Java tutorial
/* * 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.bookkeeper.statelib.impl.mvcc; import com.google.protobuf.CodedOutputStream; import com.google.protobuf.InvalidProtocolBufferException; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import java.io.IOException; import java.nio.ByteBuffer; import lombok.AccessLevel; import lombok.NoArgsConstructor; import org.apache.bookkeeper.common.coder.Coder; import org.apache.bookkeeper.statelib.api.exceptions.StateStoreRuntimeException; import org.apache.bookkeeper.stream.proto.kv.store.KeyMeta; /** * A coder for encoding and decoding {@link MVCCRecord}s. */ @NoArgsConstructor(access = AccessLevel.PRIVATE) final class MVCCRecordCoder implements Coder<MVCCRecord> { public static MVCCRecordCoder of() { return INSTANCE; } private static final MVCCRecordCoder INSTANCE = new MVCCRecordCoder(); @Override public byte[] encode(MVCCRecord record) { KeyMeta meta = KeyMeta.newBuilder().setCreateRevision(record.getCreateRev()) .setModRevision(record.getModRev()).setVersion(record.getVersion()) .setValueType(record.getValueType()).build(); int metaLen = meta.getSerializedSize(); int valLen = record.getValue().readableBytes(); int totalLen = Integer.BYTES // meta len + metaLen // meta bytes + Integer.BYTES // val len + valLen; // val bytes // NOTE: currently rocksdb jni only supports `byte[]` // we can improve this if rocksdb jni support ByteBuffer or ByteBuf byte[] data = new byte[totalLen]; ByteBuf buf = Unpooled.wrappedBuffer(data); buf.writerIndex(0); buf.writeInt(metaLen); CodedOutputStream out = CodedOutputStream.newInstance(data, Integer.BYTES, metaLen); try { meta.writeTo(out); } catch (IOException e) { throw new StateStoreRuntimeException("Failed to serialize key metadata", e); } buf.writerIndex(buf.writerIndex() + metaLen); buf.writeInt(valLen); buf.writeBytes(record.getValue().slice()); buf.release(); return data; } @Override public void encode(MVCCRecord value, ByteBuf destBuf) { destBuf.writeBytes(encode(value)); } @Override public int getSerializedSize(MVCCRecord record) { KeyMeta meta = KeyMeta.newBuilder().setCreateRevision(record.getCreateRev()) .setModRevision(record.getModRev()).setVersion(record.getVersion()) .setValueType(record.getValueType()).build(); int metaLen = meta.getSerializedSize(); int valLen = record.getValue().readableBytes(); return Integer.BYTES // meta len + metaLen // meta bytes + Integer.BYTES // val len + valLen; // val bytes } @Override public MVCCRecord decode(ByteBuf data) { ByteBuf copy = data.slice(); int metaLen = copy.readInt(); ByteBuffer metaBuf = copy.slice(copy.readerIndex(), metaLen).nioBuffer(); KeyMeta meta; try { meta = KeyMeta.parseFrom(metaBuf); } catch (InvalidProtocolBufferException e) { throw new StateStoreRuntimeException("Failed to deserialize key metadata", e); } copy.skipBytes(metaLen); int valLen = copy.readInt(); ByteBuf valBuf = copy.retainedSlice(copy.readerIndex(), valLen); MVCCRecord record = MVCCRecord.newRecord(); record.setCreateRev(meta.getCreateRevision()); record.setModRev(meta.getModRevision()); record.setVersion(meta.getVersion()); record.setValue(valBuf, meta.getValueType()); return record; } }