sync: move sync.atomic2 to sync.stdatomic, cleanup

vlib/sync/stdatomic/atomic_test.v

@@ -0,0 +1,103 @@
+import sync
+import sync.stdatomic
+
+const iterations_per_cycle = 100_000
+
+struct Counter {
+mut:
+	counter u64
+}
+
+// without proper syncronization this would fail
+fn test_count_10_times_1_cycle_should_result_10_cycles_with_sync() {
+	desired_iterations := 10 * iterations_per_cycle
+	mut wg := sync.new_waitgroup()
+	mut counter := &Counter{}
+	wg.add(10)
+	for i := 0; i < 10; i++ {
+		go count_one_cycle(mut counter, mut wg)
+	}
+	wg.wait()
+	assert counter.counter == desired_iterations
+	eprintln('   with synchronization the counter is: ${counter.counter:10} , expectedly == ${desired_iterations:10}')
+}
+
+// This test just to make sure that we have an anti-test to prove it works
+fn test_count_10_times_1_cycle_should_not_be_10_cycles_without_sync() {
+	desired_iterations := 10 * iterations_per_cycle
+	mut wg := sync.new_waitgroup()
+	mut counter := &Counter{}
+	wg.add(10)
+	for i := 0; i < 10; i++ {
+		go count_one_cycle_without_sync(mut counter, mut wg)
+	}
+	wg.wait()
+	// NB: we do not assert here, just print, because sometimes by chance counter.counter may be == desired_iterations
+	eprintln('without synchronization the counter is: ${counter.counter:10} , expectedly != ${desired_iterations:10}')
+}
+
+fn test_atomic_count_plus_one_u64() {
+	mut c := u64(0)
+	stdatomic.add_u64(&c, 1)
+	assert stdatomic.load_u64(&c) == 1
+}
+
+fn test_atomic_count_plus_one_i64() {
+	mut c := i64(0)
+	stdatomic.add_i64(&c, 1)
+	assert stdatomic.load_i64(&c) == 1
+}
+
+fn test_atomic_count_plus_greater_than_one_u64() {
+	mut c := u64(0)
+	stdatomic.add_u64(&c, 10)
+	assert stdatomic.load_u64(&c) == 10
+}
+
+fn test_atomic_count_plus_greater_than_one_i64() {
+	mut c := i64(0)
+	stdatomic.add_i64(&c, 10)
+	assert stdatomic.load_i64(&c) == 10
+}
+
+fn test_atomic_count_minus_one_u64() {
+	mut c := u64(1)
+	stdatomic.sub_u64(&c, 1)
+	assert stdatomic.load_u64(&c) == 0
+}
+
+fn test_atomic_count_minus_one_i64() {
+	mut c := i64(0)
+	stdatomic.sub_i64(&c, 1)
+	assert stdatomic.load_i64(&c) == -1
+}
+
+fn test_atomic_count_minus_greater_than_one_u64() {
+	mut c := u64(0)
+	stdatomic.store_u64(&c, 10)
+	stdatomic.sub_u64(&c, 10)
+	assert stdatomic.load_u64(&c) == 0
+}
+
+fn test_atomic_count_minus_greater_than_one_i64() {
+	mut c := i64(0)
+	stdatomic.store_i64(&c, 10)
+	stdatomic.sub_i64(&c, 20)
+	assert stdatomic.load_i64(&c) == -10
+}
+
+// count_one_cycle counts the common counter iterations_per_cycle times in thread-safe way
+fn count_one_cycle(mut counter Counter, mut group sync.WaitGroup) {
+	for i := 0; i < iterations_per_cycle; i++ {
+		stdatomic.add_u64(&counter.counter, 1)
+	}
+	group.done()
+}
+
+// count_one_cycle_without_sync counts the common counter iterations_per_cycle times in none thread-safe way
+fn count_one_cycle_without_sync(mut counter Counter, mut group sync.WaitGroup) {
+	for i := 0; i < iterations_per_cycle; i++ {
+		counter.counter++
+	}
+	group.done()
+}