org.apache.hudi.org.apache.hadoop.hbase.io.hfile.Cacheable Maven / Gradle / Ivy
/**
*
* 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;
import java.nio.ByteBuffer;
import org.apache.hadoop.hbase.io.HeapSize;
import org.apache.hadoop.hbase.nio.HBaseReferenceCounted;
import org.apache.yetus.audience.InterfaceAudience;
/**
* Cacheable is an interface that allows for an object to be cached. If using an
* on heap cache, just use heapsize. If using an off heap cache, Cacheable
* provides methods for serialization of the object.
*
* Some objects cannot be moved off heap, those objects will return a
* getSerializedLength() of 0.
*
*/
@InterfaceAudience.Private
public interface Cacheable extends HeapSize, HBaseReferenceCounted {
/**
* Returns the length of the ByteBuffer required to serialized the object. If the
* object cannot be serialized, it should return 0.
*
* @return int length in bytes of the serialized form or 0 if the object cannot be cached.
*/
int getSerializedLength();
/**
* Serializes its data into destination.
* @param destination Where to serialize to
* @param includeNextBlockMetadata Whether to include nextBlockMetadata in the Cache block.
*/
void serialize(ByteBuffer destination, boolean includeNextBlockMetadata);
/**
* Returns CacheableDeserializer instance which reconstructs original object from ByteBuffer.
*
* @return CacheableDeserialzer instance.
*/
CacheableDeserializer getDeserializer();
/**
* @return the block type of this cached HFile block
*/
BlockType getBlockType();
/******************************* ReferenceCounted Interfaces ***********************************/
/**
* Increase its reference count, and only when no reference we can free the object's memory.
*/
default Cacheable retain() {
return this;
}
/**
* Reference count of this Cacheable.
*/
default int refCnt() {
return 0;
}
/**
* Decrease its reference count, and if no reference then free the memory of this object, its
* backend is usually a {@link org.apache.hadoop.hbase.nio.ByteBuff}, and we will put its NIO
* ByteBuffers back to {@link org.apache.hadoop.hbase.io.ByteBuffAllocator}
*/
default boolean release() {
return false;
}
}