/**
    * 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.regionserver.wal;
  
  import static org.junit.Assert.assertFalse;
  import java.io.IOException;
  import java.util.TreeMap;
  import java.util.concurrent.ThreadLocalRandom;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  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.regionserver.MultiVersionConcurrencyControl;
  import org.apache.hadoop.hbase.testclassification.SmallTests;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.FSTableDescriptors;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.hbase.util.Threads;
  import org.apache.hadoop.hbase.wal.WAL;
  import org.apache.hadoop.hbase.wal.WALFactory;
  import org.apache.hadoop.hbase.wal.WALKey;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  /**
   * Test many concurrent appenders to an WAL while rolling the log.
   */
  @Category(SmallTests.class)
  public class TestLogRollingNoCluster {
    private final static HBaseTestingUtility TEST_UTIL = new HBaseTestingUtility();
    private final static byte [] EMPTY_1K_ARRAY = new byte[1024];
    private static final int NUM_THREADS = 100; // Spin up this many threads
    private static final int NUM_ENTRIES = 100; // How many entries to write
  
    /** ProtobufLogWriter that simulates higher latencies in sync() call */
    public static class HighLatencySyncWriter extends  ProtobufLogWriter {
      @Override
      public void sync(boolean forceSync) throws IOException {
        Threads.sleep(ThreadLocalRandom.current().nextInt(10));
        super.sync(forceSync);
        Threads.sleep(ThreadLocalRandom.current().nextInt(10));
      }
    }
  
    /**
     * Spin up a bunch of threads and have them all append to a WAL.  Roll the
     * WAL frequently to try and trigger NPE.
     * @throws IOException
     * @throws InterruptedException
     */
    @Test
    public void testContendedLogRolling() throws Exception {
      TEST_UTIL.startMiniDFSCluster(3);
      Path dir = TEST_UTIL.getDataTestDirOnTestFS();
  
      // The implementation needs to know the 'handler' count.
      TEST_UTIL.getConfiguration().setInt(HConstants.REGION_SERVER_HANDLER_COUNT, NUM_THREADS);
      final Configuration conf = new Configuration(TEST_UTIL.getConfiguration());
      FSUtils.setRootDir(conf, dir);
      conf.set("hbase.regionserver.hlog.writer.impl", HighLatencySyncWriter.class.getName());
      final WALFactory wals = new WALFactory(conf, null, TestLogRollingNoCluster.class.getName());
      final WAL wal = wals.getWAL(new byte[]{}, null);
      
      Appender [] appenders = null;
  
      final int numThreads = NUM_THREADS;
      appenders = new Appender[numThreads];
      try {
        for (int i = 0; i < numThreads; i++) {
          // Have each appending thread write 'count' entries
          appenders[i] = new Appender(wal, i, NUM_ENTRIES);
        }
        for (int i = 0; i < numThreads; i++) {
          appenders[i].start();
        }
        for (int i = 0; i < numThreads; i++) {
          //ensure that all threads are joined before closing the wal
          appenders[i].join();
       }
     } finally {
       wals.close();
     }
     for (int i = 0; i < numThreads; i++) {
       assertFalse(appenders[i].isException());
     }
     TEST_UTIL.shutdownMiniDFSCluster();
   }
 
   /**
    * Appender thread.  Appends to passed wal file.
    */
   static class Appender extends Thread {
     private final Log log;
     private final WAL wal;
     private final int count;
     private Exception e = null;
 
     Appender(final WAL wal, final int index, final int count) {
       super("" + index);
       this.wal = wal;
       this.count = count;
       this.log = LogFactory.getLog("Appender:" + getName());
     }
 
     /**
      * @return Call when the thread is done.
      */
     boolean isException() {
       return !isAlive() && this.e != null;
     }
 
     Exception getException() {
       return this.e;
     }
 
     @Override
     public void run() {
       this.log.info(getName() +" started");
       final MultiVersionConcurrencyControl mvcc = new MultiVersionConcurrencyControl();
       try {
         for (int i = 0; i < this.count; i++) {
           long now = System.currentTimeMillis();
           // Roll every ten edits
           if (i % 10 == 0) {
             this.wal.rollWriter();
           }
           WALEdit edit = new WALEdit();
           byte[] bytes = Bytes.toBytes(i);
           edit.add(new KeyValue(bytes, bytes, bytes, now, EMPTY_1K_ARRAY));
           final HRegionInfo hri = HRegionInfo.FIRST_META_REGIONINFO;
           final FSTableDescriptors fts = new FSTableDescriptors(TEST_UTIL.getConfiguration());
           final HTableDescriptor htd = fts.get(TableName.META_TABLE_NAME);
           final long txid = wal.append(htd, hri, new WALKey(hri.getEncodedNameAsBytes(),
               TableName.META_TABLE_NAME, now, mvcc), edit, true);
           Threads.sleep(ThreadLocalRandom.current().nextInt(5));
           wal.sync(txid);
         }
         String msg = getName() + " finished";
         if (isException())
           this.log.info(msg, getException());
         else
           this.log.info(msg);
       } catch (Exception e) {
         this.e = e;
         log.info("Caught exception from Appender:" + getName(), e);
       } finally {
         // Call sync on our log.else threads just hang out.
         try {
           this.wal.sync();
         } catch (IOException e) {
           throw new RuntimeException(e);
         }
       }
     }
   }
 
   //@org.junit.Rule
   //public org.apache.hadoop.hbase.ResourceCheckerJUnitRule cu =
   //  new org.apache.hadoop.hbase.ResourceCheckerJUnitRule();
 }