| /* |
| * 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.phoenix.util; |
| |
| import java.io.DataInput; |
| import java.io.IOException; |
| |
| import org.apache.hadoop.hbase.io.ImmutableBytesWritable; |
| import org.apache.hadoop.io.WritableUtils; |
| |
| /** |
| * |
| * Prefix decoder for byte arrays. For encoding, see {@link PrefixByteEncoder}. |
| * |
| */ |
| public class PrefixByteDecoder { |
| private final int maxLength; |
| private final ImmutableBytesWritable previous; |
| |
| /** |
| * Used when the maximum length of encoded byte array is not known. Will |
| * cause a new byte array to be allocated for each call to {@link #decode(DataInput)}. |
| */ |
| public PrefixByteDecoder() { |
| maxLength = -1; |
| previous = new ImmutableBytesWritable(ByteUtil.EMPTY_BYTE_ARRAY); |
| } |
| |
| /** |
| * Used when the maximum length of encoded byte array is known in advance. |
| * Will not allocate new byte array with each call to {@link #decode(DataInput)}. |
| * @param maxLength maximum length needed for any call to {@link #decode(DataInput)}. |
| */ |
| public PrefixByteDecoder(int maxLength) { |
| if (maxLength > 0) { |
| this.maxLength = maxLength; |
| this.previous = new ImmutableBytesWritable(new byte[maxLength], 0, 0); |
| } else { |
| this.maxLength = -1; |
| previous = new ImmutableBytesWritable(ByteUtil.EMPTY_BYTE_ARRAY); |
| } |
| } |
| |
| /** |
| * Resets state of decoder if it will be used to decode bytes from a |
| * different DataInput. |
| */ |
| public void reset() { |
| previous.set(previous.get(),0,0); |
| } |
| |
| /** |
| * Decodes bytes encoded with {@link PrefixByteEncoder}. |
| * @param in Input from which bytes are read. |
| * @return Pointer containing bytes that were decoded. Note that the |
| * same pointer will be returned with each call, so it must be consumed |
| * prior to calling decode again. |
| * @throws IOException |
| */ |
| public ImmutableBytesWritable decode(DataInput in) throws IOException { |
| int prefixLen = WritableUtils.readVInt(in); |
| int suffixLen = WritableUtils.readVInt(in); |
| int length = prefixLen + suffixLen; |
| byte[] b; |
| if (maxLength == -1) { // Allocate new byte array each time |
| b = new byte[length]; |
| System.arraycopy(previous.get(), previous.getOffset(), b, 0, prefixLen); |
| } else { // Reuse same buffer each time |
| b = previous.get(); |
| } |
| in.readFully(b, prefixLen, suffixLen); |
| previous.set(b, 0, length); |
| return previous; |
| } |
| } |