Add contains

ringbuffer/ringbuffer.go

@@ -73,3 +73,16 @@ func (rb *RingBuffer) GetLastPosition() int {
 	return rb.tail
 }
 
+func (rb *RingBuffer) ContainsItem(item string) bool {
+	rb.mu.Lock()
+	defer rb.mu.Unlock()
+
+	for i := 0; i < rb.size; i++ {
+		index := (rb.head + i) % rb.size
+		if rb.buffer[index] == item {
+			return true
+		}
+	}
+
+	return false
+}