| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 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 | */ |
| 16 | |
| 17 | package org.springframework.batch.repeat.context; |
| 18 | |
| 19 | import org.springframework.core.AttributeAccessor; |
| 20 | import org.springframework.core.AttributeAccessorSupport; |
| 21 | |
| 22 | /** |
| 23 | * An {@link AttributeAccessor} that synchronizes on a mutex (not this) before |
| 24 | * modifying or accessing the underlying attributes. |
| 25 | * |
| 26 | * @author Dave Syer |
| 27 | * |
| 28 | */ |
| 29 | public class SynchronizedAttributeAccessor implements AttributeAccessor { |
| 30 | |
| 31 | /** |
| 32 | * All methods are delegated to this support object. |
| 33 | */ |
| 34 | AttributeAccessorSupport support = new AttributeAccessorSupport() { |
| 35 | /** |
| 36 | * Generated serial UID. |
| 37 | */ |
| 38 | private static final long serialVersionUID = -7664290016506582290L; |
| 39 | }; |
| 40 | |
| 41 | /* |
| 42 | * (non-Javadoc) |
| 43 | * @see org.springframework.core.AttributeAccessor#attributeNames() |
| 44 | */ |
| 45 | public String[] attributeNames() { |
| 46 | synchronized (support) { |
| 47 | return support.attributeNames(); |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | /* |
| 52 | * (non-Javadoc) |
| 53 | * @see java.lang.Object#equals(java.lang.Object) |
| 54 | */ |
| 55 | public boolean equals(Object other) { |
| 56 | if (this == other) { |
| 57 | return true; |
| 58 | } |
| 59 | AttributeAccessorSupport that; |
| 60 | if (other instanceof SynchronizedAttributeAccessor) { |
| 61 | that = ((SynchronizedAttributeAccessor) other).support; |
| 62 | } |
| 63 | else if (other instanceof AttributeAccessorSupport) { |
| 64 | that = (AttributeAccessorSupport) other; |
| 65 | } |
| 66 | else { |
| 67 | return false; |
| 68 | } |
| 69 | synchronized (support) { |
| 70 | return support.equals(that); |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * (non-Javadoc) |
| 76 | * @see org.springframework.core.AttributeAccessor#getAttribute(java.lang.String) |
| 77 | */ |
| 78 | public Object getAttribute(String name) { |
| 79 | synchronized (support) { |
| 80 | return support.getAttribute(name); |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | /* |
| 85 | * (non-Javadoc) |
| 86 | * @see org.springframework.core.AttributeAccessor#hasAttribute(java.lang.String) |
| 87 | */ |
| 88 | public boolean hasAttribute(String name) { |
| 89 | synchronized (support) { |
| 90 | return support.hasAttribute(name); |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * (non-Javadoc) |
| 96 | * @see java.lang.Object#hashCode() |
| 97 | */ |
| 98 | public int hashCode() { |
| 99 | return support.hashCode(); |
| 100 | } |
| 101 | |
| 102 | /* |
| 103 | * (non-Javadoc) |
| 104 | * @see org.springframework.core.AttributeAccessor#removeAttribute(java.lang.String) |
| 105 | */ |
| 106 | public Object removeAttribute(String name) { |
| 107 | synchronized (support) { |
| 108 | return support.removeAttribute(name); |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * (non-Javadoc) |
| 114 | * @see org.springframework.core.AttributeAccessor#setAttribute(java.lang.String, |
| 115 | * java.lang.Object) |
| 116 | */ |
| 117 | public void setAttribute(String name, Object value) { |
| 118 | synchronized (support) { |
| 119 | support.setAttribute(name, value); |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Additional support for atomic put if absent. |
| 125 | * @param name the key for the attribute name |
| 126 | * @param value the value of the attribute |
| 127 | * @return null if the attribute was not already set, the existing value |
| 128 | * otherwise. |
| 129 | */ |
| 130 | public Object setAttributeIfAbsent(String name, Object value) { |
| 131 | synchronized (support) { |
| 132 | Object old = getAttribute(name); |
| 133 | if (old != null) { |
| 134 | return old; |
| 135 | } |
| 136 | setAttribute(name, value); |
| 137 | } |
| 138 | return null; |
| 139 | } |
| 140 | |
| 141 | /* |
| 142 | * (non-Javadoc) |
| 143 | * @see java.lang.Object#toString() |
| 144 | */ |
| 145 | public String toString() { |
| 146 | StringBuffer buffer = new StringBuffer("SynchronizedAttributeAccessor: ["); |
| 147 | synchronized (support) { |
| 148 | String[] names = attributeNames(); |
| 149 | for (int i = 0; i < names.length; i++) { |
| 150 | String name = names[i]; |
| 151 | buffer.append(names[i] + "=" + getAttribute(name)); |
| 152 | if (i < names.length - 1) { |
| 153 | buffer.append(", "); |
| 154 | } |
| 155 | } |
| 156 | buffer.append("]"); |
| 157 | return buffer.toString(); |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | } |