1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.pool2.proxy;
18
19 import java.lang.reflect.Method;
20
21 import org.apache.commons.pool2.UsageTracking;
22
23 /**
24 * Base implementation for object wrappers when using a
25 * {@link ProxiedObjectPool}.
26 *
27 * @param <T> type of the wrapped pooled object
28 *
29 * @since 2.0
30 */
31 class BaseProxyHandler<T> {
32
33 private volatile T pooledObject;
34 private final UsageTracking<T> usageTracking;
35
36
37 /**
38 * Constructs a new wrapper for the given pooled object.
39 *
40 * @param pooledObject The object to wrap
41 * @param usageTracking The instance, if any (usually the object pool) to
42 * be provided with usage tracking information for this
43 * wrapped object
44 */
45 BaseProxyHandler(final T pooledObject, final UsageTracking<T> usageTracking) {
46 this.pooledObject = pooledObject;
47 this.usageTracking = usageTracking;
48 }
49
50
51 /**
52 * Disable the proxy wrapper. Called when the object has been returned to
53 * the pool. Further use of the wrapper should result in an
54 * {@link IllegalStateException}.
55 *
56 * @return the object that this proxy was wrapping
57 */
58 T disableProxy() {
59 final T result = pooledObject;
60 pooledObject = null;
61 return result;
62 }
63
64
65 /**
66 * Invoke the given method on the wrapped object.
67 *
68 * @param method The method to invoke
69 * @param args The arguments to the method
70 * @return The result of the method call
71 * @throws Throwable If the method invocation fails
72 */
73 Object doInvoke(final Method method, final Object[] args) throws Throwable {
74 validateProxiedObject();
75 final T object = getPooledObject();
76 if (usageTracking != null) {
77 usageTracking.use(object);
78 }
79 return method.invoke(object, args);
80 }
81
82
83 /**
84 * Gets the wrapped, pooled object.
85 *
86 * @return the underlying pooled object
87 */
88 T getPooledObject() {
89 return pooledObject;
90 }
91
92
93 /**
94 * @since 2.4.3
95 */
96 @Override
97 public String toString() {
98 final StringBuilder builder = new StringBuilder();
99 builder.append(getClass().getName());
100 builder.append(" [pooledObject=");
101 builder.append(pooledObject);
102 builder.append(", usageTracking=");
103 builder.append(usageTracking);
104 builder.append("]");
105 return builder.toString();
106 }
107
108
109 /**
110 * Check that the proxy is still valid (i.e. that {@link #disableProxy()}
111 * has not been called).
112 *
113 * @throws IllegalStateException if {@link #disableProxy()} has been called
114 */
115 void validateProxiedObject() {
116 if (pooledObject == null) {
117 throw new IllegalStateException("This object may no longer be " +
118 "used as it has been returned to the Object Pool.");
119 }
120 }
121 }