| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| TransientRandom |
|
| 1.0;1 |
| 1 | /* | |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one | |
| 3 | * or more contributor license agreements. See the NOTICE file | |
| 4 | * distributed with this work for additional information | |
| 5 | * regarding copyright ownership. The ASF licenses this file | |
| 6 | * to you under the Apache License, Version 2.0 (the | |
| 7 | * "License"); you may not use this file except in compliance | |
| 8 | * with the License. You may obtain a copy of the License at | |
| 9 | * | |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 | |
| 11 | * | |
| 12 | * Unless required by applicable law or agreed to in writing, software | |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, | |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 15 | * See the License for the specific language governing permissions and | |
| 16 | * limitations under the License. | |
| 17 | */ | |
| 18 | package org.apache.giraph.writable.kryo; | |
| 19 | ||
| 20 | import java.util.Random; | |
| 21 | ||
| 22 | /** | |
| 23 | * Transient Random class. Seed/state is not kept after | |
| 24 | * serializing/deserializing. | |
| 25 | * | |
| 26 | * Within Blocks Framework - if we initialize Random within the Piece, when | |
| 27 | * it's serialzied and copied to all workers and all threads - keeping seed | |
| 28 | * would cause same series of random numbers to be generated everywhere. | |
| 29 | * | |
| 30 | * So this class is safe to be used in Pieces, while using regular Random | |
| 31 | * class is forbidden to be serialized. | |
| 32 | * Best approach would be to not have Random serialized, and create it on | |
| 33 | * workers, where possible. | |
| 34 | */ | |
| 35 | 0 | public class TransientRandom { |
| 36 | /** Instance of random object */ | |
| 37 | 0 | private final transient Random random = new Random(); |
| 38 | ||
| 39 | /** | |
| 40 | * Get instance of Random | |
| 41 | * @return Random instance | |
| 42 | */ | |
| 43 | public Random get() { | |
| 44 | 0 | return random; |
| 45 | } | |
| 46 | ||
| 47 | /** | |
| 48 | * Returns a pseudorandom, uniformly distributed {@code int} value | |
| 49 | * between 0 (inclusive) and the specified value (exclusive), drawn from | |
| 50 | * this random number generator's sequence. | |
| 51 | * | |
| 52 | * @param n Given upper limit | |
| 53 | * @return pseudorandom integer number in [0, n) range. | |
| 54 | */ | |
| 55 | public int nextInt(int n) { | |
| 56 | 0 | return random.nextInt(n); |
| 57 | } | |
| 58 | ||
| 59 | /** | |
| 60 | * Returns the next pseudorandom, uniformly distributed | |
| 61 | * {@code double} value between {@code 0.0} and | |
| 62 | * {@code 1.0} from this random number generator's sequence. | |
| 63 | * | |
| 64 | * @return pseudorandom number in [0, 1) | |
| 65 | */ | |
| 66 | public double nextDouble() { | |
| 67 | 0 | return random.nextDouble(); |
| 68 | } | |
| 69 | } |