/*
    *
    * 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.
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  package org.apache.hadoop.hbase.io.hfile;
  
  import static org.junit.Assert.assertArrayEquals;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNull;
  import static org.junit.Assert.assertTrue;
  import static org.junit.Assert.fail;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.Arrays;
  import java.util.HashSet;
  import java.util.Random;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.MultithreadedTestUtil;
  import org.apache.hadoop.hbase.MultithreadedTestUtil.TestThread;
  import org.apache.hadoop.hbase.io.HeapSize;
  import org.apache.hadoop.hbase.io.compress.Compression;
  import org.apache.hadoop.hbase.io.hfile.bucket.BucketCache;
  import org.apache.hadoop.hbase.util.ChecksumType;
  
  import com.google.common.annotations.VisibleForTesting;
  
  public class CacheTestUtils {
  
    private static final boolean includesMemstoreTS = true;
  
    /**
     * Just checks if heapsize grows when something is cached, and gets smaller
     * when the same object is evicted
     */
  
    public static void testHeapSizeChanges(final BlockCache toBeTested,
        final int blockSize) {
      HFileBlockPair[] blocks = generateHFileBlocks(blockSize, 1);
      long heapSize = ((HeapSize) toBeTested).heapSize();
      toBeTested.cacheBlock(blocks[0].blockName, blocks[0].block);
  
      /*When we cache something HeapSize should always increase */
      assertTrue(heapSize < ((HeapSize) toBeTested).heapSize());
  
      toBeTested.evictBlock(blocks[0].blockName);
  
      /*Post eviction, heapsize should be the same */
      assertEquals(heapSize, ((HeapSize) toBeTested).heapSize());
    }
  
    public static void testCacheMultiThreaded(final BlockCache toBeTested,
        final int blockSize, final int numThreads, final int numQueries,
        final double passingScore) throws Exception {
  
      Configuration conf = new Configuration();
      MultithreadedTestUtil.TestContext ctx = new MultithreadedTestUtil.TestContext(
          conf);
  
      final AtomicInteger totalQueries = new AtomicInteger();
      final ConcurrentLinkedQueue<HFileBlockPair> blocksToTest = new ConcurrentLinkedQueue<HFileBlockPair>();
      final AtomicInteger hits = new AtomicInteger();
      final AtomicInteger miss = new AtomicInteger();
  
      HFileBlockPair[] blocks = generateHFileBlocks(numQueries, blockSize);
      blocksToTest.addAll(Arrays.asList(blocks));
  
      for (int i = 0; i < numThreads; i++) {
        TestThread t = new MultithreadedTestUtil.RepeatingTestThread(ctx) {
          @Override
          public void doAnAction() throws Exception {
            if (!blocksToTest.isEmpty()) {
              HFileBlockPair ourBlock = blocksToTest.poll();
              // if we run out of blocks to test, then we should stop the tests.
              if (ourBlock == null) {
                ctx.setStopFlag(true);
                return;
              }
              toBeTested.cacheBlock(ourBlock.blockName, ourBlock.block);
              Cacheable retrievedBlock = toBeTested.getBlock(ourBlock.blockName,
                  false, false, true);
             if (retrievedBlock != null) {
               assertEquals(ourBlock.block, retrievedBlock);
               toBeTested.evictBlock(ourBlock.blockName);
               hits.incrementAndGet();
               assertNull(toBeTested.getBlock(ourBlock.blockName, false, false, true));
             } else {
               miss.incrementAndGet();
             }
             totalQueries.incrementAndGet();
           }
         }
       };
       t.setDaemon(true);
       ctx.addThread(t);
     }
     ctx.startThreads();
     while (!blocksToTest.isEmpty() && ctx.shouldRun()) {
       Thread.sleep(10);
     }
     ctx.stop();
     if (hits.get() / ((double) hits.get() + (double) miss.get()) < passingScore) {
       fail("Too many nulls returned. Hits: " + hits.get() + " Misses: "
           + miss.get());
     }
   }
 
   public static void testCacheSimple(BlockCache toBeTested, int blockSize,
       int numBlocks) throws Exception {
 
     HFileBlockPair[] blocks = generateHFileBlocks(numBlocks, blockSize);
     // Confirm empty
     for (HFileBlockPair block : blocks) {
       assertNull(toBeTested.getBlock(block.blockName, true, false, true));
     }
 
     // Add blocks
     for (HFileBlockPair block : blocks) {
       toBeTested.cacheBlock(block.blockName, block.block);
     }
 
     // Check if all blocks are properly cached and contain the right
     // information, or the blocks are null.
     // MapMaker makes no guarantees when it will evict, so neither can we.
 
     for (HFileBlockPair block : blocks) {
       HFileBlock buf = (HFileBlock) toBeTested.getBlock(block.blockName, true, false, true);
       if (buf != null) {
         assertEquals(block.block, buf);
       }
 
     }
 
     // Re-add some duplicate blocks. Hope nothing breaks.
 
     for (HFileBlockPair block : blocks) {
       try {
         if (toBeTested.getBlock(block.blockName, true, false, true) != null) {
           toBeTested.cacheBlock(block.blockName, block.block);
           if (!(toBeTested instanceof BucketCache)) {
             // BucketCache won't throw exception when caching already cached
             // block
             fail("Cache should not allow re-caching a block");
           }
         }
       } catch (RuntimeException re) {
         // expected
       }
     }
 
   }
 
   public static void hammerSingleKey(final BlockCache toBeTested,
       int BlockSize, int numThreads, int numQueries) throws Exception {
     final BlockCacheKey key = new BlockCacheKey("key", 0);
     final byte[] buf = new byte[5 * 1024];
     Arrays.fill(buf, (byte) 5);
 
     final ByteArrayCacheable bac = new ByteArrayCacheable(buf);
     Configuration conf = new Configuration();
     MultithreadedTestUtil.TestContext ctx = new MultithreadedTestUtil.TestContext(
         conf);
 
     final AtomicInteger totalQueries = new AtomicInteger();
     toBeTested.cacheBlock(key, bac);
 
     for (int i = 0; i < numThreads; i++) {
       TestThread t = new MultithreadedTestUtil.RepeatingTestThread(ctx) {
         @Override
         public void doAnAction() throws Exception {
           ByteArrayCacheable returned = (ByteArrayCacheable) toBeTested
               .getBlock(key, false, false, true);
           if (returned != null) {
             assertArrayEquals(buf, returned.buf);
           } else {
             Thread.sleep(10);
           }
           totalQueries.incrementAndGet();
         }
       };
 
       t.setDaemon(true);
       ctx.addThread(t);
     }
 
     // add a thread to periodically evict and re-cache the block
     final long blockEvictPeriod = 50;
     TestThread t = new MultithreadedTestUtil.RepeatingTestThread(ctx) {
       @Override
       public void doAnAction() throws Exception {
         toBeTested.evictBlock(key);
         toBeTested.cacheBlock(key, bac);
         Thread.sleep(blockEvictPeriod);
       }
     };
     t.setDaemon(true);
     ctx.addThread(t);
 
     ctx.startThreads();
     while (totalQueries.get() < numQueries && ctx.shouldRun()) {
       Thread.sleep(10);
     }
     ctx.stop();
   }
 
   public static void hammerEviction(final BlockCache toBeTested, int BlockSize,
       int numThreads, int numQueries) throws Exception {
 
     Configuration conf = new Configuration();
     MultithreadedTestUtil.TestContext ctx = new MultithreadedTestUtil.TestContext(
         conf);
 
     final AtomicInteger totalQueries = new AtomicInteger();
 
     for (int i = 0; i < numThreads; i++) {
       final int finalI = i;
 
       final byte[] buf = new byte[5 * 1024];
       TestThread t = new MultithreadedTestUtil.RepeatingTestThread(ctx) {
         @Override
         public void doAnAction() throws Exception {
           for (int j = 0; j < 100; j++) {
             BlockCacheKey key = new BlockCacheKey("key_" + finalI + "_" + j, 0);
             Arrays.fill(buf, (byte) (finalI * j));
             final ByteArrayCacheable bac = new ByteArrayCacheable(buf);
 
             ByteArrayCacheable gotBack = (ByteArrayCacheable) toBeTested
                 .getBlock(key, true, false, true);
             if (gotBack != null) {
               assertArrayEquals(gotBack.buf, bac.buf);
             } else {
               toBeTested.cacheBlock(key, bac);
             }
           }
           totalQueries.incrementAndGet();
         }
       };
 
       t.setDaemon(true);
       ctx.addThread(t);
     }
 
     ctx.startThreads();
     while (totalQueries.get() < numQueries && ctx.shouldRun()) {
       Thread.sleep(10);
     }
     ctx.stop();
 
     assertTrue(toBeTested.getStats().getEvictedCount() > 0);
   }
 
   public static class ByteArrayCacheable implements Cacheable {
 
     static final CacheableDeserializer<Cacheable> blockDeserializer =
       new CacheableDeserializer<Cacheable>() {
 
       @Override
       public Cacheable deserialize(ByteBuffer b) throws IOException {
         int len = b.getInt();
         Thread.yield();
         byte buf[] = new byte[len];
         b.get(buf);
         return new ByteArrayCacheable(buf);
       }
 
       @Override
       public int getDeserialiserIdentifier() {
         return deserializerIdentifier;
       }
 
       @Override
       public Cacheable deserialize(ByteBuffer b, boolean reuse)
           throws IOException {
         return deserialize(b);
       }
     };
 
     final byte[] buf;
 
     public ByteArrayCacheable(byte[] buf) {
       this.buf = buf;
     }
 
     @Override
     public long heapSize() {
       return 4 + buf.length;
     }
 
     @Override
     public int getSerializedLength() {
       return 4 + buf.length;
     }
 
     @Override
     public void serialize(ByteBuffer destination) {
       destination.putInt(buf.length);
       Thread.yield();
       destination.put(buf);
       destination.rewind();
     }
 
     @Override
     public CacheableDeserializer<Cacheable> getDeserializer() {
       return blockDeserializer;
     }
 
     private static final int deserializerIdentifier;
     static {
       deserializerIdentifier = CacheableDeserializerIdManager
           .registerDeserializer(blockDeserializer);
     }
 
     @Override
     public BlockType getBlockType() {
       return BlockType.DATA;
     }
   }
 
 
   public static HFileBlockPair[] generateHFileBlocks(int blockSize, int numBlocks) {
     HFileBlockPair[] returnedBlocks = new HFileBlockPair[numBlocks];
     Random rand = new Random();
     HashSet<String> usedStrings = new HashSet<String>();
     for (int i = 0; i < numBlocks; i++) {
       ByteBuffer cachedBuffer = ByteBuffer.allocate(blockSize);
       rand.nextBytes(cachedBuffer.array());
       cachedBuffer.rewind();
       int onDiskSizeWithoutHeader = blockSize;
       int uncompressedSizeWithoutHeader = blockSize;
       long prevBlockOffset = rand.nextLong();
       BlockType.DATA.write(cachedBuffer);
       cachedBuffer.putInt(onDiskSizeWithoutHeader);
       cachedBuffer.putInt(uncompressedSizeWithoutHeader);
       cachedBuffer.putLong(prevBlockOffset);
       cachedBuffer.rewind();
       HFileContext meta = new HFileContextBuilder()
                           .withHBaseCheckSum(false)
                           .withIncludesMvcc(includesMemstoreTS)
                           .withIncludesTags(false)
                           .withCompression(Compression.Algorithm.NONE)
                           .withBytesPerCheckSum(0)
                           .withChecksumType(ChecksumType.NULL)
                           .build();
       HFileBlock generated = new HFileBlock(BlockType.DATA,
           onDiskSizeWithoutHeader, uncompressedSizeWithoutHeader,
           prevBlockOffset, cachedBuffer, HFileBlock.DONT_FILL_HEADER,
           blockSize,
           onDiskSizeWithoutHeader + HConstants.HFILEBLOCK_HEADER_SIZE, -1, meta);
 
       String strKey;
       /* No conflicting keys */
       for (strKey = new Long(rand.nextLong()).toString(); !usedStrings
           .add(strKey); strKey = new Long(rand.nextLong()).toString())
         ;
 
       returnedBlocks[i] = new HFileBlockPair();
       returnedBlocks[i].blockName = new BlockCacheKey(strKey, 0);
       returnedBlocks[i].block = generated;
     }
     return returnedBlocks;
   }
 
   @VisibleForTesting
   public static class HFileBlockPair {
     BlockCacheKey blockName;
     HFileBlock block;
 
     public BlockCacheKey getBlockName() {
       return this.blockName;
     }
 
     public HFileBlock getBlock() {
       return this.block;
     }
   }
 }