core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/util/OverflowingLRUCache.java - cdt/org.eclipse.cdt - Git at Google

 package org.eclipse.cdt.internal.core.util;

 /**********************************************************************
  * Copyright (c) 2002,2003 Rational Software Corporation and others.
  * All rights reserved.   This program and the accompanying materials
  * are made available under the terms of the Common Public License v0.5
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/cpl-v05.html
  *
  * Contributors:
  * Rational Software - Initial API and implementation
 ***********************************************************************/

 import java.util.Enumeration;
 import java.util.Iterator;

 import org.eclipse.cdt.internal.core.util.LRUCache;

 /**
  *	The <code>OverflowingLRUCache</code> is an LRUCache which attempts
  *	to maintain a size equal or less than its <code>fSpaceLimit</code>
  *	by removing the least recently used elements.
  *
  *	<p>The cache will remove elements which successfully close and all
  *	elements which are explicitly removed.
  *
  *	<p>If the cache cannot remove enough old elements to add new elements
  *	it will grow beyond <code>fSpaceLimit</code>. Later, it will attempt to
  *	shink back to the maximum space limit.
  *
  *	The method <code>close</code> should attempt to close the element.  If
  *	the element is successfully closed it will return true and the element will
  *	be removed from the cache.  Otherwise the element will remain in the cache.
  *
  *	<p>The cache implicitly attempts shrinks on calls to <code>put</code>and
  *	<code>setSpaceLimit</code>.  Explicitly calling the <code>shrink</code> method
  *	will also cause the cache to attempt to shrink.
  *
  *	<p>The cache calculates the used space of all elements which implement
  *	<code>ILRUCacheable</code>.  All other elements are assumed to be of size one.
  *
  *	<p>Use the <code>#peek(Object)</code> and <code>#disableTimestamps()</code> method to
  *	circumvent the timestamp feature of the cache.  This feature is intended to be used
  *	only when the <code>#close(LRUCacheEntry)</code> method causes changes to the cache.
  *	For example, if a parent closes its children when </code>#close(LRUCacheEntry)</code> is called,
  *	it should be careful not to change the LRU linked list.  It can be sure it is not causing
  *	problems by calling <code>#peek(Object)</code> instead of <code>#get(Object)</code> method.
  *
  *	@see LRUCache
  *
  * This class is similar to the JDT OverflowingLRUCache class.
  */
 public abstract class OverflowingLRUCache extends LRUCache {
 	/**
 	 * Indicates if the cache has been over filled and by how much.
 	 */
 	protected int fOverflow = 0;
 	/**
 	 *	Indicates whether or not timestamps should be updated
 	 */
 	protected boolean fTimestampsOn = true;
 	/**
 	 *	Indicates how much space should be reclaimed when the cache overflows.
 	 *	Inital load factor of one third.
 	 */
 	protected double fLoadFactor = 0.333;
 	/**
 	 * Creates a OverflowingLRUCache.
 	 * @param size Size limit of cache.
 	 */
 	public OverflowingLRUCache(int size) {
 		this(size, 0);
 	}
 	/**
 	 * Creates a OverflowingLRUCache.
 	 * @param size Size limit of cache.
 	 * @param overflow Size of the overflow.
 	 */
 	public OverflowingLRUCache(int size, int overflow) {
 		super(size);
 		fOverflow = overflow;
 	}
 	/**
 	 * Returns a new cache containing the same contents.
 	 *
 	 * @return New copy of this object.
 	 */
 	public Object clone() {

 		OverflowingLRUCache newCache = (OverflowingLRUCache)newInstance(fSpaceLimit, fOverflow);
 		LRUCacheEntry qEntry;

 		/* Preserve order of entries by copying from oldest to newest */
 		qEntry = this.fEntryQueueTail;
 		while (qEntry != null) {
 			newCache.privateAdd (qEntry._fKey, qEntry._fValue, qEntry._fSpace);
 			qEntry = qEntry._fPrevious;
 		}
 		return newCache;
 	}
 	/**
 	 * Returns true if the element is successfully closed and
 	 * removed from the cache, otherwise false.
 	 *
 	 * <p>NOTE: this triggers an external remove from the cache
 	 * by closing the obejct.
 	 *
 	 */
 	protected abstract boolean close(LRUCacheEntry entry);
 	/**
 	 *	Returns an enumerator of the values in the cache with the most
 	 *	recently used first.
 	 */
 	public Enumeration elements() {
 		if (fEntryQueue == null)
 			return new LRUCacheEnumerator(null);
 		LRUCacheEnumerator.LRUEnumeratorElement head =
 			new LRUCacheEnumerator.LRUEnumeratorElement(fEntryQueue._fValue);
 		LRUCacheEntry currentEntry = fEntryQueue._fNext;
 		LRUCacheEnumerator.LRUEnumeratorElement currentElement = head;
 		while(currentEntry != null) {
 			currentElement.fNext = new LRUCacheEnumerator.LRUEnumeratorElement(currentEntry._fValue);
 			currentElement = currentElement.fNext;

 			currentEntry = currentEntry._fNext;
 		}
 		return new LRUCacheEnumerator(head);
 	}
 	public double fillingRatio() {
 		return (fCurrentSpace + fOverflow) * 100.0 / fSpaceLimit;
 	}
 	/**
 	 * For internal testing only.
 	 * This method exposed only for testing purposes!
 	 *
 	 * @return Hashtable of entries
 	 */
 	public java.util.Hashtable getEntryTable() {
 		return fEntryTable;
 	}
 	/**
 	 * Returns the load factor for the cache.  The load factor determines how
 	 * much space is reclaimed when the cache exceeds its space limit.
 	 * @return double
 	 */
 	public double getLoadFactor() {
 		return fLoadFactor;
 	}
 	/**
 	 *	@return The space by which the cache has overflown.
 	 */
 	public int getOverflow() {
 		return fOverflow;
 	}
 	/**
 	 * Ensures there is the specified amount of free space in the receiver,
 	 * by removing old entries if necessary.  Returns true if the requested space was
 	 * made available, false otherwise.  May not be able to free enough space
 	 * since some elements cannot be removed until they are saved.
 	 *
 	 * @param space Amount of space to free up
 	 */
 	protected boolean makeSpace(int space) {

 		int limit = fSpaceLimit;
 		if (fOverflow == 0) {
 			/* if space is already available */
 			if (fCurrentSpace + space <= limit) {
 				return true;
 			}
 		}

 		/* Free up space by removing oldest entries */
 		int spaceNeeded = (int)((1 - fLoadFactor) * fSpaceLimit);
 		spaceNeeded = (spaceNeeded > space) ? spaceNeeded : space;
 		LRUCacheEntry entry = fEntryQueueTail;

 		while (fCurrentSpace + spaceNeeded > limit && entry != null) {
 			this.privateRemoveEntry(entry, false, false);
 			entry = entry._fPrevious;
 		}

 		/* check again, since we may have aquired enough space */
 		if (fCurrentSpace + space <= limit) {
 			fOverflow = 0;
 			return true;
 		}

 		/* update fOverflow */
 		fOverflow = fCurrentSpace + space - limit;
 		return false;
 	}
 	/**
 	 * Returns a new instance of the reciever.
 	 */
 	protected abstract LRUCache newInstance(int size, int overflow);
 	/**
 	 * Answers the value in the cache at the given key.
 	 * If the value is not in the cache, returns null
 	 *
 	 * This function does not modify timestamps.
 	 */
 	public Object peek(Object key) {

 		LRUCacheEntry entry = (LRUCacheEntry) fEntryTable.get(key);
 		if (entry == null) {
 			return null;
 		}
 		return entry._fValue;
 	}
 	/**
 	 * For testing purposes only
 	 */
 	public void printStats() {
 		int forwardListLength = 0;
 		LRUCacheEntry entry = fEntryQueue;
 		while(entry != null) {
 			forwardListLength++;
 			entry = entry._fNext;
 		}
 		System.out.println("Forward length: " + forwardListLength); //$NON-NLS-1$

 		int backwardListLength = 0;
 		entry = fEntryQueueTail;
 		while(entry != null) {
 			backwardListLength++;
 			entry = entry._fPrevious;
 		}
 		System.out.println("Backward length: " + backwardListLength); //$NON-NLS-1$

 		Enumeration keys = fEntryTable.keys();
 		class Temp {
 			public Class fClass;
 			public int fCount;
 			public Temp(Class aClass) {
 				fClass = aClass;
 				fCount = 1;
 			}
 			public String toString() {
 				return "Class: " + fClass + " has " + fCount + " entries."; //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-1$
 			}
 		}
 		java.util.HashMap h = new java.util.HashMap();
 		while(keys.hasMoreElements()) {
 			entry = (LRUCacheEntry)fEntryTable.get(keys.nextElement());
 			Class key = entry._fValue.getClass();
 			Temp t = (Temp)h.get(key);
 			if (t == null) {
 				h.put(key, new Temp(key));
 			} else {
 				t.fCount++;
 			}
 		}

 		for (Iterator iter = h.keySet().iterator(); iter.hasNext();){
 			System.out.println(h.get(iter.next()));
 		}
 	}
 	/**
 	 *	Removes the entry from the entry queue.
 	 *	Calls <code>privateRemoveEntry</code> with the external functionality enabled.
 	 *
 	 * @param shuffle indicates whether we are just shuffling the queue
 	 * (i.e., the entry table is left alone).
 	 */
 	protected void privateRemoveEntry (LRUCacheEntry entry, boolean shuffle) {
 		privateRemoveEntry(entry, shuffle, true);
 	}
 	/**
 	 *	Removes the entry from the entry queue.  If <i>external</i> is true, the entry is removed
 	 *	without checking if it can be removed.  It is assumed that the client has already closed
 	 *	the element it is trying to remove (or will close it promptly).
 	 *
 	 *	If <i>external</i> is false, and the entry could not be closed, it is not removed and the
 	 *	pointers are not changed.
 	 *
 	 *	@param shuffle indicates whether we are just shuffling the queue
 	 *	(i.e., the entry table is left alone).
 	 */
 	protected void privateRemoveEntry(LRUCacheEntry entry, boolean shuffle, boolean external) {

 		if (!shuffle) {
 			if (external) {
 				fEntryTable.remove(entry._fKey);
 				fCurrentSpace -= entry._fSpace;
 				privateNotifyDeletionFromCache(entry);
 			} else {
 				if (!close(entry)) return;
 				// buffer close will recursively call #privateRemoveEntry with external==true
 				// thus entry will already be removed if reaching this point.
 				if (fEntryTable.get(entry._fKey) == null){
 					return;
 				} else {
 					// basic removal
 					fEntryTable.remove(entry._fKey);
 					fCurrentSpace -= entry._fSpace;
 					privateNotifyDeletionFromCache(entry);
 				}
 			}
 		}
 		LRUCacheEntry previous = entry._fPrevious;
 		LRUCacheEntry next = entry._fNext;

 		/* if this was the first entry */
 		if (previous == null) {
 			fEntryQueue = next;
 		} else {
 			previous._fNext = next;
 		}
 		/* if this was the last entry */
 		if (next == null) {
 			fEntryQueueTail = previous;
 		} else {
 			next._fPrevious = previous;
 		}
 	}
 	/**
 	 * Sets the value in the cache at the given key. Returns the value.
 	 *
 	 * @param key Key of object to add.
 	 * @param value Value of object to add.
 	 * @return added value.
 	 */
 	public Object put(Object key, Object value) {
 		/* attempt to rid ourselves of the overflow, if there is any */
 		if (fOverflow > 0)
 			shrink();

 		/* Check whether there's an entry in the cache */
 		int newSpace = spaceFor (key, value);
 		LRUCacheEntry entry = (LRUCacheEntry) fEntryTable.get (key);

 		if (entry != null) {

 			/**
 			 * Replace the entry in the cache if it would not overflow
 			 * the cache.  Otherwise flush the entry and re-add it so as
 			 * to keep cache within budget
 			 */
 			int oldSpace = entry._fSpace;
 			int newTotal = fCurrentSpace - oldSpace + newSpace;
 			if (newTotal <= fSpaceLimit) {
 				updateTimestamp (entry);
 				entry._fValue = value;
 				entry._fSpace = newSpace;
 				fCurrentSpace = newTotal;
 				fOverflow = 0;
 				return value;
 			} else {
 				privateRemoveEntry (entry, false, false);
 			}
 		}

 		// attempt to make new space
 		makeSpace(newSpace);

 		// add without worring about space, it will
 		// be handled later in a makeSpace call
 		privateAdd (key, value, newSpace);

 		return value;
 	}
 	/**
 	 * Removes and returns the value in the cache for the given key.
 	 * If the key is not in the cache, returns null.
 	 *
 	 * @param key Key of object to remove from cache.
 	 * @return Value removed from cache.
 	 */
 	public Object remove(Object key) {
 		return removeKey(key);
 	}
 	/**
 	 * Sets the load factor for the cache.  The load factor determines how
 	 * much space is reclaimed when the cache exceeds its space limit.
 	 * @param newLoadFactor double
 	 * @throws IllegalArgumentException when the new load factor is not in (0.0, 1.0]
 	 */
 	public void setLoadFactor(double newLoadFactor) throws IllegalArgumentException {
 		if(newLoadFactor <= 1.0 && newLoadFactor > 0.0)
 			fLoadFactor = newLoadFactor;
 		else
 			throw new IllegalArgumentException("cache.invalidLoadFactor"); //$NON-NLS-1$
 	}
 	/**
 	 * Sets the maximum amount of space that the cache can store
 	 *
 	 * @param limit Number of units of cache space
 	 */
 	public void setSpaceLimit(int limit) {
 		if (limit < fSpaceLimit) {
 			makeSpace(fSpaceLimit - limit);
 		}
 		fSpaceLimit = limit;
 	}
 	/**
 	 * Attempts to shrink the cache if it has overflown.
 	 * Returns true if the cache shrinks to less than or equal to <code>fSpaceLimit</code>.
 	 */
 	public boolean shrink() {
 		if (fOverflow > 0)
 			return makeSpace(0);
 		return true;
 	}
 	/**
 	 * Returns a String that represents the value of this object.  This method
 	 * is for debugging purposes only.
 	 */
 	public String toString() {
 		return
 			"OverflowingLRUCache " + this.fillingRatio() + "% full\n" + //$NON-NLS-1$ //$NON-NLS-2$
 			this.toStringContents();
 	}
 	/**
 	 * Updates the timestamp for the given entry, ensuring that the queue is
 	 * kept in correct order.  The entry must exist.
 	 *
 	 * <p>This method will do nothing if timestamps have been disabled.
 	 */
 	protected void updateTimestamp(LRUCacheEntry entry) {
 		if (fTimestampsOn) {
 			entry._fTimestamp = fTimestampCounter++;
 			if (fEntryQueue != entry) {
 				this.privateRemoveEntry(entry, true);
 				this.privateAddEntry(entry, true);
 			}
 		}
 	}
 }
	package org.eclipse.cdt.internal.core.util;

	/**********************************************************************
	* Copyright (c) 2002,2003 Rational Software Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Common Public License v0.5
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/cpl-v05.html
	*
	* Contributors:
	* Rational Software - Initial API and implementation
	***********************************************************************/

	import java.util.Enumeration;
	import java.util.Iterator;

	import org.eclipse.cdt.internal.core.util.LRUCache;

	/**
	* The <code>OverflowingLRUCache</code> is an LRUCache which attempts
	* to maintain a size equal or less than its <code>fSpaceLimit</code>
	* by removing the least recently used elements.
	*
	* <p>The cache will remove elements which successfully close and all
	* elements which are explicitly removed.
	*
	* <p>If the cache cannot remove enough old elements to add new elements
	* it will grow beyond <code>fSpaceLimit</code>. Later, it will attempt to
	* shink back to the maximum space limit.
	*
	* The method <code>close</code> should attempt to close the element. If
	* the element is successfully closed it will return true and the element will
	* be removed from the cache. Otherwise the element will remain in the cache.
	*
	* <p>The cache implicitly attempts shrinks on calls to <code>put</code>and
	* <code>setSpaceLimit</code>. Explicitly calling the <code>shrink</code> method
	* will also cause the cache to attempt to shrink.
	*
	* <p>The cache calculates the used space of all elements which implement
	* <code>ILRUCacheable</code>. All other elements are assumed to be of size one.
	*
	* <p>Use the <code>#peek(Object)</code> and <code>#disableTimestamps()</code> method to
	* circumvent the timestamp feature of the cache. This feature is intended to be used
	* only when the <code>#close(LRUCacheEntry)</code> method causes changes to the cache.
	* For example, if a parent closes its children when </code>#close(LRUCacheEntry)</code> is called,
	* it should be careful not to change the LRU linked list. It can be sure it is not causing
	* problems by calling <code>#peek(Object)</code> instead of <code>#get(Object)</code> method.
	*
	* @see LRUCache
	*
	* This class is similar to the JDT OverflowingLRUCache class.
	*/
	public abstract class OverflowingLRUCache extends LRUCache {
	/**
	* Indicates if the cache has been over filled and by how much.
	*/
	protected int fOverflow = 0;
	/**
	* Indicates whether or not timestamps should be updated
	*/
	protected boolean fTimestampsOn = true;
	/**
	* Indicates how much space should be reclaimed when the cache overflows.
	* Inital load factor of one third.
	*/
	protected double fLoadFactor = 0.333;
	/**
	* Creates a OverflowingLRUCache.
	* @param size Size limit of cache.
	*/
	public OverflowingLRUCache(int size) {
	this(size, 0);
	}
	/**
	* Creates a OverflowingLRUCache.
	* @param size Size limit of cache.
	* @param overflow Size of the overflow.
	*/
	public OverflowingLRUCache(int size, int overflow) {
	super(size);
	fOverflow = overflow;
	}
	/**
	* Returns a new cache containing the same contents.
	*
	* @return New copy of this object.
	*/
	public Object clone() {

	OverflowingLRUCache newCache = (OverflowingLRUCache)newInstance(fSpaceLimit, fOverflow);
	LRUCacheEntry qEntry;

	/* Preserve order of entries by copying from oldest to newest */
	qEntry = this.fEntryQueueTail;
	while (qEntry != null) {
	newCache.privateAdd (qEntry._fKey, qEntry._fValue, qEntry._fSpace);
	qEntry = qEntry._fPrevious;
	}
	return newCache;
	}
	/**
	* Returns true if the element is successfully closed and
	* removed from the cache, otherwise false.
	*
	* <p>NOTE: this triggers an external remove from the cache
	* by closing the obejct.
	*
	*/
	protected abstract boolean close(LRUCacheEntry entry);
	/**
	* Returns an enumerator of the values in the cache with the most
	* recently used first.
	*/
	public Enumeration elements() {
	if (fEntryQueue == null)
	return new LRUCacheEnumerator(null);
	LRUCacheEnumerator.LRUEnumeratorElement head =
	new LRUCacheEnumerator.LRUEnumeratorElement(fEntryQueue._fValue);
	LRUCacheEntry currentEntry = fEntryQueue._fNext;
	LRUCacheEnumerator.LRUEnumeratorElement currentElement = head;
	while(currentEntry != null) {
	currentElement.fNext = new LRUCacheEnumerator.LRUEnumeratorElement(currentEntry._fValue);
	currentElement = currentElement.fNext;

	currentEntry = currentEntry._fNext;
	}
	return new LRUCacheEnumerator(head);
	}
	public double fillingRatio() {
	return (fCurrentSpace + fOverflow) * 100.0 / fSpaceLimit;
	}
	/**
	* For internal testing only.
	* This method exposed only for testing purposes!
	*
	* @return Hashtable of entries
	*/
	public java.util.Hashtable getEntryTable() {
	return fEntryTable;
	}
	/**
	* Returns the load factor for the cache. The load factor determines how
	* much space is reclaimed when the cache exceeds its space limit.
	* @return double
	*/
	public double getLoadFactor() {
	return fLoadFactor;
	}
	/**
	* @return The space by which the cache has overflown.
	*/
	public int getOverflow() {
	return fOverflow;
	}
	/**
	* Ensures there is the specified amount of free space in the receiver,
	* by removing old entries if necessary. Returns true if the requested space was
	* made available, false otherwise. May not be able to free enough space
	* since some elements cannot be removed until they are saved.
	*
	* @param space Amount of space to free up
	*/
	protected boolean makeSpace(int space) {

	int limit = fSpaceLimit;
	if (fOverflow == 0) {
	/* if space is already available */
	if (fCurrentSpace + space <= limit) {
	return true;
	}
	}

	/* Free up space by removing oldest entries */
	int spaceNeeded = (int)((1 - fLoadFactor) * fSpaceLimit);
	spaceNeeded = (spaceNeeded > space) ? spaceNeeded : space;
	LRUCacheEntry entry = fEntryQueueTail;

	while (fCurrentSpace + spaceNeeded > limit && entry != null) {
	this.privateRemoveEntry(entry, false, false);
	entry = entry._fPrevious;
	}

	/* check again, since we may have aquired enough space */
	if (fCurrentSpace + space <= limit) {
	fOverflow = 0;
	return true;
	}

	/* update fOverflow */
	fOverflow = fCurrentSpace + space - limit;
	return false;
	}
	/**
	* Returns a new instance of the reciever.
	*/
	protected abstract LRUCache newInstance(int size, int overflow);
	/**
	* Answers the value in the cache at the given key.
	* If the value is not in the cache, returns null
	*
	* This function does not modify timestamps.
	*/
	public Object peek(Object key) {

	LRUCacheEntry entry = (LRUCacheEntry) fEntryTable.get(key);
	if (entry == null) {
	return null;
	}
	return entry._fValue;
	}
	/**
	* For testing purposes only
	*/
	public void printStats() {
	int forwardListLength = 0;
	LRUCacheEntry entry = fEntryQueue;
	while(entry != null) {
	forwardListLength++;
	entry = entry._fNext;
	}
	System.out.println("Forward length: " + forwardListLength); //$NON-NLS-1$

	int backwardListLength = 0;
	entry = fEntryQueueTail;
	while(entry != null) {
	backwardListLength++;
	entry = entry._fPrevious;
	}
	System.out.println("Backward length: " + backwardListLength); //$NON-NLS-1$

	Enumeration keys = fEntryTable.keys();
	class Temp {
	public Class fClass;
	public int fCount;
	public Temp(Class aClass) {
	fClass = aClass;
	fCount = 1;
	}
	public String toString() {
	return "Class: " + fClass + " has " + fCount + " entries."; //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-1$
	}
	}
	java.util.HashMap h = new java.util.HashMap();
	while(keys.hasMoreElements()) {
	entry = (LRUCacheEntry)fEntryTable.get(keys.nextElement());
	Class key = entry._fValue.getClass();
	Temp t = (Temp)h.get(key);
	if (t == null) {
	h.put(key, new Temp(key));
	} else {
	t.fCount++;
	}
	}

	for (Iterator iter = h.keySet().iterator(); iter.hasNext();){
	System.out.println(h.get(iter.next()));
	}
	}
	/**
	* Removes the entry from the entry queue.
	* Calls <code>privateRemoveEntry</code> with the external functionality enabled.
	*
	* @param shuffle indicates whether we are just shuffling the queue
	* (i.e., the entry table is left alone).
	*/
	protected void privateRemoveEntry (LRUCacheEntry entry, boolean shuffle) {
	privateRemoveEntry(entry, shuffle, true);
	}
	/**
	* Removes the entry from the entry queue. If <i>external</i> is true, the entry is removed
	* without checking if it can be removed. It is assumed that the client has already closed
	* the element it is trying to remove (or will close it promptly).
	*
	* If <i>external</i> is false, and the entry could not be closed, it is not removed and the
	* pointers are not changed.
	*
	* @param shuffle indicates whether we are just shuffling the queue
	* (i.e., the entry table is left alone).
	*/
	protected void privateRemoveEntry(LRUCacheEntry entry, boolean shuffle, boolean external) {

	if (!shuffle) {
	if (external) {
	fEntryTable.remove(entry._fKey);
	fCurrentSpace -= entry._fSpace;
	privateNotifyDeletionFromCache(entry);
	} else {
	if (!close(entry)) return;
	// buffer close will recursively call #privateRemoveEntry with external==true
	// thus entry will already be removed if reaching this point.
	if (fEntryTable.get(entry._fKey) == null){
	return;
	} else {
	// basic removal
	fEntryTable.remove(entry._fKey);
	fCurrentSpace -= entry._fSpace;
	privateNotifyDeletionFromCache(entry);
	}
	}
	}
	LRUCacheEntry previous = entry._fPrevious;
	LRUCacheEntry next = entry._fNext;

	/* if this was the first entry */
	if (previous == null) {
	fEntryQueue = next;
	} else {
	previous._fNext = next;
	}
	/* if this was the last entry */
	if (next == null) {
	fEntryQueueTail = previous;
	} else {
	next._fPrevious = previous;
	}
	}
	/**
	* Sets the value in the cache at the given key. Returns the value.
	*
	* @param key Key of object to add.
	* @param value Value of object to add.
	* @return added value.
	*/
	public Object put(Object key, Object value) {
	/* attempt to rid ourselves of the overflow, if there is any */
	if (fOverflow > 0)
	shrink();

	/* Check whether there's an entry in the cache */
	int newSpace = spaceFor (key, value);
	LRUCacheEntry entry = (LRUCacheEntry) fEntryTable.get (key);

	if (entry != null) {

	/**
	* Replace the entry in the cache if it would not overflow
	* the cache. Otherwise flush the entry and re-add it so as
	* to keep cache within budget
	*/
	int oldSpace = entry._fSpace;
	int newTotal = fCurrentSpace - oldSpace + newSpace;
	if (newTotal <= fSpaceLimit) {
	updateTimestamp (entry);
	entry._fValue = value;
	entry._fSpace = newSpace;
	fCurrentSpace = newTotal;
	fOverflow = 0;
	return value;
	} else {
	privateRemoveEntry (entry, false, false);
	}
	}

	// attempt to make new space
	makeSpace(newSpace);

	// add without worring about space, it will
	// be handled later in a makeSpace call
	privateAdd (key, value, newSpace);

	return value;
	}
	/**
	* Removes and returns the value in the cache for the given key.
	* If the key is not in the cache, returns null.
	*
	* @param key Key of object to remove from cache.
	* @return Value removed from cache.
	*/
	public Object remove(Object key) {
	return removeKey(key);
	}
	/**
	* Sets the load factor for the cache. The load factor determines how
	* much space is reclaimed when the cache exceeds its space limit.
	* @param newLoadFactor double
	* @throws IllegalArgumentException when the new load factor is not in (0.0, 1.0]
	*/
	public void setLoadFactor(double newLoadFactor) throws IllegalArgumentException {
	if(newLoadFactor <= 1.0 && newLoadFactor > 0.0)
	fLoadFactor = newLoadFactor;
	else
	throw new IllegalArgumentException("cache.invalidLoadFactor"); //$NON-NLS-1$
	}
	/**
	* Sets the maximum amount of space that the cache can store
	*
	* @param limit Number of units of cache space
	*/
	public void setSpaceLimit(int limit) {
	if (limit < fSpaceLimit) {
	makeSpace(fSpaceLimit - limit);
	}
	fSpaceLimit = limit;
	}
	/**
	* Attempts to shrink the cache if it has overflown.
	* Returns true if the cache shrinks to less than or equal to <code>fSpaceLimit</code>.
	*/
	public boolean shrink() {
	if (fOverflow > 0)
	return makeSpace(0);
	return true;
	}
	/**
	* Returns a String that represents the value of this object. This method
	* is for debugging purposes only.
	*/
	public String toString() {
	return
	"OverflowingLRUCache " + this.fillingRatio() + "% full\n" + //$NON-NLS-1$ //$NON-NLS-2$
	this.toStringContents();
	}
	/**
	* Updates the timestamp for the given entry, ensuring that the queue is
	* kept in correct order. The entry must exist.
	*
	* <p>This method will do nothing if timestamps have been disabled.
	*/
	protected void updateTimestamp(LRUCacheEntry entry) {
	if (fTimestampsOn) {
	entry._fTimestamp = fTimestampCounter++;
	if (fEntryQueue != entry) {
	this.privateRemoveEntry(entry, true);
	this.privateAddEntry(entry, true);
	}
	}
	}
	}