/**
    *
    * 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.wal;
  
  import static org.junit.Assert.assertArrayEquals;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertNull;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  import java.io.IOException;
  import java.lang.reflect.Method;
  import java.net.BindException;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataInputStream;
  import org.apache.hadoop.fs.FSDataOutputStream;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.Coprocessor;
  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.KeyValue;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.coprocessor.CoprocessorHost;
  import org.apache.hadoop.hbase.coprocessor.SampleRegionWALObserver;
  import org.apache.hadoop.hbase.regionserver.MultiVersionConcurrencyControl;
  import org.apache.hadoop.hbase.regionserver.wal.HLogKey;
  import org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogReader;
  import org.apache.hadoop.hbase.regionserver.wal.SequenceFileLogWriter;
  import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
  import org.apache.hadoop.hbase.regionserver.wal.WALCoprocessorHost;
  import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.hbase.util.Threads;
  import org.apache.hadoop.hdfs.DistributedFileSystem;
  import org.apache.hadoop.hdfs.MiniDFSCluster;
  import org.apache.hadoop.hdfs.protocol.HdfsConstants;
  import org.junit.After;
  import org.junit.AfterClass;
  import org.junit.Before;
  import org.junit.BeforeClass;
  import org.junit.Rule;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  import org.junit.rules.TestName;
  
  /**
   * WAL tests that can be reused across providers.
   */
  @Category(MediumTests.class)
  public class TestWALFactory {
    private static final Log LOG = LogFactory.getLog(TestWALFactory.class);
  
    protected static Configuration conf;
    private static MiniDFSCluster cluster;
    protected final static HBaseTestingUtility TEST_UTIL = new HBaseTestingUtility();
    protected static Path hbaseDir;
    protected static Path hbaseWALDir;
  
    protected FileSystem fs;
    protected Path dir;
    protected WALFactory wals;
  
    @Rule
    public final TestName currentTest = new TestName();
  
    @Before
    public void setUp() throws Exception {
      fs = cluster.getFileSystem();
      dir = new Path(hbaseDir, currentTest.getMethodName());
     wals = new WALFactory(conf, null, currentTest.getMethodName());
   }
 
   @After
   public void tearDown() throws Exception {
     // testAppendClose closes the FileSystem, which will prevent us from closing cleanly here.
     try {
       wals.close();
     } catch (IOException exception) {
       LOG.warn("Encountered exception while closing wal factory. If you have other errors, this" +
           " may be the cause. Message: " + exception);
       LOG.debug("Exception details for failure to close wal factory.", exception);
     }
     FileStatus[] entries = fs.listStatus(new Path("/"));
     for (FileStatus dir : entries) {
       fs.delete(dir.getPath(), true);
     }
   }
 
   @BeforeClass
   public static void setUpBeforeClass() throws Exception {
     FSUtils.setWALRootDir(TEST_UTIL.getConfiguration(), new Path("file:///tmp/wal"));
     // Make block sizes small.
     TEST_UTIL.getConfiguration().setInt("dfs.blocksize", 1024 * 1024);
     // needed for testAppendClose()
     TEST_UTIL.getConfiguration().setBoolean("dfs.support.broken.append", true);
     TEST_UTIL.getConfiguration().setBoolean("dfs.support.append", true);
     // quicker heartbeat interval for faster DN death notification
     TEST_UTIL.getConfiguration().setInt("dfs.namenode.heartbeat.recheck-interval", 5000);
     TEST_UTIL.getConfiguration().setInt("dfs.heartbeat.interval", 1);
     TEST_UTIL.getConfiguration().setInt("dfs.client.socket-timeout", 5000);
 
     // faster failover with cluster.shutdown();fs.close() idiom
     TEST_UTIL.getConfiguration()
         .setInt("hbase.ipc.client.connect.max.retries", 1);
     TEST_UTIL.getConfiguration().setInt(
         "dfs.client.block.recovery.retries", 1);
     TEST_UTIL.getConfiguration().setInt(
       "hbase.ipc.client.connection.maxidletime", 500);
     TEST_UTIL.getConfiguration().set(CoprocessorHost.WAL_COPROCESSOR_CONF_KEY,
         SampleRegionWALObserver.class.getName());
     TEST_UTIL.startMiniDFSCluster(3);
 
     conf = TEST_UTIL.getConfiguration();
     cluster = TEST_UTIL.getDFSCluster();
 
     hbaseDir = TEST_UTIL.createRootDir();
     hbaseWALDir = TEST_UTIL.createWALRootDir();
   }
 
   @AfterClass
   public static void tearDownAfterClass() throws Exception {
     TEST_UTIL.shutdownMiniCluster();
   }
 
   @Test
   public void canCloseSingleton() throws IOException {
     WALFactory.getInstance(conf).close();
   }
 
   /**
    * Just write multiple logs then split.  Before fix for HADOOP-2283, this
    * would fail.
    * @throws IOException
    */
   @Test
   public void testSplit() throws IOException {
     final TableName tableName = TableName.valueOf(currentTest.getMethodName());
     final byte [] rowName = tableName.getName();
     final MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl(1);
     final Path logdir = new Path(hbaseWALDir,
         DefaultWALProvider.getWALDirectoryName(currentTest.getMethodName()));
     Path oldLogDir = new Path(hbaseWALDir, HConstants.HREGION_OLDLOGDIR_NAME);
     final int howmany = 3;
     HRegionInfo[] infos = new HRegionInfo[3];
     Path tabledir = FSUtils.getWALTableDir(conf, tableName);
     fs.mkdirs(tabledir);
     for(int i = 0; i < howmany; i++) {
       infos[i] = new HRegionInfo(tableName,
                 Bytes.toBytes("" + i), Bytes.toBytes("" + (i+1)), false);
       fs.mkdirs(new Path(tabledir, infos[i].getEncodedName()));
       LOG.info("allo " + new Path(tabledir, infos[i].getEncodedName()).toString());
     }
     HTableDescriptor htd = new HTableDescriptor(tableName);
     htd.addFamily(new HColumnDescriptor("column"));
 
     // Add edits for three regions.
     for (int ii = 0; ii < howmany; ii++) {
       for (int i = 0; i < howmany; i++) {
         final WAL log =
             wals.getWAL(infos[i].getEncodedNameAsBytes(), infos[i].getTable().getNamespace());
         for (int j = 0; j < howmany; j++) {
           WALEdit edit = new WALEdit();
           byte [] family = Bytes.toBytes("column");
           byte [] qualifier = Bytes.toBytes(Integer.toString(j));
           byte [] column = Bytes.toBytes("column:" + Integer.toString(j));
           edit.add(new KeyValue(rowName, family, qualifier,
               System.currentTimeMillis(), column));
           LOG.info("Region " + i + ": " + edit);
           WALKey walKey =  new WALKey(infos[i].getEncodedNameAsBytes(), tableName,
               System.currentTimeMillis(), mvcc);
           log.append(htd, infos[i], walKey, edit, true);
           walKey.getWriteEntry();
         }
         log.sync();
         log.rollWriter(true);
       }
     }
     wals.shutdown();
     List<Path> splits = WALSplitter.split(hbaseWALDir, logdir, oldLogDir, fs, conf, wals);
     verifySplits(splits, howmany);
   }
 
   /**
    * Test new HDFS-265 sync.
    * @throws Exception
    */
   @Test
   public void Broken_testSync() throws Exception {
     TableName tableName = TableName.valueOf(currentTest.getMethodName());
     MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl(1);
     // First verify that using streams all works.
     Path p = new Path(dir, currentTest.getMethodName() + ".fsdos");
     FSDataOutputStream out = fs.create(p);
     out.write(tableName.getName());
     Method syncMethod = null;
     try {
       syncMethod = out.getClass().getMethod("hflush", new Class<?> []{});
     } catch (NoSuchMethodException e) {
       try {
         syncMethod = out.getClass().getMethod("sync", new Class<?> []{});
       } catch (NoSuchMethodException ex) {
         fail("This version of Hadoop supports neither Syncable.sync() " +
             "nor Syncable.hflush().");
       }
     }
     syncMethod.invoke(out, new Object[]{});
     FSDataInputStream in = fs.open(p);
     assertTrue(in.available() > 0);
     byte [] buffer = new byte [1024];
     int read = in.read(buffer);
     assertEquals(tableName.getName().length, read);
     out.close();
     in.close();
 
     final int total = 20;
     WAL.Reader reader = null;
 
     try {
       HRegionInfo info = new HRegionInfo(tableName,
                   null,null, false);
       HTableDescriptor htd = new HTableDescriptor();
       htd.addFamily(new HColumnDescriptor(tableName.getName()));
       final WAL wal = wals.getWAL(info.getEncodedNameAsBytes(), info.getTable().getNamespace());
 
       for (int i = 0; i < total; i++) {
         WALEdit kvs = new WALEdit();
         kvs.add(new KeyValue(Bytes.toBytes(i), tableName.getName(), tableName.getName()));
         wal.append(htd, info, new WALKey(info.getEncodedNameAsBytes(), tableName,
             System.currentTimeMillis(), mvcc), kvs, true);
       }
       // Now call sync and try reading.  Opening a Reader before you sync just
       // gives you EOFE.
       wal.sync();
       // Open a Reader.
       Path walPath = DefaultWALProvider.getCurrentFileName(wal);
       reader = wals.createReader(fs, walPath);
       int count = 0;
       WAL.Entry entry = new WAL.Entry();
       while ((entry = reader.next(entry)) != null) count++;
       assertEquals(total, count);
       reader.close();
       // Add test that checks to see that an open of a Reader works on a file
       // that has had a sync done on it.
       for (int i = 0; i < total; i++) {
         WALEdit kvs = new WALEdit();
         kvs.add(new KeyValue(Bytes.toBytes(i), tableName.getName(), tableName.getName()));
         wal.append(htd, info, new WALKey(info.getEncodedNameAsBytes(), tableName,
             System.currentTimeMillis(), mvcc), kvs, true);
       }
       wal.sync();
       reader = wals.createReader(fs, walPath);
       count = 0;
       while((entry = reader.next(entry)) != null) count++;
       assertTrue(count >= total);
       reader.close();
       // If I sync, should see double the edits.
       wal.sync();
       reader = wals.createReader(fs, walPath);
       count = 0;
       while((entry = reader.next(entry)) != null) count++;
       assertEquals(total * 2, count);
       reader.close();
       // Now do a test that ensures stuff works when we go over block boundary,
       // especially that we return good length on file.
       final byte [] value = new byte[1025 * 1024];  // Make a 1M value.
       for (int i = 0; i < total; i++) {
         WALEdit kvs = new WALEdit();
         kvs.add(new KeyValue(Bytes.toBytes(i), tableName.getName(), value));
         wal.append(htd, info, new WALKey(info.getEncodedNameAsBytes(), tableName,
             System.currentTimeMillis(), mvcc), kvs,  true);
       }
       // Now I should have written out lots of blocks.  Sync then read.
       wal.sync();
       reader = wals.createReader(fs, walPath);
       count = 0;
       while((entry = reader.next(entry)) != null) count++;
       assertEquals(total * 3, count);
       reader.close();
       // shutdown and ensure that Reader gets right length also.
       wal.shutdown();
       reader = wals.createReader(fs, walPath);
       count = 0;
       while((entry = reader.next(entry)) != null) count++;
       assertEquals(total * 3, count);
       reader.close();
     } finally {
       if (reader != null) reader.close();
     }
   }
 
   private void verifySplits(final List<Path> splits, final int howmany)
   throws IOException {
     assertEquals(howmany * howmany, splits.size());
     for (int i = 0; i < splits.size(); i++) {
       LOG.info("Verifying=" + splits.get(i));
       WAL.Reader reader = wals.createReader(fs, splits.get(i));
       try {
         int count = 0;
         String previousRegion = null;
         long seqno = -1;
         WAL.Entry entry = new WAL.Entry();
         while((entry = reader.next(entry)) != null) {
           WALKey key = entry.getKey();
           String region = Bytes.toString(key.getEncodedRegionName());
           // Assert that all edits are for same region.
           if (previousRegion != null) {
             assertEquals(previousRegion, region);
           }
           LOG.info("oldseqno=" + seqno + ", newseqno=" + key.getLogSeqNum());
           assertTrue(seqno < key.getLogSeqNum());
           seqno = key.getLogSeqNum();
           previousRegion = region;
           count++;
         }
         assertEquals(howmany, count);
       } finally {
         reader.close();
       }
     }
   }
 
   /*
    * We pass different values to recoverFileLease() so that different code paths are covered
    *
    * For this test to pass, requires:
    * 1. HDFS-200 (append support)
    * 2. HDFS-988 (SafeMode should freeze file operations
    *              [FSNamesystem.nextGenerationStampForBlock])
    * 3. HDFS-142 (on restart, maintain pendingCreates)
    */
   @Test (timeout=300000)
   public void testAppendClose() throws Exception {
     TableName tableName =
         TableName.valueOf(currentTest.getMethodName());
     HRegionInfo regioninfo = new HRegionInfo(tableName,
              HConstants.EMPTY_START_ROW, HConstants.EMPTY_END_ROW, false);
 
     final WAL wal =
         wals.getWAL(regioninfo.getEncodedNameAsBytes(), regioninfo.getTable().getNamespace());
     final int total = 20;
 
     HTableDescriptor htd = new HTableDescriptor();
     htd.addFamily(new HColumnDescriptor(tableName.getName()));
     MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl();
     for (int i = 0; i < total; i++) {
       WALEdit kvs = new WALEdit();
       kvs.add(new KeyValue(Bytes.toBytes(i), tableName.getName(), tableName.getName()));
       wal.append(htd, regioninfo, new WALKey(regioninfo.getEncodedNameAsBytes(), tableName,
           System.currentTimeMillis(), mvcc), kvs,  true);
     }
     // Now call sync to send the data to HDFS datanodes
     wal.sync();
      int namenodePort = cluster.getNameNodePort();
     final Path walPath = DefaultWALProvider.getCurrentFileName(wal);
 
 
     // Stop the cluster.  (ensure restart since we're sharing MiniDFSCluster)
     try {
       DistributedFileSystem dfs = (DistributedFileSystem) cluster.getFileSystem();
       dfs.setSafeMode(HdfsConstants.SafeModeAction.SAFEMODE_ENTER);
       TEST_UTIL.shutdownMiniDFSCluster();
       try {
         // wal.writer.close() will throw an exception,
         // but still call this since it closes the LogSyncer thread first
         wal.shutdown();
       } catch (IOException e) {
         LOG.info(e);
       }
       fs.close(); // closing FS last so DFSOutputStream can't call close
       LOG.info("STOPPED first instance of the cluster");
     } finally {
       // Restart the cluster
       while (cluster.isClusterUp()){
         LOG.error("Waiting for cluster to go down");
         Thread.sleep(1000);
       }
       assertFalse(cluster.isClusterUp());
       cluster = null;
       for (int i = 0; i < 100; i++) {
         try {
           cluster = TEST_UTIL.startMiniDFSClusterForTestWAL(namenodePort);
           break;
         } catch (BindException e) {
           LOG.info("Sleeping.  BindException bringing up new cluster");
           Threads.sleep(1000);
         }
       }
       cluster.waitActive();
       fs = cluster.getFileSystem();
       LOG.info("STARTED second instance.");
     }
 
     // set the lease period to be 1 second so that the
     // namenode triggers lease recovery upon append request
     Method setLeasePeriod = cluster.getClass()
       .getDeclaredMethod("setLeasePeriod", new Class[]{Long.TYPE, Long.TYPE});
     setLeasePeriod.setAccessible(true);
     setLeasePeriod.invoke(cluster, 1000L, 1000L);
     try {
       Thread.sleep(1000);
     } catch (InterruptedException e) {
       LOG.info(e);
     }
 
     // Now try recovering the log, like the HMaster would do
     final FileSystem recoveredFs = fs;
     final Configuration rlConf = conf;
 
     class RecoverLogThread extends Thread {
       public Exception exception = null;
       public void run() {
           try {
             FSUtils.getInstance(fs, rlConf)
               .recoverFileLease(recoveredFs, walPath, rlConf, null);
           } catch (IOException e) {
             exception = e;
           }
       }
     }
 
     RecoverLogThread t = new RecoverLogThread();
     t.start();
     // Timeout after 60 sec. Without correct patches, would be an infinite loop
     t.join(60 * 1000);
     if(t.isAlive()) {
       t.interrupt();
       throw new Exception("Timed out waiting for WAL.recoverLog()");
     }
 
     if (t.exception != null)
       throw t.exception;
 
     // Make sure you can read all the content
     WAL.Reader reader = wals.createReader(fs, walPath);
     int count = 0;
     WAL.Entry entry = new WAL.Entry();
     while (reader.next(entry) != null) {
       count++;
       assertTrue("Should be one KeyValue per WALEdit",
                   entry.getEdit().getCells().size() == 1);
     }
     assertEquals(total, count);
     reader.close();
 
     // Reset the lease period
     setLeasePeriod.invoke(cluster, new Object[]{new Long(60000), new Long(3600000)});
   }
 
   /**
    * Tests that we can write out an edit, close, and then read it back in again.
    * @throws IOException
    */
   @Test
   public void testEditAdd() throws IOException {
     final int COL_COUNT = 10;
     final HTableDescriptor htd =
         new HTableDescriptor(TableName.valueOf("tablename")).addFamily(new HColumnDescriptor(
             "column"));
     final byte [] row = Bytes.toBytes("row");
     WAL.Reader reader = null;
     try {
       final MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl(1);
 
       // Write columns named 1, 2, 3, etc. and then values of single byte
       // 1, 2, 3...
       long timestamp = System.currentTimeMillis();
       WALEdit cols = new WALEdit();
       for (int i = 0; i < COL_COUNT; i++) {
         cols.add(new KeyValue(row, Bytes.toBytes("column"),
             Bytes.toBytes(Integer.toString(i)),
           timestamp, new byte[] { (byte)(i + '0') }));
       }
       HRegionInfo info = new HRegionInfo(htd.getTableName(),
         row,Bytes.toBytes(Bytes.toString(row) + "1"), false);
       final WAL log = wals.getWAL(info.getEncodedNameAsBytes(), info.getTable().getNamespace());
 
       final long txid = log.append(htd, info,
         new WALKey(info.getEncodedNameAsBytes(), htd.getTableName(), System.currentTimeMillis(),
             mvcc),
         cols, true);
       log.sync(txid);
       log.startCacheFlush(info.getEncodedNameAsBytes(), htd.getFamiliesKeys());
       log.completeCacheFlush(info.getEncodedNameAsBytes());
       log.shutdown();
       Path filename = DefaultWALProvider.getCurrentFileName(log);
       // Now open a reader on the log and assert append worked.
       reader = wals.createReader(fs, filename);
       // Above we added all columns on a single row so we only read one
       // entry in the below... thats why we have '1'.
       for (int i = 0; i < 1; i++) {
         WAL.Entry entry = reader.next(null);
         if (entry == null) break;
         WALKey key = entry.getKey();
         WALEdit val = entry.getEdit();
         assertTrue(Bytes.equals(info.getEncodedNameAsBytes(), key.getEncodedRegionName()));
         assertTrue(htd.getTableName().equals(key.getTablename()));
         Cell cell = val.getCells().get(0);
         assertTrue(Bytes.equals(row, cell.getRow()));
         assertEquals((byte)(i + '0'), cell.getValue()[0]);
         System.out.println(key + " " + val);
       }
     } finally {
       if (reader != null) {
         reader.close();
       }
     }
   }
 
   /**
    * @throws IOException
    */
   @Test
   public void testAppend() throws IOException {
     final int COL_COUNT = 10;
     final HTableDescriptor htd =
         new HTableDescriptor(TableName.valueOf("tablename")).addFamily(new HColumnDescriptor(
             "column"));
     final byte [] row = Bytes.toBytes("row");
     WAL.Reader reader = null;
     final MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl(1);
     try {
       // Write columns named 1, 2, 3, etc. and then values of single byte
       // 1, 2, 3...
       long timestamp = System.currentTimeMillis();
       WALEdit cols = new WALEdit();
       for (int i = 0; i < COL_COUNT; i++) {
         cols.add(new KeyValue(row, Bytes.toBytes("column"),
           Bytes.toBytes(Integer.toString(i)),
           timestamp, new byte[] { (byte)(i + '0') }));
       }
       HRegionInfo hri = new HRegionInfo(htd.getTableName(),
           HConstants.EMPTY_START_ROW, HConstants.EMPTY_END_ROW);
       final WAL log = wals.getWAL(hri.getEncodedNameAsBytes(), hri.getTable().getNamespace());
       final long txid = log.append(htd, hri,
         new WALKey(hri.getEncodedNameAsBytes(), htd.getTableName(), System.currentTimeMillis(),
             mvcc),
         cols, true);
       log.sync(txid);
       log.startCacheFlush(hri.getEncodedNameAsBytes(), htd.getFamiliesKeys());
       log.completeCacheFlush(hri.getEncodedNameAsBytes());
       log.shutdown();
       Path filename = DefaultWALProvider.getCurrentFileName(log);
       // Now open a reader on the log and assert append worked.
       reader = wals.createReader(fs, filename);
       WAL.Entry entry = reader.next();
       assertEquals(COL_COUNT, entry.getEdit().size());
       int idx = 0;
       for (Cell val : entry.getEdit().getCells()) {
         assertTrue(Bytes.equals(hri.getEncodedNameAsBytes(),
           entry.getKey().getEncodedRegionName()));
         assertTrue(htd.getTableName().equals(entry.getKey().getTablename()));
         assertTrue(Bytes.equals(row, val.getRow()));
         assertEquals((byte)(idx + '0'), val.getValue()[0]);
         System.out.println(entry.getKey() + " " + val);
         idx++;
       }
     } finally {
       if (reader != null) {
         reader.close();
       }
     }
   }
 
   /**
    * Test that we can visit entries before they are appended
    * @throws Exception
    */
   @Test
   public void testVisitors() throws Exception {
     final int COL_COUNT = 10;
     final TableName tableName =
         TableName.valueOf("tablename");
     final byte [] row = Bytes.toBytes("row");
     final DumbWALActionsListener visitor = new DumbWALActionsListener();
     final MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl(1);
     long timestamp = System.currentTimeMillis();
     HTableDescriptor htd = new HTableDescriptor();
     htd.addFamily(new HColumnDescriptor("column"));
 
     HRegionInfo hri = new HRegionInfo(tableName,
         HConstants.EMPTY_START_ROW, HConstants.EMPTY_END_ROW);
     final WAL log = wals.getWAL(hri.getEncodedNameAsBytes(), hri.getTable().getNamespace());
     log.registerWALActionsListener(visitor);
     for (int i = 0; i < COL_COUNT; i++) {
       WALEdit cols = new WALEdit();
       cols.add(new KeyValue(row, Bytes.toBytes("column"),
           Bytes.toBytes(Integer.toString(i)),
           timestamp, new byte[]{(byte) (i + '0')}));
       log.append(htd, hri, new WALKey(hri.getEncodedNameAsBytes(), tableName,
           System.currentTimeMillis(), mvcc), cols, true);
     }
     log.sync();
     assertEquals(COL_COUNT, visitor.increments);
     log.unregisterWALActionsListener(visitor);
     WALEdit cols = new WALEdit();
     cols.add(new KeyValue(row, Bytes.toBytes("column"),
         Bytes.toBytes(Integer.toString(11)),
         timestamp, new byte[]{(byte) (11 + '0')}));
     log.append(htd, hri, new WALKey(hri.getEncodedNameAsBytes(), tableName,
         System.currentTimeMillis(), mvcc), cols, true);
     log.sync();
     assertEquals(COL_COUNT, visitor.increments);
   }
 
   /**
    * A loaded WAL coprocessor won't break existing WAL test cases.
    */
   @Test
   public void testWALCoprocessorLoaded() throws Exception {
     // test to see whether the coprocessor is loaded or not.
     WALCoprocessorHost host = wals.getWAL(UNSPECIFIED_REGION, null).getCoprocessorHost();
     Coprocessor c = host.findCoprocessor(SampleRegionWALObserver.class.getName());
     assertNotNull(c);
   }
 
   /**
    * @throws IOException
    */
   @Test
   public void testReadLegacyLog() throws IOException {
     final int columnCount = 5;
     final int recordCount = 5;
     final TableName tableName =
         TableName.valueOf("tablename");
     final byte[] row = Bytes.toBytes("row");
     long timestamp = System.currentTimeMillis();
     Path path = new Path(dir, "tempwal");
     SequenceFileLogWriter sflw = null;
     WAL.Reader reader = null;
     try {
       HRegionInfo hri = new HRegionInfo(tableName,
           HConstants.EMPTY_START_ROW, HConstants.EMPTY_END_ROW);
       HTableDescriptor htd = new HTableDescriptor(tableName);
       fs.mkdirs(dir);
       // Write log in pre-PB format.
       sflw = new SequenceFileLogWriter();
       sflw.init(fs, path, conf, false);
       for (int i = 0; i < recordCount; ++i) {
         WALKey key = new HLogKey(
             hri.getEncodedNameAsBytes(), tableName, i, timestamp, HConstants.DEFAULT_CLUSTER_ID);
         WALEdit edit = new WALEdit();
         for (int j = 0; j < columnCount; ++j) {
           if (i == 0) {
             htd.addFamily(new HColumnDescriptor("column" + j));
           }
           String value = i + "" + j;
           edit.add(new KeyValue(row, row, row, timestamp, Bytes.toBytes(value)));
         }
         sflw.append(new WAL.Entry(key, edit));
       }
       sflw.sync();
       sflw.close();
 
       // Now read the log using standard means.
       reader = wals.createReader(fs, path);
       assertTrue(reader instanceof SequenceFileLogReader);
       for (int i = 0; i < recordCount; ++i) {
         WAL.Entry entry = reader.next();
         assertNotNull(entry);
         assertEquals(columnCount, entry.getEdit().size());
         assertArrayEquals(hri.getEncodedNameAsBytes(), entry.getKey().getEncodedRegionName());
         assertEquals(tableName, entry.getKey().getTablename());
         int idx = 0;
         for (Cell val : entry.getEdit().getCells()) {
           assertTrue(Bytes.equals(row, val.getRow()));
           String value = i + "" + idx;
           assertArrayEquals(Bytes.toBytes(value), val.getValue());
           idx++;
         }
       }
       WAL.Entry entry = reader.next();
       assertNull(entry);
     } finally {
       if (sflw != null) {
         sflw.close();
       }
       if (reader != null) {
         reader.close();
       }
     }
   }
 
   static class DumbWALActionsListener extends WALActionsListener.Base {
     int increments = 0;
 
     @Override
     public void visitLogEntryBeforeWrite(HRegionInfo info, WALKey logKey,
                                          WALEdit logEdit) {
       increments++;
     }
 
     @Override
     public void visitLogEntryBeforeWrite(HTableDescriptor htd, WALKey logKey, WALEdit logEdit) {
       //To change body of implemented methods use File | Settings | File Templates.
       increments++;
     }
   }
 
   private static final byte[] UNSPECIFIED_REGION = new byte[]{};
 
 }