Using of pooled list refined

core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/language/settings/providers/LanguageSettingsBaseProvider.java

@@ -1,12 +1,12 @@
 /*******************************************************************************
- * Copyright (c) 2009, 2010 Andrew Gvozdev (Quoin Inc.) and others.
+ * Copyright (c) 2009, 2011 Andrew Gvozdev 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:
- *     Andrew Gvozdev (Quoin Inc.) - initial API and implementation
+ *     Andrew Gvozdev - initial API and implementation
  *******************************************************************************/
 
 package org.eclipse.cdt.core.language.settings.providers;
@@ -18,7 +18,6 @@ import java.util.List;
 import org.eclipse.cdt.core.AbstractExecutableExtensionBase;
 import org.eclipse.cdt.core.settings.model.ICConfigurationDescription;
 import org.eclipse.cdt.core.settings.model.ICLanguageSettingEntry;
-import org.eclipse.cdt.internal.core.settings.model.SettingsModelMessages;
 import org.eclipse.core.resources.IResource;
 
 /**
@@ -131,6 +130,7 @@ public class LanguageSettingsBaseProvider extends AbstractExecutableExtensionBas
 	 * @param languageId - language id. If {@code null}, then entries defined for
 	 *    the language scope are returned. See {@link #getLanguageScope()}
 	 */
+	@Override
 	public List<ICLanguageSettingEntry> getSettingEntries(ICConfigurationDescription cfgDescription, IResource rc, String languageId) {
 		if (languageScope==null) {
 			if (entries==null)

core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/language/settings/providers/LanguageSettingsProvidersSerializer.java

@@ -1025,17 +1025,17 @@ projects:
 		}
 	}
 
-	private static List<ICLanguageSettingEntry> safeGetSettingEntries(ILanguageSettingsProvider provider,
+	private static List<ICLanguageSettingEntry> getSettingEntriesPooled(ILanguageSettingsProvider provider,
 			ICConfigurationDescription cfgDescription, IResource rc, String languageId) {
 
 		try {
-			return provider.getSettingEntries(cfgDescription, rc, languageId);
+			return LanguageSettingsStorage.getPooledList(provider.getSettingEntries(cfgDescription, rc, languageId));
 		} catch (Throwable e) {
 			String cfgId = cfgDescription!=null ? cfgDescription.getId() : null;
 			String msg = "Exception in provider "+provider.getId()+": getSettingEntries("+cfgId+", "+rc+", "+languageId+")";
 			CCorePlugin.log(msg, e);
-			// return empty array to prevent climbing up the resource tree 
+			// return empty list to prevent getting potentially non-empty list from up the resource tree
-			return new ArrayList<ICLanguageSettingEntry>(0);
+			return LanguageSettingsStorage.getPooledEmptyList();
 		}
 	}
 
@@ -1050,15 +1050,15 @@ projects:
 	 * @param rc - resource such as file or folder.
 	 * @param languageId - language id.
 	 *
-	 * @return the list of setting entries. Never returns {@code null}
+	 * @return the list of setting entries which is unmodifiable. Never returns {@code null}
 	 *     although individual providers mandated to return {@code null} if no settings defined.
 	 */
 	public static List<ICLanguageSettingEntry> getSettingEntriesUpResourceTree(ILanguageSettingsProvider provider, ICConfigurationDescription cfgDescription, IResource rc, String languageId) {
 		Assert.isTrue( !(rc instanceof IWorkspaceRoot) );
 		if (provider!=null) {
-			List<ICLanguageSettingEntry> entries = safeGetSettingEntries(provider, cfgDescription, rc, languageId);
+			List<ICLanguageSettingEntry> entries = getSettingEntriesPooled(provider, cfgDescription, rc, languageId);
 			if (entries!=null) {
-				return new ArrayList<ICLanguageSettingEntry>(entries);
+				return entries;
 			}
 			if (rc!=null) {
 				IResource parentFolder = (rc instanceof IProject) ? null : rc.getParent();
@@ -1066,14 +1066,14 @@ projects:
 					return getSettingEntriesUpResourceTree(provider, cfgDescription, parentFolder, languageId);
 				}
 				// if out of parent resources - get default entries for the applicable language scope
-				entries = safeGetSettingEntries(provider, null, null, languageId);
+				entries = getSettingEntriesPooled(provider, null, null, languageId);
 				if (entries!=null) {
-					return new ArrayList<ICLanguageSettingEntry>(entries);
+					return entries;
 				}
 			}
 		}
 
-		return new ArrayList<ICLanguageSettingEntry>(0);
+		return LanguageSettingsStorage.getPooledEmptyList();
 	}
 
 	/**

core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/language/settings/providers/LanguageSettingsStorage.java

@@ -55,8 +55,8 @@ public class LanguageSettingsStorage {
 	};
 
 	/**
-	 * <br> Note that this list is <b>unmodifiable</b>. To modify the list copy it, change and use
+	 * TODO
-	 * {@link #setSettingEntries(ICConfigurationDescription, IResource, String, List)}.
+	 * <br> Note that this list is <b>unmodifiable</b>.
 	 *
 	 */
 	public List<ICLanguageSettingEntry> getSettingEntries(ICConfigurationDescription cfgDescription, IResource rc, String languageId) {
@@ -108,7 +108,7 @@ public class LanguageSettingsStorage {
 					langMap = new HashMap<String, List<ICLanguageSettingEntry>>();
 					fStorage.put(languageId, langMap);
 				}
-				List<ICLanguageSettingEntry> sortedEntries = listPool.add(Collections.unmodifiableList(sortEntries(entries)));
+				List<ICLanguageSettingEntry> sortedEntries = getPooledList(sortEntries(entries), false);
 				langMap.put(rcProjectPath, sortedEntries);
 			} else {
 				// do not keep nulls in the tables
@@ -319,6 +319,53 @@ public class LanguageSettingsStorage {
 		}
 	}
 
+	/**
+	 * Returns the equal list of entries from the pool to conserve the memory.
+	 *
+	 * @param entries - list of entries to pool.
+	 * @param copy - specify {@code true} to copy the list in order to prevent
+	 *    back-door modification on the original list changes.
+	 * @return returns the list of entries from the pool.
+	 */
+	private static List<ICLanguageSettingEntry> getPooledList(List<ICLanguageSettingEntry> entries, boolean copy) {
+		if (entries == null)
+			return null;
+
+		List<ICLanguageSettingEntry> pooledList = listPool.get(entries);
+		if (pooledList != null) {
+			return pooledList;
+		}
+
+		if (entries.size() == 0) {
+			return getPooledEmptyList();
+		}
+
+		if (copy) {
+			entries = new ArrayList<ICLanguageSettingEntry>(entries);
+		}
+		pooledList = Collections.unmodifiableList(entries);
+		return listPool.add(pooledList);
+	}
+
+	/**
+	 * Returns the equal list of entries from the pool to conserve the memory.
+	 *
+	 * @param entries - list of entries to pool.
+	 * @return returns the list of entries from the pool.
+	 */
+	public static List<ICLanguageSettingEntry> getPooledList(List<ICLanguageSettingEntry> entries) {
+		return getPooledList(entries, true);
+	}
+
+	/**
+	 * @return the empty immutable list which is pooled. Use this call rather than creating
+	 * new empty array to ensure that operator '==' can be used instead of deep equals().
+	 */
+	public static List<ICLanguageSettingEntry> getPooledEmptyList() {
+		List<ICLanguageSettingEntry> pooledEmptyList = Collections.emptyList();
+		return listPool.add(pooledEmptyList);
+	}
+
 	/**
 	 * Clone storage for the entries. Copies references for lists of entries as a whole.
 	 * Note that is OK as the lists kept in storage are unmodifiable.

core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/language/settings/providers/LanguageSettingsEntriesTab.java

@@ -170,16 +170,25 @@ public class LanguageSettingsEntriesTab extends AbstractCPropertyTab {
 	 * Content provider for setting entries tree.
 	 */
 	private class EntriesTreeContentProvider implements ITreeContentProvider {
+		@Override
 		public Object[] getElements(Object inputElement) {
 			return getChildren(inputElement);
 		}
 
+		@Override
 		public Object[] getChildren(Object parentElement) {
 			if (parentElement instanceof Object[])
 				return (Object[]) parentElement;
+
 			if (parentElement instanceof ILanguageSettingsProvider) {
 				ILanguageSettingsProvider lsProvider = (ILanguageSettingsProvider)parentElement;
 				List<ICLanguageSettingEntry> entriesList = getSettingEntriesUpResourceTree(lsProvider);
+				if (entriesList == null) {
+					return null;
+				}
+
+				// convert to modifiable list
+				entriesList = new ArrayList<ICLanguageSettingEntry>(entriesList);
 
 				if (builtInCheckBox.getSelection()==false) {
 					for (Iterator<ICLanguageSettingEntry> iter = entriesList.iterator(); iter.hasNext();) {
@@ -189,26 +198,28 @@ public class LanguageSettingsEntriesTab extends AbstractCPropertyTab {
 						}
 					}
 				}
-
+				return entriesList.toArray();
-				if (entriesList!=null) {
-					return entriesList.toArray();
-				}
 			}
+
 			return null;
 		}
 
+		@Override
 		public Object getParent(Object element) {
 			return null;
 		}
 
+		@Override
 		public boolean hasChildren(Object element) {
 			Object[] children = getChildren(element);
 			return children!=null && children.length>0;
 		}
 
+		@Override
 		public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
 		}
 
+		@Override
 		public void dispose() {
 		}
 
@@ -323,6 +334,7 @@ public class LanguageSettingsEntriesTab extends AbstractCPropertyTab {
 		columnLanguages.setToolTipText(Messages.AbstractLangsListTab_Languages);
 
 		treeLanguages.addPaintListener(new PaintListener() {
+			@Override
 			public void paintControl(PaintEvent e) {
 				int x = treeLanguages.getBounds().width - 5;
 				if (columnLanguages.getWidth() != x)
@@ -340,6 +352,7 @@ public class LanguageSettingsEntriesTab extends AbstractCPropertyTab {
 
 		final TreeColumn treeCol = new TreeColumn(treeEntries, SWT.NONE);
 		treeEntries.addPaintListener(new PaintListener() {
+			@Override
 			public void paintControl(PaintEvent e) {
 				int x = treeEntries.getClientArea().width;
 				if (treeCol.getWidth() != x)
@@ -692,7 +705,7 @@ public class LanguageSettingsEntriesTab extends AbstractCPropertyTab {
 		ICConfigurationDescription cfgDescription = getConfigurationDescription();
 		IResource rc = getResource();
 		List<ICLanguageSettingEntry> entries = provider.getSettingEntries(cfgDescription, rc, currentLanguageId);
-		if (entries==null) {
+		if (entries == null) {
 			entries = getSettingEntriesUpResourceTree(provider);
 		}
 		entries = new ArrayList<ICLanguageSettingEntry>(entries);
@@ -770,7 +783,7 @@ public class LanguageSettingsEntriesTab extends AbstractCPropertyTab {
 			String providerId = provider.getId();
 
 			List<ICLanguageSettingEntry> entries = getWritableEntries(provider);
-			int pos = getExactIndex(getSettingEntriesUpResourceTree(provider), entry);
+			int pos = getExactIndex(entries, entry);
 			entries.remove(entry);
 			saveEntries(provider, entries);