src.gov.nasa.worldwind.cache.ShapeDataCache Maven / Gradle / Ivy
/*
* Copyright (C) 2012 United States Government as represented by the Administrator of the
* National Aeronautics and Space Administration.
* All Rights Reserved.
*/
package gov.nasa.worldwind.cache;
import gov.nasa.worldwind.avlist.AVListImpl;
import gov.nasa.worldwind.geom.Extent;
import gov.nasa.worldwind.globes.*;
import gov.nasa.worldwind.render.DrawContext;
import gov.nasa.worldwind.util.TimedExpirySupport;
import java.util.*;
/**
* Provides a mechanism to manage globe-specific representations of shapes. Typically used to manage per-globe state
* when the application associates the same shape with multiple {@link gov.nasa.worldwind.WorldWindow}s.
*
* This cache limits the amount of time an entry remains in the cache unused. The maximum unused time may be specified.
* Entries unused within the specified duration are removed from the cache each time {@link
* #getEntry(gov.nasa.worldwind.globes.Globe)} is called.
*
* @author tag
* @version $Id: ShapeDataCache.java 1171 2013-02-11 21:45:02Z dcollins $
*/
public class ShapeDataCache implements Iterable
{
public static class ShapeDataCacheEntry extends AVListImpl
{
/** Determines whether the cache entry has expired. */
protected TimedExpirySupport timer;
/** Indicates the last time, in milliseconds, the entry was requested or added. */
protected long lastUsed = System.currentTimeMillis();
/** Identifies the associated globe's state at the time the entry was created. */
protected GlobeStateKey globeStateKey;
/** Indicates the vertical exaggeration in effect when the entry was cached. */
protected double verticalExaggeration;
/** Indicates the associated shape's extent, in model coordinates relative to the associated globe. */
protected Extent extent;
/** Indicates the eye distance of the shape in the globe-relative coordinate system. */
protected double eyeDistance;
/**
* Constructs an entry using the globe and vertical exaggeration of a specified draw context.
*
* @param dc the draw context. Must contain a globe.
* @param minExpiryTime the minimum expiration duration, in milliseconds.
* @param maxExpiryTime the maximum expiration duration, in milliseconds.
*
* @throws IllegalArgumentException if the draw context is null.
*/
public ShapeDataCacheEntry(DrawContext dc, long minExpiryTime, long maxExpiryTime)
{
this.timer = new TimedExpirySupport(Math.max(minExpiryTime, 0), Math.max(maxExpiryTime, 0));
this.globeStateKey = dc != null ? dc.getGlobe().getGlobeStateKey(dc) : null;
this.verticalExaggeration = dc != null ? dc.getVerticalExaggeration() : 1d;
}
/**
* Indicates whether this shape data's globe state and vertical exaggeration are the same as that in the current
* draw context.
*
* @param dc the current draw context.
*
* @return true if the shape is valid, otherwise false.
*/
public boolean isValid(DrawContext dc)
{
return this.verticalExaggeration == dc.getVerticalExaggeration()
&& (this.globeStateKey != null && globeStateKey.equals(dc.getGlobe().getGlobeStateKey(dc)));
}
/**
* Indicates whether this entry has expired.
*
* @param dc the current draw context.
*
* @return true if the entry has expired, otherwise false.
*/
public boolean isExpired(DrawContext dc)
{
return dc != null ? timer.isExpired(dc) : timer.isExpired(System.currentTimeMillis());
}
/**
* Sets this entry's expiration state.
*
* @param isExpired true to expire the entry, otherwise false.
*/
public void setExpired(boolean isExpired)
{
this.timer.setExpired(isExpired);
}
/**
* Resets the timer to the current time.
*
* @param dc the current draw context.
*
* @throws IllegalArgumentException if the draw context is null.
*/
public void restartTimer(DrawContext dc)
{
this.timer.restart(dc);
}
/**
* Indicates this entry's eye distance.
*
* @return this entry's eye distance, in meters.
*/
public double getEyeDistance()
{
return eyeDistance;
}
/**
* Specifies this entry's eye distance.
*
* @param eyeDistance the eye distance, in meters.
*/
public void setEyeDistance(double eyeDistance)
{
this.eyeDistance = eyeDistance;
}
/**
* Returns this entry's extent.
*
* @return this entry's extent.
*/
public Extent getExtent()
{
return this.extent;
}
/**
* Specifies this entry's extent.
*
* @param extent the new extent. May be null.
*/
public void setExtent(Extent extent)
{
this.extent = extent;
}
/**
* Returns this entry's expiration timer.
*
* @return this entry's expiration timer.
*/
public TimedExpirySupport getTimer()
{
return timer;
}
/**
* Specifies this entry's expiration timer.
*
* @param timer the new expiration timer.
*/
public void setTimer(TimedExpirySupport timer)
{
this.timer = timer;
}
/**
* Indicates this entry's globe state key, captured when this entry was constructed or when explicitly set.
*
* @return this entry's globe state key.
*/
public GlobeStateKey getGlobeStateKey()
{
return globeStateKey;
}
/**
* Specifies this entry's globe state key.
*
* @param globeStateKey the new globe state key.
*/
public void setGlobeStateKey(GlobeStateKey globeStateKey)
{
this.globeStateKey = globeStateKey;
}
/**
* Indicates this entry's vertical exaggeration, captured when the entry was constructed or when explicitly
* set.
*
* @return this entry's vertical exaggeration.
*/
public double getVerticalExaggeration()
{
return verticalExaggeration;
}
public void setVerticalExaggeration(double verticalExaggeration)
{
this.verticalExaggeration = verticalExaggeration;
}
}
// usually only 1, but few at most
/** This cache's map of entries. Typically one entry per open window. */
protected HashMap entries = new HashMap(1);
/** The maximum number of milliseconds an entry may remain in the cache without being used. */
protected long maxTimeSinceLastUsed;
/**
* Construct a cache with a specified entry lifetime.
*
* @param maxTimeSinceLastUsed the maximum number of milliseconds an entry may remain in the cache without being
* used.
*/
public ShapeDataCache(long maxTimeSinceLastUsed)
{
this.maxTimeSinceLastUsed = maxTimeSinceLastUsed;
}
public Iterator iterator()
{
return this.entries.values().iterator();
}
/**
* Adds a specified entry to the cache or replaces an entry associated with the same globe.
*
* @param entry the entry to add. If null, the cache remains unchanged.
*/
public void addEntry(ShapeDataCacheEntry entry)
{
if (entry == null)
return;
this.entries.put(entry.globeStateKey.getGlobe(), entry);
entry.lastUsed = System.currentTimeMillis();
}
/**
* Retrieves a specified entry from the cache.
*
* Note: Each time this method is called the cache is cleared of dead entries, as defined by their last-used time
* relative to this cache's maximum unused time.
*
* @param globe the globe the entry is associated with.
*
* @return the entry if it exists, otherwise null.
*/
public ShapeDataCacheEntry getEntry(Globe globe)
{
long now = System.currentTimeMillis();
// this.removeDeadEntries(now);
if (globe == null)
return null;
ShapeDataCacheEntry entry = this.entries.get(globe);
if (entry != null)
entry.lastUsed = now;
return entry;
}
/**
* Set all entries in this cache to a specified expiration state.
*
* @param isExpired the expiration state.
*/
public void setAllExpired(boolean isExpired)
{
for (ShapeDataCacheEntry entry : this.entries.values())
{
entry.setExpired(isExpired);
}
}
/** Set to null the extent field of all entries in this cache. */
public void clearExtents()
{
for (ShapeDataCacheEntry entry : this.entries.values())
{
entry.setExtent(null);
}
}
/** Remove all entries from this cache. */
public void removeAllEntries()
{
this.entries.clear();
}
//
// /**
// * Remove entries from the cache that have not been used within this cache's maximum unused time.
// *
// * @param now the time to compare with entries' last-used time.
// */
// protected void removeDeadEntries(long now)
// {
// List deadEntries = new ArrayList();
//
// for (Map.Entry mapEntry : this.entries.entrySet())
// {
// if (mapEntry.getValue().lastUsed + this.maxTimeSinceLastUsed < now)
// deadEntries.add(mapEntry.getKey());
// }
//
// for (Globe key : deadEntries)
// {
// this.entries.remove(key);
// }
// }
}