8013395: StringBuffer.toString performance regression impacting embedded benchmarks
Summary: cache a copy of the char[] to use with toString() and clear it when ever the sb content is modified
Reviewed-by: alanb, plevart, mduigou, forax
diff --git a/test/java/lang/StringBuffer/ToStringCache.java b/test/java/lang/StringBuffer/ToStringCache.java
new file mode 100644
index 0000000..6259e27
--- /dev/null
+++ b/test/java/lang/StringBuffer/ToStringCache.java
@@ -0,0 +1,289 @@
+/*
+ * Copyright (c) 2013, 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 8013395
+ * @summary Test StringBuffer.toString caching
+ */
+
+public class ToStringCache {
+
+ // we can't test that we actually use a cached value (the benchmarks
+ // verify that) but we have to test that the cache is cleared when
+ // expected
+
+ public static void main(String[] args) throws Exception {
+ String original = "The original String";
+
+ StringBuffer sb = new StringBuffer(original);
+
+ String a = sb.toString();
+ checkEqual(a, original);
+
+ String b = sb.toString();
+ checkEqual(a, b);
+
+ // mutating methods
+
+ sb.setLength(12);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.setCharAt(0, 'X');
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(new Character('X'));
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append("More text");
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(sb);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(new StringBuilder("Build"));
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(new StringBuilder("Build2"), 0, 1);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(new char[] { 'a', 'b' });
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(true);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append('c');
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(23);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.appendCodePoint(Character.codePointAt(new char[] { 'X'}, 0));
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(1L);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(1.0f);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.append(1.0d);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.delete(0, 5);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.deleteCharAt(0);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.replace(0,2, "123");
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, new char[] { 'a', 'b', 'c'}, 0, 3);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, new Object());
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, "abc");
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, new char[] { 'a', 'b', 'c' });
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, new StringBuilder("Build"));
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, new StringBuilder("Build"), 0, 1);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, false);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, 'X');
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, 1);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, 1L);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, 1.0f);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.insert(0, 1.0d);
+ b = sb.toString();
+ checkUnequal(a, b);
+ a = b;
+
+ sb.reverse();
+ b = sb.toString();
+ checkUnequal(a, b);
+
+ // non-mutating methods
+
+ // Reset to known value
+ sb = new StringBuffer(original);
+ a = sb.toString();
+ b = sb.toString();
+ checkEqual(a, b);
+
+ int l = sb.length();
+ b = sb.toString();
+ checkEqual(a, b);
+
+ int cap = sb.capacity();
+ b = sb.toString();
+ checkEqual(a, b);
+
+ sb.ensureCapacity(100);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ sb.trimToSize();
+ b = sb.toString();
+ checkEqual(a, b);
+
+ char c = sb.charAt(1);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ int cp = sb.codePointAt(1);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ cp = sb.codePointBefore(2);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ int count = sb.codePointCount(0,1);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ count = sb.offsetByCodePoints(0, 1);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ sb.getChars(0, 1, new char[2], 0);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ String sub = sb.substring(0);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ CharSequence cs = sb.subSequence(0,1);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ sub = sb.substring(0, 3);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ int index = sb.indexOf("rig");
+ b = sb.toString();
+ checkEqual(a, b);
+
+ index = sb.indexOf("rig", 2);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ index = sb.lastIndexOf("rig");
+ b = sb.toString();
+ checkEqual(a, b);
+
+ index = sb.lastIndexOf("rig", 3);
+ b = sb.toString();
+ checkEqual(a, b);
+
+ }
+
+ private static void checkEqual(String s1, String s2) {
+ if (!s1.equals(s2))
+ throw new RuntimeException("Unmatched strings: s1 = "
+ + s1 + " s2 = " + s2);
+ }
+ private static void checkUnequal(String s1, String s2) {
+ if (s1.equals(s2))
+ throw new RuntimeException("Unexpected matched strings: " + s1);
+ }
+}