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25 
26 package sun.misc;
27 
28 /**
29  * The request processor allows functors (Request instances) to be created
30  * in arbitrary threads, and to be posted for execution in a non-restricted
31  * thread.
32  *
33  * @author      Steven B. Byrne
34  */
35 
36 
37 public class RequestProcessor implements Runnable {
38 
39     private static Queue<Request> requestQueue;
40     private static Thread dispatcher;
41 
42     /**
43      * Queues a Request instance for execution by the request procesor
44      * thread.
45      */
postRequest(Request req)46     public static void postRequest(Request req) {
47         lazyInitialize();
48         requestQueue.enqueue(req);
49     }
50 
51     /**
52      * Process requests as they are queued.
53      */
run()54     public void run() {
55         lazyInitialize();
56         while (true) {
57             try {
58                 Request req = requestQueue.dequeue();
59                 try {
60                     req.execute();
61                 } catch (Throwable t) {
62                     // do nothing at the moment...maybe report an error
63                     // in the future
64                 }
65             } catch (InterruptedException e) {
66                 // do nothing at the present time.
67             }
68         }
69     }
70 
71 
72     /**
73      * This method initiates the request processor thread.  It is safe
74      * to call it after the thread has been started.  It provides a way for
75      * clients to deliberately control the context in which the request
76      * processor thread is created
77      */
startProcessing()78     public static synchronized void startProcessing() {
79         if (dispatcher == null) {
80             dispatcher = new Thread(new RequestProcessor(), "Request Processor");
81             dispatcher.setPriority(Thread.NORM_PRIORITY + 2);
82             dispatcher.start();
83         }
84     }
85 
86 
87     /**
88      * This method performs lazy initialization.
89      */
lazyInitialize()90     private static synchronized void lazyInitialize() {
91         if (requestQueue == null) {
92             requestQueue = new Queue<Request>();
93         }
94     }
95 
96 }
97