8080535: (ch) Expected size of Character.UnicodeBlock.map is not optimal
Reviewed-by: martin, chegar
--- a/jdk/src/java.base/share/classes/java/lang/Character.java Mon May 18 17:38:38 2015 +0300
+++ b/jdk/src/java.base/share/classes/java/lang/Character.java Mon May 18 19:15:50 2015 +0300
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 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
@@ -645,8 +645,14 @@
* @since 1.2
*/
public static final class UnicodeBlock extends Subset {
-
- private static Map<String, UnicodeBlock> map = new HashMap<>(256);
+ /**
+ * 510 - the expected number of enteties
+ * 0.75 - the default load factor of HashMap
+ */
+ private static final int INITIAL_CAPACITY =
+ (int)(510 / 0.75f + 1.0f);
+ private static Map<String, UnicodeBlock> map =
+ new HashMap<>(INITIAL_CAPACITY);
/**
* Creates a UnicodeBlock with the given identifier name.
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/lang/Character/UnicodeBlock/NonOptimalMapSize.java Mon May 18 19:15:50 2015 +0300
@@ -0,0 +1,72 @@
+/*
+ * 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 8080535
+ * @summary Expected size of Character.UnicodeBlock.map is not optimal
+ */
+
+import java.lang.reflect.Field;
+import java.util.HashMap;
+import java.util.Map;
+
+public class NonOptimalMapSize {
+ public static void main(String[] args) throws Throwable {
+ Class<?> ubCls = Character.UnicodeBlock.class;
+ Field mapField = ubCls.getDeclaredField("map");
+ mapField.setAccessible(true);
+ Map<?,?> map = (Map<?,?>)mapField.get(null);
+ if (!map.getClass().equals(HashMap.class)) {
+ throw new RuntimeException(
+ "Character.UnicodeBlock.map is expected to be HashMap");
+ }
+ int mapSize = map.size();
+
+ Field sizeField = ubCls.getDeclaredField("INITIAL_CAPACITY");
+ sizeField.setAccessible(true);
+ int INITIAL_CAPACITY = sizeField.getInt(null);
+
+ // Construct a HashMap with specified initial capacity
+ HashMap<Object,Object> map1 = new HashMap<>(INITIAL_CAPACITY);
+ Class<?> hmCls = HashMap.class;
+ Field tableField = hmCls.getDeclaredField("table");
+ tableField.setAccessible(true);
+ // ... and fill it up
+ map1.put(new Object(), new Object());
+ final Object initialTable = tableField.get(map1);
+ while (map1.size() < map.size() &&
+ initialTable == tableField.get(map1)) {
+ map1.put(new Object(), new Object());
+ }
+
+ // Now check that internal storage didn't change
+ if (initialTable != tableField.get(map1)) {
+ throw new RuntimeException(
+ "Initial capacity " + INITIAL_CAPACITY +
+ " was only enough to hold " + (map1.size()-1) +
+ " entries, but needed " + map.size());
+ }
+ }
+}