| /** |
| * 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.ambari.metrics.timeline; |
| |
| import java.io.IOException; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.codehaus.jackson.map.ObjectMapper; |
| import org.codehaus.jackson.map.ObjectReader; |
| import org.codehaus.jackson.map.ObjectWriter; |
| |
| /** |
| * A utility class providing methods for serializing and deserializing |
| * objects. The {@link #write(Object)} and {@link #read(byte[])} methods are |
| * used by the {@link LeveldbTimelineStore} to store and retrieve arbitrary |
| * JSON, while the {@link #writeReverseOrderedLong} and {@link |
| * #readReverseOrderedLong} methods are used to sort entities in descending |
| * start time order. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Unstable |
| public class GenericObjectMapper { |
| private static final byte[] EMPTY_BYTES = new byte[0]; |
| |
| public static final ObjectReader OBJECT_READER; |
| public static final ObjectWriter OBJECT_WRITER; |
| |
| static { |
| ObjectMapper mapper = new ObjectMapper(); |
| OBJECT_READER = mapper.reader(Object.class); |
| OBJECT_WRITER = mapper.writer(); |
| } |
| |
| /** |
| * Serializes an Object into a byte array. Along with {@link #read(byte[])}, |
| * can be used to serialize an Object and deserialize it into an Object of |
| * the same type without needing to specify the Object's type, |
| * as long as it is one of the JSON-compatible objects understood by |
| * ObjectMapper. |
| * |
| * @param o An Object |
| * @return A byte array representation of the Object |
| * @throws IOException if there is a write error |
| */ |
| public static byte[] write(Object o) throws IOException { |
| if (o == null) { |
| return EMPTY_BYTES; |
| } |
| return OBJECT_WRITER.writeValueAsBytes(o); |
| } |
| |
| /** |
| * Deserializes an Object from a byte array created with |
| * {@link #write(Object)}. |
| * |
| * @param b A byte array |
| * @return An Object |
| * @throws IOException if there is a read error |
| */ |
| public static Object read(byte[] b) throws IOException { |
| return read(b, 0); |
| } |
| |
| /** |
| * Deserializes an Object from a byte array at a specified offset, assuming |
| * the bytes were created with {@link #write(Object)}. |
| * |
| * @param b A byte array |
| * @param offset Offset into the array |
| * @return An Object |
| * @throws IOException if there is a read error |
| */ |
| public static Object read(byte[] b, int offset) throws IOException { |
| if (b == null || b.length == 0) { |
| return null; |
| } |
| return OBJECT_READER.readValue(b, offset, b.length - offset); |
| } |
| |
| /** |
| * Converts a long to a 8-byte array so that lexicographic ordering of the |
| * produced byte arrays sort the longs in descending order. |
| * |
| * @param l A long |
| * @return A byte array |
| */ |
| public static byte[] writeReverseOrderedLong(long l) { |
| byte[] b = new byte[8]; |
| return writeReverseOrderedLong(l, b, 0); |
| } |
| |
| public static byte[] writeReverseOrderedLong(long l, byte[] b, int offset) { |
| b[offset] = (byte)(0x7f ^ ((l >> 56) & 0xff)); |
| for (int i = offset+1; i < offset+7; i++) { |
| b[i] = (byte)(0xff ^ ((l >> 8*(7-i)) & 0xff)); |
| } |
| b[offset+7] = (byte)(0xff ^ (l & 0xff)); |
| return b; |
| } |
| |
| /** |
| * Reads 8 bytes from an array starting at the specified offset and |
| * converts them to a long. The bytes are assumed to have been created |
| * with {@link #writeReverseOrderedLong}. |
| * |
| * @param b A byte array |
| * @param offset An offset into the byte array |
| * @return A long |
| */ |
| public static long readReverseOrderedLong(byte[] b, int offset) { |
| long l = b[offset] & 0xff; |
| for (int i = 1; i < 8; i++) { |
| l = l << 8; |
| l = l | (b[offset+i]&0xff); |
| } |
| return l ^ 0x7fffffffffffffffl; |
| } |
| |
| } |