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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package com.google.protobuf;
import java.lang.reflect.Field;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.security.AccessController;
import java.security.PrivilegedExceptionAction;
import java.util.logging.Level;
import java.util.logging.Logger;
/** Utility class for working with unsafe operations. */
final class UnsafeUtil {
private static final Logger logger = Logger.getLogger(UnsafeUtil.class.getName());
private static final sun.misc.Unsafe UNSAFE = getUnsafe();
private static final MemoryAccessor MEMORY_ACCESSOR = getMemoryAccessor();
private static final boolean HAS_UNSAFE_BYTEBUFFER_OPERATIONS =
supportsUnsafeByteBufferOperations();
private static final boolean HAS_UNSAFE_ARRAY_OPERATIONS = supportsUnsafeArrayOperations();
static final long BYTE_ARRAY_BASE_OFFSET = arrayBaseOffset(byte[].class);
// Micro-optimization: we can assume a scale of 1 and skip the multiply
// private static final long BYTE_ARRAY_INDEX_SCALE = 1;
private static final long BOOLEAN_ARRAY_BASE_OFFSET = arrayBaseOffset(boolean[].class);
private static final long BOOLEAN_ARRAY_INDEX_SCALE = arrayIndexScale(boolean[].class);
private static final long INT_ARRAY_BASE_OFFSET = arrayBaseOffset(int[].class);
private static final long INT_ARRAY_INDEX_SCALE = arrayIndexScale(int[].class);
private static final long LONG_ARRAY_BASE_OFFSET = arrayBaseOffset(long[].class);
private static final long LONG_ARRAY_INDEX_SCALE = arrayIndexScale(long[].class);
private static final long FLOAT_ARRAY_BASE_OFFSET = arrayBaseOffset(float[].class);
private static final long FLOAT_ARRAY_INDEX_SCALE = arrayIndexScale(float[].class);
private static final long DOUBLE_ARRAY_BASE_OFFSET = arrayBaseOffset(double[].class);
private static final long DOUBLE_ARRAY_INDEX_SCALE = arrayIndexScale(double[].class);
private static final long OBJECT_ARRAY_BASE_OFFSET = arrayBaseOffset(Object[].class);
private static final long OBJECT_ARRAY_INDEX_SCALE = arrayIndexScale(Object[].class);
private static final long BUFFER_ADDRESS_OFFSET = fieldOffset(bufferAddressField());
private static final int STRIDE = 8;
private static final int STRIDE_ALIGNMENT_MASK = STRIDE - 1;
private static final int BYTE_ARRAY_ALIGNMENT =
(int) (BYTE_ARRAY_BASE_OFFSET & STRIDE_ALIGNMENT_MASK);
static final boolean IS_BIG_ENDIAN = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
private UnsafeUtil() {}
static boolean hasUnsafeArrayOperations() {
return HAS_UNSAFE_ARRAY_OPERATIONS;
}
static boolean hasUnsafeByteBufferOperations() {
return HAS_UNSAFE_BYTEBUFFER_OPERATIONS;
}
@SuppressWarnings("unchecked") // safe by method contract
static T allocateInstance(Class clazz) {
try {
return (T) UNSAFE.allocateInstance(clazz);
} catch (InstantiationException e) {
throw new IllegalStateException(e);
}
}
static long objectFieldOffset(Field field) {
return MEMORY_ACCESSOR.objectFieldOffset(field);
}
private static int arrayBaseOffset(Class clazz) {
return HAS_UNSAFE_ARRAY_OPERATIONS ? MEMORY_ACCESSOR.arrayBaseOffset(clazz) : -1;
}
private static int arrayIndexScale(Class clazz) {
return HAS_UNSAFE_ARRAY_OPERATIONS ? MEMORY_ACCESSOR.arrayIndexScale(clazz) : -1;
}
static byte getByte(Object target, long offset) {
return MEMORY_ACCESSOR.getByte(target, offset);
}
static void putByte(Object target, long offset, byte value) {
MEMORY_ACCESSOR.putByte(target, offset, value);
}
static int getInt(Object target, long offset) {
return MEMORY_ACCESSOR.getInt(target, offset);
}
static void putInt(Object target, long offset, int value) {
MEMORY_ACCESSOR.putInt(target, offset, value);
}
static long getLong(Object target, long offset) {
return MEMORY_ACCESSOR.getLong(target, offset);
}
static void putLong(Object target, long offset, long value) {
MEMORY_ACCESSOR.putLong(target, offset, value);
}
static boolean getBoolean(Object target, long offset) {
return MEMORY_ACCESSOR.getBoolean(target, offset);
}
static void putBoolean(Object target, long offset, boolean value) {
MEMORY_ACCESSOR.putBoolean(target, offset, value);
}
static float getFloat(Object target, long offset) {
return MEMORY_ACCESSOR.getFloat(target, offset);
}
static void putFloat(Object target, long offset, float value) {
MEMORY_ACCESSOR.putFloat(target, offset, value);
}
static double getDouble(Object target, long offset) {
return MEMORY_ACCESSOR.getDouble(target, offset);
}
static void putDouble(Object target, long offset, double value) {
MEMORY_ACCESSOR.putDouble(target, offset, value);
}
static Object getObject(Object target, long offset) {
return MEMORY_ACCESSOR.getObject(target, offset);
}
static void putObject(Object target, long offset, Object value) {
MEMORY_ACCESSOR.putObject(target, offset, value);
}
static byte getByte(byte[] target, long index) {
return MEMORY_ACCESSOR.getByte(target, BYTE_ARRAY_BASE_OFFSET + index);
}
static void putByte(byte[] target, long index, byte value) {
MEMORY_ACCESSOR.putByte(target, BYTE_ARRAY_BASE_OFFSET + index, value);
}
static int getInt(int[] target, long index) {
return MEMORY_ACCESSOR.getInt(target, INT_ARRAY_BASE_OFFSET + (index * INT_ARRAY_INDEX_SCALE));
}
static void putInt(int[] target, long index, int value) {
MEMORY_ACCESSOR.putInt(target, INT_ARRAY_BASE_OFFSET + (index * INT_ARRAY_INDEX_SCALE), value);
}
static long getLong(long[] target, long index) {
return MEMORY_ACCESSOR.getLong(
target, LONG_ARRAY_BASE_OFFSET + (index * LONG_ARRAY_INDEX_SCALE));
}
static void putLong(long[] target, long index, long value) {
MEMORY_ACCESSOR.putLong(
target, LONG_ARRAY_BASE_OFFSET + (index * LONG_ARRAY_INDEX_SCALE), value);
}
static boolean getBoolean(boolean[] target, long index) {
return MEMORY_ACCESSOR.getBoolean(
target, BOOLEAN_ARRAY_BASE_OFFSET + (index * BOOLEAN_ARRAY_INDEX_SCALE));
}
static void putBoolean(boolean[] target, long index, boolean value) {
MEMORY_ACCESSOR.putBoolean(
target, BOOLEAN_ARRAY_BASE_OFFSET + (index * BOOLEAN_ARRAY_INDEX_SCALE), value);
}
static float getFloat(float[] target, long index) {
return MEMORY_ACCESSOR.getFloat(
target, FLOAT_ARRAY_BASE_OFFSET + (index * FLOAT_ARRAY_INDEX_SCALE));
}
static void putFloat(float[] target, long index, float value) {
MEMORY_ACCESSOR.putFloat(
target, FLOAT_ARRAY_BASE_OFFSET + (index * FLOAT_ARRAY_INDEX_SCALE), value);
}
static double getDouble(double[] target, long index) {
return MEMORY_ACCESSOR.getDouble(
target, DOUBLE_ARRAY_BASE_OFFSET + (index * DOUBLE_ARRAY_INDEX_SCALE));
}
static void putDouble(double[] target, long index, double value) {
MEMORY_ACCESSOR.putDouble(
target, DOUBLE_ARRAY_BASE_OFFSET + (index * DOUBLE_ARRAY_INDEX_SCALE), value);
}
static Object getObject(Object[] target, long index) {
return MEMORY_ACCESSOR.getObject(
target, OBJECT_ARRAY_BASE_OFFSET + (index * OBJECT_ARRAY_INDEX_SCALE));
}
static void putObject(Object[] target, long index, Object value) {
MEMORY_ACCESSOR.putObject(
target, OBJECT_ARRAY_BASE_OFFSET + (index * OBJECT_ARRAY_INDEX_SCALE), value);
}
static void copyMemory(byte[] src, long srcIndex, long targetOffset, long length) {
MEMORY_ACCESSOR.copyMemory(src, srcIndex, targetOffset, length);
}
static void copyMemory(long srcOffset, byte[] target, long targetIndex, long length) {
MEMORY_ACCESSOR.copyMemory(srcOffset, target, targetIndex, length);
}
static void copyMemory(byte[] src, long srcIndex, byte[] target, long targetIndex, long length) {
System.arraycopy(src, (int) srcIndex, target, (int) targetIndex, (int) length);
}
static byte getByte(long address) {
return MEMORY_ACCESSOR.getByte(address);
}
static void putByte(long address, byte value) {
MEMORY_ACCESSOR.putByte(address, value);
}
static int getInt(long address) {
return MEMORY_ACCESSOR.getInt(address);
}
static void putInt(long address, int value) {
MEMORY_ACCESSOR.putInt(address, value);
}
static long getLong(long address) {
return MEMORY_ACCESSOR.getLong(address);
}
static void putLong(long address, long value) {
MEMORY_ACCESSOR.putLong(address, value);
}
/** Gets the offset of the {@code address} field of the given direct {@link ByteBuffer}. */
static long addressOffset(ByteBuffer buffer) {
return MEMORY_ACCESSOR.getLong(buffer, BUFFER_ADDRESS_OFFSET);
}
static Object getStaticObject(Field field) {
return MEMORY_ACCESSOR.getStaticObject(field);
}
/**
* Gets the {@code sun.misc.Unsafe} instance, or {@code null} if not available on this platform.
*/
static sun.misc.Unsafe getUnsafe() {
sun.misc.Unsafe unsafe = null;
try {
unsafe =
AccessController.doPrivileged(
new PrivilegedExceptionAction() {
@Override
public sun.misc.Unsafe run() throws Exception {
Class k = sun.misc.Unsafe.class;
for (Field f : k.getDeclaredFields()) {
f.setAccessible(true);
Object x = f.get(null);
if (k.isInstance(x)) {
return k.cast(x);
}
}
// The sun.misc.Unsafe field does not exist.
return null;
}
});
} catch (Throwable e) {
// Catching Throwable here due to the fact that Google AppEngine raises NoClassDefFoundError
// for Unsafe.
}
return unsafe;
}
/** Get a {@link MemoryAccessor} appropriate for the platform, or null if not supported. */
private static MemoryAccessor getMemoryAccessor() {
if (UNSAFE == null) {
return null;
}
return new JvmMemoryAccessor(UNSAFE);
}
/** Indicates whether or not unsafe array operations are supported on this platform. */
private static boolean supportsUnsafeArrayOperations() {
if (UNSAFE == null) {
return false;
}
try {
Class clazz = UNSAFE.getClass();
clazz.getMethod("objectFieldOffset", Field.class);
clazz.getMethod("arrayBaseOffset", Class.class);
clazz.getMethod("arrayIndexScale", Class.class);
clazz.getMethod("getInt", Object.class, long.class);
clazz.getMethod("putInt", Object.class, long.class, int.class);
clazz.getMethod("getLong", Object.class, long.class);
clazz.getMethod("putLong", Object.class, long.class, long.class);
clazz.getMethod("getObject", Object.class, long.class);
clazz.getMethod("putObject", Object.class, long.class, Object.class);
clazz.getMethod("getByte", Object.class, long.class);
clazz.getMethod("putByte", Object.class, long.class, byte.class);
clazz.getMethod("getBoolean", Object.class, long.class);
clazz.getMethod("putBoolean", Object.class, long.class, boolean.class);
clazz.getMethod("getFloat", Object.class, long.class);
clazz.getMethod("putFloat", Object.class, long.class, float.class);
clazz.getMethod("getDouble", Object.class, long.class);
clazz.getMethod("putDouble", Object.class, long.class, double.class);
return true;
} catch (Throwable e) {
logger.log(
Level.WARNING,
"platform method missing - proto runtime falling back to safer methods: " + e);
}
return false;
}
private static boolean supportsUnsafeByteBufferOperations() {
if (UNSAFE == null) {
return false;
}
try {
Class clazz = UNSAFE.getClass();
// Methods for getting direct buffer address.
clazz.getMethod("objectFieldOffset", Field.class);
clazz.getMethod("getLong", Object.class, long.class);
if (bufferAddressField() == null) {
return false;
}
clazz.getMethod("getByte", long.class);
clazz.getMethod("putByte", long.class, byte.class);
clazz.getMethod("getInt", long.class);
clazz.getMethod("putInt", long.class, int.class);
clazz.getMethod("getLong", long.class);
clazz.getMethod("putLong", long.class, long.class);
clazz.getMethod("copyMemory", long.class, long.class, long.class);
clazz.getMethod("copyMemory", Object.class, long.class, Object.class, long.class, long.class);
return true;
} catch (Throwable e) {
logger.log(
Level.WARNING,
"platform method missing - proto runtime falling back to safer methods: " + e);
}
return false;
}
/** Finds the address field within a direct {@link Buffer}. */
private static Field bufferAddressField() {
Field field = field(Buffer.class, "address");
return field != null && field.getType() == long.class ? field : null;
}
/**
* Returns the index of the first byte where left and right differ, in the range [0, 8]. If {@code
* left == right}, the result will be 8, otherwise less than 8.
*
* This counts from the *first* byte, which may be the most or least significant byte depending
* on the system endianness.
*/
private static int firstDifferingByteIndexNativeEndian(long left, long right) {
int n =
IS_BIG_ENDIAN
? Long.numberOfLeadingZeros(left ^ right)
: Long.numberOfTrailingZeros(left ^ right);
return n >> 3;
}
/**
* Returns the lowest {@code index} such that {@code 0 <= index < length} and {@code left[leftOff
* + index] != right[rightOff + index]}. If no such value exists -- if {@code left} and {@code
* right} match up to {@code length} bytes from their respective offsets -- returns -1.
*
*
{@code leftOff + length} must be less than or equal to {@code left.length}, and the same for
* {@code right}.
*/
static int mismatch(byte[] left, int leftOff, byte[] right, int rightOff, int length) {
if (leftOff < 0
|| rightOff < 0
|| length < 0
|| leftOff + length > left.length
|| rightOff + length > right.length) {
throw new IndexOutOfBoundsException();
}
int index = 0;
if (HAS_UNSAFE_ARRAY_OPERATIONS) {
int leftAlignment = (BYTE_ARRAY_ALIGNMENT + leftOff) & STRIDE_ALIGNMENT_MASK;
// Most CPUs handle getting chunks of bytes better on addresses that are a multiple of 4
// or 8.
// We walk one byte at a time until the left address, at least, is a multiple of 8.
// If the right address is, too, so much the better.
for (;
index < length && (leftAlignment & STRIDE_ALIGNMENT_MASK) != 0;
index++, leftAlignment++) {
if (left[leftOff + index] != right[rightOff + index]) {
return index;
}
}
// Stride! Grab eight bytes at a time from left and right and check them for equality.
int strideLength = ((length - index) & ~STRIDE_ALIGNMENT_MASK) + index;
// strideLength is the point where we want to stop striding: it differs from index by
// a multiple of STRIDE, and it's the largest such number <= length.
for (; index < strideLength; index += STRIDE) {
long leftLongWord = getLong(left, BYTE_ARRAY_BASE_OFFSET + leftOff + index);
long rightLongWord = getLong(right, BYTE_ARRAY_BASE_OFFSET + rightOff + index);
if (leftLongWord != rightLongWord) {
// one of these eight bytes differ! use a helper to find out which one
return index + firstDifferingByteIndexNativeEndian(leftLongWord, rightLongWord);
}
}
}
// If we were able to stride, there are at most STRIDE - 1 bytes left to compare.
// If we weren't, then this loop covers the whole thing.
for (; index < length; index++) {
if (left[leftOff + index] != right[rightOff + index]) {
return index;
}
}
return -1;
}
/**
* Returns the offset of the provided field, or {@code -1} if {@code sun.misc.Unsafe} is not
* available.
*/
private static long fieldOffset(Field field) {
return field == null || MEMORY_ACCESSOR == null ? -1 : MEMORY_ACCESSOR.objectFieldOffset(field);
}
/**
* Gets the field with the given name within the class, or {@code null} if not found.
*/
private static Field field(Class clazz, String fieldName) {
Field field;
try {
field = clazz.getDeclaredField(fieldName);
} catch (Throwable t) {
// Failed to access the fields.
field = null;
}
return field;
}
private abstract static class MemoryAccessor {
sun.misc.Unsafe unsafe;
MemoryAccessor(sun.misc.Unsafe unsafe) {
this.unsafe = unsafe;
}
public final long objectFieldOffset(Field field) {
return unsafe.objectFieldOffset(field);
}
public abstract byte getByte(Object target, long offset);
public abstract void putByte(Object target, long offset, byte value);
public final int getInt(Object target, long offset) {
return unsafe.getInt(target, offset);
}
public final void putInt(Object target, long offset, int value) {
unsafe.putInt(target, offset, value);
}
public final long getLong(Object target, long offset) {
return unsafe.getLong(target, offset);
}
public final void putLong(Object target, long offset, long value) {
unsafe.putLong(target, offset, value);
}
public abstract boolean getBoolean(Object target, long offset);
public abstract void putBoolean(Object target, long offset, boolean value);
public abstract float getFloat(Object target, long offset);
public abstract void putFloat(Object target, long offset, float value);
public abstract double getDouble(Object target, long offset);
public abstract void putDouble(Object target, long offset, double value);
public final Object getObject(Object target, long offset) {
return unsafe.getObject(target, offset);
}
public final void putObject(Object target, long offset, Object value) {
unsafe.putObject(target, offset, value);
}
public final int arrayBaseOffset(Class clazz) {
return unsafe.arrayBaseOffset(clazz);
}
public final int arrayIndexScale(Class clazz) {
return unsafe.arrayIndexScale(clazz);
}
public abstract byte getByte(long address);
public abstract void putByte(long address, byte value);
public abstract int getInt(long address);
public abstract void putInt(long address, int value);
public abstract long getLong(long address);
public abstract void putLong(long address, long value);
public abstract Object getStaticObject(Field field);
public abstract void copyMemory(long srcOffset, byte[] target, long targetIndex, long length);
public abstract void copyMemory(byte[] src, long srcIndex, long targetOffset, long length);
}
private static final class JvmMemoryAccessor extends MemoryAccessor {
JvmMemoryAccessor(sun.misc.Unsafe unsafe) {
super(unsafe);
}
@Override
public byte getByte(long address) {
return unsafe.getByte(address);
}
@Override
public void putByte(long address, byte value) {
unsafe.putByte(address, value);
}
@Override
public int getInt(long address) {
return unsafe.getInt(address);
}
@Override
public void putInt(long address, int value) {
unsafe.putInt(address, value);
}
@Override
public long getLong(long address) {
return unsafe.getLong(address);
}
@Override
public void putLong(long address, long value) {
unsafe.putLong(address, value);
}
@Override
public byte getByte(Object target, long offset) {
return unsafe.getByte(target, offset);
}
@Override
public void putByte(Object target, long offset, byte value) {
unsafe.putByte(target, offset, value);
}
@Override
public boolean getBoolean(Object target, long offset) {
return unsafe.getBoolean(target, offset);
}
@Override
public void putBoolean(Object target, long offset, boolean value) {
unsafe.putBoolean(target, offset, value);
}
@Override
public float getFloat(Object target, long offset) {
return unsafe.getFloat(target, offset);
}
@Override
public void putFloat(Object target, long offset, float value) {
unsafe.putFloat(target, offset, value);
}
@Override
public double getDouble(Object target, long offset) {
return unsafe.getDouble(target, offset);
}
@Override
public void putDouble(Object target, long offset, double value) {
unsafe.putDouble(target, offset, value);
}
@Override
public void copyMemory(long srcOffset, byte[] target, long targetIndex, long length) {
unsafe.copyMemory(null, srcOffset, target, BYTE_ARRAY_BASE_OFFSET + targetIndex, length);
}
@Override
public void copyMemory(byte[] src, long srcIndex, long targetOffset, long length) {
unsafe.copyMemory(src, BYTE_ARRAY_BASE_OFFSET + srcIndex, null, targetOffset, length);
}
@Override
public Object getStaticObject(Field field) {
return getObject(unsafe.staticFieldBase(field), unsafe.staticFieldOffset(field));
}
}
}