com.threerings.presents.data.TimeBaseObject Maven / Gradle / Ivy
//
// $Id$
//
// Narya library - tools for developing networked games
// Copyright (C) 2002-2012 Three Rings Design, Inc., All Rights Reserved
// http://code.google.com/p/narya/
//
// This library is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation; either version 2.1 of the License, or
// (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package com.threerings.presents.data;
import javax.annotation.Generated;
import com.threerings.presents.dobj.DObject;
/**
* Used to communicate time bases to clients so that more efficient delta
* times can be transmitted over the network. Two time stamps are
* maintained: even and odd. When the even time base is sufficiently old
* that our delta time container (usually a short or an int) will exceed
* its maximum value, we switch to the odd time base. The bouncing between
* two separate values prevents problems from arising when the base time
* is changed, yet values using the old base time might still be
* propagating through the system.
*
* Note that for sufficiently small delta time containers, stale
* values could still linger longer than the time required for two swaps
* (two byte delta stamps for example, must swap every 30 seconds).
*/
public class TimeBaseObject extends DObject
{
// AUTO-GENERATED: FIELDS START
/** The field name of the evenBase field. */
@Generated(value={"com.threerings.presents.tools.GenDObjectTask"})
public static final String EVEN_BASE = "evenBase";
/** The field name of the oddBase field. */
@Generated(value={"com.threerings.presents.tools.GenDObjectTask"})
public static final String ODD_BASE = "oddBase";
// AUTO-GENERATED: FIELDS END
/** The even time base, used to decode even delta times. */
public long evenBase;
/** The odd time base, used to decode odd delta times. */
public long oddBase;
/**
* Converts the supplied time stamp into a time delta (measured
* relative to the appropriate time base, even or odd) with maximum
* value of 2^15. (One bit must be used to indicate that it is an even
* or odd time stamp).
*/
public short toShortDelta (long timeStamp)
{
return (short)getDelta(timeStamp, Short.MAX_VALUE);
}
/**
* Converts the supplied time stamp into a time delta (measured
* relative to the appropriate time base, even or odd) with maximum
* value of 2^31. (One bit must be used to indicate that it is an even
* or odd time stamp).
*/
public int toIntDelta (long timeStamp)
{
return (int)getDelta(timeStamp, Integer.MAX_VALUE);
}
/**
* Converts the supplied delta time back to a wall time based on the
* base time in this time base object. Either an int or short delta
* can be passed to this method (the short will have been promoted to
* an int in the process but that will not mess up its encoded value).
*/
public long fromDelta (int delta)
{
boolean even = (delta > 0);
long time = even ? evenBase : oddBase;
if (even) {
time += delta;
} else {
time += (-1 - delta);
}
return time;
}
/**
* Obtains a delta with the specified maximum value, swapping from
* even to odd, if necessary.
*/
protected long getDelta (long timeStamp, long maxValue)
{
boolean even = (evenBase > oddBase);
long base = even ? evenBase : oddBase;
long delta = timeStamp - base;
// make sure this timestamp is not sufficiently old that we can't
// generate a delta time with it
if (delta < 0) {
String errmsg = "Time stamp too old for conversion to delta time";
throw new IllegalArgumentException(errmsg);
}
// see if it's time to swap
if (delta > maxValue) {
if (even) {
setOddBase(timeStamp);
} else {
setEvenBase(timeStamp);
}
delta = 0;
}
// if we're odd, we need to mark the value as such
if (!even) {
delta = (-1 - delta);
}
return delta;
}
// AUTO-GENERATED: METHODS START
/**
* Requests that the evenBase field be set to the
* specified value. The local value will be updated immediately and an
* event will be propagated through the system to notify all listeners
* that the attribute did change. Proxied copies of this object (on
* clients) will apply the value change when they received the
* attribute changed notification.
*/
@Generated(value={"com.threerings.presents.tools.GenDObjectTask"})
public void setEvenBase (long value)
{
long ovalue = this.evenBase;
requestAttributeChange(
EVEN_BASE, Long.valueOf(value), Long.valueOf(ovalue));
this.evenBase = value;
}
/**
* Requests that the oddBase field be set to the
* specified value. The local value will be updated immediately and an
* event will be propagated through the system to notify all listeners
* that the attribute did change. Proxied copies of this object (on
* clients) will apply the value change when they received the
* attribute changed notification.
*/
@Generated(value={"com.threerings.presents.tools.GenDObjectTask"})
public void setOddBase (long value)
{
long ovalue = this.oddBase;
requestAttributeChange(
ODD_BASE, Long.valueOf(value), Long.valueOf(ovalue));
this.oddBase = value;
}
// AUTO-GENERATED: METHODS END
}