TestMessageHandler
 	root_relative bool // used by CI runs, so that the output is stable everywhere
+	nmessages chan string // many publishers, single consumer/printer
+	nmessage_idx int // currently printed message index
 }
 
-pub fn (mut mh TestMessageHandler) append_message(msg string) {
-	mh.mtx.m_lock()
-	mh.messages << msg
-	mh.mtx.unlock()
+pub fn (mut ts TestSession) append_message(msg string) {
+	ts.nmessages <- msg
+}
+
+pub fn (mut ts TestSession) print_messages() {
+	for {
+		mut nm := <- ts.nmessages
+		ts.nmessage_idx++
+		msg := nm.replace("TMP1", "${ts.nmessage_idx:1d}").
+			replace("TMP2", "${ts.nmessage_idx:2d}").
+			replace("TMP3", "${ts.nmessage_idx:3d}")
+		eprintln(msg)
+	}
 }
 
 pub fn new_test_session(_vargs string) TestSession {
@@ -53,7 +55,6 @@ pub fn new_test_session(_vargs string) TestSession {
 		skip_files: skip_files
 		vargs: vargs
 		show_ok_tests: !_vargs.contains('-silent')
-		message_handler: &TestMessageHandler(0)
 	}
 }
 
@@ -105,9 +106,9 @@ pub fn (mut ts TestSession) test() {
 		callback: worker_trunner
 	})
 	// for handling messages across threads
-	ts.message_handler = &TestMessageHandler{
-		mtx: sync.new_mutex()
-	}
+	ts.nmessages = chan string{cap: 10000}
+	ts.nmessage_idx = 0
+	go ts.print_messages()
 	pool_of_test_runners.set_shared_context(ts)
 	pool_of_test_runners.work_on_pointers(remaining_files.pointers())
 	ts.benchmark.stop()
@@ -118,25 +119,8 @@ pub fn (mut ts TestSession) test() {
 	}
 }
 
-pub fn (mut m TestMessageHandler) display_message() {
-	m.mtx.m_lock()
-	defer {
-		m.messages.clear()
-		m.mtx.unlock()
-	}
-	for msg in m.messages {
-		m.message_idx++
-		eprintln(msg.
-			replace("TMP1", "${m.message_idx:1d}").
-			replace("TMP2", "${m.message_idx:2d}").
-			replace("TMP3", "${m.message_idx:3d}")
-		)
-	}
-}
-
 fn worker_trunner(mut p sync.PoolProcessor, idx int, thread_id int) voidptr {
 	mut ts := &TestSession(p.get_shared_context())
-	defer { ts.message_handler.display_message() }
 	tmpd := os.temp_dir()
 	show_stats := '-stats' in ts.vargs.split(' ')
 	// tls_bench is used to format the step messages/timings
@@ -172,11 +156,11 @@ fn worker_trunner(mut p sync.PoolProcessor, idx int, thread_id int) voidptr {
 	if relative_file.replace('\\', '/') in ts.skip_files {
 	   ts.benchmark.skip()
 	   tls_bench.skip()
-	   ts.message_handler.append_message(tls_bench.step_message_skip(relative_file))
+	   ts.append_message(tls_bench.step_message_skip(relative_file))
 	   return sync.no_result
 	}
 	if show_stats {
-		ts.message_handler.append_message(term.h_divider('-'))
+		ts.append_message(term.h_divider('-'))
 		status := os.system(cmd)
 		if status == 0 {
 			ts.benchmark.ok()
@@ -194,20 +178,20 @@ fn worker_trunner(mut p sync.PoolProcessor, idx int, thread_id int) voidptr {
 			ts.failed = true
 			ts.benchmark.fail()
 			tls_bench.fail()
-			ts.message_handler.append_message(tls_bench.step_message_fail(relative_file))
+			ts.append_message(tls_bench.step_message_fail(relative_file))
 			return sync.no_result
 		}
 		if r.exit_code != 0 {
 			ts.failed = true
 			ts.benchmark.fail()
 			tls_bench.fail()
-			ts.message_handler.append_message(tls_bench.step_message_fail('${relative_file}\n$r.output\n'))
+			ts.append_message(tls_bench.step_message_fail('${relative_file}\n$r.output\n'))
 		}
 		else {
 			ts.benchmark.ok()
 			tls_bench.ok()
 			if ts.show_ok_tests {
-				ts.message_handler.append_message(tls_bench.step_message_ok(relative_file))
+				ts.append_message(tls_bench.step_message_ok(relative_file))
 			}
 		}
 	}