Refactor ExclusiveOperatorEngine

mode/core/src/main/java/org/apache/shardingsphere/mode/exclusive/ExclusiveOperationCallback.java

@@ -19,13 +19,19 @@
 
 import java.sql.SQLException;
 
+/**
+ * Exclusive operation callback.
+ *
+ * @param <T> type of return value
+ */
 @FunctionalInterface
-public interface ExclusiveOperationCallback {
+public interface ExclusiveOperationCallback<T> {
 
     /**
      * Execute.
      *
+     * @return execution result
      * @throws SQLException SQL exception
      */
-    void execute() throws SQLException;
+    T execute() throws SQLException;
 }

mode/core/src/main/java/org/apache/shardingsphere/mode/exclusive/ExclusiveOperationVoidCallback.java

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.shardingsphere.mode.exclusive;
+
+import java.sql.SQLException;
+
+/**
+ * Exclusive operation void callback.
+ */
+@FunctionalInterface
+public interface ExclusiveOperationVoidCallback {
+
+    /**
+     * Execute.
+     *
+     * @throws SQLException SQL exception
+     */
+    void execute() throws SQLException;
+}

mode/core/src/main/java/org/apache/shardingsphere/mode/exclusive/ExclusiveOperatorEngine.java

@@ -30,20 +30,42 @@ public final class ExclusiveOperatorEngine {
     private final ExclusiveOperatorContext exclusiveOperatorContext;
 
     /**
-     * Operate with exclusive lock.
+     * Operate with exclusive operation and void callback.
+     *
+     * @param operation exclusive operation
+     * @param timeoutMillis timeout millis
+     * @param voidCallback void callback
+     * @throws SQLException SQL exception
+     */
+    public void operate(final ExclusiveOperation operation, final long timeoutMillis, final ExclusiveOperationVoidCallback voidCallback) throws SQLException {
+        operateWithResult(operation, timeoutMillis, asVoidCallback(voidCallback));
+    }
+
+    private ExclusiveOperationCallback<Void> asVoidCallback(final ExclusiveOperationVoidCallback voidCallback) {
+        return () -> {
+            voidCallback.execute();
+            return null;
+        };
+    }
+
+    /**
+     * Operate with exclusive operation and return result.
      *
      * @param operation exclusive operation
      * @param timeoutMillis timeout millis
      * @param callback callback
+     * @param <T> type of return value
+     * @return execution result
      * @throws SQLException SQL exception
      */
-    public void operate(final ExclusiveOperation operation, final long timeoutMillis, final ExclusiveOperationCallback callback) throws SQLException {
+    public <T> T operateWithResult(final ExclusiveOperation operation, final long timeoutMillis, final ExclusiveOperationCallback<T> callback) throws SQLException {
         if (exclusiveOperatorContext.start(operation, timeoutMillis)) {
             try {
-                callback.execute();
+                return callback.execute();
             } finally {
                 exclusiveOperatorContext.stop(operation);
             }
         }
+        return null;
     }
 }