| 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.interceptor; |
| 18 | |
| 19 | import org.aopalliance.intercept.MethodInterceptor; |
| 20 | import org.aopalliance.intercept.MethodInvocation; |
| 21 | import org.springframework.aop.ProxyMethodInvocation; |
| 22 | import org.springframework.batch.repeat.RepeatStatus; |
| 23 | import org.springframework.batch.repeat.RepeatCallback; |
| 24 | import org.springframework.batch.repeat.RepeatContext; |
| 25 | import org.springframework.batch.repeat.RepeatException; |
| 26 | import org.springframework.batch.repeat.RepeatOperations; |
| 27 | import org.springframework.batch.repeat.support.RepeatTemplate; |
| 28 | import org.springframework.util.Assert; |
| 29 | |
| 30 | /** |
| 31 | * A {@link MethodInterceptor} that can be used to automatically repeat calls to |
| 32 | * a method on a service. The injected {@link RepeatOperations} is used to |
| 33 | * control the completion of the loop. Independent of the completion policy in |
| 34 | * the {@link RepeatOperations} the loop will repeat until the target method |
| 35 | * returns null or false. Be careful when injecting a bespoke |
| 36 | * {@link RepeatOperations} that the loop will actually terminate, because the |
| 37 | * default policy for a vanilla {@link RepeatTemplate} will never complete if |
| 38 | * the return type of the target method is void (the value returned is always |
| 39 | * not-null, representing the {@link Void#TYPE}). |
| 40 | * |
| 41 | * @author Dave Syer |
| 42 | */ |
| 43 | public class RepeatOperationsInterceptor implements MethodInterceptor { |
| 44 | |
| 45 | private RepeatOperations repeatOperations = new RepeatTemplate(); |
| 46 | |
| 47 | /** |
| 48 | * Setter for the {@link RepeatOperations}. |
| 49 | * |
| 50 | * @param batchTempate |
| 51 | * @throws IllegalArgumentException if the argument is null. |
| 52 | */ |
| 53 | public void setRepeatOperations(RepeatOperations batchTempate) { |
| 54 | Assert.notNull(batchTempate, "'repeatOperations' cannot be null."); |
| 55 | this.repeatOperations = batchTempate; |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Invoke the proceeding method call repeatedly, according to the properties |
| 60 | * of the injected {@link RepeatOperations}. |
| 61 | * |
| 62 | * @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation) |
| 63 | */ |
| 64 | @Override |
| 65 | public Object invoke(final MethodInvocation invocation) throws Throwable { |
| 66 | |
| 67 | final ResultHolder result = new ResultHolder(); |
| 68 | // Cache void return value if intercepted method returns void |
| 69 | final boolean voidReturnType = Void.TYPE.equals(invocation.getMethod().getReturnType()); |
| 70 | if (voidReturnType) { |
| 71 | // This will be ignored anyway, but we want it to be non-null for |
| 72 | // convenience of checking that there is a result. |
| 73 | result.setValue(new Object()); |
| 74 | } |
| 75 | |
| 76 | try { |
| 77 | repeatOperations.iterate(new RepeatCallback() { |
| 78 | |
| 79 | @Override |
| 80 | public RepeatStatus doInIteration(RepeatContext context) throws Exception { |
| 81 | try { |
| 82 | |
| 83 | MethodInvocation clone = invocation; |
| 84 | if (invocation instanceof ProxyMethodInvocation) { |
| 85 | clone = ((ProxyMethodInvocation) invocation).invocableClone(); |
| 86 | } |
| 87 | else { |
| 88 | throw new IllegalStateException( |
| 89 | "MethodInvocation of the wrong type detected - this should not happen with Spring AOP, so please raise an issue if you see this exception"); |
| 90 | } |
| 91 | |
| 92 | Object value = clone.proceed(); |
| 93 | if (voidReturnType) { |
| 94 | return RepeatStatus.CONTINUABLE; |
| 95 | } |
| 96 | if (!isComplete(value)) { |
| 97 | // Save the last result |
| 98 | result.setValue(value); |
| 99 | return RepeatStatus.CONTINUABLE; |
| 100 | } |
| 101 | else { |
| 102 | result.setFinalValue(value); |
| 103 | return RepeatStatus.FINISHED; |
| 104 | } |
| 105 | } |
| 106 | catch (Throwable e) { |
| 107 | if (e instanceof Exception) { |
| 108 | throw (Exception) e; |
| 109 | } |
| 110 | else { |
| 111 | throw new RepeatOperationsInterceptorException("Unexpected error in batch interceptor", e); |
| 112 | } |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | }); |
| 117 | } |
| 118 | catch (Throwable t) { |
| 119 | // The repeat exception should be unwrapped by the template |
| 120 | throw t; |
| 121 | } |
| 122 | |
| 123 | if (result.isReady()) { |
| 124 | return result.getValue(); |
| 125 | } |
| 126 | |
| 127 | // No result means something weird happened |
| 128 | throw new IllegalStateException("No result available for attempted repeat call to " + invocation |
| 129 | + ". The invocation was never called, so maybe there is a problem with the completion policy?"); |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * @param result |
| 134 | * @return |
| 135 | */ |
| 136 | private boolean isComplete(Object result) { |
| 137 | return result == null || (result instanceof Boolean) && !((Boolean) result).booleanValue(); |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Simple wrapper exception class to enable nasty errors to be passed out of |
| 142 | * the scope of the repeat operations and handled by the caller. |
| 143 | * |
| 144 | * @author Dave Syer |
| 145 | * |
| 146 | */ |
| 147 | private static class RepeatOperationsInterceptorException extends RepeatException { |
| 148 | /** |
| 149 | * @param message |
| 150 | * @param e |
| 151 | */ |
| 152 | public RepeatOperationsInterceptorException(String message, Throwable e) { |
| 153 | super(message, e); |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * Simple wrapper object for the result from a method invocation. |
| 159 | * |
| 160 | * @author Dave Syer |
| 161 | * |
| 162 | */ |
| 163 | private static class ResultHolder { |
| 164 | private Object value = null; |
| 165 | |
| 166 | private boolean ready = false; |
| 167 | |
| 168 | /** |
| 169 | * Public setter for the Object. |
| 170 | * @param value the value to set |
| 171 | */ |
| 172 | public void setValue(Object value) { |
| 173 | this.ready = true; |
| 174 | this.value = value; |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * @param value |
| 179 | */ |
| 180 | public void setFinalValue(Object value) { |
| 181 | if (ready) { |
| 182 | // Only set the value the last time if the last time was also |
| 183 | // the first time |
| 184 | return; |
| 185 | } |
| 186 | setValue(value); |
| 187 | } |
| 188 | |
| 189 | /** |
| 190 | * Public getter for the Object. |
| 191 | * @return the value |
| 192 | */ |
| 193 | public Object getValue() { |
| 194 | return value; |
| 195 | } |
| 196 | |
| 197 | /** |
| 198 | * @return true if a value has been set |
| 199 | */ |
| 200 | public boolean isReady() { |
| 201 | return ready; |
| 202 | } |
| 203 | } |
| 204 | |
| 205 | } |