alshabib | ab98466 | 2014-12-04 18:56:18 -0800 | [diff] [blame] | 1 | /* |
Brian O'Connor | 5ab426f | 2016-04-09 01:19:45 -0700 | [diff] [blame] | 2 | * Copyright 2014-present Open Networking Laboratory |
alshabib | ab98466 | 2014-12-04 18:56:18 -0800 | [diff] [blame] | 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
Brian O'Connor | abafb50 | 2014-12-02 22:26:20 -0800 | [diff] [blame] | 16 | package org.onosproject.core; |
Brian O'Connor | 520c052 | 2014-11-23 23:50:47 -0800 | [diff] [blame] | 17 | |
| 18 | import com.google.common.base.MoreObjects; |
| 19 | |
| 20 | import java.util.concurrent.atomic.AtomicLong; |
| 21 | |
| 22 | import static com.google.common.base.Preconditions.checkArgument; |
| 23 | |
| 24 | /** |
| 25 | * A class representing an ID space. |
| 26 | */ |
| 27 | public final class IdBlock { |
| 28 | private final long start; |
| 29 | private final long size; |
| 30 | |
| 31 | private final AtomicLong currentId; |
| 32 | |
| 33 | /** |
| 34 | * Constructs a new ID block with the specified size and initial value. |
| 35 | * |
| 36 | * @param start initial value of the block |
| 37 | * @param size size of the block |
| 38 | * @throws IllegalArgumentException if the size is less than or equal to 0 |
| 39 | */ |
| 40 | public IdBlock(long start, long size) { |
| 41 | checkArgument(size > 0, "size should be more than 0, but %s", size); |
| 42 | |
| 43 | this.start = start; |
| 44 | this.size = size; |
| 45 | |
| 46 | this.currentId = new AtomicLong(start); |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * Returns the initial value. |
| 51 | * |
| 52 | * @return initial value |
| 53 | */ |
| 54 | private long getStart() { |
| 55 | return start; |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Returns the last value. |
| 60 | * |
| 61 | * @return last value |
| 62 | */ |
| 63 | private long getEnd() { |
| 64 | return start + size - 1; |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Returns the block size. |
| 69 | * |
| 70 | * @return block size |
| 71 | */ |
| 72 | public long getSize() { |
| 73 | return size; |
| 74 | } |
| 75 | |
| 76 | /** |
| 77 | * Returns the next ID in the block. |
| 78 | * |
| 79 | * @return next ID |
| 80 | * @throws UnavailableIdException if there is no available ID in the block. |
| 81 | */ |
| 82 | public long getNextId() { |
| 83 | final long id = currentId.getAndIncrement(); |
| 84 | if (id > getEnd()) { |
| 85 | throw new UnavailableIdException(String.format( |
| 86 | "used all IDs in allocated space (size: %d, end: %d, current: %d)", |
| 87 | size, getEnd(), id |
| 88 | )); |
| 89 | } |
| 90 | |
| 91 | return id; |
| 92 | } |
| 93 | |
| 94 | @Override |
| 95 | public String toString() { |
| 96 | return MoreObjects.toStringHelper(getClass()) |
| 97 | .add("start", start) |
| 98 | .add("size", size) |
| 99 | .add("currentId", currentId) |
| 100 | .toString(); |
| 101 | } |
| 102 | } |