ThreadPoolExecutorFactoryBean


1   /*
2    * Copyright (C) 2005 Alfresco, Inc.
3    *
4    * Licensed under the Mozilla Public License version 1.1 
5    * with a permitted attribution clause. You may obtain a
6    * copy of the License at
7    *
8    *   http://www.alfresco.org/legal/license.txt
9    *
10   * Unless required by applicable law or agreed to in writing,
11   * software distributed under the License is distributed on an
12   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
13   * either express or implied. See the License for the specific
14   * language governing permissions and limitations under the
15   * License.
16   */
17  package org.alfresco.util;
18  
19  import java.util.concurrent.ArrayBlockingQueue  ;
20  import java.util.concurrent.BlockingQueue  ;
21  import java.util.concurrent.ThreadPoolExecutor  ;
22  import java.util.concurrent.TimeUnit  ;
23  
24  import org.alfresco.error.AlfrescoRuntimeException;
25  import org.springframework.beans.factory.FactoryBean;
26  import org.springframework.beans.factory.InitializingBean;
27  
28  /**
29   * Factory for {@link java.util.concurrent.ThreadPoolExecutor} instances,
30   * which cannot easily be constructed using constructor injection.
31   * <p>
32   * This factory provides the a singleton instance of the pool.
33   * 
34   * @author Derek Hulley
35   */
36  public class ThreadPoolExecutorFactoryBean implements FactoryBean, InitializingBean
37  {
38      private int corePoolSize;
39      private int maximumPoolSize;
40      private int keepAliveTime;
41      private BlockingQueue  <Runnable  > workQueue;
42      private ThreadPoolExecutor   instance;
43      
44      /**
45       * Constructor setting default properties:
46       * <ul>
47       *   <li>corePoolSize: 5</li>
48       *   <li>maximumPoolSize: 20</li>
49       *   <li>keepAliveTime: 60s</li>
50       *   <li>workQueue: {@link ArrayBlockingQueue}</li>
51       * </ul>
52       */
53      public ThreadPoolExecutorFactoryBean()
54      {
55          corePoolSize = 5;
56          maximumPoolSize = 20;
57          keepAliveTime = 30;
58      }
59      
60      /**
61       * The number of threads to keep in the pool, even if idle.
62       * 
63       * @param corePoolSize core thread count
64       */
65      public void setCorePoolSize(int corePoolSize)
66      {
67          this.corePoolSize = corePoolSize;
68      }
69  
70      /**
71       * The maximum number of threads to keep in the pool
72       * 
73       * @param maximumPoolSize the maximum number of threads in the pool
74       */
75      public void setMaximumPoolSize(int maximumPoolSize)
76      {
77          this.maximumPoolSize = maximumPoolSize;
78      }
79  
80      /**
81       * The time (in seconds) to keep non-core idle threads in the pool
82       * 
83       * @param keepAliveTime time to stay idle in seconds
84       */
85      public void setKeepAliveTime(int keepAliveTime)
86      {
87          this.keepAliveTime = keepAliveTime;
88      }
89  
90      /**
91       * The optional queue instance to use
92       * 
93       * @param workQueue optional queue implementation
94       */
95      public void setWorkQueue(BlockingQueue  <Runnable  > workQueue)
96      {
97          this.workQueue = workQueue;
98      }
99  
100     public void afterPropertiesSet() throws Exception  
101     {
102         if (workQueue == null)
103         {
104             workQueue = new ArrayBlockingQueue  <Runnable  >(corePoolSize);
105         }
106         // construct the instance
107         instance = new ThreadPoolExecutor  (corePoolSize, maximumPoolSize, keepAliveTime, TimeUnit.SECONDS, workQueue);
108     }
109 
110     /**
111      * @return Returns true always.
112      */
113     public boolean isSingleton()
114     {
115         return true;
116     }
117 
118     /**
119      * @return Returns the singleton {@link ThreadPoolExecutor instance}.
120      */
121     public Object   getObject() throws Exception  
122     {
123         if (instance == null)
124         {
125             throw new AlfrescoRuntimeException("The ThreadPoolExecutor instance has not been created");
126         }
127         return instance;
128     }
129 
130     /**
131      * @see ThreadPoolExecutor
132      */
133     public Class   getObjectType()
134     {
135         return ThreadPoolExecutor  .class;
136     }
137 }
138
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