org.nd4j.linalg.api.buffer.unsafe.UnsafeHolder Maven / Gradle / Ivy
package org.nd4j.linalg.api.buffer.unsafe;
import sun.misc.Unsafe;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.nio.ByteBuffer;
/**
* Unsafe singleton holder
* @author Adam Gibson
*/
public class UnsafeHolder {
private static Unsafe INSTANCE;
private static Field ADDRESS_FIELD;
private static boolean is64Bit = System.getProperty("sun.arch.data.model").equals("64");
private UnsafeHolder() {}
/**
* Returns true if the jvm is 64 bit
* @return
*/
public static boolean is64Bit() {
return is64Bit;
}
/**
* Returns the field singleton
* used in the byte buffer
* @return the address field in the bytebuffer
* for reflection
* @throws NoSuchFieldException
*/
public static Field getAddressField() throws NoSuchFieldException {
if (ADDRESS_FIELD == null) {
ADDRESS_FIELD = getDeclaredFieldRecursive(ByteBuffer.class, "address");
}
return ADDRESS_FIELD;
}
private static Field getDeclaredFieldRecursive(final Class root, final String fieldName)
throws NoSuchFieldException {
Class type = root;
do {
try {
return type.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
type = type.getSuperclass();
}
} while (type != null);
throw new NoSuchFieldException(
fieldName + " does not exist in " + root.getSimpleName() + " or any of its superclasses.");
}
/**
* Unsafe singleton
* @return the unsafe singleton
* Reference:
* https://github.com/LWJGL/lwjgl/blob/master/src/java/org/lwjgl/MemoryUtilSun.java#L73
* @throws Exception
*/
public static Unsafe getUnsafe() throws Exception {
if (INSTANCE == null) {
final Field[] fields = Unsafe.class.getDeclaredFields();
/*
Different runtimes use different names for the Unsafe singleton,
so we cannot use .getDeclaredField and we scan instead. For example:
Oracle: theUnsafe
PERC : m_unsafe_instance
Android: THE_ONE
*/
for (Field field : fields) {
if (!field.getType().equals(Unsafe.class))
continue;
final int modifiers = field.getModifiers();
if (!(Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers)))
continue;
field.setAccessible(true);
try {
INSTANCE = (Unsafe) field.get(null);
} catch (IllegalAccessException e) {
// ignore
}
break;
}
}
return INSTANCE;
}
}