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    * Licensed to the Apache Software Foundation (ASF) under one
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    * distributed with this work for additional information
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    * 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
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  package org.apache.hadoop.hbase.regionserver.compactions;
  
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertFalse;
  import static org.junit.Assert.assertTrue;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.when;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  import java.util.concurrent.CountDownLatch;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.HColumnDescriptor;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.Stoppable;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.client.Scan;
  import org.apache.hadoop.hbase.regionserver.CompactedHFilesDischarger;
  import org.apache.hadoop.hbase.regionserver.HRegion;
  import org.apache.hadoop.hbase.regionserver.HStore;
  import org.apache.hadoop.hbase.regionserver.Region;
  import org.apache.hadoop.hbase.regionserver.RegionScanner;
  import org.apache.hadoop.hbase.regionserver.RegionServerServices;
  import org.apache.hadoop.hbase.regionserver.Store;
  import org.apache.hadoop.hbase.regionserver.StoreFile;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.hbase.testclassification.RegionServerTests;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.junit.After;
  import org.junit.Before;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  @Category({ MediumTests.class, RegionServerTests.class })
  public class TestCompactedHFilesDischarger {
    private final HBaseTestingUtility testUtil = new HBaseTestingUtility();
    private Region region;
    private final static byte[] fam = Bytes.toBytes("cf_1");
    private final static byte[] qual1 = Bytes.toBytes("qf_1");
    private final static byte[] val = Bytes.toBytes("val");
    private static CountDownLatch latch = new CountDownLatch(3);
    private static AtomicInteger counter = new AtomicInteger(0);
    private static AtomicInteger scanCompletedCounter = new AtomicInteger(0);
    private RegionServerServices rss;
  
    @Before
    public void setUp() throws Exception {
      TableName tableName = TableName.valueOf(getClass().getSimpleName());
      HTableDescriptor htd = new HTableDescriptor(tableName);
      htd.addFamily(new HColumnDescriptor(fam));
      HRegionInfo info = new HRegionInfo(tableName, null, null, false);
      Path path = testUtil.getDataTestDir(getClass().getSimpleName());
      region = HBaseTestingUtility.createRegionAndWAL(info, path, testUtil.getConfiguration(), htd);
      rss = mock(RegionServerServices.class);
      List<Region> regions = new ArrayList<Region>();
      regions.add(region);
      when(rss.getOnlineRegions()).thenReturn(regions);
    }
  
    @After
    public void tearDown() throws IOException {
      counter.set(0);
      scanCompletedCounter.set(0);
      latch = new CountDownLatch(3);
      HBaseTestingUtility.closeRegionAndWAL(region);
      testUtil.cleanupTestDir();
    }
  
    @Test
    public void testCompactedHFilesCleaner() throws Exception {
      // Create the cleaner object
      CompactedHFilesDischarger cleaner =
          new CompactedHFilesDischarger(1000, (Stoppable) null, rss, false);
      // Add some data to the region and do some flushes
     for (int i = 1; i < 10; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
     for (int i = 11; i < 20; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
     for (int i = 21; i < 30; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
 
     Store store = region.getStore(fam);
     assertEquals(3, store.getStorefilesCount());
 
     Collection<StoreFile> storefiles = store.getStorefiles();
     Collection<StoreFile> compactedfiles =
         ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     // None of the files should be in compacted state.
     for (StoreFile file : storefiles) {
       assertFalse(file.isCompactedAway());
     }
     // Try to run the cleaner without compaction. there should not be any change
     cleaner.chore();
     storefiles = store.getStorefiles();
     // None of the files should be in compacted state.
     for (StoreFile file : storefiles) {
       assertFalse(file.isCompactedAway());
     }
     // now do some compaction
     region.compact(true);
     // Still the flushed files should be present until the cleaner runs. But the state of it should
     // be in COMPACTED state
     assertEquals(1, store.getStorefilesCount());
     assertEquals(3,
       ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles().size());
 
     // Run the cleaner
     cleaner.chore();
     assertEquals(1, store.getStorefilesCount());
     storefiles = store.getStorefiles();
     for (StoreFile file : storefiles) {
       // Should not be in compacted state
       assertFalse(file.isCompactedAway());
     }
     compactedfiles = ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     assertTrue(compactedfiles.size() == 0);
     
   }
 
   @Test
   public void testCleanerWithParallelScannersAfterCompaction() throws Exception {
     // Create the cleaner object
     CompactedHFilesDischarger cleaner =
         new CompactedHFilesDischarger(1000, (Stoppable) null, rss, false);
     // Add some data to the region and do some flushes
     for (int i = 1; i < 10; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
     for (int i = 11; i < 20; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
     for (int i = 21; i < 30; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
 
     Store store = region.getStore(fam);
     assertEquals(3, store.getStorefilesCount());
 
     Collection<StoreFile> storefiles = store.getStorefiles();
     Collection<StoreFile> compactedfiles =
         ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     // None of the files should be in compacted state.
     for (StoreFile file : storefiles) {
       assertFalse(file.isCompactedAway());
     }
     // Do compaction
     region.compact(true);
     startScannerThreads();
 
     storefiles = store.getStorefiles();
     int usedReaderCount = 0;
     int unusedReaderCount = 0;
     for (StoreFile file : storefiles) {
       if (file.getRefCount() == 3) {
         usedReaderCount++;
       }
     }
     compactedfiles = ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     for(StoreFile file : compactedfiles) {
       assertEquals("Refcount should be 3", 0, file.getRefCount());
       unusedReaderCount++;
     }
     // Though there are files we are not using them for reads
     assertEquals("unused reader count should be 3", 3, unusedReaderCount);
     assertEquals("used reader count should be 1", 1, usedReaderCount);
     // now run the cleaner
     cleaner.chore();
     countDown();
     assertEquals(1, store.getStorefilesCount());
     storefiles = store.getStorefiles();
     for (StoreFile file : storefiles) {
       // Should not be in compacted state
       assertFalse(file.isCompactedAway());
     }
     compactedfiles = ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     assertTrue(compactedfiles.size() == 0);
   }
 
   @Test
   public void testCleanerWithParallelScanners() throws Exception {
     // Create the cleaner object
     CompactedHFilesDischarger cleaner =
         new CompactedHFilesDischarger(1000, (Stoppable) null, rss, false);
     // Add some data to the region and do some flushes
     for (int i = 1; i < 10; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
     for (int i = 11; i < 20; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
     for (int i = 21; i < 30; i++) {
       Put p = new Put(Bytes.toBytes("row" + i));
       p.addColumn(fam, qual1, val);
       region.put(p);
     }
     // flush them
     region.flush(true);
 
     Store store = region.getStore(fam);
     assertEquals(3, store.getStorefilesCount());
 
     Collection<StoreFile> storefiles = store.getStorefiles();
     Collection<StoreFile> compactedfiles =
         ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     // None of the files should be in compacted state.
     for (StoreFile file : storefiles) {
       assertFalse(file.isCompactedAway());
     }
     startScannerThreads();
     // Do compaction
     region.compact(true);
 
     storefiles = store.getStorefiles();
     int usedReaderCount = 0;
     int unusedReaderCount = 0;
     for (StoreFile file : storefiles) {
       if (file.getRefCount() == 0) {
         unusedReaderCount++;
       }
     }
     compactedfiles =
         ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     for(StoreFile file : compactedfiles) {
       assertEquals("Refcount should be 3", 3, file.getRefCount());
       usedReaderCount++;
     }
     // The newly compacted file will not be used by any scanner
     assertEquals("unused reader count should be 1", 1, unusedReaderCount);
     assertEquals("used reader count should be 3", 3, usedReaderCount);
     // now run the cleaner
     cleaner.chore();
     countDown();
     // No change in the number of store files as none of the compacted files could be cleaned up
     assertEquals(1, store.getStorefilesCount());
     assertEquals(3,
       ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles().size());
     while (scanCompletedCounter.get() != 3) {
       Thread.sleep(100);
     }
     // reset
     latch = new CountDownLatch(3);
     scanCompletedCounter.set(0);
     counter.set(0);
     // Try creating a new scanner and it should use only the new file created after compaction
     startScannerThreads();
     storefiles = store.getStorefiles();
     usedReaderCount = 0;
     unusedReaderCount = 0;
     for (StoreFile file : storefiles) {
       if (file.getRefCount() == 3) {
         usedReaderCount++;
       }
     }
     compactedfiles = ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     for(StoreFile file : compactedfiles) {
       assertEquals("Refcount should be 0", 0, file.getRefCount());
       unusedReaderCount++;
     }
     // Though there are files we are not using them for reads
     assertEquals("unused reader count should be 3", 3, unusedReaderCount);
     assertEquals("used reader count should be 1", 1, usedReaderCount);
     countDown();
     while (scanCompletedCounter.get() != 3) {
       Thread.sleep(100);
     }
     // Run the cleaner again
     cleaner.chore();
     // Now the cleaner should be able to clear it up because there are no active readers
     assertEquals(1, store.getStorefilesCount());
     storefiles = store.getStorefiles();
     for (StoreFile file : storefiles) {
       // Should not be in compacted state
       assertFalse(file.isCompactedAway());
     }
     compactedfiles = ((HStore) store).getStoreEngine().getStoreFileManager().getCompactedfiles();
     assertTrue(compactedfiles.size() == 0);
   }
 
   protected void countDown() {
     // count down 3 times
     latch.countDown();
     latch.countDown();
     latch.countDown();
   }
 
   protected void startScannerThreads() throws InterruptedException {
     // Start parallel scan threads
     ScanThread[] scanThreads = new ScanThread[3];
     for (int i = 0; i < 3; i++) {
       scanThreads[i] = new ScanThread((HRegion) region);
     }
     for (ScanThread thread : scanThreads) {
       thread.start();
     }
     while (counter.get() != 3) {
       Thread.sleep(100);
     }
   }
 
   private static class ScanThread extends Thread {
     private final HRegion region;
 
     public ScanThread(HRegion region) {
       this.region = region;
     }
 
     @Override
     public void run() {
       try {
         initiateScan(region);
       } catch (IOException e) {
         // do nothing
       }
     }
 
     private void initiateScan(HRegion region) throws IOException {
       Scan scan = new Scan();
       scan.setCaching(1);
       RegionScanner resScanner = null;
       try {
         resScanner = region.getScanner(scan);
         List<Cell> results = new ArrayList<Cell>();
         boolean next = resScanner.next(results);
         try {
           counter.incrementAndGet();
           latch.await();
         } catch (InterruptedException e) {
         }
         while (!next) {
           resScanner.next(results);
         }
       } finally {
         scanCompletedCounter.incrementAndGet();
         resScanner.close();
       }
     }
   }
 }