--- a/jdk/src/share/classes/com/sun/jmx/event/LeaseManager.java Wed Oct 21 16:28:57 2009 +0200
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,155 +0,0 @@
-/*
- * Copyright 2007-2008 Sun Microsystems, Inc. All Rights Reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation. Sun designates this
- * particular file as subject to the "Classpath" exception as provided
- * by Sun in the LICENSE file that accompanied this code.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
- * CA 95054 USA or visit www.sun.com if you need additional information or
- * have any questions.
- */
-
-package com.sun.jmx.event;
-
-import com.sun.jmx.remote.util.ClassLogger;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.ThreadFactory;
-import java.util.concurrent.TimeUnit;
-
-/**
- * <p>Manage a renewable lease. The lease can be renewed indefinitely
- * but if the lease runs to its current expiry date without being renewed
- * then the expiry callback is invoked. If the lease has already expired
- * when renewal is attempted then the lease method returns zero.</p>
- * @author sjiang
- * @author emcmanus
- */
-// The synchronization logic of this class is tricky to deal correctly with the
-// case where the lease expires at the same time as the |lease| or |stop| method
-// is called. If the lease is active then the field |scheduled| represents
-// the expiry task; otherwise |scheduled| is null. Renewing or stopping the
-// lease involves canceling this task and setting |scheduled| either to a new
-// task (to renew) or to null (to stop).
-//
-// Suppose the expiry task runs at the same time as the |lease| method is called.
-// If the task enters its synchronized block before the method starts, then
-// it will set |scheduled| to null and the method will return 0. If the method
-// starts before the task enters its synchronized block, then the method will
-// cancel the task which will see that when it later enters the block.
-// Similar reasoning applies to the |stop| method. It is not expected that
-// different threads will call |lease| or |stop| simultaneously, although the
-// logic should be correct then too.
-public class LeaseManager {
- public LeaseManager(Runnable callback) {
- this(callback, EventParams.getLeaseTimeout());
- }
-
- public LeaseManager(Runnable callback, long timeout) {
- if (logger.traceOn()) {
- logger.trace("LeaseManager", "new manager with lease: "+timeout);
- }
- if (callback == null) {
- throw new NullPointerException("Null callback.");
- }
- if (timeout <= 0)
- throw new IllegalArgumentException("Timeout must be positive: " + timeout);
-
- this.callback = callback;
- schedule(timeout);
- }
-
- /**
- * <p>Renew the lease for the given time. The new time can be shorter
- * than the previous one, in which case the lease will expire earlier
- * than it would have.</p>
- *
- * <p>Calling this method after the lease has expired will return zero
- * immediately and have no other effect.</p>
- *
- * @param timeout the new lifetime. If zero, the lease
- * will expire immediately.
- */
- public synchronized long lease(long timeout) {
- if (logger.traceOn()) {
- logger.trace("lease", "new lease to: "+timeout);
- }
-
- if (timeout < 0)
- throw new IllegalArgumentException("Negative lease: " + timeout);
-
- if (scheduled == null)
- return 0L;
-
- scheduled.cancel(false);
-
- if (logger.traceOn())
- logger.trace("lease", "start lease: "+timeout);
- schedule(timeout);
-
- return timeout;
- }
-
- private class Expire implements Runnable {
- ScheduledFuture<?> task;
-
- public void run() {
- synchronized (LeaseManager.this) {
- if (task.isCancelled())
- return;
- scheduled = null;
- }
- callback.run();
- executor.shutdown();
- }
- }
-
- private synchronized void schedule(long timeout) {
- Expire expire = new Expire();
- scheduled = executor.schedule(expire, timeout, TimeUnit.MILLISECONDS);
- expire.task = scheduled;
- }
-
- /**
- * <p>Cancel the lease without calling the expiry callback.</p>
- */
- public synchronized void stop() {
- logger.trace("stop", "canceling lease");
- scheduled.cancel(false);
- scheduled = null;
- try {
- executor.shutdown();
- } catch (SecurityException e) {
- // OK: caller doesn't have RuntimePermission("modifyThread")
- // which is unlikely in reality but triggers a test failure otherwise
- logger.trace("stop", "exception from executor.shutdown", e);
- }
- }
-
- private final Runnable callback;
- private ScheduledFuture<?> scheduled; // If null, the lease has expired.
-
- private static final ThreadFactory threadFactory =
- new DaemonThreadFactory("JMX LeaseManager %d");
- private final ScheduledExecutorService executor
- = Executors.newScheduledThreadPool(1, threadFactory);
-
- private static final ClassLogger logger =
- new ClassLogger("javax.management.event", "LeaseManager");
-
-}