1 /*

     2  * Copyright 2007-2008 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    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).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package com.sun.jmx.event;

    27 

    28 import com.sun.jmx.remote.util.ClassLogger;

    29 import java.util.concurrent.Callable;

    30 import java.util.concurrent.ScheduledExecutorService;

    31 import java.util.concurrent.ScheduledFuture;

    32 import java.util.concurrent.TimeUnit;

    33 

    34 /**

    35  *

    36  * @author sjiang

    37  */

    38 public class LeaseRenewer {

    39     public LeaseRenewer(ScheduledExecutorService scheduler, Callable<Long> doRenew) {

    40         if (logger.traceOn()) {

    41             logger.trace("LeaseRenewer", "New LeaseRenewer.");

    42         }

    43 

    44         if (doRenew == null) {

    45             throw new NullPointerException("Null job to call server.");

    46         }

    47 

    48         this.doRenew = doRenew;

    49         nextRenewTime = System.currentTimeMillis();

    50 

    51         this.scheduler = scheduler;

    52         future = this.scheduler.schedule(myRenew, 0, TimeUnit.MILLISECONDS);

    53     }

    54 

    55     public void close() {

    56         if (logger.traceOn()) {

    57             logger.trace("close", "Close the lease.");

    58         }

    59 

    60         synchronized(lock) {

    61             if (closed) {

    62                 return;

    63             } else {

    64                 closed = true;

    65             }

    66         }

    67 

    68         try {

    69             future.cancel(false); // not interrupt if running

    70         } catch (Exception e) {

    71             // OK

    72             if (logger.debugOn()) {

    73                 logger.debug("close", "Failed to cancel the leasing job.", e);

    74             }

    75         }

    76     }

    77 

    78     public boolean closed() {

    79         synchronized(lock) {

    80             return closed;

    81         }

    82     }

    83 

    84     // ------------------------------

    85     // private

    86     // ------------------------------

    87     private final Runnable myRenew = new Runnable() {

    88         public void run() {

    89             synchronized(lock) {

    90                 if (closed()) {

    91                     return;

    92                 }

    93             }

    94 

    95             long next = nextRenewTime - System.currentTimeMillis();

    96             if (next < MIN_MILLIS) {

    97                 try {

    98                     if (logger.traceOn()) {

    99                         logger.trace("myRenew-run", "");

   100                     }

   101                     next = doRenew.call().longValue();

   102 

   103                 } catch (Exception e) {

   104                     logger.fine("myRenew-run", "Failed to renew lease", e);

   105                     close();

   106                 }

   107 

   108                 if (next > 0 && next < Long.MAX_VALUE) {

   109                     next = next/2;

   110                     next = (next < MIN_MILLIS) ? MIN_MILLIS : next;

   111                 } else {

   112                     close();

   113                 }

   114             }

   115 

   116             nextRenewTime = System.currentTimeMillis() + next;

   117 

   118             if (logger.traceOn()) {

   119                 logger.trace("myRenew-run", "Next leasing: "+next);

   120             }

   121 

   122             synchronized(lock) {

   123                 if (!closed) {

   124                     future = scheduler.schedule(this, next, TimeUnit.MILLISECONDS);

   125                 }

   126             }

   127         }

   128     };

   129 

   130     private final Callable<Long> doRenew;

   131     private ScheduledFuture<?> future;

   132     private boolean closed = false;

   133     private long nextRenewTime;

   134 

   135     private final int[] lock = new int[0];

   136 

   137     private final ScheduledExecutorService scheduler;

   138 

   139     private static final long MIN_MILLIS = 50;

   140 

   141     private static final ClassLogger logger =

   142             new ClassLogger("javax.management.event", "LeaseRenewer");

   143 }