canal server metrics refactor.

common/src/main/java/com/alibaba/otter/canal/common/utils/SerializedLongAdder.java

@@ -0,0 +1,31 @@
+package com.alibaba.otter.canal.common.utils;
+
+/**
+ * 用于dump记录counter
+ * 这种场景下，
+ * <strong>写操作>>读操作</strong>
+ * dump线程为串行，读取counter时，并不严格要求最新值可见，使用普通long即可。
+ *
+ * @author Chuanyi Li
+ */
+public class SerializedLongAdder {
+
+    private long value = 0;
+
+    public SerializedLongAdder(long initial) {
+        this.value = initial;
+    }
+
+    public void add(long x) {
+        value += x;
+    }
+
+    public void increment() {
+        value ++;
+    }
+
+    public long get() {
+        return value;
+    }
+
+}