109 lines
3.6 KiB
Java
109 lines
3.6 KiB
Java
/*
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* Copyright (c) 2002-2011 LWJGL Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* * Neither the name of 'LWJGL' nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.lwjgl.util.mapped;
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import java.lang.reflect.Field;
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import java.lang.reflect.Modifier;
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import java.nio.ByteBuffer;
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import sun.misc.Unsafe;
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/**
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* [INTERNAL USE ONLY]
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*
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* @author Riven
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*/
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public class MappedObjectUnsafe {
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public static final Unsafe INSTANCE = getUnsafeInstance();
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private static final long BUFFER_ADDRESS_OFFSET = getObjectFieldOffset(ByteBuffer.class, "address");
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private static final long BUFFER_CAPACITY_OFFSET = getObjectFieldOffset(ByteBuffer.class, "capacity");
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private static final ByteBuffer global = ByteBuffer.allocateDirect(4 * 1024);
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static ByteBuffer newBuffer(long address, int capacity) {
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if ( address <= 0L || capacity < 0 )
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throw new IllegalStateException("you almost crashed the jvm");
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ByteBuffer buffer = global.duplicate();
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INSTANCE.putLong(buffer, BUFFER_ADDRESS_OFFSET, address);
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INSTANCE.putInt(buffer, BUFFER_CAPACITY_OFFSET, capacity);
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buffer.position(0);
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buffer.limit(capacity);
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return buffer;
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}
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private static long getObjectFieldOffset(Class<?> type, String fieldName) {
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while ( type != null ) {
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try {
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return INSTANCE.objectFieldOffset(type.getDeclaredField(fieldName));
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} catch (Throwable t) {
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type = type.getSuperclass();
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}
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}
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throw new UnsupportedOperationException();
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}
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private static Unsafe getUnsafeInstance() {
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final Field[] fields = Unsafe.class.getDeclaredFields();
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/*
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Different runtimes use different names for the Unsafe singleton,
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so we cannot use .getDeclaredField and we scan instead. For example:
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Oracle: theUnsafe
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PERC : m_unsafe_instance
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Android: THE_ONE
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*/
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for ( Field field : fields ) {
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if ( !field.getType().equals(Unsafe.class) )
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continue;
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final int modifiers = field.getModifiers();
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if ( !(Modifier.isStatic(modifiers) && Modifier.isFinal(modifiers)) )
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continue;
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field.setAccessible(true);
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try {
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return (Unsafe)field.get(null);
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} catch (IllegalAccessException e) {
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// ignore
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}
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break;
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}
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throw new UnsupportedOperationException();
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}
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} |