Region


1   /*
2    * JBoss, the OpenSource J2EE webOS
3    *
4    * Distributable under LGPL license.
5    * See terms of license at gnu.org.
6    * Created on March 25 2003
7    */
8   package org.jboss.cache.eviction;
9   
10  import EDU.oswego.cs.dl.util.concurrent.BoundedBuffer;
11  import org.jboss.cache.Fqn;
12  import org.jboss.logging.Logger;
13  
14  /**
15   * A region is a collection of tree cache nodes that share the same eviction
16   * policy configurations, e.g., maxNodes, etc. The region is specified via
17   * Fqn.
18   *
19   * @author Ben Wang 2-2004
20   */
21  public class Region
22  {
23  
24     public static final long WAIT_TIME = 10000; // time to wait for the queue to free up
25  
26     // Policy-specific config
27     private int maxNodes_ = 0; // 0 is no limit
28     private long timeToLiveSeconds_ = 0; // 0 is forever
29     // Region name
30     private String   fqn_;
31     // Policy-spefic algorithm, e.g., LRU
32     private EvictionAlgorithm algorithm_;
33     // Parent policy provider
34     private EvictionPolicy policy_;
35     // These queues can do put and take concurrently.
36     protected BoundedBuffer nodeEventQueue_;
37     protected Logger log_ = Logger.getLogger(Region.class);
38  
39     /**
40      * Default to package namespace on purpose so no one outside the package can instantiate it,
41      */
42     Region()
43     {
44        createQueue();
45     }
46  
47     void createQueue()
48     {
49        nodeEventQueue_ = new BoundedBuffer(RegionManager.CAPACITY);
50     }
51  
52     Region(String   fqn, EvictionPolicy policy, EvictionAlgorithm algorithm) {
53        fqn_ = fqn;
54        policy_ = policy;
55        algorithm_ = algorithm;
56  
57        createQueue();
58     }
59  
60     public int getMaxNodes() { return maxNodes_; }
61  
62     public void setMaxNodes(int maxNodes) { maxNodes_ = maxNodes; }
63  
64  //   public long getTimeToIdleSeconds() { return timeToLiveSeconds_; }
65  
66  //   public void setTimeToIdleSeconds(long secs) { timeToLiveSeconds_ = secs; }
67  
68     public long getTimeToLiveSeconds() { return timeToLiveSeconds_; }
69  
70     public void setTimeToLiveSeconds(long secs) { timeToLiveSeconds_ = secs; }
71  
72     public EvictionAlgorithm getEvictionAlgorithm() { return algorithm_; }
73  
74     public EvictionPolicy getEvictionPolicy() { return policy_; }
75  
76     public String   getFqn() { return fqn_; }
77  
78     public void setAddedNode(Fqn fqn)
79     {
80        putNodeEvent(fqn, EvictedEventNode.ADD_EVENT);
81     }
82  
83     public void setRemovedNode(Fqn fqn)
84     {
85        putNodeEvent(fqn, EvictedEventNode.REMOVE_EVENT);
86     }
87  
88     public void setVisitedNode(Fqn fqn)
89     {
90        putNodeEvent(fqn, EvictedEventNode.VISIT_EVENT);
91     }
92  
93     protected void putNodeEvent(Fqn fqn, Integer   event) {
94        try {
95  //         if(!nodeQueue_.offer(fqn, WAIT_TIME)) return;
96           if( nodeEventQueue_.size() > (100*RegionManager.CAPACITY)/98 ) {
97              log_.warn("putNodeEvent(): eviction node event queue size is at 98% threshold value of capacity: "
98                    +RegionManager.CAPACITY + " You will need to reduce the wakeUpIntervalSeconds parameter.");
99           }
100          nodeEventQueue_.put(new EvictedEventNode(fqn, event));
101       } catch (InterruptedException   e) {
102          e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
103       }
104    }
105 
106    /**
107     * Take the last node from node queue. It will also
108     * remove it from the queue.
109     * @return
110     */
111    public EvictedEventNode takeLastEventNode()
112    {
113       try {
114          return (EvictedEventNode)nodeEventQueue_.poll(0);
115       } catch (InterruptedException   e) {
116          e.printStackTrace();
117       }
118       return null;
119    }
120 
121    public int nodeEventQueueSize()
122    {
123       return nodeEventQueue_.size();
124    }
125 
126    public void resetEvictionQueues()
127    {
128       BoundedBuffer q1 = nodeEventQueue_;
129       log_.info("reseteEvictionQueues(): node queue size: " +q1.size() +
130               " region name: " +fqn_);
131       createQueue();
132       // Help to recycle
133       for(int i=0; i < q1.size(); i++) {
134          try {
135             q1.take();
136          } catch (InterruptedException   e) {
137             e.printStackTrace();
138          }
139       }
140    }
141 
142    public String   toString() {
143       StringBuffer   buf = new StringBuffer  ();
144       buf.append("Regions--- fqn: ").append(getFqn()).append(" maxNodes " +getMaxNodes());
145       buf.append(" TimeToIdleSeconds " +getTimeToLiveSeconds());
146       return buf.toString();
147    }
148 }
149
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