/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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 eu.stratosphere.core.memory;
import java.lang.reflect.Field;
import java.nio.ByteOrder;
/**
* Utility class for native (unsafe) memory accesses.
*/
public class MemoryUtils {
/**
* The "unsafe", which can be used to perform native memory accesses.
*/
@SuppressWarnings("restriction")
public static final sun.misc.Unsafe UNSAFE = getUnsafe();
/**
* The native byte order of the platform on which the system currently runs.
*/
public static final ByteOrder NATIVE_BYTE_ORDER = getByteOrder();
@SuppressWarnings("restriction")
private static sun.misc.Unsafe getUnsafe() {
try {
Field unsafeField = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
unsafeField.setAccessible(true);
return (sun.misc.Unsafe) unsafeField.get(null);
} catch (SecurityException e) {
throw new RuntimeException("Could not access the unsafe handle.", e);
} catch (NoSuchFieldException e) {
throw new RuntimeException("The static unsafe handle field was not be found.");
} catch (IllegalArgumentException e) {
throw new RuntimeException("Bug: Illegal argument reflection access for static field.");
} catch (IllegalAccessException e) {
throw new RuntimeException("Access to the unsafe handle is forbidden by the runtime.", e);
}
}
@SuppressWarnings("restriction")
private static ByteOrder getByteOrder() {
final byte[] bytes = new byte[8];
final long value = 0x12345678900abdefL;
UNSAFE.putLong(bytes, (long) UNSAFE.arrayBaseOffset(byte[].class), value);
final int lower = bytes[0] & 0xff;
final int higher = bytes[7] & 0xff;
if (lower == 0x12 && higher == 0xef) {
return ByteOrder.BIG_ENDIAN;
} else if (lower == 0xef && higher == 0x12) {
return ByteOrder.LITTLE_ENDIAN;
} else {
throw new RuntimeException("Unrecognized byte order.");
}
}
private MemoryUtils() {}
}