Attachment 183481 Details for Bug 329385 – Replace StringPool implementation with String.intern()

[patch] Replace StringPool implementation with String.intern()

stringIntern.txt (text/plain), 5.59 KB, created by Dean Roberts

on 2010-11-19 11:20:02 EST

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Creator: Dean Roberts

Created: 2010-11-19 11:20:02 EST

Size: 5.59 KB

patch

obsolete

>### Eclipse Workspace Patch 1.0
>#P org.eclipse.equinox.p2.core
>Index: src/org/eclipse/equinox/internal/p2/core/StringPool.java
>===================================================================
>RCS file: src/org/eclipse/equinox/internal/p2/core/StringPool.java
>diff -N src/org/eclipse/equinox/internal/p2/core/StringPool.java
>--- src/org/eclipse/equinox/internal/p2/core/StringPool.java	13 Jan 2010 17:20:33 -0000	1.5
>+++ /dev/null	1 Jan 1970 00:00:00 -0000
>@@ -1,73 +0,0 @@
>-/*******************************************************************************
>- *  Copyright (c) 2004, 2009 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 - Initial API and implementation
>- *******************************************************************************/
>-package org.eclipse.equinox.internal.p2.core;
>-
>-import java.util.HashMap;
>-
>-/**
>- * A string pool is used for sharing strings in a way that eliminates duplicate
>- * equal strings.  A string pool instance can be maintained over a long period
>- * of time, or used as a temporary structure during a string sharing pass over
>- * a data structure.
>- * <p>
>- * This class is not intended to be subclassed by clients.
>- * </p>
>- */
>-public final class StringPool {
>-	private int savings;
>-	private final HashMap<String, String> map = new HashMap<String, String>();
>-
>-	/**
>-	 * Creates a new string pool.
>-	 */
>-	public StringPool() {
>-		super();
>-	}
>-
>-	/**
>-	 * Adds a <code>String</code> to the pool.  Returns a <code>String</code>
>-	 * that is equal to the argument but that is unique within this pool.
>-	 * @param string The string to add to the pool
>-	 * @return A string that is equal to the argument.
>-	 */
>-	public String add(String string) {
>-		if (string == null)
>-			return string;
>-		String result = map.get(string);
>-		if (result != null) {
>-			if (result != string)
>-				savings += 44 + 2 * string.length();
>-			return result;
>-		}
>-		//explicitly copy the string to trim excess baggage
>-		String trim = new String(string.toCharArray());
>-		map.put(string, trim);
>-		return trim;
>-	}
>-
>-	/**
>-	 * Returns an estimate of the size in bytes that was saved by sharing strings in 
>-	 * the pool.  In particular, this returns the size of all strings that were added to the
>-	 * pool after an equal string had already been added.  This value can be used
>-	 * to estimate the effectiveness of a string sharing operation, in order to 
>-	 * determine if or when it should be performed again.
>-	 * 
>-	 * In some cases this does not precisely represent the number of bytes that 
>-	 * were saved.  For example, say the pool already contains string S1.  Now 
>-	 * string S2, which is equal to S1 but not identical, is added to the pool five 
>-	 * times. This method will return the size of string S2 multiplied by the 
>-	 * number of times it was added, even though the actual savings in this case
>-	 * is only the size of a single copy of S2.
>-	 */
>-	public int getSavedStringCount() {
>-		return savings;
>-	}
>-}
>#P org.eclipse.equinox.p2.repository
>Index: src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java
>===================================================================
>RCS file: /cvsroot/rt/org.eclipse.equinox/p2/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java,v
>retrieving revision 1.10
>diff -u -r1.10 XMLParser.java
>--- src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java	4 Oct 2010 16:59:44 -0000	1.10
>+++ src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java	19 Nov 2010 15:56:07 -0000
>@@ -16,7 +16,6 @@
> import javax.xml.parsers.*;
> import org.eclipse.core.runtime.*;
> import org.eclipse.equinox.internal.p2.core.Activator;
>-import org.eclipse.equinox.internal.p2.core.StringPool;
> import org.eclipse.equinox.internal.p2.core.helpers.OrderedProperties;
> import org.eclipse.equinox.internal.p2.core.helpers.Tracing;
> import org.eclipse.equinox.p2.metadata.Version;
>@@ -44,7 +43,6 @@
> 	protected MultiStatus status = null; // accumulation of non-fatal errors
> 	protected Locator locator = null; // document locator, if supported by the parser
> 
>-	protected StringPool stringPool = new StringPool();//used to eliminate string duplication
> 	private IProgressMonitor monitor;
> 
> 	private static ServiceTracker<SAXParserFactory, SAXParserFactory> xmlTracker = null;
>@@ -62,14 +60,6 @@
> 		return (status != null ? status : Status.OK_STATUS);
> 	}
> 
>-	/**
>-	 * Returns the canonical form of a string. Used to eliminate duplicate equal 
>-	 * strings.
>-	 */
>-	protected String canonicalize(String string) {
>-		return stringPool == null ? string : stringPool.add(string);
>-	}
>-
> 	public boolean isValidXML() {
> 		return (status == null || !status.matches(IStatus.ERROR | IStatus.CANCEL));
> 	}
>@@ -320,7 +310,7 @@
> 			String[] result = new String[required.length + optional.length];
> 			for (int i = 0; i < attributes.getLength(); i += 1) {
> 				String name = attributes.getLocalName(i);
>-				String value = canonicalize(attributes.getValue(i).trim());
>+				String value = attributes.getValue(i).trim().intern();
> 				int j;
> 				if ((j = indexOf(required, name)) >= 0) {
> 					result[j] = value;
>@@ -468,7 +458,7 @@
> 		}
> 
> 		protected void processCharacters(String data) {
>-			this.text = canonicalize(data);
>+			this.text = data == null ? null : data.intern();
> 		}
> 
> 	}

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Attachments on bug 329385: 183481