Indexer performance with long include search path, bug 225302.

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/index/IndexBasedCodeReaderFactory.java

@@ -35,17 +35,19 @@ import org.eclipse.cdt.core.parser.ICodeReaderCache;
 import org.eclipse.cdt.core.parser.ParserUtil;
 import org.eclipse.cdt.internal.core.parser.scanner.IIndexBasedCodeReaderFactory;
 import org.eclipse.cdt.internal.core.parser.scanner.IncludeFileContent;
+import org.eclipse.cdt.internal.core.parser.scanner.IncludeFileResolutionCache;
 import org.eclipse.cdt.internal.core.parser.scanner.IncludeFileContent.InclusionKind;
 import org.eclipse.cdt.internal.core.pdom.ASTFilePathResolver;
 import org.eclipse.cdt.internal.core.pdom.AbstractIndexerTask;
 import org.eclipse.cdt.internal.core.pdom.AbstractIndexerTask.FileContent;
 import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IAdaptable;
 
 /**
  * Code reader factory, that fakes code readers for header files already stored in the 
  * index.
  */
-public final class IndexBasedCodeReaderFactory implements IIndexBasedCodeReaderFactory {
+public final class IndexBasedCodeReaderFactory implements IIndexBasedCodeReaderFactory, IAdaptable {
 	private static final class NeedToParseException extends Exception {}
 
 	private final IIndex fIndex;
@@ -55,6 +57,7 @@ public final class IndexBasedCodeReaderFactory implements IIndexBasedCodeReaderF
 	private final ICodeReaderFactory fFallBackFactory;
 	private final ASTFilePathResolver fPathResolver;
 	private final AbstractIndexerTask fRelatedIndexerTask;
+	private final IncludeFileResolutionCache fIncludeFileResolutionCache;
 	
 	public IndexBasedCodeReaderFactory(IIndex index, ASTFilePathResolver pathResolver, int linkage, 
 			ICodeReaderFactory fallbackFactory) {
@@ -68,6 +71,7 @@ public final class IndexBasedCodeReaderFactory implements IIndexBasedCodeReaderF
 		fPathResolver= pathResolver;
 		fRelatedIndexerTask= relatedIndexerTask;
 		fLinkage= linkage;
+		fIncludeFileResolutionCache= new IncludeFileResolutionCache(1024);
 	}
 
 	public int getUniqueIdentifier() {
@@ -179,4 +183,12 @@ public final class IndexBasedCodeReaderFactory implements IIndexBasedCodeReaderF
 	public void setLinkage(int linkageID) {
 		fLinkage= linkageID;
 	}
+
+	@SuppressWarnings("unchecked")
+	public Object getAdapter(Class adapter) {
+		if (adapter.isInstance(fIncludeFileResolutionCache)) {
+			return fIncludeFileResolutionCache;
+		}
+		return null;
+	}
 }

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/CPreprocessor.java

@@ -45,6 +45,8 @@ import org.eclipse.cdt.core.parser.util.CharArrayIntMap;
 import org.eclipse.cdt.core.parser.util.CharArrayMap;
 import org.eclipse.cdt.core.parser.util.CharArrayUtils;
 import org.eclipse.cdt.internal.core.parser.scanner.ExpressionEvaluator.EvalException;
+import org.eclipse.cdt.internal.core.parser.scanner.IncludeFileResolutionCache.ISPKey;
+import org.eclipse.cdt.internal.core.parser.scanner.IncludeFileResolutionCache.LookupKey;
 import org.eclipse.cdt.internal.core.parser.scanner.Lexer.LexerOptions;
 import org.eclipse.cdt.internal.core.parser.scanner.MacroDefinitionParser.InvalidMacroDefinitionException;
 import org.eclipse.core.runtime.IAdaptable;
@@ -85,18 +87,18 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     private static final DynamicMacro __TIME__ = new TimeMacro("__TIME__".toCharArray()); //$NON-NLS-1$
     private static final DynamicMacro __LINE__ = new LineMacro("__LINE__".toCharArray()); //$NON-NLS-1$
 
-	private interface IIncludeFileTester {
-    	Object checkFile(String path, String fileName);
+	private interface IIncludeFileTester<T> {
+    	T checkFile(String path, String fileName);
     }
 
-    final private IIncludeFileTester createCodeReaderTester= new IIncludeFileTester() { 
-    	public Object checkFile(String path, String fileName) {
+    final private IIncludeFileTester<IncludeFileContent> createCodeReaderTester= new IIncludeFileTester<IncludeFileContent>() { 
+    	public IncludeFileContent checkFile(String path, String fileName) {
     		return createReader(path, fileName);
     	}
     };
     
-    final private IIncludeFileTester createPathTester= new IIncludeFileTester() { 
-    	public Object checkFile(String path, String fileName) {
+    final private IIncludeFileTester<String> createPathTester= new IIncludeFileTester<String>() { 
+    	public String checkFile(String path, String fileName) {
     		path= ScannerUtility.createReconciledPath(path, fileName);
     		if (new File(path).exists()) {
     			return path;
@@ -119,6 +121,9 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     final private String[] fIncludePaths;
     final private String[] fQuoteIncludePaths;
     private String[][] fPreIncludedFiles= null;
+	private final IncludeFileResolutionCache fIncludeResolutionCache;
+	private final ISPKey fIncludePathKey;
+	private final ISPKey fQuoteIncludePathKey;
 
     private int fContentAssistLimit= -1;
 	private boolean fHandledCompletion= false;
@@ -151,12 +156,16 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
     	fIncludePaths= info.getIncludePaths();
     	fQuoteIncludePaths= getQuoteIncludePath(info);
-    	
+
         fExpressionEvaluator= new ExpressionEvaluator();
         fMacroDefinitionParser= new MacroDefinitionParser();
         fMacroExpander= new MacroExpander(this, fMacroDictionary, fLocationMap, fLexOptions);
         fCodeReaderFactory= wrapReaderFactory(readerFactory);
 
+    	fIncludeResolutionCache= getIncludeResolutionCache(readerFactory);
+    	fIncludePathKey= fIncludeResolutionCache.getKey(fIncludePaths);
+    	fQuoteIncludePathKey= fIncludeResolutionCache.getKey(fQuoteIncludePaths);
+
         setupMacroDictionary(configuration, info, language);		
                 
         final String filePath= new String(reader.filename);
@@ -169,8 +178,18 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         	fPreIncludedFiles= new String[][] {einfo.getMacroFiles(), einfo.getIncludeFiles()};
         }
     }
-    
-    private IIndexBasedCodeReaderFactory wrapReaderFactory(final ICodeReaderFactory readerFactory) {
+        
+	private IncludeFileResolutionCache getIncludeResolutionCache(ICodeReaderFactory readerFactory) {
+		if (readerFactory instanceof IAdaptable) {
+			IncludeFileResolutionCache cache= (IncludeFileResolutionCache) ((IAdaptable) readerFactory).getAdapter(IncludeFileResolutionCache.class);
+			if (cache != null) {
+				return cache;
+			}
+		}
+		return new IncludeFileResolutionCache(1024);
+	}
+
+	private IIndexBasedCodeReaderFactory wrapReaderFactory(final ICodeReaderFactory readerFactory) {
     	if (readerFactory instanceof IIndexBasedCodeReaderFactory) {
     		return (IIndexBasedCodeReaderFactory) readerFactory;
     	}
@@ -301,7 +320,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		fCurrentContext= new ScannerContext(ctx, fCurrentContext, new Lexer(buffer, fLexOptions, this, this));
     		ScannerContext preCtx= fCurrentContext;
     		try {
-				while(internalFetchToken(true, false, true, preCtx).getType() != IToken.tEND_OF_INPUT) {
+				while(internalFetchToken(true, false, false, true, preCtx).getType() != IToken.tEND_OF_INPUT) {
 				// just eat the tokens
 				}
             	final ILocationCtx locationCtx = fCurrentContext.getLocationCtx();
@@ -385,7 +404,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	}
     	
     	try {
-			t= internalFetchToken(true, false, true, fRootContext);
+			t= internalFetchToken(true, false, false, true, fRootContext);
 		} catch (OffsetLimitReachedException e) {
 			fHandledCompletion= true;
 			throw e;
@@ -514,7 +533,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	buf.append(image, start, image.length-start-1);
 	}
 
-	Token internalFetchToken(final boolean expandMacros, final boolean stopAtNewline, 
+	Token internalFetchToken(final boolean expandMacros, final boolean isPPCondition, final boolean stopAtNewline, 
 			final boolean checkNumbers, final ScannerContext uptoEndOfCtx) throws OffsetLimitReachedException {
         Token ppToken= fCurrentContext.currentLexerToken();
         while(true) {
@@ -563,7 +582,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         		fCurrentContext.nextPPToken(); // consume the identifier
         		if (expandMacros) {
         			final Lexer lexer= fCurrentContext.getLexer();
-        			if (lexer != null && expandMacro(ppToken, lexer, stopAtNewline)) {
+        			if (lexer != null && expandMacro(ppToken, lexer, stopAtNewline, isPPCondition)) {
         				ppToken= fCurrentContext.currentLexerToken();
         				continue;
         			}
@@ -718,12 +737,12 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 
     private IncludeFileContent findInclusion(final String filename, final boolean quoteInclude, 
     		final boolean includeNext, final File currentDir) {
-    	return (IncludeFileContent) findInclusion(filename, quoteInclude, includeNext, currentDir, createCodeReaderTester);
+    	return findInclusion(filename, quoteInclude, includeNext, currentDir, createCodeReaderTester);
     }
 
-    private Object findInclusion(final String filename, final boolean quoteInclude, 
-    		final boolean includeNext, final File currentDirectory, final IIncludeFileTester tester) {
-        Object reader = null;
+    private <T> T findInclusion(final String filename, final boolean quoteInclude, 
+    		final boolean includeNext, final File currentDirectory, final IIncludeFileTester<T> tester) {
+        T reader = null;
 		// filename is an absolute path or it is a Linux absolute path on a windows machine
 		if (new File(filename).isAbsolute() || filename.startsWith("/")) {  //$NON-NLS-1$
 		    return tester.checkFile( EMPTY_STRING, filename );
@@ -740,18 +759,46 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
         
         // if we're not include_next, then we are looking for the first occurrence of 
         // the file, otherwise, we ignore all the paths before the current directory
-        String[] includePathsToUse = quoteInclude ? fQuoteIncludePaths : fIncludePaths;
-        if (includePathsToUse != null ) {
-            int startpos = 0;
+        String[] isp;
+        ISPKey ispKey;
+        if (quoteInclude) {
+        	isp= fQuoteIncludePaths;
+        	ispKey= fQuoteIncludePathKey;
+        }
+        else {
+        	isp= fIncludePaths;
+        	ispKey= fIncludePathKey;
+        }
+        
+        if (isp != null ) {
             if (includeNext && currentDirectory != null) {
-                startpos = findIncludePos(includePathsToUse, currentDirectory) + 1;
+                final int startpos = findIncludePos(isp, currentDirectory) + 1;
+                for (int i= startpos; i < isp.length; ++i) {
+                    reader= tester.checkFile(isp[i], filename);
+                    if (reader != null) {
+                    	return reader;
+                    }
+                }
+                return null;
             }
-            for (int i = startpos; i < includePathsToUse.length; ++i) {
-                reader = tester.checkFile(includePathsToUse[i], filename);
+
+            final LookupKey lookupKey= fIncludeResolutionCache.getKey(ispKey, filename.toCharArray());
+            Integer offset= fIncludeResolutionCache.getCachedPathOffset(lookupKey);
+        	if (offset != null) {
+        		if (offset < 0) {
+        			return null;
+        		}
+        		return tester.checkFile(isp[offset], filename);
+        	}
+
+        	for (int i= 0; i < isp.length; ++i) {
+                reader = tester.checkFile(isp[i], filename);
                 if (reader != null) {
+                	fIncludeResolutionCache.putCachedPathOffset(lookupKey, i);
                 	return reader;
                 }
             }
+        	fIncludeResolutionCache.putCachedPathOffset(lookupKey, -1);
         }
         return null;
     }
@@ -1000,7 +1047,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 		if (!active) {
 			// test if the include is inactive just because it was included before (bug 167100)
 			final File currentDir= userInclude || include_next ? new File(String.valueOf(getCurrentFilename())).getParentFile() : null;
-			final String resolved= (String) findInclusion(new String(headerName), userInclude, include_next, currentDir, createPathTester);
+			final String resolved= findInclusion(new String(headerName), userInclude, include_next, currentDir, createPathTester);
 			if (resolved != null && fCodeReaderFactory.hasFileBeenIncludedInCurrentTranslationUnit(resolved)) {
 				path= resolved;
 			}
@@ -1185,7 +1232,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     	final ScannerContext scannerCtx= fCurrentContext;
     	boolean expandMacros= true;
     	loop: while(true) {
-    		Token t= internalFetchToken(expandMacros, true, false, scannerCtx);
+    		Token t= internalFetchToken(expandMacros, isCondition, true, false, scannerCtx);
     		switch(t.getType()) {
     		case IToken.tEND_OF_INPUT:
     		case IToken.tCOMPLETION:
@@ -1340,8 +1387,10 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
 	 * @param identifier the token where macro expansion may occur.
 	 * @param lexer the input for the expansion.
 	 * @param stopAtNewline whether or not tokens to be read are limited to the current line. 
+	 * @param isPPCondition whether the expansion is inside of a preprocessor condition. This
+	 * implies a specific handling for the defined token.
 	 */
-	private boolean expandMacro(final Token identifier, Lexer lexer, boolean stopAtNewline) throws OffsetLimitReachedException {
+	private boolean expandMacro(final Token identifier, Lexer lexer, boolean stopAtNewline, final boolean isPPCondition) throws OffsetLimitReachedException {
 		final char[] name= identifier.getCharImage();
         PreprocessorMacro macro= fMacroDictionary.get(name);
         if (macro == null) {
@@ -1360,7 +1409,7 @@ public class CPreprocessor implements ILexerLog, IScanner, IAdaptable {
     		}
         }
         final boolean contentAssist = fContentAssistLimit>=0 && fCurrentContext == fRootContext;
-        TokenList replacement= fMacroExpander.expand(lexer, stopAtNewline, macro, identifier, contentAssist);
+        TokenList replacement= fMacroExpander.expand(lexer, stopAtNewline, isPPCondition, macro, identifier, contentAssist);
     	final IASTName[] expansions= fMacroExpander.clearImplicitExpansions();
     	final ImageLocationInfo[] ili= fMacroExpander.clearImageLocationInfos();
     	final Token last= replacement.last();

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner/IncludeFileResolutionCache.java

@@ -0,0 +1,107 @@
+/*******************************************************************************
+ * Copyright (c) 2008 Wind River Systems, Inc. and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *    Markus Schorn - initial API and implementation
+ *******************************************************************************/ 
+package org.eclipse.cdt.internal.core.parser.scanner;
+
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.eclipse.cdt.internal.core.parser.util.WeakHashSet;
+
+/**
+ * A limited LRU cache for looking up files in an include search path.
+ * @since 5.0
+ */
+public final class IncludeFileResolutionCache {
+	public static class ISPKey  {
+		private String[] fISP;
+		private int fHashCode;
+
+		private ISPKey(String[] isp) {
+			fISP= isp;
+			fHashCode= Arrays.hashCode(isp);
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+			if (this == obj) {
+				return true;
+			}
+			return obj != null && Arrays.equals(fISP, ((ISPKey) obj).fISP);
+		}
+
+		@Override
+		public int hashCode() {
+			return fHashCode;
+		}
+	}
+	
+	public static class LookupKey {
+		private ISPKey fCanonicISP;
+		private char[] fName;
+		private int fHashCode;
+
+		private LookupKey(ISPKey ispKey, char[] include) {
+			fCanonicISP= ispKey;
+			fName= include;
+			fHashCode= Arrays.hashCode(include) * 31 + ispKey.hashCode();
+		}
+		
+		@Override
+		public int hashCode() {
+			return fHashCode;
+		}
+
+		@Override
+		public boolean equals(Object obj) {
+			LookupKey other= (LookupKey) obj;
+			if (fCanonicISP != other.fCanonicISP)
+				return false;
+			if (!Arrays.equals(fName, other.fName))
+				return false;
+			return true;
+		}
+	}
+
+	private WeakHashSet<ISPKey> fCanonicISPs;
+	private LinkedHashMap<LookupKey, Integer> fCache;
+		
+	/**
+	 * Creates a cache for include file resolution using up to the given amount of memory
+	 * @param maxSizeKBytes the maximum size of the cache in kilobytes
+	 */
+	public IncludeFileResolutionCache(final int maxSizeKBytes) {
+		final int size= maxSizeKBytes*1024/72; // HashEntry 32 bytes, Key 16 bytes, Name 16 bytes, Integer 8 bytes 
+		fCache= new LinkedHashMap<LookupKey, Integer>(size, 0.75f, true) {
+			@Override
+			protected boolean removeEldestEntry(Map.Entry<LookupKey, Integer> eldest) {
+				return size() > size;
+			}
+		};
+		fCanonicISPs= new WeakHashSet<ISPKey>();
+	}
+	
+	public ISPKey getKey(String[] isp) {
+		return fCanonicISPs.add(new ISPKey(isp));
+	}
+
+	public LookupKey getKey(ISPKey ispKey, char[] filename) {
+		return new LookupKey(ispKey, filename);
+	}
+
+	public Integer getCachedPathOffset(LookupKey key) {
+        return fCache.get(key);
+	}
+
+	public void putCachedPathOffset(LookupKey key, int offset) {
+		fCache.put(key, offset);
+	}
+}

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/util/WeakHashSet.java

@@ -0,0 +1,225 @@
+/*******************************************************************************
+ * Copyright (c) 2004, 2008 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     IBM Corporation - initial API and implementation
+ *     Markus Schorn (Wind River Systems)
+ *******************************************************************************/
+package org.eclipse.cdt.internal.core.parser.util;
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+
+/**
+ * A hashset whose values can be garbage collected. 
+ * This is a clone of org.eclipse.jdt.internal.core.util.WeakHashSet.
+ */
+public class WeakHashSet<T> {
+	
+	public static class HashableWeakReference<T> extends WeakReference<T> {
+		public int hashCode;
+		public HashableWeakReference(T referent, ReferenceQueue<T> queue) {
+			super(referent, queue);
+			this.hashCode = referent.hashCode();
+		}
+		@Override
+		public boolean equals(Object obj) {
+			if (!(obj instanceof HashableWeakReference)) return false;
+			Object referent = get();
+			Object other = ((HashableWeakReference<?>) obj).get();
+			if (referent == null) return other == null;
+			return referent.equals(other);
+		}
+		@Override
+		public int hashCode() {
+			return this.hashCode;
+		}
+		@Override
+		public String toString() {
+			Object referent = get();
+			if (referent == null) return "[hashCode=" + this.hashCode + "] <referent was garbage collected>"; //$NON-NLS-1$  //$NON-NLS-2$
+			return "[hashCode=" + this.hashCode + "] " + referent.toString(); //$NON-NLS-1$ //$NON-NLS-2$
+		}
+	}
+	
+	HashableWeakReference<T>[] values;
+	public int elementSize; // number of elements in the table
+	int threshold;
+	ReferenceQueue<T> referenceQueue = new ReferenceQueue<T>();	
+	
+	public WeakHashSet() {
+		this(5);
+	}
+	
+	@SuppressWarnings("unchecked")
+	public WeakHashSet(int size) {
+		this.elementSize = 0;
+		this.threshold = size; // size represents the expected number of elements
+		int extraRoom = (int) (size * 1.75f);
+		if (this.threshold == extraRoom)
+			extraRoom++;
+		this.values = new HashableWeakReference[extraRoom];
+	}
+	
+	/*
+	 * Adds the given object to this set.
+	 * If an object that is equals to the given object already exists, do nothing.
+	 * Returns the existing object or the new object if not found.
+	 */
+	public T add(T obj) {
+		cleanupGarbageCollectedValues();
+		int valuesLength = this.values.length,
+			index = (obj.hashCode() & 0x7FFFFFFF) % valuesLength;
+		HashableWeakReference<T> currentValue;
+		while ((currentValue = this.values[index]) != null) {
+			T referent;
+			if (obj.equals(referent = currentValue.get())) {
+				return referent;
+			}
+			if (++index == valuesLength) {
+				index = 0;
+			}
+		}
+		this.values[index] = new HashableWeakReference<T>(obj, this.referenceQueue);
+
+		// assumes the threshold is never equal to the size of the table
+		if (++this.elementSize > this.threshold)
+			rehash();
+		
+		return obj;
+	}
+		
+	private void addValue(HashableWeakReference<T> value) {
+		T obj = value.get();
+		if (obj == null) return;
+		int valuesLength = this.values.length;
+		int index = (value.hashCode & 0x7FFFFFFF) % valuesLength;
+		HashableWeakReference<T> currentValue;
+		while ((currentValue = this.values[index]) != null) {
+			if (obj.equals(currentValue.get())) {
+				return;
+			}
+			if (++index == valuesLength) {
+				index = 0;
+			}
+		}
+		this.values[index] = value;
+
+		// assumes the threshold is never equal to the size of the table
+		if (++this.elementSize > this.threshold)
+			rehash();
+	}
+	
+	@SuppressWarnings("unchecked")
+	private void cleanupGarbageCollectedValues() {
+		HashableWeakReference<T> toBeRemoved;
+		while ((toBeRemoved = (HashableWeakReference<T>) this.referenceQueue.poll()) != null) {
+			int hashCode = toBeRemoved.hashCode;
+			int valuesLength = this.values.length;
+			int index = (hashCode & 0x7FFFFFFF) % valuesLength;
+			HashableWeakReference<T> currentValue;
+			while ((currentValue = this.values[index]) != null) {
+				if (currentValue == toBeRemoved) {
+					// replace the value at index with the last value with the same hash
+					int sameHash = index;
+					int current;
+					while ((currentValue = this.values[current = (sameHash + 1) % valuesLength]) != null && currentValue.hashCode == hashCode)
+						sameHash = current;
+					this.values[index] = this.values[sameHash];
+					this.values[sameHash] = null;
+					this.elementSize--;
+					break;
+				}
+				if (++index == valuesLength) {
+					index = 0;
+				}
+			}
+		}
+	}
+	
+	public boolean contains(T obj) {
+		return get(obj) != null;
+	}
+	
+	/*
+	 * Return the object that is in this set and that is equals to the given object.
+	 * Return null if not found.
+	 */
+	public T get(T obj) {
+		cleanupGarbageCollectedValues();
+		int valuesLength = this.values.length;
+		int index = (obj.hashCode() & 0x7FFFFFFF) % valuesLength;
+		HashableWeakReference<T> currentValue;
+		while ((currentValue = this.values[index]) != null) {
+			T referent;
+			if (obj.equals(referent = currentValue.get())) {
+				return referent;
+			}
+			if (++index == valuesLength) {
+				index = 0;
+			}
+		}
+		return null;
+	}
+		
+	private void rehash() {
+		WeakHashSet<T> newHashSet = new WeakHashSet<T>(this.elementSize * 2);		// double the number of expected elements
+		newHashSet.referenceQueue = this.referenceQueue;
+		HashableWeakReference<T> currentValue;
+		for (int i = 0, length = this.values.length; i < length; i++)
+			if ((currentValue = this.values[i]) != null)
+				newHashSet.addValue(currentValue);
+
+		this.values = newHashSet.values;
+		this.threshold = newHashSet.threshold;
+		this.elementSize = newHashSet.elementSize;
+	}
+
+	/*
+	 * Removes the object that is in this set and that is equals to the given object.
+	 * Return the object that was in the set, or null if not found.
+	 */
+	public T remove(T obj) {
+		cleanupGarbageCollectedValues();
+		int valuesLength = this.values.length;
+		int index = (obj.hashCode() & 0x7FFFFFFF) % valuesLength;
+		HashableWeakReference<T> currentValue;
+		while ((currentValue = this.values[index]) != null) {
+			T referent;
+			if (obj.equals(referent = currentValue.get())) {
+				this.elementSize--;
+				this.values[index] = null;
+				rehash();
+				return referent;
+			}
+			if (++index == valuesLength) {
+				index = 0;
+			}
+		}
+		return null;
+	}
+
+	public int size() {
+		return this.elementSize;
+	}
+
+	@Override
+	public String toString() {
+		StringBuffer buffer = new StringBuffer("{"); //$NON-NLS-1$
+		for (int i = 0, length = this.values.length; i < length; i++) {
+			HashableWeakReference<T> value = this.values[i];
+			if (value != null) {
+				Object ref = value.get();
+				if (ref != null) {
+					buffer.append(ref.toString());
+					buffer.append(", "); //$NON-NLS-1$
+				}
+			}
+		}
+		buffer.append("}"); //$NON-NLS-1$
+		return buffer.toString();
+	}
+}