fix(max_counter): improve the Sub() method, considering the case of reduction.

gemone · gemone · commit dd21f6684c66 · 2023-05-28T01:00:40.000+08:00
diff --git a/max_counter.go b/max_counter.go
@@ -131,11 +131,15 @@ func (c *MaxCounter) Add(delta float64) bool {
 	max := c.GetMax()
 	realNum := c.Real()
 
-	if realNum >= max && delta >= 0 {
+	if realNum >= max && delta > 0 {
 		c.setDone()
 		return false
 	}
 
+	if realNum <= 0 && delta < 0 {
+		return false
+	}
+
 	return c.counter.Add(delta)
 }
 
diff --git a/max_counter_test.go b/max_counter_test.go
@@ -60,6 +60,43 @@ func TestMaxCounterSetAndGet(t *testing.T) {
 	testGo(t, testMaxCounterSetAndGet, 10000)
 }
 
+func TestMaxCounterAddAndSub(t *testing.T) {
+	t.Parallel()
+
+	c := AcquireMaxCounter(50)
+	defer ReleaseMaxCounter(c)
+
+	for i := 0; i < 100; i += 1 {
+		ok := c.Add(1)
+		if i >= 50 && ok {
+			t.Error("should false, but true")
+
+			// check done
+			can := c.Can()
+			if can {
+				t.Fatal("can not add")
+			}
+		}
+	}
+
+	v := c.Get()
+	if v != 50 {
+		t.Fatalf("should %d, but %f", 50, v)
+	}
+
+	for i := 0; i < 100; i += 1 {
+		ok := c.Sub(1)
+		if i >= 50 && ok {
+			t.Error("should false, but true.")
+		}
+	}
+
+	v = c.Get()
+	if v != 0 {
+		t.Fatalf("should %d, but %f", 0, v)
+	}
+}
+
 func TestMaxCounter_Reset(t *testing.T) {
 	t.Parallel()
 

Original file line number	Diff line number	Diff line change
`@@ -131,11 +131,15 @@ func (c *MaxCounter) Add(delta float64) bool {`
`131`	`131`	`max := c.GetMax()`
`132`	`132`	`realNum := c.Real()`
`133`	`133`
`134`		`- if realNum >= max && delta >= 0 {`
	`134`	`+ if realNum >= max && delta > 0 {`
`135`	`135`	`c.setDone()`
`136`	`136`	`return false`
`137`	`137`	`}`
`138`	`138`
	`139`	`+ if realNum <= 0 && delta < 0 {`
	`140`	`+ return false`
	`141`	`+ }`
	`142`	`+`
`139`	`143`	`return c.counter.Add(delta)`
`140`	`144`	`}`
`141`	`145`