content: /*
   * Copyright 1999-2017 Alibaba Group.
   *
   * 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.p3c.pmd.lang.java.rule.concurrent;
  
  import java.util.List;
  import java.util.concurrent.CountDownLatch;
  
  import com.alibaba.p3c.pmd.lang.java.rule.AbstractAliRule;
  
  import net.sourceforge.pmd.lang.ast.Node;
  import net.sourceforge.pmd.lang.java.ast.ASTName;
  import net.sourceforge.pmd.lang.java.ast.ASTTryStatement;
  import org.jaxen.JaxenException;
  
  /**
   * [Recommended] When using CountDownLatch to convert asynchronous operations to synchronous ones,
   * each thread must call countdown method before quitting.
   * Make sure to catch any exception during thread running, to let countdown method be executed.
   * If main thread cannot reach await method, program will return until timeout.
   *
   * Note: Be careful, exception thrown by sub-thread cannot be caught by main thread.
   *
   * @author caikang
   * @date 2017/03/29
   */
  public class CountDownShouldInFinallyRule extends AbstractAliRule {
      private static final String XPATH = "./Block/BlockStatement/Statement/StatementExpression"
          + "/PrimaryExpression/PrimaryPrefix/Name[ends-with(@Image,'.countDown')]";
  
      @Override
      public Object visit(ASTTryStatement node, Object data) {
          try {
              List<Node> nodes = node.findChildNodesWithXPath(XPATH);
              if (nodes == null || nodes.isEmpty()) {
                  return super.visit(node, data);
              }
              for (Node nameNode : nodes) {
                  if (!(nameNode instanceof ASTName)) {
                      continue;
                  }
                  ASTName name = (ASTName)nameNode;
                  if (name.getType() != CountDownLatch.class) {
                      continue;
                  }
                  addViolationWithMessage(data, name, "java.concurrent.CountDownShouldInFinallyRule.violation.msg",
                      new Object[] {name.getImage()});
              }
          } catch (JaxenException ignore) {
          }
          return super.visit(node, data);
      }
  }
  