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8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
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11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
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25 
26 package com.sun.tools.sjavac.server;
27 
28 import com.sun.tools.javac.main.Main.Result;
29 import com.sun.tools.sjavac.Log;
30 
31 import java.util.Timer;
32 import java.util.TimerTask;
33 
34 /**
35  * An sjavac implementation that keeps track of idleness and shuts down the
36  * given Terminable upon idleness timeout.
37  *
38  * An idleness timeout kicks in {@code idleTimeout} milliseconds after the last
39  * request is completed.
40  *
41  *  <p><b>This is NOT part of any supported API.
42  *  If you write code that depends on this, you do so at your own risk.
43  *  This code and its internal interfaces are subject to change or
44  *  deletion without notice.</b>
45  */
46 public class IdleResetSjavac implements Sjavac {
47 
48     private final Sjavac delegate;
49     private final Terminable toShutdown;
50     private final Timer idlenessTimer = new Timer();
51     private final long idleTimeout;
52     private int outstandingCalls = 0;
53 
54     // Class invariant: idlenessTimerTask != null <-> idlenessTimerTask is scheduled
55     private TimerTask idlenessTimerTask;
56 
IdleResetSjavac(Sjavac delegate, Terminable toShutdown, long idleTimeout)57     public IdleResetSjavac(Sjavac delegate,
58                            Terminable toShutdown,
59                            long idleTimeout) {
60         this.delegate = delegate;
61         this.toShutdown = toShutdown;
62         this.idleTimeout = idleTimeout;
63         scheduleTimeout();
64     }
65 
66     @Override
compile(String[] args)67     public Result compile(String[] args) {
68         startCall();
69         try {
70             return delegate.compile(args);
71         } finally {
72             endCall();
73         }
74     }
75 
startCall()76     private synchronized void startCall() {
77         // Was there no outstanding calls before this call?
78         if (++outstandingCalls == 1) {
79             // Then the timer task must have been scheduled
80             if (idlenessTimerTask == null)
81                 throw new IllegalStateException("Idle timeout already cancelled");
82             // Cancel timeout task
83             idlenessTimerTask.cancel();
84             idlenessTimerTask = null;
85         }
86     }
87 
endCall()88     private synchronized void endCall() {
89         if (--outstandingCalls == 0) {
90             // No more outstanding calls. Schedule timeout.
91             scheduleTimeout();
92         }
93     }
94 
scheduleTimeout()95     private void scheduleTimeout() {
96         if (idlenessTimerTask != null)
97             throw new IllegalStateException("Idle timeout already scheduled");
98         idlenessTimerTask = new TimerTask() {
99             public void run() {
100                 Log.setLogForCurrentThread(ServerMain.getErrorLog());
101                 toShutdown.shutdown("Server has been idle for " + (idleTimeout / 1000) + " seconds.");
102             }
103         };
104         idlenessTimer.schedule(idlenessTimerTask, idleTimeout);
105     }
106 
107     @Override
shutdown()108     public void shutdown() {
109         idlenessTimer.cancel();
110         delegate.shutdown();
111     }
112 
113 }
114