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    *
    * 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.hadoop.hbase.coprocessor;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  import java.io.IOException;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.Abortable;
  import org.apache.hadoop.hbase.CoprocessorEnvironment;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.HColumnDescriptor;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.hbase.MiniHBaseCluster;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.Admin;
  import org.apache.hadoop.hbase.master.HMaster;
  import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperNodeTracker;
  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  /**
   * Tests unhandled exceptions thrown by coprocessors running on master.
   * Expected result is that the master will abort with an informative
   * error message describing the set of its loaded coprocessors for crash diagnosis.
   * (HBASE-4014).
   */
  @Category(MediumTests.class)
  public class TestMasterCoprocessorExceptionWithAbort {
  
    public static class MasterTracker extends ZooKeeperNodeTracker {
      public boolean masterZKNodeWasDeleted = false;
  
      public MasterTracker(ZooKeeperWatcher zkw, String masterNode, Abortable abortable) {
        super(zkw, masterNode, abortable);
      }
  
      @Override
      public synchronized void nodeDeleted(String path) {
        if (path.equals("/hbase/master")) {
          masterZKNodeWasDeleted = true;
        }
      }
    }
  
    public static class CreateTableThread extends Thread {
      HBaseTestingUtility UTIL;
      public CreateTableThread(HBaseTestingUtility UTIL) {
        this.UTIL = UTIL;
      }
  
      @Override
      public void run() {
        // create a table : master coprocessor will throw an exception and not
        // catch it.
        HTableDescriptor htd = new HTableDescriptor(TableName.valueOf(TEST_TABLE));
        htd.addFamily(new HColumnDescriptor(TEST_FAMILY));
        try {
          Admin admin = UTIL.getHBaseAdmin();
          admin.createTable(htd);
          fail("BuggyMasterObserver failed to throw an exception.");
        } catch (IOException e) {
          assertEquals("HBaseAdmin threw an interrupted IOException as expected.",
              e.getClass().getName(), "java.io.InterruptedIOException");
        }
     }
    }
  
    public static class BuggyMasterObserver extends BaseMasterObserver {
      private boolean preCreateTableCalled;
     private boolean postCreateTableCalled;
     private boolean startCalled;
     private boolean postStartMasterCalled;
 
     @Override
     @SuppressWarnings("null")
     @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="NP_NULL_ON_SOME_PATH",
       justification="Preconditions checks insure we are not going to dereference a null value")
     public void postCreateTable(ObserverContext<MasterCoprocessorEnvironment> env,
         HTableDescriptor desc, HRegionInfo[] regions) throws IOException {
       // cause a NullPointerException and don't catch it: this will cause the
       // master to abort().
       Integer i;
       i = null;
       i = i++;
     }
 
     public boolean wasCreateTableCalled() {
       return preCreateTableCalled && postCreateTableCalled;
     }
 
     @Override
     public void postStartMaster(ObserverContext<MasterCoprocessorEnvironment> ctx)
         throws IOException {
       postStartMasterCalled = true;
     }
 
     public boolean wasStartMasterCalled() {
       return postStartMasterCalled;
     }
 
     @Override
     public void start(CoprocessorEnvironment env) throws IOException {
       startCalled = true;
     }
 
     public boolean wasStarted() {
       return startCalled;
     }
   }
 
   private static HBaseTestingUtility UTIL = new HBaseTestingUtility();
   private static byte[] TEST_TABLE = Bytes.toBytes("observed_table");
   private static byte[] TEST_FAMILY = Bytes.toBytes("fam1");
 
   @BeforeClass
   public static void setupBeforeClass() throws Exception {
     Configuration conf = UTIL.getConfiguration();
     conf.set(CoprocessorHost.MASTER_COPROCESSOR_CONF_KEY,
         BuggyMasterObserver.class.getName());
     conf.setBoolean(CoprocessorHost.ABORT_ON_ERROR_KEY, true);
     conf.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 2);  // Fail fast
     UTIL.startMiniCluster();
   }
 
   @AfterClass
   public static void teardownAfterClass() throws Exception {
     UTIL.shutdownMiniCluster();
   }
 
   @Test(timeout=30000)
   public void testExceptionFromCoprocessorWhenCreatingTable()
       throws IOException {
     MiniHBaseCluster cluster = UTIL.getHBaseCluster();
 
     HMaster master = cluster.getMaster();
     MasterCoprocessorHost host = master.getMasterCoprocessorHost();
     BuggyMasterObserver cp = (BuggyMasterObserver)host.findCoprocessor(
         BuggyMasterObserver.class.getName());
     assertFalse("No table created yet", cp.wasCreateTableCalled());
 
     // set a watch on the zookeeper /hbase/master node. If the master dies,
     // the node will be deleted.
     ZooKeeperWatcher zkw = new ZooKeeperWatcher(UTIL.getConfiguration(),
       "unittest", new Abortable() {
       @Override
       public void abort(String why, Throwable e) {
         throw new RuntimeException("Fatal ZK error: " + why, e);
       }
       @Override
       public boolean isAborted() {
         return false;
       }
     });
 
     MasterTracker masterTracker = new MasterTracker(zkw,"/hbase/master",
         new Abortable() {
           @Override
           public void abort(String why, Throwable e) {
             throw new RuntimeException("Fatal ZK master tracker error, why=", e);
           }
           @Override
           public boolean isAborted() {
             return false;
           }
         });
 
     masterTracker.start();
     zkw.registerListener(masterTracker);
 
     // Test (part of the) output that should have be printed by master when it aborts:
     // (namely the part that shows the set of loaded coprocessors).
     // In this test, there is only a single coprocessor (BuggyMasterObserver).
     assertTrue(master.getLoadedCoprocessors().
       contains(TestMasterCoprocessorExceptionWithAbort.BuggyMasterObserver.class.getName()));
 
     CreateTableThread createTableThread = new CreateTableThread(UTIL);
 
     // Attempting to create a table (using createTableThread above) triggers an NPE in BuggyMasterObserver.
     // Master will then abort and the /hbase/master zk node will be deleted.
     createTableThread.start();
 
     // Wait up to 30 seconds for master's /hbase/master zk node to go away after master aborts.
     for (int i = 0; i < 30; i++) {
       if (masterTracker.masterZKNodeWasDeleted == true) {
         break;
       }
       try {
         Thread.sleep(1000);
       } catch (InterruptedException e) {
         fail("InterruptedException while waiting for master zk node to "
             + "be deleted.");
       }
     }
 
     assertTrue("Master aborted on coprocessor exception, as expected.",
         masterTracker.masterZKNodeWasDeleted);
 
     createTableThread.interrupt();
     try {
       createTableThread.join(1000);
     } catch (InterruptedException e) {
       assertTrue("Ignoring InterruptedException while waiting for " +
           " createTableThread.join().", true);
     }
   }
 
 }