8000316: Huge performance bottleneck in com.sun.tools.javac.comp.Check.localClassName

Speed up Check.localClassName by avoiding generating names known to be in use already

Reviewed-by: mcimadamore, jlahoda, sadayapalam

langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Check.java

@@ -409,6 +409,9 @@ public class Check {
  * Class name generation
  **************************************************************************/
 
+
+    private Map<Pair<Name, Name>, Integer> localClassNameIndexes = new HashMap<>();
+
     /** Return name of local class.
      *  This is of the form   {@code <enclClass> $ n <classname> }
      *  where
@@ -416,17 +419,28 @@ public class Check {
      *    classname is the simple name of the local class
      */
     Name localClassName(ClassSymbol c) {
-        for (int i=1; ; i++) {
-            Name flatname = names.
-                fromString("" + c.owner.enclClass().flatname +
-                           syntheticNameChar + i +
-                           c.name);
-            if (compiled.get(flatname) == null) return flatname;
+        Name enclFlatname = c.owner.enclClass().flatname;
+        String enclFlatnameStr = enclFlatname.toString();
+        Pair<Name, Name> key = new Pair<>(enclFlatname, c.name);
+        Integer index = localClassNameIndexes.get(key);
+        for (int i = (index == null) ? 1 : index; ; i++) {
+            Name flatname = names.fromString(enclFlatnameStr
+                    + syntheticNameChar + i + c.name);
+            if (compiled.get(flatname) == null) {
+                localClassNameIndexes.put(key, i + 1);
+                return flatname;
+            }
         }
     }
 
+    void clearLocalClassNameIndexes(ClassSymbol c) {
+        localClassNameIndexes.remove(new Pair<>(
+                c.owner.enclClass().flatname, c.name));
+    }
+
     public void newRound() {
         compiled.clear();
+        localClassNameIndexes.clear();
     }
 
 /* *************************************************************************

langtools/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/DeferredAttr.java

@@ -472,6 +472,7 @@ public class DeferredAttr extends JCTree.Visitor {
                 if (csym == null) return;
                 typeEnvs.remove(csym);
                 chk.compiled.remove(csym.flatname);
+                chk.clearLocalClassNameIndexes(csym);
                 syms.classes.remove(csym.flatname);
                 super.visitClassDef(tree);
             }

langtools/test/tools/javac/T8000316/T8000316.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8000316
+ * @summary Huge performance bottleneck in com.sun.tools.javac.comp.Check.localClassName
+ * @modules jdk.compiler
+ * @run main T8000316
+ */
+
+import com.sun.source.util.JavacTask;
+import java.net.URI;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Locale;
+import javax.tools.Diagnostic;
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.StandardJavaFileManager;
+import javax.tools.ToolProvider;
+
+public class T8000316 {
+
+    final static int N_METHODS = 1024;
+    final static int N_CLASSES = 8;
+
+    static class TestClass extends SimpleJavaFileObject {
+
+        String methTemplate = "    public static Runnable get#N() {\n" +
+                              "        return new Runnable() {\n" +
+                              "            @Override\n" +
+                              "            public void run() {\n" +
+                              "                return;\n" +
+                              "            }\n" +
+                              "        };\n" +
+                              "    }\n";
+
+        String classTemplate = "\n\nclass Chain#N {\n\n#M }";
+
+        String source;
+
+        public TestClass() {
+            super(URI.create("myfo:/Test.java"), JavaFileObject.Kind.SOURCE);
+            StringBuilder buf = new StringBuilder();
+            StringBuilder fileBuf = new StringBuilder();
+
+            for (int i = 0 ; i < N_CLASSES ; i++) {
+                for (int j = 0; j < N_METHODS; j++) {
+                    buf.append(methTemplate.replace("#N", String.valueOf(j)));
+                    buf.append("\n");
+                }
+                fileBuf.append(classTemplate.replace("#M", buf.toString()).replace("#N", String.valueOf(i)));
+                buf = new StringBuilder();
+                source = fileBuf.toString();
+            }
+        }
+
+        @Override
+        public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+            return source;
+        }
+    }
+
+    public static void main(String... args) throws Exception {
+        ArrayList<JavaFileObject> sources = new ArrayList<>();
+        sources.add(new TestClass());
+        new T8000316().run(sources);
+    }
+
+    void run(List<JavaFileObject> sources) throws Exception {
+        javax.tools.DiagnosticListener<JavaFileObject> dc = (diagnostic) -> {
+            if (diagnostic.getKind() == Diagnostic.Kind.ERROR) {
+                throw new AssertionError("unexpected diagnostic: " + diagnostic.getMessage(Locale.getDefault()));
+            }
+        };
+        JavaCompiler comp = ToolProvider.getSystemJavaCompiler();
+        try (StandardJavaFileManager fm = comp.getStandardFileManager(null, null, null)) {
+            JavacTask ct = (JavacTask)comp.getTask(null, fm, dc,
+                    null, null, sources);
+            ct.analyze();
+        }
+    }
+}