/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership. The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at
    * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package net.jini.lease;
  
  import org.apache.river.config.Config;
  import org.apache.river.constants.ThrowableConstants;
  import org.apache.river.logging.Levels;
  import org.apache.river.logging.LogManager;
  import org.apache.river.proxy.ConstrainableProxyUtil;
  import java.lang.reflect.Method;
  import java.rmi.RemoteException;
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.SortedMap;
  import java.util.TreeMap;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.SynchronousQueue;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.ThreadPoolExecutor.CallerRunsPolicy;
  import java.util.concurrent.TimeUnit;
  import java.util.logging.Level;
  import java.util.logging.LogRecord;
  import java.util.logging.Logger;
  import net.jini.config.Configuration;
  import net.jini.config.ConfigurationException;
  import net.jini.core.constraint.RemoteMethodControl;
  import net.jini.core.lease.Lease;
  import net.jini.core.lease.LeaseException;
  import net.jini.core.lease.LeaseMap;
  import net.jini.core.lease.LeaseMapException;
  import net.jini.core.lease.UnknownLeaseException;
  import org.apache.river.thread.NamedThreadFactory;
  
  /**
   * Provides for the systematic renewal and overall management of a set
   * of leases associated with one or more remote entities on behalf of a
   * local entity.
   * <p>
   * This class removes much of the administrative burden associated with
   * lease renewal. Clients of the renewal manager simply give their
   * leases to the manager and the manager renews each lease as necessary
   * to achieve a <em>desired expiration</em> time (which may be later
   * than the lease's current <em>actual expiration</em> time). Failures
   * encountered while renewing a lease can optionally be reflected to the
   * client via <code>LeaseRenewalEvent</code> instances.
   * <p>
   * Note that this class is not remote. Entities wishing to use this
   * class must create an instance of this class in their own virtual
   * machine to locally manage the leases granted to them. If the virtual
   * machine that the manager was created in exits or crashes, the renewal
   * manager will be destroyed.
   * <p>
   * The <code>LeaseRenewalManager</code> distinguishes between two time
   * values associated with lease expiration: the <em>desired
   * expiration</em> time for the lease, and the <em>actual
   * expiration</em> time granted when the lease is created or last
   * renewed. The desired expiration represents when the client would like
   * the lease to expire. The actual expiration represents when the lease
   * is going to expire if it is not renewed. Both time values are
   * absolute times, not relative time durations. The desired expiration
   * time can be retrieved using the renewal manager's
   * <code>getExpiration</code> method. The actual expiration time of a
   * lease object can be retrieved by invoking the lease's
   * <code>getExpiration</code> method.
   * <p>
   * Each lease in the managed set also has two other associated
   * attributes: a desired <em>renewal duration</em>, and a <em>remaining
   * desired duration</em>. The desired renewal duration is specified
   * (directly or indirectly) when the lease is added to the set. This
   * duration must normally be a positive number; however, it may be
   * <code>Lease.ANY</code> if the lease's desired expiration is
   * <code>Lease.FOREVER</code>. The remaining desired duration is always
   * the desired expiration less the current time.
   * <p>
   * Each time a lease is renewed, the renewal manager will ask for an
   * extension equal to the lease's renewal duration if the renewal
   * duration is:
   * <ul>
   * <li> <code>Lease.ANY</code>, or 
   * <li> less than the remaining desired duration,
  * </ul>
  * otherwise it will ask for an extension equal to the lease's remaining
  * desired duration.
  * <p>
  * Once a lease is given to a lease renewal manager, the manager will
  * continue to renew the lease until one of the following occurs:
  * <ul>
  * <li> The lease's desired or actual expiration time is reached.
  * <li> An explicit removal of the lease from the set is requested via a
  *	<code>cancel</code>, <code>clear</code>, or <code>remove</code>
  *	call on the renewal manager.
  * <li> The renewal manager tries to renew the lease and gets a bad
  *	object exception, bad invocation exception, or
  *	<code>LeaseException</code>.
  * </ul>
  * <p>
  * The methods of this class are appropriately synchronized for
  * concurrent operation. Additionally, this class makes certain
  * guarantees with respect to concurrency. When this class makes a
  * remote call (for example, when requesting the renewal of a lease),
  * any invocations made on the methods of this class will not be
  * blocked. Similarly, this class makes a reentrancy guarantee with
  * respect to the listener objects registered with this class. Should
  * this class invoke a method on a registered listener (a local call),
  * calls from that method to any other method of this class are
  * guaranteed not to result in a deadlock condition.
  *
  * @author Sun Microsystems, Inc.
  * @see Lease
  * @see LeaseException
  * @see LeaseRenewalEvent 
  *
  *  <!-- Implementation Specifics -->
  *
  * The following implementation-specific items are discussed below:
  * <ul>
  * <li><a href="#configEntries">Configuring LeaseRenewalManager</a>
  * <li><a href="#logging">Logging</a>
  * <li><a href="#algorithm">The renewal algorithm</a>
  * </ul>
  *
  * <a name="configEntries"><b>Configuring LeaseRenewalManager</b></a>
  *
  * This implementation of <code>LeaseRenewalManager</code> supports the
  * following configuration entries, with component
  * <code>net.jini.lease.LeaseRenewalManager</code>:
  *
  * <table summary="Describes the renewBatchTimeWindow configuration entry"
  *	  border="0" cellpadding="2">
  *   <tr valign="top">
  *     <th scope="col">&#X2022;
  *     <th scope="col" align="left" colspan="2"><code>
  *	 renewBatchTimeWindow</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Type: <td> <code>long</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Default: <td> <code>5 * 60 * 1000 // 5 minutes</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Description: <td> The maximum number of milliseconds earlier than
  *     a lease would typically be renewed to allow it to be renewed in
  *     order to permit batching its renewal with that of other
  *     leases. The value must not be negative. This entry is obtained
  *     in the constructor.
  * </table>
  * <table summary="Describes the roundTripTime configuration entry"
  *	  border="0" cellpadding="2">
  *   <tr valign="top">
  *     <th scope="col">&#X2022;
  *     <th scope="col" align="left" colspan="2"><code>
  *	 roundTripTime</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Type: <td> <code>long</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Default: <td> <code>10 * 1000 // 10 seconds</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Description: <td> The worst-case latency, expressed in milliseconds,
  *     to assume for a remote call to renew a lease. The value must be greater 
  *     than zero. Unrealistically low values for this entry may
  *     result in failure to renew a lease. Leases managed by this manager
  *     should have durations exceeding the <code>roundTripTime</code>.
  *     This entry is obtained in the constructor.
  * </table>
  * <table summary="Describes the executorService configuration entry"
  *	  border="0" cellpadding="2">
  *   <tr valign="top">
  *     <th scope="col">&#X2022;
  *     <th scope="col" align="left" colspan="2"><code>
  *	 executorService</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Type: <td> {@link ExecutorService}
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Default: <td> <code>new ThreadPoolExecutor(1,11,15,TimeUnit.SECONDS,
  *     new LinkedBlockingQueue())</code>
  *   <tr valign="top"> <td> &nbsp; <th scope="row" align="right">
  *     Description: <td> The object used to manage queuing tasks
  *     involved with renewing leases and sending notifications. The
  *     value must not be <code>null</code>. The default value creates
  *     a maximum of 11 threads for performing operations, waits 15
  *     seconds before removing idle threads.
  * </table>
  * <p>
  * <a name="logging"><b>Logging</b></a>
  * </p>
  * <p>
  * This implementation uses the {@link Logger} named
  * <code>net.jini.lease.LeaseRenewalManager</code> to log information at
  * the following logging levels: </p>
  *
  * <table border="1" cellpadding="5"
  *	  summary="Describes logging performed by the
  *		   LeaseRenewalManager at different logging levels">
  *
  * <caption><b><code>net.jini.lease.LeaseRenewalManager</code></b></caption>
  *
  * <tr> <th scope="col"> Level <th scope="col"> Description
  *
  * <tr> <td> {@link Levels#FAILED FAILED}
  *	<td> Lease renewal failure events, or leases that expire before
  *           reaching the desired expiration time
  *
  * <tr> <td> {@link Levels#HANDLED HANDLED}
  *	<td> Lease renewal attempts that produce indefinite exceptions
  *
  * <tr> <td> {@link Level#FINE FINE}
  *	<td> Adding and removing leases, lease renewal attempts, and desired
  *	     lease expiration events
  *
  * </table> 
  * <p>
  *
  * For a way of using the <code>FAILED</code> and <code>HANDLED</code> logging
  * levels in standard logging configuration files, see the {@link LogManager}
  * class.</p>
  * <p>
  * <a name="algorithm"><b>The renewal algorithm</b></a></p>
  * <p>
  * The time at which a lease is scheduled for renewal is based on the
  * expiration time of the lease, possibly adjusted to account for the
  * latency of the remote renewal call. The configuration entry
  * <code>roundTripTime</code>, which defaults to ten seconds, represents
  * the total time to make the remote call.</p>
  * <p>
  * The following pseudocode was derived from the code which computes
  * the renewal time. In this code, <code>rtt</code> represents the
  * value of the <code>roundTripTime</code>:</p>
  *
  * <pre>    
  *          endTime = lease.getExpiration();
  *          delta = endTime - now;
  *          if (delta &lt;= rtt * 2) {
  *	        delta = rtt;
  *          } else if (delta &lt;= rtt * 8) {
  *	        delta /= 2;
  *          } else if (delta &lt;= 1000 * 60 * 60 * 24 * 7) {
  *	        delta /= 8;
  *          } else if (delta &lt;= 1000 * 60 * 60 * 24 * 14) {
  *	        delta = 1000 * 60 * 60 * 24;
  *          } else {
  *	        delta = 1000 * 60 * 60 * 24 * 3;
  *          }
  *          renew = endTime - delta;
  *</pre>
  * <p>
  * It is important to note that <code>delta</code> is never less than
  * <code>rtt</code> when the renewal time is computed. A lease which 
  * would expire within this time range will be scheduled for immediate
  * renewal. The use of very short lease durations (at or below <code>rtt</code>)
  * can cause the renewal manager to effectively ignore the lease duration
  * and repeatedly schedule the lease for immediate renewal.
  * </p><p>
  * If an attempt to renew a lease fails with an indefinite exception, a
  * renewal is rescheduled with an updated renewal time as computed by the
  * following pseudocode:</p>
  *
  * <pre>
  *          delta = endTime - renew;
  *          if (delta &gt; rtt) {
  *              if (delta &lt;= rtt * 3) {
  *	            delta = rtt;
  *              } else if (delta &lt;= 1000 * 60 * 60) {
  *	            delta /= 3;
  *              } else if (delta &lt;= 1000 * 60 * 60 * 24) {
  *	            delta = 1000 * 60 * 30;
  *              } else if (delta &lt;= 1000 * 60 * 60 * 24 * 7) {
  *	            delta = 1000 * 60 * 60 * 3;
  *              } else {
  *	            delta = 1000 * 60 * 60 * 8;
  *              }
  *              renew += delta;
  *          }
  * </pre>
  *
  * Client leases are maintained in a collection sorted by descending renewal
  * time. A renewal thread is spawned whenever the renewal time of the last lease
  * in the collection is reached. This renewal thread examines all of the leases
  * in the collection whose renewal time falls within
  * <code>renewBatchTimeWindow</code> milliseconds of the renewal time of the
  * last lease. If any of these leases can be batch renewed with the last lease (as
  * determined by calling the {@link Lease#canBatch canBatch} method of
  * the last lease) then a {@link LeaseMap} is created, all eligible leases
  * are added to it and the {@link LeaseMap#renewAll} method is called. Otherwise, the
  * last lease is renewed directly.
  * <p> 
  * The <code>ExecutorService</code> that manages the renewal threads has a bound on
  * the number of simultaneous threads it will support. The renewal time of
  * leases may be adjusted earlier in time to reduce the likelihood that the
  * renewal of a lease will be delayed due to exhaustion of the thread pool.
  * Actual renewal times are determined by starting with the lease with the
  * latest (farthest off) desired renewal time and working backwards.  When
  * computing the actual renewal time for a lease, the renewals of all leases
  * with later renewal times, which will be initiated during the round trip time
  * of the current lease's renewal, are considered.  If using the desired
  * renewal time for the current lease would result in more in-progress renewals
  * than the number of threads allowed, the renewal time of the current lease is
  * shifted earlier in time, such that the maximum number of threads is not
  * exceeded.
  * 
  */
 
 public class LeaseRenewalManager {
 
     private static final String LRM = "net.jini.lease.LeaseRenewalManager";
 
     private static final Logger logger = Logger.getLogger(LRM);
 
     /* Method objects for manipulating method constraints */
     private static final Method cancelMethod;
     private static final Method cancelAllMethod;
     private static final Method renewMethod;
     private static final Method renewAllMethod;
     static {
 	try {
 	    cancelMethod = Lease.class.getMethod(
 		"cancel", new Class[] { });
 	    cancelAllMethod = LeaseMap.class.getMethod(
 		"cancelAll", new Class[] { });
 	    renewMethod = Lease.class.getMethod(
 		"renew", new Class[] { long.class });
 	    renewAllMethod = LeaseMap.class.getMethod(
 		"renewAll", new Class[] { });
 	} catch (NoSuchMethodException e) {
 	    throw new NoSuchMethodError(e.getMessage());
 	}
     }
 
     /* Methods for comparing lease constraints. */
     private static final Method[] leaseToLeaseMethods = {
 	cancelMethod, cancelMethod, renewMethod, renewMethod
     };
 
     /* Methods for converting lease constraints to lease map constraints. */
     private static final Method[] leaseToLeaseMapMethods = {
 	cancelMethod, cancelAllMethod, renewMethod, renewAllMethod
     };
 
     private final long renewBatchTimeWindow;
 
     /** Task manager for queuing and renewing leases 
      *  NOTE: test failures occur with queue's that have capacity, 
      *  no test failures occur with SynchronousQueue, for the time
      *  being, until the cause is sorted out we may need to rely on 
      *  a larger pool, if necessary.  TaskManager is likely to have 
      *  lower throughput capacity that ExecutorService with a
      *  SynchronousQueue although this hasn't been confirmed yet.
      */
     final ExecutorService leaseRenewalExecutor;
 
     /**
      * The worst-case renewal round-trip-time
      */
     private final long renewalRTT ;
 
     /** 
      * Entries for leases that are not actively being renewed.
      * Lease with the earliest renewal is last in the map.
      */
     private final SortedMap leases = new TreeMap();
 
     /** Entries for leases that are actively being renewed */
     private final List leaseInRenew = new ArrayList(1);
     /** The queuer task */
     private QueuerTask queuer = null;
 
     /**
      * Used to determine concurrency constraints when calculating actual
      * renewals.  The list is stored in a field to avoid reallocating it.
      */
     private List calcList;
 
     private final class RenewTask implements Runnable {
 	/** Entries of leases to renew (if multiple, all can be batched) */
 	private final List bList;
 
 	/** 
 	 * True if this task only holds leases that have reached their
 	 * actual or desired expiration
 	 */
 	private final boolean noRenewals;
 
 	/**
 	 * Create a collection of entries whose leases can be batch
 	 * renewed with the last lease in the map, or a list of entries
 	 * whose leases need to be removed.  Which is created depends on
 	 * the state of the last lease in the map.  Remove each entry
 	 * from the map, and add them to leaseInRenew.
 	 */
 	RenewTask(long now) {
 	    bList = new ArrayList(1);
 	    Entry e = (Entry) leases.lastKey();
 
 	    if (e.renewalsDone() || e.endTime <= now) {
 		noRenewals = true;
 		Map lMap = leases.tailMap(new Entry(now, renewalRTT));
 		for (Iterator iter = lMap.values().iterator(); 
 		     iter.hasNext(); )
 		{
 		    Entry be = (Entry) iter.next();
 		    if (be.renewalsDone() || be.endTime <= now) {
 			iter.remove();
 			logExpiration(be);
 			/*
 			 * Only add to bList if we need to tell someone
 			 * about this lease's departure
 			 */
 			if (be.listener != null)
 			    bList.add(be);
 		    }
 		}
 	    } else {
 		noRenewals = false;
 		Map lMap = leases.tailMap(new Entry(e.renew + renewBatchTimeWindow, renewalRTT));
 		for (Iterator iter = lMap.values().iterator(); 
 		     iter.hasNext(); )
 		{
 		    Entry be = (Entry) iter.next();
 		    if (be == e || be.canBatch(e)) {
 			iter.remove();
 			leaseInRenew.add(be);
 			bList.add(be);
 		    }
 		}
 	    }
 	}
 
         @Override
 	public void run() {
 	    if (noRenewals) {
 		// Just notify
 		tell(bList);
 	    } else {
 		/*
 		 * Get rid of any leases that have expired and then do
 		 * renewals
 		 */
 		long now = System.currentTimeMillis();
 		List bad = processBadLeases(now);
 		if (!bList.isEmpty())
 		    renewAll(bList, now);
 		if (bad != null)
 		    tell(bad);
 	    }
 	}
 
 	/**
 	 * Find any expired leases, remove them from bList and
 	 * leaseInRenew, and return any with listeners.
 	 */
 	private List processBadLeases(long now) {
 	    List bad = null;
 	    synchronized (LeaseRenewalManager.this) {
 		for (Iterator iter = bList.iterator(); iter.hasNext(); ) {
 		    Entry e = (Entry) iter.next();
 		    if (e.endTime <= now) {
 			iter.remove();
 			logExpiration(e);
 			removeLeaseInRenew(e);
 			if (e.listener != null) {
 			    if (bad == null)
 				bad = new ArrayList(1);
 			    bad.add(e);
 			}
 		    }
 		}
 	    }
 	    return bad;
 	}
     }
 
     private static class Entry implements Comparable {
 	/*
 	 * Since the cnt only gets modified in the constructor, and the
 	 * constructor is always called from synchronized code, the cnt
 	 * does not need to be synchronized.
 	 */
 	private static long cnt = 0;
 
 	/** Unique id */
 	public final long id;
 	/** The lease */
 	public final Lease lease;
 	/** Desired expiration */
 	public long expiration;
 	/** Renew duration */
 	public long renewDuration;
 	/** The listener, or null */
 	public final LeaseListener listener;
 	/** Current actual expiration */
 	public long endTime;
         private final long renewalRTT;
 
 	/** 
 	 * The next time we have to do something with this lease.
 	 * Usually a renewal, but could be removing it from the managed
 	 * set because its desired expiration has been reached.
 	 */
 	public long renew;
 
 	/** Actual time to renew, given concurrency limitations */
 	public long actualRenew;
 	/** Renewal exception, or null */
 	public Throwable ex = null;
 
 	public Entry(Lease lease, long expiration, long renewDuration, long renewalRTT, LeaseListener listener)
 	{
 	    this.endTime = lease.getExpiration();
 	    this.lease = lease;
 	    this.expiration = expiration;
 	    this.renewDuration = renewDuration;
 	    this.listener = listener;
             this.renewalRTT = renewalRTT;
 	    id = cnt++;
 	}
 
 	/** Create a fake entry for tailMap */
 	public Entry(long renew, long renewalRTT) {
 	    this.renew = renew;
 	    id = Long.MAX_VALUE;
 	    lease = null;
 	    listener = null;
             this.renewalRTT = renewalRTT;
 	}
 
 	/**
 	 * If the renewDuration is ANY, return ANY, otherwise return the
 	 * minimum of the renewDuration and the time remaining until the
 	 * desired expiration.
 	 */
 	public long getRenewDuration(long now) {
 	    if (renewDuration == Lease.ANY)
 		return renewDuration;
 	    return Math.min(expiration - now, renewDuration);
 	}
 
 	/** Calculate the renew time for the lease entry */
 	public void calcRenew(long now) {
 	    endTime = lease.getExpiration();
 	    if (renewalsDone()) {
 		if (null == desiredExpirationListener()) {
 		    // Nothing urgent needs to be done with this lease
 		    renew = Long.MAX_VALUE;
 		} else {
 		    /*
 		     * Tell listener about dropping this lease in a
 		     * timely fashion
 		     */
 		    renew = expiration; 
 		}
 		return;
 	    }
 	    long delta = endTime - now;
 	    if (delta <= renewalRTT * 2) {
 		delta = renewalRTT;
 	    } else if (delta <= renewalRTT * 8) {
 		delta /= 2;
 	    } else if (delta <= 1000 * 60 * 60 * 24 * 7) {
 		delta /= 8;
 	    } else if (delta <= 1000 * 60 * 60 * 24 * 14) {
 		delta = 1000 * 60 * 60 * 24;
 	    } else {
 		delta = 1000 * 60 * 60 * 24 * 3;
 	    }
 	    renew = endTime - delta;
 	}
 
 	/** Calculate a new renew time due to an indefinite exception */
 	public void delayRenew() {
 	    long delta = endTime - renew;
 	    if (delta <= renewalRTT) {
 		return;
 	    } else if (delta <= renewalRTT * 3) {
 		 delta = renewalRTT;
 	    } else if (delta <= 1000 * 60 * 60) {
 		delta /= 3;
 	    } else if (delta <= 1000 * 60 * 60 * 24) {
 		delta = 1000 * 60 * 30;
 	    } else if (delta <= 1000 * 60 * 60 * 24 * 7) {
 		delta = 1000 * 60 * 60 * 3;
 	    } else {
 		delta = 1000 * 60 * 60 * 8;
 	    }
 	    renew += delta;
 	}
 
 	/** Sort by decreasing renew time, secondary sort by decreasing id */
         @Override
 	public int compareTo(Object obj) {
 	    if (this == obj)
 		return 0;
 	    Entry e = (Entry) obj;
 	    if (renew < e.renew || (renew == e.renew && id < e.id))
 		return 1;
 	    return -1;
 	}
 	
 	@Override
 	public boolean equals(Object o){
 	    if (!(o instanceof Entry)) return false;
 	    Entry that = (Entry) o;
 	    if (this.id != that.id) return false;
 	    if (this.renew != that.renew) return false;
 	    if (this.renewalRTT != that.renewalRTT) return false;
 	    if (!Objects.equals(this.lease, that.lease)) return false;
 	    return Objects.equals(this.listener, that.listener);
 	}
 
 	@Override
 	public int hashCode() {
 	    int hash = 7;
 	    hash = 67 * hash + (int) (this.id ^ (this.id >>> 32));
 	    hash = 67 * hash + (this.lease != null ? this.lease.hashCode() : 0);
 	    hash = 67 * hash + (this.listener != null ? this.listener.hashCode() : 0);
 	    hash = 67 * hash + (int) (this.renewalRTT ^ (this.renewalRTT >>> 32));
 	    hash = 67 * hash + (int) (this.renew ^ (this.renew >>> 32));
 	    return hash;
 	}
 
 	/**
 	 * Returns true if the renewal of this lease can be batched with
 	 * the (earlier) renewal of the given lease.  This method must
 	 * be called with an entry such that e.renew &lt;= this.renew. <p>
 	 * 
 	 * First checks that both leases require renewal, have the same
 	 * client constraints, and can be batched.  Then enforces
 	 * additional requirements to avoid renewing the lease too much
 	 * more often than necessary. <p>
 	 *
 	 * One of the following must be true: <ul>
 	 *
 	 * <li> This lease has a renewal duration of Lease.ANY, meaning
 	 * it doesn't specify its renewal duration.
 	 *
 	 * <li> The amount of time from the other lease's renewal time
 	 * to this one's is less than half of the estimated time needed
 	 * to perform renewals (renewalRTT).  In this case, the renewal
 	 * times are so close together that the renewal duration
 	 * shouldn't be materially affected.
 	 *
 	 * <li> This lease's expiration time is no more than half its
 	 * renewal duration greater than the renewal time of the other
 	 * lease.  This case insures that this lease is not renewed
 	 * until at least half of it's renewal duration has
 	 * elapsed. </ul> <p>
 	 *
 	 * In addition, one of the following must be true: <ul>
 	 *
 	 * <li> The other lease has a renewal duration of Lease.ANY,
 	 * meaning we don't know how long its next renewal will be.
 	 *
 	 * <li> The other lease is not going to be renewed again before
 	 * this lease's renewal time, because either its next renewal
 	 * will last until after this lease's renewal time or it will
 	 * only be renewed once more. </ul>
 	 */
 	public boolean canBatch(Entry e) {
 	    return (!renewalsDone() &&
 		    !e.renewalsDone() &&
 		    sameConstraints(lease, e.lease) &&
 		    lease.canBatch(e.lease) &&
 		    (renewDuration == Lease.ANY ||
 		     renew - e.renew <= renewalRTT / 2 ||
 		     endTime - e.renew <= renewDuration / 2) &&
 		    (e.renewDuration == Lease.ANY ||
 		     e.renew > renew - e.renewDuration ||
 		     e.renew >= e.expiration - e.renewDuration));
 	}
 
 	/**
 	 * Returns true if the two leases both implement RemoteMethodControl
 	 * and have the same constraints for Lease methods, or both don't
 	 * implement RemoteMethodControl, else returns false.
 	 */
 	private static boolean sameConstraints(Lease l1, Lease l2) {
 	    if (!(l1 instanceof RemoteMethodControl)) {
 		return !(l2 instanceof RemoteMethodControl);
 	    } else if (!(l2 instanceof RemoteMethodControl)) {
 		return false;
 	    } else {
 		return ConstrainableProxyUtil.equivalentConstraints(
 		    ((RemoteMethodControl) l1).getConstraints(),
 		    ((RemoteMethodControl) l2).getConstraints(),
 		    leaseToLeaseMethods);
 	    }
 	}
 
 	/**
 	 * Return the DesiredExpirationListener associated with this
 	 * lease, or null if there is none.
 	 */
 	public DesiredExpirationListener desiredExpirationListener() {
 	    if (listener == null)
 		return null;
 
 	    if (listener instanceof DesiredExpirationListener) 
 		return (DesiredExpirationListener) listener;
 
 	    return null;
 	}
 
 	/**
 	 * Return true if the actual expiration is greater than or equal
 	 * to the desired expiration (e.g. we don't need to renew this
 	 * lease any more.
 	 */
 	public boolean renewalsDone() {
 	    return expiration <= endTime;
 	}
     }
 
     /**
      * No-argument constructor that creates an instance of this class
      * that initially manages no leases.
      */
     public LeaseRenewalManager() {
         this.renewBatchTimeWindow = 1000 * 60 * 5;
         this.renewalRTT = 10 * 1000;
         leaseRenewalExecutor = 
             new ThreadPoolExecutor(
                     1,  /* min threads */
                     11, /* max threads */
                     15,
                     TimeUnit.SECONDS, 
                     new SynchronousQueue<Runnable>(), /* Queue has no capacity */
                     new NamedThreadFactory("LeaseRenewalManager",false),
                     new CallerRunsPolicy()
             );
     }
     
     private static Init init(Configuration config) throws ConfigurationException{
         return new Init(config);
     }
     
     private static class Init {
         long renewBatchTimeWindow = 1000 * 60 * 5 ;
         long renewalRTT = 10 * 1000;
         ExecutorService leaseRenewalExecutor;
         
         Init(Configuration config) throws ConfigurationException{
             if (config == null) {
 	    throw new NullPointerException("config is null");
             }
             renewBatchTimeWindow = Config.getLongEntry(
                 config, LRM, "renewBatchTimeWindow",
                 renewBatchTimeWindow, 0, Long.MAX_VALUE);
             renewalRTT = Config.getLongEntry(
                 config, LRM, "roundTripTime",
                 renewalRTT, 1, Long.MAX_VALUE);
             leaseRenewalExecutor = Config.getNonNullEntry(
                 config, 
                 LRM, 
                 "executorService", 
                 ExecutorService.class,
                 new ThreadPoolExecutor(
                         1,  /* Min Threads */
                         11, /* Max Threads */
                         15,
                         TimeUnit.SECONDS, 
                         new SynchronousQueue<Runnable>(), /* No capacity */
                         new NamedThreadFactory("LeaseRenewalManager",false),
                         new CallerRunsPolicy()
                 ) 
             );
         }
     }
 
     /**
      * Constructs an instance of this class that initially manages no leases
      * and that uses <code>config</code> to control implementation-specific
      * details of the behavior of the instance created.
      *
      * @param config supplies entries that control the configuration of this
      *	      instance
      * @throws ConfigurationException if a problem occurs when obtaining
      *	       entries from the configuration
      * @throws NullPointerException if the configuration is <code>null</code>
      */
     public LeaseRenewalManager(Configuration config)
 	throws ConfigurationException
     {
 	this(init(config));
     }
     
     private LeaseRenewalManager(Init init){
         this.renewBatchTimeWindow = init.renewBatchTimeWindow;
         this.renewalRTT = init.renewalRTT;
         this.leaseRenewalExecutor = init.leaseRenewalExecutor;
     }
 
     /**
      * Constructs an instance of this class that will initially manage a
      * single lease. Employing this form of the constructor is
      * equivalent to invoking the no-argument form of the constructor
      * followed by an invocation of the three-argument form of the
      * <code>renewUntil</code> method. See <code>renewUntil</code> for
      * details on the arguments and what exceptions may be thrown by
      * this constructor.
      *
      * @param lease reference to the initial lease to manage
      * @param desiredExpiration the desired expiration for
      *	      <code>lease</code>
      * @param listener reference to the <code>LeaseListener</code>
      *	      object that will receive notifications of any exceptional
      *	      conditions that occur during renewal attempts. If
      *	      <code>null</code> no notifications will be sent.
      * @throws NullPointerException if <code>lease</code> is
      *	       <code>null</code>
      * @see LeaseListener
      * @see #renewUntil 
      */
     public LeaseRenewalManager(Lease lease,
 			       long desiredExpiration,
 			       LeaseListener listener)
     {
         this.renewBatchTimeWindow = 1000 * 60 * 5;
         this.renewalRTT = 10 * 1000;
         leaseRenewalExecutor = new ThreadPoolExecutor(
                 1,  /* Min Threads */
                 11, /* Max Threads */
                 15,
                 TimeUnit.SECONDS, 
                 new SynchronousQueue<Runnable>(), /* No Capacity */
                 new NamedThreadFactory("LeaseRenewalManager",false),
                 new CallerRunsPolicy()
         );
 	renewUntil(lease, desiredExpiration, listener);
     }
 
     /**
      * Include a lease in the managed set until a specified time. 
      * <p>
      * If <code>desiredExpiration</code> is <code>Lease.ANY</code>
      * calling this method is equivalent the following call:
      * <pre>
      *     renewUntil(lease, Lease.FOREVER, Lease.ANY, listener)
      * </pre>
      * otherwise it is equivalent to this call:
      * <pre>
      *     renewUntil(lease, desiredExpiration, Lease.FOREVER, listener)
      * </pre>
      * <p>
      * @param lease the <code>Lease</code> to be managed
      * @param desiredExpiration when the client wants the lease to
      *	      expire, in milliseconds since the beginning of the epoch
      * @param listener reference to the <code>LeaseListener</code>
      *	      object that will receive notifications of any exceptional
      *	      conditions that occur during renewal attempts. If
      *	      <code>null</code> no notifications will be sent.
      * @throws NullPointerException if <code>lease</code> is
      *	       <code>null</code>
      * @see #renewUntil
      */
     public final void renewUntil(Lease lease,
 			   long desiredExpiration,
 			   LeaseListener listener)
     {
 	if (desiredExpiration == Lease.ANY) {
 	    renewUntil(lease, Lease.FOREVER, Lease.ANY, listener);
 	} else {
 	    renewUntil(lease, desiredExpiration, Lease.FOREVER, listener);
 	}
     }
 
     /**
      * Include a lease in the managed set until a specified time and
      * with a specified renewal duration.
      * <p>
      * This method takes as arguments: a reference to the lease to
      * manage, the desired expiration time of the lease, the renewal
      * duration time for the lease, and a reference to the
      * <code>LeaseListener</code> object that will receive notification
      * of exceptional conditions when attempting to renew this
      * lease. The <code>LeaseListener</code> argument may be
      * <code>null</code>.
      * <p>
      * If the <code>lease</code> argument is <code>null</code>, a
      * <code>NullPointerException</code> will be thrown. If the
      * <code>desiredExpiration</code> argument is
      * <code>Lease.FOREVER</code>, the <code>renewDuration</code>
      * argument may be <code>Lease.ANY</code> or any positive value;
      * otherwise, the <code>renewDuration</code> argument must be a
      * positive value. If the <code>renewDuration</code> argument does
      * not meet these requirements, an
      * <code>IllegalArgumentException</code> will be thrown.
      * <p>
      * If the lease passed to this method is already in the set of
      * managed leases, the listener object, the desired expiration, and
      * the renewal duration associated with that lease will be replaced
      * with the new listener, desired expiration, and renewal duration.
      * <p>
      * The lease will remain in the set until one of the following
      * occurs:
      * <ul>
      * <li> The lease's desired or actual expiration time is reached.
      * <li> An explicit removal of the lease from the set is requested
      *	    via a <code>cancel</code>, <code>clear</code>, or
      *	    <code>remove</code> call on the renewal manager.
      * <li> The renewal manager tries to renew the lease and gets a bad
      *	    object exception, bad invocation exception, or
      *	    <code>LeaseException</code>.
      * </ul>
      * <p>
      * This method will interpret the value of the
      * <code>desiredExpiration</code> argument as the desired absolute
      * system time after which the lease is no longer valid. This
      * argument provides the ability to indicate an expiration time that
      * extends beyond the actual expiration of the lease. If the value
      * passed for this argument does indeed extend beyond the lease's
      * actual expiration time, then the lease will be systematically
      * renewed at appropriate times until one of the conditions listed
      * above occurs. If the value is less than or equal to the actual
      * expiration time, nothing will be done to modify the time when the
      * lease actually expires. That is, the lease will not be renewed
      * with an expiration time that is less than the actual expiration
      * time of the lease at the time of the call.
      * <p>
      * If the <code>LeaseListener</code> argument is a
      * non-<code>null</code> object reference, it will receive
      * notification of exceptional conditions occurring upon a renewal
      * attempt of the lease. In particular, exceptional conditions
      * include the reception of a <code>LeaseException</code>, bad
      * object exception, or bad invocation exception (collectively these
      * are referred to as <em>definite exceptions</em>) during a renewal
      * attempt or the lease's actual expiration being reached before its
      * desired expiration.
      * <p>
      * If a definite exception occurs during a lease renewal request,
      * the exception will be wrapped in an instance of the
      * <code>LeaseRenewalEvent</code> class and sent to the listener.
      * <p>
      * If an indefinite exception occurs during a renewal request for
      * the lease, renewal requests will continue to be made for that
      * lease until: the lease is renewed successfully, a renewal attempt
      * results in a definite exception, or the lease's actual expiration
      * time has been exceeded. If the lease cannot be successfully
      * renewed before its actual expiration is reached, the exception
      * associated with the most recent renewal attempt will be wrapped
      * in an instance of the <code>LeaseRenewalEvent</code> class and
      * sent to the listener.
      * <p>
      * If the lease's actual expiration is reached before the lease's
      * desired expiration time, and either 1) the last renewal attempt
      * succeeded or 2) there have been no renewal attempts, a
      * <code>LeaseRenewalEvent</code> containing a <code>null</code>
      * exception will be sent to the listener.
      *
      * @param lease the <code>Lease</code> to be managed
      * @param desiredExpiration when the client wants the lease to
      *	      expire, in milliseconds since the beginning of the epoch
      * @param renewDuration the renewal duration to associate with the
      *	      lease, in milliseconds
      * @param listener reference to the <code>LeaseListener</code>
      *	      object that will receive notifications of any exceptional
      *	      conditions that occur during renewal attempts. If
      *	      <code>null</code>, no notifications will be sent.
      * @throws NullPointerException if <code>lease</code> is
      *	       <code>null</code>
      * @throws IllegalArgumentException if <code>renewDuration</code> is
      *	       invalid
      * @see LeaseRenewalEvent
      * @see LeaseException
      */
     public void renewUntil(Lease lease,
 			   long desiredExpiration,
 			   long renewDuration,
 			   LeaseListener listener)
     {
 	validateDuration(renewDuration, desiredExpiration == Lease.FOREVER,
 			 "desiredExpiration");
 	addLease(lease, desiredExpiration, renewDuration, listener,
 		 System.currentTimeMillis());
     }
 
     /**
      * Include a lease in the managed set for a specified duration.
      * <p>
      * Calling this method is equivalent the following call:
      * <pre>
      *     renewFor(lease, desiredDuration, Lease.FOREVER, listener)
      * </pre>
      *
      * @param lease reference to the new lease to manage
      * @param desiredDuration the desired duration (relative time) that
      *	      the caller wants <code>lease</code> to be valid for, in
      *	      milliseconds
      * @param listener reference to the <code>LeaseListener</code>
      *	      object that will receive notifications of any exceptional
      *	      conditions that occur during renewal attempts. If
      *	      <code>null</code>, no notifications will be sent.
      * @throws NullPointerException if <code>lease</code> is
      *	       <code>null</code>
      * @see #renewFor 
      */
     public void renewFor(Lease lease, long desiredDuration, 
 			 LeaseListener listener) 
     {
 	renewFor(lease, desiredDuration, Lease.FOREVER, listener);
     }	 
 
     /**
      * Include a lease in the managed set for a specified duration and
      * with specified renewal duration.
      * <p>
      * The semantics of this method are similar to those of the
      * four-argument form of <code>renewUntil</code>, with
      * <code>desiredDuration</code> + current time being used for the
      * value of the <code>desiredExpiration</code> argument of
      * <code>renewUntil</code>. The only exception to this is that, in
      * the context of <code>renewFor</code>, the value of the
      * <code>renewDuration</code> argument may only be
      * <code>Lease.ANY</code> if the value of the
      * <code>desiredDuration</code> argument is <em>exactly</em>
      * <code>Lease.FOREVER.</code>
      * <p>
      * This method tests for arithmetic overflow in the desired
      * expiration time computed from the value of
      * <code>desiredDuration</code> argument
      * (<code>desiredDuration</code> + current time). Should such
      * overflow be present, a value of <code>Lease.FOREVER</code> is
      * used to represent the lease's desired expiration time.
      *
      * @param lease reference to the new lease to manage
      * @param desiredDuration the desired duration (relative time) that
      *	      the caller wants <code>lease</code> to be valid for, in
      *	      milliseconds
      * @param renewDuration the renewal duration to associate with the
      *	      lease, in milliseconds
      * @param listener reference to the <code>LeaseListener</code>
      *	      object that will receive notifications of any exceptional
      *	      conditions that occur during renewal attempts. If
      *	      <code>null</code>, no notifications will be sent.
      * @throws NullPointerException if <code>lease</code> is
      *	       <code>null</code>
      * @throws IllegalArgumentException if <code>renewDuration</code> is
      *	       invalid
      * @see #renewUntil 
      */
     public void renewFor(Lease lease,
 			 long desiredDuration,
 			 long renewDuration,
 			 LeaseListener listener)
     {
 	/*
 	 * Validate before calculating effective desiredExpiration, if
 	 * they want a renewDuration of Lease.ANY, desiredDuration has
 	 * to be exactly Lease.FOREVER
 	 */
 	validateDuration(renewDuration, desiredDuration == Lease.FOREVER,
 			 "desiredDuration");
 
 	long now = System.currentTimeMillis();
 	long desiredExpiration;
 	if (desiredDuration < Lease.FOREVER - now) { // check overflow.
 	    desiredExpiration = now + desiredDuration;
 	} else {
 	    desiredExpiration = Lease.FOREVER;
 	}
 	addLease(lease, desiredExpiration, renewDuration, listener, now);
     }
 
     /**
      * Error checking function that ensures renewDuration is valid taking
      * into account the whether or not the desired expiration/duration is
      * Lease.FOREVER. Throws an appropriate IllegalArgumentException if
      * an invalid renewDuration is passed.
      *
      * @param renewDuration renew duration the clients wants
      * @param isForever should be true if client asked for a desired
      *	      expiration/duration of exactly Lease.FOREVER
      * @param name name of the desired expiration/duration field, used
      *	      to construct exception
      * @throws IllegalArgumentException if renewDuration is invalid
      */
     private void validateDuration(long renewDuration, boolean isForever, 
 				  String name) 
     {
 	if (renewDuration <= 0 && 
 	    !(renewDuration == Lease.ANY && isForever))
 	{
 	    /*
 	     * A negative renew duration and is not lease.ANY with a
 	     * forever desired expiration
 	     */
 	    if (renewDuration == Lease.ANY) {
 		/*
 		 * Must have been Lease.ANY with a non-FOREVER desired
 		 * expiration
 		 */
 		throw new IllegalArgumentException("A renewDuration of " +
 		     "Lease.ANY can only be used with a " + name + " of " +
 		     "Lease.FOREVER");
 	    } 
 
 	    if (isForever) {
 		// Must have been a non-Lease.ANY, non-positive renewDuration
 		throw new IllegalArgumentException("When " + name + " is " +
 		    "Lease.FOREVER the only valid values for renewDuration " +
 		    "are a positive number, Lease.ANY, or Lease.FOREVER");
 	    }
 
 	    /*
 	     * Must be a non-positive renewDuration with a non-Forever 
 	     * desired expiration
 	     */
 	    throw new IllegalArgumentException("When the " + name +
 		" is not Lease.FOREVER the only valid values for " +
 		"renewDuration are a positive number or Lease.FOREVER");
 	}
     }
 
     private synchronized void addLease(Lease lease,
 				       long desiredExpiration,
 				       long renewDuration,
 				       LeaseListener listener,
 				       long now)
     {	    
 	Entry e = findEntryDo(lease);
 	if (e != null && !removeLeaseInRenew(e))
 	    leases.remove(e);
 	insertEntry(new Entry(lease, desiredExpiration, renewDuration, renewalRTT,
 			      listener),
 		    now);
 	calcActualRenews(now);
 	logger.log(Level.FINE, "Added lease {0}", lease);
     }
 
     /** Calculate the preferred renew time, and put in the map */
     private void insertEntry(Entry e, long now) {
 	e.calcRenew(now);
 	leases.put(e, e);
     }
 
     /**
      * Returns the current desired expiration time associated with a
      * particular lease, (not the actual expiration that was granted
      * when the lease was created or last renewed).
      *
      * @param lease the lease the caller wants the current desired
      *	      expiration for
      * @return a <code>long</code> value corresponding to the current
      *	       desired expiration time associated with <code>lease</code>
      * @throws UnknownLeaseException if the lease passed to this method
      *	       is not in the set of managed leases
      * @see UnknownLeaseException
      * @see #setExpiration 
      */
     public synchronized long getExpiration(Lease lease)
 	throws UnknownLeaseException
     {
 	return findEntry(lease).expiration;
     }
 
     /**
      * Replaces the current desired expiration of a given lease from the
      * managed set with a new desired expiration time.
      * <p>
      * Note that an invocation of this method with a lease that is
      * currently a member of the managed set is equivalent to an
      * invocation of the <code>renewUntil</code> method with the lease's
      * current listener as that method's <code>listener</code>
      * argument. Specifically, if the value of the
      * <code>expiration</code> argument is less than or equal to the
      * lease's current desired expiration, this method takes no action.
      *
      * @param lease the lease whose desired expiration time should be
      *	      replaced
      * @param expiration <code>long</code> value representing the new
      *	      desired expiration time for the <code>lease</code>
      *	      argument
      * @throws UnknownLeaseException if the lease passed to this method
      *	       is not in the set of managed leases
      * @see #renewUntil
      * @see UnknownLeaseException
      * @see #getExpiration 
      */
     public synchronized void setExpiration(Lease lease, long expiration)
 	throws UnknownLeaseException
     {
 	Entry e = findEntry(lease);
 	e.expiration = expiration;
 	if (expiration != Lease.FOREVER && e.renewDuration == Lease.ANY)
 	    e.renewDuration = Lease.FOREVER;
 	if (leaseInRenew.indexOf(e) < 0) {
 	    leases.remove(e);
 	    long now = System.currentTimeMillis();
 	    insertEntry(e, now);
 	    calcActualRenews(now);
 	}
     }
 
     /**
      * Removes a given lease from the managed set, and cancels it.
      * <p>
      * Note that even if an exception is thrown as a result of the
      * cancel operation, the lease will still have been removed from the
      * set of leases managed by this class. Additionally, any exception
      * thrown by the <code>cancel</code> method of the lease object
      * itself may also be thrown by this method.
      *
      * @param lease the lease to remove and cancel
      * @throws UnknownLeaseException if the lease passed to this method
      *	       is not in the set of managed leases
      * @throws RemoteException typically, this exception occurs when
      *         there is a communication failure between the client and
      *         the server. When this exception does occur, the lease may
      *         or may not have been successfully cancelled, (but the
      *         lease is guaranteed to have been removed from the managed
      *         set).
      * @see Lease#cancel
      * @see UnknownLeaseException
      */
     public void cancel(Lease lease)
 	throws UnknownLeaseException, RemoteException
     {
 	remove(lease);
 	lease.cancel();
     }
     
     public void close(){
         leaseRenewalExecutor.shutdown();
     }
 
     /**
      * Removes a given lease from the managed set of leases; but does
      * not cancel the given lease.
      *
      * @param lease the lease to remove from the managed set
      * @throws UnknownLeaseException if the lease passed to this method
      *         is not in the set of managed leases
      * @see UnknownLeaseException
      */
     public synchronized void remove(Lease lease) throws UnknownLeaseException {
 	Entry e = findEntry(lease);
 	if (!removeLeaseInRenew(e))
 	    leases.remove(e);
 	calcActualRenews();
 	logger.log(Level.FINE, "Removed lease {0}", lease);
     }
 
     /**
      * Removes all leases from the managed set of leases. This method
      * does not request the cancellation of the removed leases.
      */
     public synchronized void clear() {
 	leases.clear();
 	leaseInRenew.clear();
 	calcActualRenews();
 	logger.log(Level.FINE, "Removed all leases");
     }
 
     /** Calculate the actual renew times, and poke/restart the queuer */
     private void calcActualRenews() {
 	calcActualRenews(System.currentTimeMillis());
     }
 
     /** Calculate the actual renew times, and poke/restart the queuer */
     private void calcActualRenews(long now) {
 	/*
 	 * Subtract one to account for the queuer thread, which should not be
 	 * counted.
 	 */
 	int maxThreads = leaseRenewalExecutor instanceof ThreadPoolExecutor ? 
             ((ThreadPoolExecutor)leaseRenewalExecutor).getMaximumPoolSize() - 1 
                 : 10;
 	if (calcList == null) {
 	    calcList = new ArrayList(maxThreads);
 	}
 	for (Iterator iter = leases.values().iterator(); iter.hasNext(); ) {
 	    Entry e = (Entry) iter.next();
 
 	    // Start by assuming we can renew the lease when we want
 	    e.actualRenew = e.renew;
 
 	    if (e.renewalsDone()) {
 		/*
 		 * The lease's actual expiration is >= desired
 		 * expiration, drop the lease if the desired expiration
 		 * has been reached and we don't have to tell anyone
 		 * about it
 		 */
 		if (now >= e.expiration && 
 		    e.desiredExpirationListener() == null) 
 		{
 		    logExpiration(e);
 		    iter.remove();
 		}
 
 		/*
 		 * Even if we have to send an event we assume that it
 		 * won't consume a slot in our schedule
 		 */
 		continue; 
 	    }
 
 	    if (e.endTime <= now && e.listener == null) {
 		// Lease has expired and no listener, just remove it.
 		logExpiration(e);
 		iter.remove();
 		continue;
 	    }
 
 	    /*
 	     * Make sure there aren't too many lease renewal threads
 	     * operating at the same time.
 	     */
 	    if (!canBatch(e)) {
 		/*
 		 * Find all renewals that start before we expect ours to
 		 * be done.
 		 */
 		for (Iterator listIter = calcList.iterator();
 		     listIter.hasNext(); )
 		{
 		    if (e.renew >=
 			((Entry) listIter.next()).actualRenew - renewalRTT)
 		    {
 			/*
 			 * This renewal starts after we expect ours to
 			 * be done.
 			 */
 			break;
 		    }
 		    listIter.remove();
 		}
 		if (calcList.size() == maxThreads) {
 		    /*
 		     * Too many renewals.  Move our actual renewal time
 		     * earlier so we'll probably be done before the last
 		     * one needs to start.  Remove that one, since it
 		     * won't overlap any earlier renewals.
 		     */
 		    Entry e1 = (Entry) calcList.remove(0);
 		    e.actualRenew = e1.actualRenew - renewalRTT;
 		}
 		calcList.add(e);
 	    }
 	}
 	calcList.clear();
 	long newWakeup = wakeupTime();
 	if (queuer == null) {
 	    if (newWakeup < Long.MAX_VALUE) {
 		queuer = new QueuerTask(newWakeup);
 		leaseRenewalExecutor.execute(queuer);
 	    }
 	} else if (newWakeup < queuer.wakeup ||
 		   (newWakeup == Long.MAX_VALUE && leaseInRenew.isEmpty()))
 	{
 	    notifyAll();
 	}
     }
 
     /**
      * Return true if e can be batched with another entry that expires
      * between e.renew - renewBatchTimeWindow and e.renew.
      */
     private boolean canBatch(Entry e) {
 	Iterator iter = leases.tailMap(e).values().iterator();
 	iter.next(); // skip e itself
 	while (iter.hasNext()) {
 	    Entry be = (Entry) iter.next();
 	    if (e.renew - be.renew > renewBatchTimeWindow)
 		break;
 	    if (e.canBatch(be))
 		return true;
 	}
 	return false;
     }
 
     /**
      * Find a lease entry, throw exception if not found or expired
      * normally
      */
     private Entry findEntry(Lease lease) throws UnknownLeaseException {
 	Entry e = findEntryDo(lease);
 	if (e != null &&
 	    (e.renew < e.endTime || System.currentTimeMillis() < e.endTime))
 	{
 	    return e;
 	}
 	throw new UnknownLeaseException();
     }
 
     /** Find a lease entry, or null */
     private Entry findEntryDo(Lease lease) {
 	Entry e = findLeaseFromIterator(leases.values().iterator(), lease);
 	if (e == null)
 	    e = findLeaseFromIterator(leaseInRenew.iterator(), lease);
 	return e;
     }
 
     /** Find a lease entry, or null */
     private static Entry findLeaseFromIterator(Iterator iter, Lease lease) {
 	while (iter.hasNext()) {
 	    Entry e = (Entry) iter.next();
 	    if (e.lease.equals(lease))
 		return e;
 	}
 	return null;
     }
 
     /** Notify the listener for each lease */
     private void tell(List bad) {
 	for (Iterator iter = bad.iterator(); iter.hasNext(); ) {
 	    Entry e = (Entry) iter.next();
 	    if (e.renewalsDone()) {
 		final DesiredExpirationListener del = 
 		    e.desiredExpirationListener();
 		if (del != null) {
 		    del.expirationReached(new LeaseRenewalEvent(this, e.lease,
 		        e.expiration, null));
 		}
 		continue; 
 	    }
 	    e.listener.notify(new LeaseRenewalEvent(this, e.lease,
 						    e.expiration, e.ex));
 	}
     }
 
     /**
      * Logs a lease expiration, distinguishing between expected
      * and premature expirations.
      *
      * @param e the <code>Entry</code> holding the lease
      */
     private void logExpiration(Entry e) {
 	if (e.renewalsDone()) {
 	    logger.log(Level.FINE,
 		       "Reached desired expiration for lease {0}",
 		       e.lease);
 	} else {
 	    logger.log(Levels.FAILED,
                "Lease '{'0'}' expired before reaching desired expiration of {0}",
                e.expiration);
 	}
     }
 		
     /**
      * Logs a throw. Use this method to log a throw when the log message needs
      * parameters.
      *
      * @param level the log level
      * @param sourceMethod name of the method where throw occurred
      * @param msg log message
      * @param params log message parameters
      * @param e exception thrown
      */
     private static void logThrow(Level level,
 				 String sourceMethod,
 				 String msg,
 				 Object[] params,
 				 Throwable e)
     {
 	LogRecord r = new LogRecord(level, msg);
 	r.setLoggerName(logger.getName());
 	r.setSourceClassName(LeaseRenewalManager.class.getName());
 	r.setSourceMethodName(sourceMethod);
 	r.setParameters(params);
 	r.setThrown(e);
 	logger.log(r);
     }
 
     /** Renew all of the leases (if multiple, all can be batched) */
     private void renewAll(List bList, long now) {
         Map lmeMap = null;
 	Throwable t = null;
 	List bad = null;
 
 	try {
 	    if (bList.size() == 1) {
 		Entry e = (Entry) bList.get(0);
 		logger.log(Level.FINE, "Renewing lease {0}", e.lease);
 		e.lease.renew(e.getRenewDuration(now));
 	    } else {
 		LeaseMap batchLeaseMap = createBatchLeaseMap(bList, now);
 		logger.log(Level.FINE, "Renewing leases {0}", batchLeaseMap);
 		batchLeaseMap.renewAll();
 	    }
 	} catch (LeaseMapException ex) {
 	    lmeMap = ex.exceptionMap;
 	    bad = new ArrayList(lmeMap.size());
 	} catch (Throwable ex) {
 	    t = ex;
 	    bad = new ArrayList(bList.size());  // They may all be bad
 	}
 
 	/*
 	 * For each lease we tried to renew determine the associated
 	 * exception (if any), and then ether add the lease back to
 	 * leases (if the renewal was successful), schedule a retry and
 	 * add back to leases (if the renewal was indefinite), or drop
 	 * the lease (by not adding it back to leases) and notify any
 	 * interested listeners.  In any event remove lease from the
 	 * list of leases being renewed.
 	 */
 
 	now = System.currentTimeMillis();
 	synchronized (this) {
 	    for (Iterator iter = bList.iterator(); iter.hasNext(); ) {
 		Entry e = (Entry) iter.next();
 
 		if (!removeLeaseInRenew(e))
 		    continue;
 
 		// Update the entries exception field 
 		if (bad == null) {
 		    e.ex = null;
 		} else {
 		    e.ex = (t != null) ? t : (Throwable) lmeMap.get(e.lease);
 		}
 
 		if (e.ex == null) {
 		    // No problems just put back in list
 		    insertEntry(e, now);
 		    continue;
 		} 
 
 		/*
 		 * Some sort of problem.  If definite don't put back
 		 * into leases and setup to notify the appropriate
 		 * listener, if indefinite schedule for a retry and put
 		 * back into leases
 		 */
 		final int cat = ThrowableConstants.retryable(e.ex);
 		if (cat == ThrowableConstants.INDEFINITE) {
 		    e.delayRenew();
 		    leases.put(e, e);
 		    if (logger.isLoggable(Levels.HANDLED)) {
 			logThrow(
 			    Levels.HANDLED, "renewAll",
 			    "Indefinite exception while renewing lease {0}",
 			    new Object[] { e.lease }, e.ex);
 		    }
 		} else {
 		    if (logger.isLoggable(Levels.FAILED)) {
 			logThrow(Levels.FAILED, "renewAll",
 				 "Lease renewal failed for lease {0}",
 				 new Object[] { e.lease }, e.ex);
 		    }
 		    if (e.listener != null) { 
 			/*
 			 * Note: For us ThrowableConstants.UNCATEGORIZED ==
 			 * definite
 			 */
 			bad.add(e);
 		    }	
 		}	
 	    }
 	    calcActualRenews(now);
 	}
 
 	if (bad != null)
 	    tell(bad);	
     }
 
     /** Create a LeaseMap for batch renewal */
     private static LeaseMap createBatchLeaseMap(List bList, long now) {
 	Iterator iter = bList.iterator();
 	Entry e = (Entry) iter.next();
 	LeaseMap batchLeaseMap =
 	    e.lease.createLeaseMap(e.getRenewDuration(now));
 	if (e.lease instanceof RemoteMethodControl &&
 	    batchLeaseMap instanceof RemoteMethodControl)
 	{
 	    batchLeaseMap = (LeaseMap)
 		((RemoteMethodControl) batchLeaseMap).setConstraints(
 		    ConstrainableProxyUtil.translateConstraints(
 			((RemoteMethodControl) e.lease).getConstraints(),
 			leaseToLeaseMapMethods));
 	}
 	while (iter.hasNext()) {
 	    e = (Entry) iter.next();
 	    batchLeaseMap.put(e.lease, Long.valueOf(e.getRenewDuration(now)));
 	}
 	return batchLeaseMap;
     }
 
     /** Remove from leaseInRenew, return true if removed */
     private boolean removeLeaseInRenew(Entry e) {
 	int index = leaseInRenew.indexOf(e); // avoid iterator cons
 	if (index < 0)
 	    return false;
 	leaseInRenew.remove(index);
 	return true;
     }
 
     /** Return the soonest actual renewal time */
     private long wakeupTime() {
 	if (leases.isEmpty())
 	    return Long.MAX_VALUE;
 	return ((Entry) leases.lastKey()).actualRenew;
     }
 
     private class QueuerTask implements Runnable {
 
 	/** When to next wake up and queue a new renew task */
 	private long wakeup;
 
 	QueuerTask(long wakeup) {
 	    this.wakeup = wakeup;
 	}
 
 
         public void run() {
 	    synchronized (LeaseRenewalManager.this) {
 		try {
 		    while (true) {
 			wakeup = wakeupTime();
 			if (wakeup == Long.MAX_VALUE && leaseInRenew.isEmpty())
 			    break;
 			final long now = System.currentTimeMillis();
 			long delta = wakeup - now;
 			if (delta <= 0) {
 			    leaseRenewalExecutor.execute(new RenewTask(now));
 			} else {
 			    LeaseRenewalManager.this.wait(delta);
 			}
 		    }
 		} catch (InterruptedException ex) {
 		}
 		queuer = null;
 	    }
 	}
     }
 }