| /* |
| * 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.DataOutput; |
| import java.io.IOException; |
| |
| import org.apache.hadoop.hbase.io.ImmutableBytesWritable; |
| import org.apache.hadoop.hbase.util.Bytes; |
| import org.apache.hadoop.io.WritableUtils; |
| |
| /** |
| * |
| * Prefix encoder for byte arrays. For decoding, see {@link PrefixByteDecoder}. |
| * |
| */ |
| public class PrefixByteEncoder { |
| private int maxLength; |
| private final ImmutableBytesWritable previous = new ImmutableBytesWritable(ByteUtil.EMPTY_BYTE_ARRAY); |
| |
| public PrefixByteEncoder() { |
| } |
| |
| /** |
| * Resets the state of the encoder to its initial state (i.e. forgetting |
| * the previous byte array that may have been encoded). |
| */ |
| public void reset() { |
| previous.set(ByteUtil.EMPTY_BYTE_ARRAY); |
| } |
| |
| /** |
| * @return the maximum length byte array encountered while encoding |
| */ |
| public int getMaxLength() { |
| return maxLength; |
| } |
| |
| /** |
| * Prefix encodes the byte array pointed to into the output stream |
| * @param out output stream to encode into |
| * @param ptr pointer to byte array to encode. |
| * @throws IOException |
| */ |
| public void encode(DataOutput out, ImmutableBytesWritable ptr) throws IOException { |
| encode(out, ptr.get(), ptr.getOffset(), ptr.getLength()); |
| } |
| |
| /** |
| * Prefix encodes the byte array into the output stream |
| * @param out output stream to encode into |
| * @param b byte array to encode |
| * @throws IOException |
| */ |
| public void encode(DataOutput out, byte[] b) throws IOException { |
| encode(out, b, 0, b.length); |
| } |
| |
| /** |
| * Prefix encodes the byte array from offset to length into output stream. |
| * Instead of writing the entire byte array, only the portion of the byte array |
| * that differs from the beginning of the previous byte array written is written. |
| * |
| * @param out output stream to encode into |
| * @param b byte array buffer |
| * @param offset offset into byte array to start encoding |
| * @param length length of byte array to encode |
| * @throws IOException |
| */ |
| public void encode(DataOutput out, byte[] b, int offset, int length) throws IOException { |
| int i = 0; |
| int prevOffset = previous.getOffset(); |
| byte[] prevBytes = previous.get(); |
| int prevLength = previous.getLength(); |
| int minLength = prevLength < b.length ? prevLength : b.length; |
| for(i = 0; (i < minLength) && (prevBytes[prevOffset + i] == b[offset + i]); i++); |
| WritableUtils.writeVInt(out, i); |
| Bytes.writeByteArray(out, b, offset + i, length - i); |
| previous.set(b, offset, length); |
| if (length > maxLength) { |
| maxLength = length; |
| } |
| } |
| } |