Bug 471103 - Add caching for performance improvements of indexing

Change-Id: I6c515202e029a030c89b7f71c013bbc2e2c1c588
Signed-off-by: Karsten Thoms <karsten.thoms@itemis.de>

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/core/dom/ast/ASTTypeUtil.java

@@ -10,6 +10,7 @@
  *     Markus Schorn (Wind River Systems)
  *     Sergey Prigogin (Google)
  *     Nathan Ridge
+ *     Karsten Thoms (itemis) - Bug#471103
  *******************************************************************************/
 package org.eclipse.cdt.core.dom.ast;
 
@@ -17,6 +18,7 @@ import java.net.URI;
 import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.List;
+import java.util.WeakHashMap;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.ast.IBasicType.Kind;
@@ -70,6 +72,37 @@ public class ASTTypeUtil {
 	private static final String SPACE = " "; //$NON-NLS-1$
 	private static final int DEAULT_ITYPE_SIZE = 2;
 
+	private static class ResultCache {
+		// Keep two separate maps for normalized and unnormalized type representations.
+		private WeakHashMap<IType, String> normalizedTypes = new WeakHashMap<>();
+		private WeakHashMap<IType, String> unnormalizedTypes = new WeakHashMap<>();
+
+		/**
+		 * Returns the cached string representation for a type. Returns {@code null}
+		 * if the value was not cached or was garbage collected.
+		 */
+		public String get(IType type, boolean normalize) {
+			if (normalize) {
+				return normalizedTypes.get(type);
+			} else {
+				return unnormalizedTypes.get(type);
+			}
+		}
+
+		/**
+		 * Stores a string representation of the given type name in the cache.
+		 */
+		public String put(IType type, boolean normalize, String result) {
+			if (normalize) {
+				return normalizedTypes.put(type, result);
+			} else {
+				return unnormalizedTypes.put(type, result);
+			}
+		}
+	}
+
+	private static final ThreadLocal<ResultCache> resultCache = new ThreadLocal<>();
+
 	private ASTTypeUtil() {}
 
 	/**
@@ -537,6 +570,20 @@ public class ASTTypeUtil {
 	 * @since 5.3
 	 */
 	public static void appendType(IType type, boolean normalize, StringBuilder result) {
+		// performance: check if type was appended before
+		ResultCache cache = resultCache.get();
+		if (cache != null) {
+			String cachedResult = cache.get(type, normalize);
+			if (cachedResult != null) {
+				result.append(cachedResult);
+				return;
+			}
+		}
+
+		// Remember type argument for caching, argument is not final and might be changed.
+		IType originalType = type;
+		// Remember the start offset of the appended string.
+		int startOffset = result.length();
 		IType[] types = new IType[DEAULT_ITYPE_SIZE];
 		int numTypes = 0;
 
@@ -659,6 +706,11 @@ public class ASTTypeUtil {
 				appendTypeString(tj, normalize, result);
 			}
 		}
+
+		if (cache != null) {
+			// Store result in the cache.
+			cache.put(originalType, normalize, result.substring(startOffset));
+		}
 	}
 
 	/**
@@ -797,7 +849,7 @@ public class ASTTypeUtil {
 								CCorePlugin.log(e);
 							}
 						} else {
-							IASTNode node = ASTInternal.getDefinitionOfBinding(binding);
+							IASTNode node = ASTInternal.getDeclaredInSourceFileOnly(binding);
 							if (node != null) {
 								IPath filePath = new Path(node.getTranslationUnit().getFilePath());
 								URI uri = UNCPathConverter.getInstance().toURI(filePath);
@@ -905,9 +957,29 @@ public class ASTTypeUtil {
 			switch (fname[i]) {
 			case '/':
 			case '\\':
-				return i + 1;
+				return i+1;
 			}
 		}
 		return 0;
 	}
+	
+	/**
+	 * Marks start of processing a translation unit during indexing.
+	 * Enables caching of string representations of types.
+	 *
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	public static void startTranslationUnit() {
+		resultCache.set(new ResultCache());
+	}
+
+	/**
+	 * Marks the end of processing a translation unit during indexing.
+	 * Disables caching of string representations of types and clears the previously cached results.
+	 *
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	public static void finishTranslationUnit() {
+		resultCache.set(null);
+	}
 }

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/AbstractIndexerTask.java

@@ -11,6 +11,7 @@
  *     Sergey Prigogin (Google)
  *     Thomas Corbat (IFS)
  *     Marc-Andre Laperle (Ericsson)
+ *     Karsten Thoms (itemis) - Bug#471103
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.pdom;
 
@@ -35,6 +36,7 @@ import java.util.regex.Pattern;
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.ILinkage;
 import org.eclipse.cdt.core.dom.IPDOMIndexerTask;
+import org.eclipse.cdt.core.dom.ast.ASTTypeUtil;
 import org.eclipse.cdt.core.dom.ast.IASTComment;
 import org.eclipse.cdt.core.dom.ast.IASTFileLocation;
 import org.eclipse.cdt.core.dom.ast.IASTPreprocessorIncludeStatement;
@@ -1083,6 +1085,7 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 			final boolean isSource = fResolver.isSourceUnit(tu);
 
 			long start= System.currentTimeMillis();
+			ASTTypeUtil.startTranslationUnit();
 			IASTTranslationUnit ast= createAST(lang, codeReader, scanInfo, isSource, fASTOptions, ctx, pm);
 			fStatistics.fParsingTime += System.currentTimeMillis() - start;
 			if (ast == null) {
@@ -1105,6 +1108,8 @@ public abstract class AbstractIndexerTask extends PDOMWriter {
 			if (--fSwallowOutOfMemoryError < 0)
 				throw e;
 			th= e;
+		} finally {
+			ASTTypeUtil.finishTranslationUnit();
 		}
 		if (th != null) {
 			swallowError(path, th);