stan/jdk-24
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

8080535: (ch) Expected size of Character.UnicodeBlock.map is not optimal

Browse Source 
Reviewed-by: martin, chegar
This commit is contained in:
Ivan Gerasimov 2015-05-18 19:15:50 +03:00
parent 7e89934d9e
commit 43b2601a96
2 changed files with 81 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
jdk/src/java.base/share/classes/java/lang/Character.java
View File

@ -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 @@ class Character implements java.io.Serializable, Comparable<Character> {
* @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.

72
jdk/test/java/lang/Character/UnicodeBlock/NonOptimalMapSize.java Normal file
View File

@ -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());
}
}
}