Bug 329385 - [repository] Share StringPool for Composite Repositories

2 files changed, 3 insertions, 86 deletions

diff --git a/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/internal/p2/core/StringPool.java b/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/internal/p2/core/StringPool.java
deleted file mode 100644
index f7ff68cd6..000000000
--- a/bundles/org.eclipse.equinox.p2.core/src/org/eclipse/equinox/internal/p2/core/StringPool.java
+++ /dev/null
@@ -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;
-	}
-}
diff --git a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java
index bdb23985f..b26843f37 100644
--- a/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java
+++ b/bundles/org.eclipse.equinox.p2.repository/src/org/eclipse/equinox/internal/p2/persistence/XMLParser.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- *  Copyright (c) 2007, 2009 IBM Corporation and others.
+ *  Copyright (c) 2007, 2010 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
@@ -16,7 +16,6 @@ import java.util.StringTokenizer;
 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 @@ public abstract class XMLParser extends DefaultHandler implements XMLConstants {
 	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 @@ public abstract class XMLParser extends DefaultHandler implements XMLConstants {
 		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 @@ public abstract class XMLParser extends DefaultHandler implements XMLConstants {
 			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 @@ public abstract class XMLParser extends DefaultHandler implements XMLConstants {
 		}
 
 		protected void processCharacters(String data) {
-			this.text = canonicalize(data);
+			this.text = data == null ? null : data.intern();
 		}
 
 	}