improve wall filter

src/main/java/com/alibaba/druid/wall/WallFunctionStat.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.wall;
+
+import java.util.concurrent.atomic.AtomicLongFieldUpdater;
+
+public class WallFunctionStat {
+
+    private volatile long                                 invokeCount;
+    final static AtomicLongFieldUpdater<WallFunctionStat> invokeCountUpdater = AtomicLongFieldUpdater.newUpdater(WallFunctionStat.class,
+                                                                                                                 "invokeCount");
+
+    public long getInvokeCount() {
+        return invokeCount;
+    }
+
+    public void incrementInvokeCount() {
+        this.invokeCount++;
+    }
+    
+    public void addSqlFunctionStat(WallSqlFunctionStat sqlFunctionStat) {
+        this.invokeCount += sqlFunctionStat.getInvokeCount();
+    }
+
+}