/*
* Copyright 2011 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package org.jboss.netty.util.internal;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.zip.Deflater;
/**
* Utility that detects various properties specific to the current runtime
* environment, such as Java version and the availability of the
* {@code sun.misc.Unsafe} object.
*
* <br>
* You can disable the use of {@code sun.misc.Unsafe} if you specify
* the System property <strong>org.jboss.netty.tryUnsafe</strong> with
* value of <code>false</code>. Default is <code>true</code>.
*/
public final class DetectionUtil {
private static final int JAVA_VERSION = javaVersion0();
private static final boolean HAS_UNSAFE = hasUnsafe(AtomicInteger.class.getClassLoader());
public static boolean hasUnsafe() {
return HAS_UNSAFE;
}
public static int javaVersion() {
return JAVA_VERSION;
}
private static boolean hasUnsafe(ClassLoader loader) {
boolean useUnsafe = Boolean.valueOf(SystemPropertyUtil.get("org.jboss.netty.tryUnsafe", "true"));
if (!useUnsafe) {
return false;
}
try {
Class<?> unsafeClazz = Class.forName("sun.misc.Unsafe", true, loader);
return hasUnsafeField(unsafeClazz);
} catch (Exception e) {
// Ignore
}
return false;
}
private static boolean hasUnsafeField(final Class<?> unsafeClass) throws PrivilegedActionException {
return AccessController.doPrivileged(new PrivilegedExceptionAction<Boolean>() {
public Boolean run() throws Exception {
unsafeClass.getDeclaredField("theUnsafe");
return true;
}
});
}
private static int javaVersion0() {
try {
// Check if its android, if so handle it the same way as java6.
//
// See https://github.com/netty/netty/issues/282
Class.forName("android.app.Application");
return 6;
} catch (ClassNotFoundException e) {
//Ignore
}
try {
Deflater.class.getDeclaredField("SYNC_FLUSH");
return 7;
} catch (Exception e) {
// Ignore
}
try {
Double.class.getDeclaredField("MIN_NORMAL");
return 6;
} catch (Exception e) {
// Ignore
}
return 5;
}
private DetectionUtil() {
// only static method supported
}
}