HBASE-20894 Use proto for BucketCache persistence

hbase-protocol-shaded/src/main/protobuf/BucketCacheEntry.proto

@@ -0,0 +1,79 @@
+/*
+ * 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.
+ */
+syntax = "proto2";
+
+package hbase.pb;
+
+option java_package = "org.apache.hadoop.hbase.shaded.protobuf.generated";
+option java_outer_classname = "BucketCacheProtos";
+option java_generic_services = true;
+option java_generate_equals_and_hash = true;
+option optimize_for = SPEED;
+
+message BucketCacheEntry {
+  required int64 cache_capacity = 1;
+  required string io_class = 2;
+  required string map_class = 3;
+  map<int32, string> deserializers = 4;
+  required BackingMap backing_map = 5;
+}
+
+message BackingMap {
+  repeated BackingMapEntry entry = 1;
+}
+
+message BackingMapEntry {
+  required BlockCacheKey key = 1;
+  required BucketEntry value = 2;
+}
+
+message BlockCacheKey {
+  required string hfilename = 1;
+  required int64 offset = 2;
+  required BlockType block_type = 3;
+  required bool primary_replica_block = 4;
+}
+
+enum BlockType {
+  data = 0;
+  encoded_data = 1;
+  leaf_index = 2;
+  bloom_chunk = 3;
+  meta = 4;
+  intermediate_index = 5;
+  root_index = 6;
+  file_info = 7;
+  general_bloom_meta = 8;
+  delete_family_bloom_meta = 9;
+  trailer = 10;
+  index_v1 = 11;
+}
+
+message BucketEntry {
+  required int64 offset = 1;
+  required int32 length = 2;
+  required int64 access_counter = 3;
+  required int32 deserialiser_index = 4;
+  required BlockPriority priority = 5;
+}
+
+enum BlockPriority {
+  single = 0;
+  multi = 1;
+  memory = 2;
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/CacheableDeserializerIdManager.java

@@ -25,8 +25,11 @@ import java.util.concurrent.atomic.AtomicInteger;
 import org.apache.yetus.audience.InterfaceAudience;
 
 /**
- * This class is used to manage the identifiers for
+ * This class is used to manage the identifiers for {@link CacheableDeserializer}.
- * {@link CacheableDeserializer}
+ * All deserializers are registered with this Manager via the
+ * {@link #registerDeserializer(CacheableDeserializer)}}. On registration, we return an
+ * int *identifier* for this deserializer. The int identifier is passed to
+ * {@link #getDeserializer(int)}} to obtain the registered deserializer instance.
  */
 @InterfaceAudience.Private
 public class CacheableDeserializerIdManager {
@@ -34,10 +37,11 @@ public class CacheableDeserializerIdManager {
   private static final AtomicInteger identifier = new AtomicInteger(0);
 
   /**
-   * Register the given cacheable deserializer and generate an unique identifier
+   * Register the given {@link Cacheable} -- usually an hfileblock instance, these implement
-   * id for it
+   * the Cacheable Interface -- deserializer and generate an unique identifier id for it and return
-   * @param cd
+   * this as our result.
    * @return the identifier of given cacheable deserializer
+   * @see #getDeserializer(int)
    */
   public static int registerDeserializer(CacheableDeserializer<Cacheable> cd) {
     int idx = identifier.incrementAndGet();
@@ -48,11 +52,25 @@ public class CacheableDeserializerIdManager {
   }
 
   /**
-   * Get the cacheable deserializer as the given identifier Id
+   * Get the cacheable deserializer registered at the given identifier Id.
-   * @param id
+   * @see #registerDeserializer(CacheableDeserializer)
-   * @return CacheableDeserializer
    */
   public static CacheableDeserializer<Cacheable> getDeserializer(int id) {
     return registeredDeserializers.get(id);
   }
+
+  /**
+   * Snapshot a map of the current identifiers to class names for reconstruction on reading out
+   * of a file.
+   */
+  public static Map<Integer,String> save() {
+    Map<Integer, String> snapshot = new HashMap<>();
+    synchronized (registeredDeserializers) {
+      for (Map.Entry<Integer, CacheableDeserializer<Cacheable>> entry :
+          registeredDeserializers.entrySet()) {
+        snapshot.put(entry.getKey(), entry.getValue().getClass().getName());
+      }
+    }
+    return snapshot;
+  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java

@@ -251,10 +251,14 @@ public class HFileBlock implements Cacheable {
    * + Metadata!  + <= See note on BLOCK_METADATA_SPACE above.
    * ++++++++++++++
    * </code>
-   * @see #serialize(ByteBuffer)
+   * @see #serialize(ByteBuffer, boolean)
    */
-  static final CacheableDeserializer<Cacheable> BLOCK_DESERIALIZER =
+  public static final CacheableDeserializer<Cacheable> BLOCK_DESERIALIZER = new BlockDeserializer();
-      new CacheableDeserializer<Cacheable>() {
+
+  public static final class BlockDeserializer implements CacheableDeserializer<Cacheable> {
+    private BlockDeserializer() {
+    }
+
     @Override
     public HFileBlock deserialize(ByteBuff buf, boolean reuse, MemoryType memType)
         throws IOException {
@@ -291,7 +295,7 @@ public class HFileBlock implements Cacheable {
       // Used only in tests
       return deserialize(b, false, MemoryType.EXCLUSIVE);
     }
-  };
+  }
 
   private static final int DESERIALIZER_IDENTIFIER;
   static {

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java

@@ -25,8 +25,6 @@ import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
@@ -68,6 +66,7 @@ import org.apache.hadoop.hbase.io.hfile.CacheableDeserializerIdManager;
 import org.apache.hadoop.hbase.io.hfile.CachedBlock;
 import org.apache.hadoop.hbase.io.hfile.HFileBlock;
 import org.apache.hadoop.hbase.nio.ByteBuff;
+import org.apache.hadoop.hbase.protobuf.ProtobufMagic;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.HasThread;
 import org.apache.hadoop.hbase.util.IdReadWriteLock;
@@ -81,6 +80,7 @@ import org.slf4j.LoggerFactory;
 import org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;
 import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
 import org.apache.hbase.thirdparty.com.google.common.util.concurrent.ThreadFactoryBuilder;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.BucketCacheProtos;
 
 /**
  * BucketCache uses {@link BucketAllocator} to allocate/free blocks, and uses
@@ -164,8 +164,6 @@ public class BucketCache implements BlockCache, HeapSize {
   private volatile boolean freeInProgress = false;
   private final Lock freeSpaceLock = new ReentrantLock();
 
-  private UniqueIndexMap<Integer> deserialiserMap = new UniqueIndexMap<>();
-
   private final LongAdder realCacheSize = new LongAdder();
   private final LongAdder heapSize = new LongAdder();
   /** Current number of cached elements */
@@ -299,10 +297,7 @@ public class BucketCache implements BlockCache, HeapSize {
       try {
         retrieveFromFile(bucketSizes);
       } catch (IOException ioex) {
-        LOG.error("Can't restore from file because of", ioex);
+        LOG.error("Can't restore from file[" + persistencePath + "] because of ", ioex);
-      } catch (ClassNotFoundException cnfe) {
-        LOG.error("Can't restore from file in rebuild because can't deserialise",cnfe);
-        throw new RuntimeException(cnfe);
       }
     }
     final String threadName = Thread.currentThread().getName();
@@ -511,7 +506,7 @@ public class BucketCache implements BlockCache, HeapSize {
             LOG.trace("Read offset=" + bucketEntry.offset() + ", len=" + len);
           }
           Cacheable cachedBlock = ioEngine.read(bucketEntry.offset(), len,
-              bucketEntry.deserializerReference(this.deserialiserMap));
+              bucketEntry.deserializerReference());
           long timeTaken = System.nanoTime() - start;
           if (updateCacheMetrics) {
             cacheStats.hit(caching, key.isPrimary(), key.getBlockType());
@@ -988,7 +983,7 @@ public class BucketCache implements BlockCache, HeapSize {
             continue;
           }
           BucketEntry bucketEntry =
-            re.writeToCache(ioEngine, bucketAllocator, deserialiserMap, realCacheSize);
+            re.writeToCache(ioEngine, bucketAllocator, realCacheSize);
           // Successfully added.  Up index and add bucketEntry. Clear io exceptions.
           bucketEntries[index] = bucketEntry;
           if (ioErrorStartTime > 0) {
@@ -1083,75 +1078,98 @@ public class BucketCache implements BlockCache, HeapSize {
     return receptacle;
   }
 
+  /**
+   * @see #retrieveFromFile(int[])
+   */
   private void persistToFile() throws IOException {
     assert !cacheEnabled;
-    FileOutputStream fos = null;
+    if (!ioEngine.isPersistent()) {
-    ObjectOutputStream oos = null;
+      throw new IOException("Attempt to persist non-persistent cache mappings!");
-    try {
+    }
-      if (!ioEngine.isPersistent()) {
+    try (FileOutputStream fos = new FileOutputStream(persistencePath, false)) {
-        throw new IOException("Attempt to persist non-persistent cache mappings!");
+      fos.write(ProtobufMagic.PB_MAGIC);
-      }
+      BucketProtoUtils.toPB(this).writeDelimitedTo(fos);
-      fos = new FileOutputStream(persistencePath, false);
-      oos = new ObjectOutputStream(fos);
-      oos.writeLong(cacheCapacity);
-      oos.writeUTF(ioEngine.getClass().getName());
-      oos.writeUTF(backingMap.getClass().getName());
-      oos.writeObject(deserialiserMap);
-      oos.writeObject(backingMap);
-    } finally {
-      if (oos != null) oos.close();
-      if (fos != null) fos.close();
     }
   }
 
-  @SuppressWarnings("unchecked")
+  /**
-  private void retrieveFromFile(int[] bucketSizes) throws IOException, BucketAllocatorException,
+   * @see #persistToFile()
-      ClassNotFoundException {
+   */
+  private void retrieveFromFile(int[] bucketSizes) throws IOException {
     File persistenceFile = new File(persistencePath);
     if (!persistenceFile.exists()) {
       return;
     }
     assert !cacheEnabled;
-    FileInputStream fis = null;
+
-    ObjectInputStream ois = null;
+    try (FileInputStream in = deleteFileOnClose(persistenceFile)) {
-    try {
+      int pblen = ProtobufMagic.lengthOfPBMagic();
-      if (!ioEngine.isPersistent())
+      byte[] pbuf = new byte[pblen];
-        throw new IOException(
+      int read = in.read(pbuf);
-            "Attempt to restore non-persistent cache mappings!");
+      if (read != pblen) {
-      fis = new FileInputStream(persistencePath);
+        throw new IOException("Incorrect number of bytes read while checking for protobuf magic "
-      ois = new ObjectInputStream(fis);
+            + "number. Requested=" + pblen + ", Received= " + read + ", File=" + persistencePath);
-      long capacitySize = ois.readLong();
-      if (capacitySize != cacheCapacity)
-        throw new IOException("Mismatched cache capacity:"
-            + StringUtils.byteDesc(capacitySize) + ", expected: "
-            + StringUtils.byteDesc(cacheCapacity));
-      String ioclass = ois.readUTF();
-      String mapclass = ois.readUTF();
-      if (!ioEngine.getClass().getName().equals(ioclass))
-        throw new IOException("Class name for IO engine mismatch: " + ioclass
-            + ", expected:" + ioEngine.getClass().getName());
-      if (!backingMap.getClass().getName().equals(mapclass))
-        throw new IOException("Class name for cache map mismatch: " + mapclass
-            + ", expected:" + backingMap.getClass().getName());
-      UniqueIndexMap<Integer> deserMap = (UniqueIndexMap<Integer>) ois
-          .readObject();
-      ConcurrentHashMap<BlockCacheKey, BucketEntry> backingMapFromFile =
-          (ConcurrentHashMap<BlockCacheKey, BucketEntry>) ois.readObject();
-      BucketAllocator allocator = new BucketAllocator(cacheCapacity, bucketSizes,
-          backingMapFromFile, realCacheSize);
-      bucketAllocator = allocator;
-      deserialiserMap = deserMap;
-      backingMap = backingMapFromFile;
-    } finally {
-      if (ois != null) ois.close();
-      if (fis != null) fis.close();
-      if (!persistenceFile.delete()) {
-        throw new IOException("Failed deleting persistence file "
-            + persistenceFile.getAbsolutePath());
       }
+      if (! ProtobufMagic.isPBMagicPrefix(pbuf)) {
+        // In 3.0 we have enough flexibility to dump the old cache data.
+        // TODO: In 2.x line, this might need to be filled in to support reading the old format
+        throw new IOException("Persistence file does not start with protobuf magic number. " +
+            persistencePath);
+      }
+      parsePB(BucketCacheProtos.BucketCacheEntry.parseDelimitedFrom(in));
+      bucketAllocator = new BucketAllocator(cacheCapacity, bucketSizes, backingMap, realCacheSize);
     }
   }
 
+  /**
+   * Create an input stream that deletes the file after reading it. Use in try-with-resources to
+   * avoid this pattern where an exception thrown from a finally block may mask earlier exceptions:
+   * <pre>
+   *   File f = ...
+   *   try (FileInputStream fis = new FileInputStream(f)) {
+   *     // use the input stream
+   *   } finally {
+   *     if (!f.delete()) throw new IOException("failed to delete");
+   *   }
+   * </pre>
+   * @param file the file to read and delete
+   * @return a FileInputStream for the given file
+   * @throws IOException if there is a problem creating the stream
+   */
+  private FileInputStream deleteFileOnClose(final File file) throws IOException {
+    return new FileInputStream(file) {
+      @Override
+      public void close() throws IOException {
+        super.close();
+        if (!file.delete()) {
+          throw new IOException("Failed deleting persistence file " + file.getAbsolutePath());
+        }
+      }
+    };
+  }
+
+  private void verifyCapacityAndClasses(long capacitySize, String ioclass, String mapclass)
+      throws IOException {
+    if (capacitySize != cacheCapacity) {
+      throw new IOException("Mismatched cache capacity:"
+          + StringUtils.byteDesc(capacitySize) + ", expected: "
+          + StringUtils.byteDesc(cacheCapacity));
+    }
+    if (!ioEngine.getClass().getName().equals(ioclass)) {
+      throw new IOException("Class name for IO engine mismatch: " + ioclass
+          + ", expected:" + ioEngine.getClass().getName());
+    }
+    if (!backingMap.getClass().getName().equals(mapclass)) {
+      throw new IOException("Class name for cache map mismatch: " + mapclass
+          + ", expected:" + backingMap.getClass().getName());
+    }
+  }
+
+  private void parsePB(BucketCacheProtos.BucketCacheEntry proto) throws IOException {
+    verifyCapacityAndClasses(proto.getCacheCapacity(), proto.getIoClass(), proto.getMapClass());
+    backingMap = BucketProtoUtils.fromPB(proto.getDeserializersMap(), proto.getBackingMap());
+  }
+
   /**
    * Check whether we tolerate IO error this time. If the duration of IOEngine
    * throwing errors exceeds ioErrorsDurationTimeTolerated, we will disable the
@@ -1287,18 +1305,19 @@ public class BucketCache implements BlockCache, HeapSize {
     private static final long serialVersionUID = -6741504807982257534L;
 
     // access counter comparator, descending order
-    static final Comparator<BucketEntry> COMPARATOR = new Comparator<BucketCache.BucketEntry>() {
+    static final Comparator<BucketEntry> COMPARATOR = Comparator
-
+        .comparingLong(BucketEntry::getAccessCounter).reversed();
-      @Override
-      public int compare(BucketEntry o1, BucketEntry o2) {
-        return Long.compare(o2.accessCounter, o1.accessCounter);
-      }
-    };
 
     private int offsetBase;
     private int length;
     private byte offset1;
+
+    /**
+     * The index of the deserializer that can deserialize this BucketEntry content.
+     * See {@link CacheableDeserializerIdManager} for hosting of index to serializers.
+     */
     byte deserialiserIndex;
+
     private volatile long accessCounter;
     private BlockPriority priority;
 
@@ -1335,17 +1354,16 @@ public class BucketCache implements BlockCache, HeapSize {
       return length;
     }
 
-    protected CacheableDeserializer<Cacheable> deserializerReference(
+    protected CacheableDeserializer<Cacheable> deserializerReference() {
-        UniqueIndexMap<Integer> deserialiserMap) {
+      return CacheableDeserializerIdManager.getDeserializer(deserialiserIndex);
-      return CacheableDeserializerIdManager.getDeserializer(deserialiserMap
-          .unmap(deserialiserIndex));
     }
 
-    protected void setDeserialiserReference(
+    protected void setDeserialiserReference(CacheableDeserializer<Cacheable> deserializer) {
-        CacheableDeserializer<Cacheable> deserializer,
+      this.deserialiserIndex = (byte) deserializer.getDeserialiserIdentifier();
-        UniqueIndexMap<Integer> deserialiserMap) {
+    }
-      this.deserialiserIndex = ((byte) deserialiserMap.map(deserializer
+
-          .getDeserialiserIdentifier()));
+    public long getAccessCounter() {
+      return accessCounter;
     }
 
     /**
@@ -1504,7 +1522,6 @@ public class BucketCache implements BlockCache, HeapSize {
 
     public BucketEntry writeToCache(final IOEngine ioEngine,
         final BucketAllocator bucketAllocator,
-        final UniqueIndexMap<Integer> deserialiserMap,
         final LongAdder realCacheSize) throws CacheFullException, IOException,
         BucketAllocatorException {
       int len = data.getSerializedLength();
@@ -1516,7 +1533,7 @@ public class BucketCache implements BlockCache, HeapSize {
               ? new UnsafeSharedMemoryBucketEntry(offset, len, accessCounter, inMemory)
               : new SharedMemoryBucketEntry(offset, len, accessCounter, inMemory)
           : new BucketEntry(offset, len, accessCounter, inMemory);
-      bucketEntry.setDeserialiserReference(data.getDeserializer(), deserialiserMap);
+      bucketEntry.setDeserialiserReference(data.getDeserializer());
       try {
         if (data instanceof HFileBlock) {
           // If an instance of HFileBlock, save on some allocations.

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketProtoUtils.java

@@ -0,0 +1,191 @@
+/*
+ * Copyright The Apache Software Foundation
+ *
+ * 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.io.hfile.bucket;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.apache.hadoop.hbase.io.hfile.BlockCacheKey;
+import org.apache.hadoop.hbase.io.hfile.BlockPriority;
+import org.apache.hadoop.hbase.io.hfile.BlockType;
+import org.apache.hadoop.hbase.io.hfile.CacheableDeserializerIdManager;
+import org.apache.hadoop.hbase.io.hfile.HFileBlock;
+import org.apache.yetus.audience.InterfaceAudience;
+
+import org.apache.hadoop.hbase.shaded.protobuf.generated.BucketCacheProtos;
+
+@InterfaceAudience.Private
+final class BucketProtoUtils {
+  private BucketProtoUtils() {
+
+  }
+
+  static BucketCacheProtos.BucketCacheEntry toPB(BucketCache cache) {
+    return BucketCacheProtos.BucketCacheEntry.newBuilder()
+        .setCacheCapacity(cache.getMaxSize())
+        .setIoClass(cache.ioEngine.getClass().getName())
+        .setMapClass(cache.backingMap.getClass().getName())
+        .putAllDeserializers(CacheableDeserializerIdManager.save())
+        .setBackingMap(BucketProtoUtils.toPB(cache.backingMap))
+        .build();
+  }
+
+  private static BucketCacheProtos.BackingMap toPB(
+      Map<BlockCacheKey, BucketCache.BucketEntry> backingMap) {
+    BucketCacheProtos.BackingMap.Builder builder = BucketCacheProtos.BackingMap.newBuilder();
+    for (Map.Entry<BlockCacheKey, BucketCache.BucketEntry> entry : backingMap.entrySet()) {
+      builder.addEntry(BucketCacheProtos.BackingMapEntry.newBuilder()
+          .setKey(toPB(entry.getKey()))
+          .setValue(toPB(entry.getValue()))
+          .build());
+    }
+    return builder.build();
+  }
+
+  private static BucketCacheProtos.BlockCacheKey toPB(BlockCacheKey key) {
+    return BucketCacheProtos.BlockCacheKey.newBuilder()
+        .setHfilename(key.getHfileName())
+        .setOffset(key.getOffset())
+        .setPrimaryReplicaBlock(key.isPrimary())
+        .setBlockType(toPB(key.getBlockType()))
+        .build();
+  }
+
+  private static BucketCacheProtos.BlockType toPB(BlockType blockType) {
+    switch(blockType) {
+      case DATA:
+        return BucketCacheProtos.BlockType.data;
+      case META:
+        return BucketCacheProtos.BlockType.meta;
+      case TRAILER:
+        return BucketCacheProtos.BlockType.trailer;
+      case INDEX_V1:
+        return BucketCacheProtos.BlockType.index_v1;
+      case FILE_INFO:
+        return BucketCacheProtos.BlockType.file_info;
+      case LEAF_INDEX:
+        return BucketCacheProtos.BlockType.leaf_index;
+      case ROOT_INDEX:
+        return BucketCacheProtos.BlockType.root_index;
+      case BLOOM_CHUNK:
+        return BucketCacheProtos.BlockType.bloom_chunk;
+      case ENCODED_DATA:
+        return BucketCacheProtos.BlockType.encoded_data;
+      case GENERAL_BLOOM_META:
+        return BucketCacheProtos.BlockType.general_bloom_meta;
+      case INTERMEDIATE_INDEX:
+        return BucketCacheProtos.BlockType.intermediate_index;
+      case DELETE_FAMILY_BLOOM_META:
+        return BucketCacheProtos.BlockType.delete_family_bloom_meta;
+      default:
+        throw new Error("Unrecognized BlockType.");
+    }
+  }
+
+  private static BucketCacheProtos.BucketEntry toPB(BucketCache.BucketEntry entry) {
+    return BucketCacheProtos.BucketEntry.newBuilder()
+        .setOffset(entry.offset())
+        .setLength(entry.getLength())
+        .setDeserialiserIndex(entry.deserialiserIndex)
+        .setAccessCounter(entry.getAccessCounter())
+        .setPriority(toPB(entry.getPriority()))
+        .build();
+  }
+
+  private static BucketCacheProtos.BlockPriority toPB(BlockPriority p) {
+    switch (p) {
+      case MULTI:
+        return BucketCacheProtos.BlockPriority.multi;
+      case MEMORY:
+        return BucketCacheProtos.BlockPriority.memory;
+      case SINGLE:
+        return BucketCacheProtos.BlockPriority.single;
+      default:
+        throw new Error("Unrecognized BlockPriority.");
+    }
+  }
+
+  static ConcurrentHashMap<BlockCacheKey, BucketCache.BucketEntry> fromPB(
+      Map<Integer, String> deserializers, BucketCacheProtos.BackingMap backingMap)
+      throws IOException {
+    ConcurrentHashMap<BlockCacheKey, BucketCache.BucketEntry> result = new ConcurrentHashMap<>();
+    for (BucketCacheProtos.BackingMapEntry entry : backingMap.getEntryList()) {
+      BucketCacheProtos.BlockCacheKey protoKey = entry.getKey();
+      BlockCacheKey key = new BlockCacheKey(protoKey.getHfilename(), protoKey.getOffset(),
+          protoKey.getPrimaryReplicaBlock(), fromPb(protoKey.getBlockType()));
+      BucketCacheProtos.BucketEntry protoValue = entry.getValue();
+      BucketCache.BucketEntry value = new BucketCache.BucketEntry(
+          protoValue.getOffset(),
+          protoValue.getLength(),
+          protoValue.getAccessCounter(),
+          protoValue.getPriority() == BucketCacheProtos.BlockPriority.memory);
+      // This is the deserializer that we stored
+      int oldIndex = protoValue.getDeserialiserIndex();
+      String deserializerClass = deserializers.get(oldIndex);
+      if (deserializerClass == null) {
+        throw new IOException("Found deserializer index without matching entry.");
+      }
+      // Convert it to the identifier for the deserializer that we have in this runtime
+      if (deserializerClass.equals(HFileBlock.BlockDeserializer.class.getName())) {
+        int actualIndex = HFileBlock.BLOCK_DESERIALIZER.getDeserialiserIdentifier();
+        value.deserialiserIndex = (byte) actualIndex;
+      } else {
+        // We could make this more plugable, but right now HFileBlock is the only implementation
+        // of Cacheable outside of tests, so this might not ever matter.
+        throw new IOException("Unknown deserializer class found: " + deserializerClass);
+      }
+      result.put(key, value);
+    }
+    return result;
+  }
+
+  private static BlockType fromPb(BucketCacheProtos.BlockType blockType) {
+    switch (blockType) {
+      case data:
+        return BlockType.DATA;
+      case meta:
+        return BlockType.META;
+      case trailer:
+        return BlockType.TRAILER;
+      case index_v1:
+        return BlockType.INDEX_V1;
+      case file_info:
+        return BlockType.FILE_INFO;
+      case leaf_index:
+        return BlockType.LEAF_INDEX;
+      case root_index:
+        return BlockType.ROOT_INDEX;
+      case bloom_chunk:
+        return BlockType.BLOOM_CHUNK;
+      case encoded_data:
+        return BlockType.ENCODED_DATA;
+      case general_bloom_meta:
+        return BlockType.GENERAL_BLOOM_META;
+      case intermediate_index:
+        return BlockType.INTERMEDIATE_INDEX;
+      case delete_family_bloom_meta:
+        return BlockType.DELETE_FAMILY_BLOOM_META;
+      default:
+        throw new Error("Unrecognized BlockType.");
+    }
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/UniqueIndexMap.java

@@ -1,56 +0,0 @@
-/**
- * Copyright The Apache Software Foundation
- *
- * 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.io.hfile.bucket;
-
-import java.io.Serializable;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.atomic.AtomicInteger;
-
-import org.apache.yetus.audience.InterfaceAudience;
-
-/**
- * Map from type T to int and vice-versa. Used for reducing bit field item
- * counts.
- */
-@InterfaceAudience.Private
-public final class UniqueIndexMap<T> implements Serializable {
-  private static final long serialVersionUID = -1145635738654002342L;
-
-  ConcurrentHashMap<T, Integer> mForwardMap = new ConcurrentHashMap<>();
-  ConcurrentHashMap<Integer, T> mReverseMap = new ConcurrentHashMap<>();
-  AtomicInteger mIndex = new AtomicInteger(0);
-
-  // Map a length to an index. If we can't, allocate a new mapping. We might
-  // race here and get two entries with the same deserialiser. This is fine.
-  int map(T parameter) {
-    Integer ret = mForwardMap.get(parameter);
-    if (ret != null) return ret.intValue();
-    int nexti = mIndex.incrementAndGet();
-    assert (nexti < Short.MAX_VALUE);
-    mForwardMap.put(parameter, nexti);
-    mReverseMap.put(nexti, parameter);
-    return nexti;
-  }
-
-  T unmap(int leni) {
-    Integer len = Integer.valueOf(leni);
-    assert mReverseMap.containsKey(len);
-    return mReverseMap.get(len);
-  }
-}

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/CacheTestUtils.java

@@ -287,6 +287,7 @@ public class CacheTestUtils {
         return deserializerIdentifier;
       }
 
+
       @Override
       public Cacheable deserialize(ByteBuff b, boolean reuse, MemoryType memType)
           throws IOException {

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestBucketCache.java

@@ -19,9 +19,11 @@ package org.apache.hadoop.hbase.io.hfile.bucket;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
+import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -246,11 +248,13 @@ public class TestBucketCache {
     Path testDir = TEST_UTIL.getDataTestDir();
     TEST_UTIL.getTestFileSystem().mkdirs(testDir);
 
-    BucketCache bucketCache = new BucketCache("file:" + testDir + "/bucket.cache", capacitySize,
+    String ioEngineName = "file:" + testDir + "/bucket.cache";
-        constructedBlockSize, constructedBlockSizes, writeThreads, writerQLen, testDir
+    String persistencePath = testDir + "/bucket.persistence";
-            + "/bucket.persistence");
+
+    BucketCache bucketCache = new BucketCache(ioEngineName, capacitySize, constructedBlockSize,
+        constructedBlockSizes, writeThreads, writerQLen, persistencePath);
     long usedSize = bucketCache.getAllocator().getUsedSize();
-    assertTrue(usedSize == 0);
+    assertEquals(0, usedSize);
 
     HFileBlockPair[] blocks = CacheTestUtils.generateHFileBlocks(constructedBlockSize, 1);
     // Add blocks
@@ -261,24 +265,26 @@ public class TestBucketCache {
       cacheAndWaitUntilFlushedToBucket(bucketCache, block.getBlockName(), block.getBlock());
     }
     usedSize = bucketCache.getAllocator().getUsedSize();
-    assertTrue(usedSize != 0);
+    assertNotEquals(0, usedSize);
     // persist cache to file
     bucketCache.shutdown();
+    assertTrue(new File(persistencePath).exists());
 
     // restore cache from file
-    bucketCache = new BucketCache("file:" + testDir + "/bucket.cache", capacitySize,
+    bucketCache = new BucketCache(ioEngineName, capacitySize, constructedBlockSize,
-        constructedBlockSize, constructedBlockSizes, writeThreads, writerQLen, testDir
+        constructedBlockSizes, writeThreads, writerQLen, persistencePath);
-            + "/bucket.persistence");
+    assertFalse(new File(persistencePath).exists());
     assertEquals(usedSize, bucketCache.getAllocator().getUsedSize());
     // persist cache to file
     bucketCache.shutdown();
+    assertTrue(new File(persistencePath).exists());
 
     // reconfig buckets sizes, the biggest bucket is small than constructedBlockSize (8k or 16k)
     // so it can't restore cache from file
     int[] smallBucketSizes = new int[] { 2 * 1024 + 1024, 4 * 1024 + 1024 };
-    bucketCache = new BucketCache("file:" + testDir + "/bucket.cache", capacitySize,
+    bucketCache = new BucketCache(ioEngineName, capacitySize, constructedBlockSize,
-        constructedBlockSize, smallBucketSizes, writeThreads,
+        smallBucketSizes, writeThreads, writerQLen, persistencePath);
-        writerQLen, testDir + "/bucket.persistence");
+    assertFalse(new File(persistencePath).exists());
     assertEquals(0, bucketCache.getAllocator().getUsedSize());
     assertEquals(0, bucketCache.backingMap.size());
 

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestBucketWriterThread.java

@@ -27,7 +27,6 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.BlockingQueue;
-import java.util.concurrent.atomic.LongAdder;
 import org.apache.hadoop.hbase.HBaseClassTestRule;
 import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.hbase.io.hfile.BlockCacheKey;
@@ -143,8 +142,7 @@ public class TestBucketWriterThread {
     RAMQueueEntry rqe = q.remove();
     RAMQueueEntry spiedRqe = Mockito.spy(rqe);
     Mockito.doThrow(new IOException("Mocked!")).when(spiedRqe).
-      writeToCache((IOEngine)Mockito.any(), (BucketAllocator)Mockito.any(),
+      writeToCache(Mockito.any(), Mockito.any(), Mockito.any());
-        (UniqueIndexMap<Integer>)Mockito.any(), (LongAdder) Mockito.any());
     this.q.add(spiedRqe);
     doDrainOfOneEntry(bc, wt, q);
     // Cache disabled when ioes w/o ever healing.
@@ -166,8 +164,7 @@ public class TestBucketWriterThread {
     BucketEntry mockedBucketEntry = Mockito.mock(BucketEntry.class);
     Mockito.doThrow(cfe).
       doReturn(mockedBucketEntry).
-      when(spiedRqe).writeToCache((IOEngine)Mockito.any(), (BucketAllocator)Mockito.any(),
+      when(spiedRqe).writeToCache(Mockito.any(), Mockito.any(), Mockito.any());
-        (UniqueIndexMap<Integer>)Mockito.any(), (LongAdder) Mockito.any());
     this.q.add(spiedRqe);
     doDrainOfOneEntry(bc, wt, q);
   }