8200788: Optimal initial capacity of java.lang.VarHandle.AccessMode.methodNameToAccessMode
Reviewed-by: redestad
--- a/src/java.base/share/classes/java/lang/invoke/VarHandle.java Fri Apr 06 08:58:22 2018 -0700
+++ b/src/java.base/share/classes/java/lang/invoke/VarHandle.java Sat Apr 07 17:07:13 2018 -0700
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2018, 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
@@ -1788,10 +1788,12 @@
static final Map<String, AccessMode> methodNameToAccessMode;
static {
- // Initial capacity of # values is sufficient to avoid resizes
- // for the smallest table size (32)
- methodNameToAccessMode = new HashMap<>(AccessMode.values().length);
- for (AccessMode am : AccessMode.values()) {
+ AccessMode[] values = AccessMode.values();
+ // Initial capacity of # values divided by the load factor is sufficient
+ // to avoid resizes for the smallest table size (64)
+ int initialCapacity = (int)(values.length / 0.75f) + 1;
+ methodNameToAccessMode = new HashMap<>(initialCapacity);
+ for (AccessMode am : values) {
methodNameToAccessMode.put(am.methodName, am);
}
}
--- a/test/jdk/java/lang/Enum/ConstantDirectoryOptimalCapacity.java Fri Apr 06 08:58:22 2018 -0700
+++ b/test/jdk/java/lang/Enum/ConstantDirectoryOptimalCapacity.java Sat Apr 07 17:07:13 2018 -0700
@@ -27,6 +27,7 @@
* @summary Initial capacity of Class.enumConstantDirectory is not optimal
* @library /lib/testlibrary
* @modules java.base/java.lang:open
+ * java.base/java.util:open
* @build jdk.testlibrary.OptimalCapacity
* @run main ConstantDirectoryOptimalCapacity
*/
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/lang/invoke/VarHandle/AccessMode/OptimalMapSize.java Sat Apr 07 17:07:13 2018 -0700
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2018, 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 8200788
+ * @summary Optimal initial capacity of AccessMode.methodNameToAccessMode
+ * @library /lib/testlibrary
+ * @modules java.base/java.lang.invoke:open
+ * java.base/java.util:open
+ * @build jdk.testlibrary.OptimalCapacity
+ * @run main OptimalMapSize
+ */
+
+import java.lang.invoke.VarHandle.AccessMode;
+import jdk.testlibrary.OptimalCapacity;
+
+public class OptimalMapSize {
+ public static void main(String[] args) throws Throwable {
+ int initialCapacity = (int)(AccessMode.values().length / 0.75f) + 1;
+ OptimalCapacity.ofHashMap(AccessMode.class, "methodNameToAccessMode",
+ initialCapacity);
+ }
+}