/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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.apache.hadoop.hbase.util;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.security.AccessController;
import java.security.PrivilegedAction;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.classification.InterfaceStability;
import sun.misc.Unsafe;
import sun.nio.ch.DirectBuffer;
@InterfaceAudience.Private
@InterfaceStability.Evolving
public final class UnsafeAccess {
private static final Log LOG = LogFactory.getLog(UnsafeAccess.class);
static final Unsafe theUnsafe;
/** The offset to the first element in a byte array. */
public static final long BYTE_ARRAY_BASE_OFFSET;
static final boolean littleEndian = ByteOrder.nativeOrder()
.equals(ByteOrder.LITTLE_ENDIAN);
// This number limits the number of bytes to copy per call to Unsafe's
// copyMemory method. A limit is imposed to allow for safepoint polling
// during a large copy
static final long UNSAFE_COPY_THRESHOLD = 1024L * 1024L;
static {
theUnsafe = (Unsafe) AccessController.doPrivileged(new PrivilegedAction<Object>() {
@Override
public Object run() {
try {
Field f = Unsafe.class.getDeclaredField("theUnsafe");
f.setAccessible(true);
return f.get(null);
} catch (Throwable e) {
LOG.warn("sun.misc.Unsafe is not accessible", e);
}
return null;
}
});
if (theUnsafe != null) {
BYTE_ARRAY_BASE_OFFSET = theUnsafe.arrayBaseOffset(byte[].class);
} else{
BYTE_ARRAY_BASE_OFFSET = -1;
}
}
private UnsafeAccess(){}
// APIs to read primitive data from a byte[] using Unsafe way
/**
* Converts a byte array to a short value considering it was written in big-endian format.
* @param bytes byte array
* @param offset offset into array
* @return the short value
*/
public static short toShort(byte[] bytes, int offset) {
if (littleEndian) {
return Short.reverseBytes(theUnsafe.getShort(bytes, offset + BYTE_ARRAY_BASE_OFFSET));
} else {
return theUnsafe.getShort(bytes, offset + BYTE_ARRAY_BASE_OFFSET);
}
}
/**
* Converts a byte array to an int value considering it was written in big-endian format.
* @param bytes byte array
* @param offset offset into array
* @return the int value
*/
public static int toInt(byte[] bytes, int offset) {
if (littleEndian) {
return Integer.reverseBytes(theUnsafe.getInt(bytes, offset + BYTE_ARRAY_BASE_OFFSET));
} else {
return theUnsafe.getInt(bytes, offset + BYTE_ARRAY_BASE_OFFSET);
}
}
/**
* Converts a byte array to a long value considering it was written in big-endian format.
* @param bytes byte array
* @param offset offset into array
* @return the long value
*/
public static long toLong(byte[] bytes, int offset) {
if (littleEndian) {
return Long.reverseBytes(theUnsafe.getLong(bytes, offset + BYTE_ARRAY_BASE_OFFSET));
} else {
return theUnsafe.getLong(bytes, offset + BYTE_ARRAY_BASE_OFFSET);
}
}
// APIs to write primitive data to a byte[] using Unsafe way
/**
* Put a short value out to the specified byte array position in big-endian format.
* @param bytes the byte array
* @param offset position in the array
* @param val short to write out
* @return incremented offset
*/
public static int putShort(byte[] bytes, int offset, short val) {
if (littleEndian) {
val = Short.reverseBytes(val);
}
theUnsafe.putShort(bytes, offset + BYTE_ARRAY_BASE_OFFSET, val);
return offset + Bytes.SIZEOF_SHORT;
}
/**
* Put an int value out to the specified byte array position in big-endian format.
* @param bytes the byte array
* @param offset position in the array
* @param val int to write out
* @return incremented offset
*/
public static int putInt(byte[] bytes, int offset, int val) {
if (littleEndian) {
val = Integer.reverseBytes(val);
}
theUnsafe.putInt(bytes, offset + BYTE_ARRAY_BASE_OFFSET, val);
return offset + Bytes.SIZEOF_INT;
}
/**
* Put a long value out to the specified byte array position in big-endian format.
* @param bytes the byte array
* @param offset position in the array
* @param val long to write out
* @return incremented offset
*/
public static int putLong(byte[] bytes, int offset, long val) {
if (littleEndian) {
val = Long.reverseBytes(val);
}
theUnsafe.putLong(bytes, offset + BYTE_ARRAY_BASE_OFFSET, val);
return offset + Bytes.SIZEOF_LONG;
}
// APIs to read primitive data from a ByteBuffer using Unsafe way
/**
* Reads a short value at the given buffer's offset considering it was written in big-endian
* format.
*
* @param buf
* @param offset
* @return short value at offset
*/
public static short toShort(ByteBuffer buf, int offset) {
if (littleEndian) {
return Short.reverseBytes(getAsShort(buf, offset));
}
return getAsShort(buf, offset);
}
/**
* Reads a short value at the given Object's offset considering it was written in big-endian
* format.
* @param ref
* @param offset
* @return short value at offset
*/
public static short toShort(Object ref, long offset) {
if (littleEndian) {
return Short.reverseBytes(theUnsafe.getShort(ref, offset));
}
return theUnsafe.getShort(ref, offset);
}
/**
* Reads bytes at the given offset as a short value.
* @param buf
* @param offset
* @return short value at offset
*/
static short getAsShort(ByteBuffer buf, int offset) {
if (buf.isDirect()) {
return theUnsafe.getShort(((DirectBuffer) buf).address() + offset);
}
return theUnsafe.getShort(buf.array(), BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset);
}
/**
* Reads an int value at the given buffer's offset considering it was written in big-endian
* format.
*
* @param buf
* @param offset
* @return int value at offset
*/
public static int toInt(ByteBuffer buf, int offset) {
if (littleEndian) {
return Integer.reverseBytes(getAsInt(buf, offset));
}
return getAsInt(buf, offset);
}
/**
* Reads a int value at the given Object's offset considering it was written in big-endian
* format.
* @param ref
* @param offset
* @return int value at offset
*/
public static int toInt(Object ref, long offset) {
if (littleEndian) {
return Integer.reverseBytes(theUnsafe.getInt(ref, offset));
}
return theUnsafe.getInt(ref, offset);
}
/**
* Reads bytes at the given offset as an int value.
* @param buf
* @param offset
* @return int value at offset
*/
static int getAsInt(ByteBuffer buf, int offset) {
if (buf.isDirect()) {
return theUnsafe.getInt(((DirectBuffer) buf).address() + offset);
}
return theUnsafe.getInt(buf.array(), BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset);
}
/**
* Reads a long value at the given buffer's offset considering it was written in big-endian
* format.
*
* @param buf
* @param offset
* @return long value at offset
*/
public static long toLong(ByteBuffer buf, int offset) {
if (littleEndian) {
return Long.reverseBytes(getAsLong(buf, offset));
}
return getAsLong(buf, offset);
}
/**
* Reads a long value at the given Object's offset considering it was written in big-endian
* format.
* @param ref
* @param offset
* @return long value at offset
*/
public static long toLong(Object ref, long offset) {
if (littleEndian) {
return Long.reverseBytes(theUnsafe.getLong(ref, offset));
}
return theUnsafe.getLong(ref, offset);
}
/**
* Reads bytes at the given offset as a long value.
* @param buf
* @param offset
* @return long value at offset
*/
static long getAsLong(ByteBuffer buf, int offset) {
if (buf.isDirect()) {
return theUnsafe.getLong(((DirectBuffer) buf).address() + offset);
}
return theUnsafe.getLong(buf.array(), BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset);
}
/**
* Put an int value out to the specified ByteBuffer offset in big-endian format.
* @param buf the ByteBuffer to write to
* @param offset offset in the ByteBuffer
* @param val int to write out
* @return incremented offset
*/
public static int putInt(ByteBuffer buf, int offset, int val) {
if (littleEndian) {
val = Integer.reverseBytes(val);
}
if (buf.isDirect()) {
theUnsafe.putInt(((DirectBuffer) buf).address() + offset, val);
} else {
theUnsafe.putInt(buf.array(), offset + buf.arrayOffset() + BYTE_ARRAY_BASE_OFFSET, val);
}
return offset + Bytes.SIZEOF_INT;
}
// APIs to copy data. This will be direct memory location copy and will be much faster
/**
* Copies the bytes from given array's offset to length part into the given buffer.
* @param src
* @param srcOffset
* @param dest
* @param destOffset
* @param length
*/
public static void copy(byte[] src, int srcOffset, ByteBuffer dest, int destOffset, int length) {
long destAddress = destOffset;
Object destBase = null;
if (dest.isDirect()) {
destAddress = destAddress + ((DirectBuffer) dest).address();
} else {
destAddress = destAddress + BYTE_ARRAY_BASE_OFFSET + dest.arrayOffset();
destBase = dest.array();
}
long srcAddress = srcOffset + BYTE_ARRAY_BASE_OFFSET;
unsafeCopy(src, srcAddress, destBase, destAddress, length);
}
private static void unsafeCopy(Object src, long srcAddr, Object dst, long destAddr, long len) {
while (len > 0) {
long size = (len > UNSAFE_COPY_THRESHOLD) ? UNSAFE_COPY_THRESHOLD : len;
theUnsafe.copyMemory(src, srcAddr, dst, destAddr, len);
len -= size;
srcAddr += size;
destAddr += size;
}
}
/**
* Copies specified number of bytes from given offset of {@code src} ByteBuffer to the
* {@code dest} array.
*
* @param src
* @param srcOffset
* @param dest
* @param destOffset
* @param length
*/
public static void copy(ByteBuffer src, int srcOffset, byte[] dest, int destOffset,
int length) {
long srcAddress = srcOffset;
Object srcBase = null;
if (src.isDirect()) {
srcAddress = srcAddress + ((DirectBuffer) src).address();
} else {
srcAddress = srcAddress + BYTE_ARRAY_BASE_OFFSET + src.arrayOffset();
srcBase = src.array();
}
long destAddress = destOffset + BYTE_ARRAY_BASE_OFFSET;
unsafeCopy(srcBase, srcAddress, dest, destAddress, length);
}
/**
* Copies specified number of bytes from given offset of {@code src} buffer into the {@code dest}
* buffer.
*
* @param src
* @param srcOffset
* @param dest
* @param destOffset
* @param length
*/
public static void copy(ByteBuffer src, int srcOffset, ByteBuffer dest, int destOffset,
int length) {
long srcAddress, destAddress;
Object srcBase = null, destBase = null;
if (src.isDirect()) {
srcAddress = srcOffset + ((DirectBuffer) src).address();
} else {
srcAddress = srcOffset + src.arrayOffset() + BYTE_ARRAY_BASE_OFFSET;
srcBase = src.array();
}
if (dest.isDirect()) {
destAddress = destOffset + ((DirectBuffer) dest).address();
} else {
destAddress = destOffset + BYTE_ARRAY_BASE_OFFSET + dest.arrayOffset();
destBase = dest.array();
}
unsafeCopy(srcBase, srcAddress, destBase, destAddress, length);
}
// APIs to add primitives to BBs
/**
* Put a short value out to the specified BB position in big-endian format.
* @param buf the byte buffer
* @param offset position in the buffer
* @param val short to write out
* @return incremented offset
*/
public static int putShort(ByteBuffer buf, int offset, short val) {
if (littleEndian) {
val = Short.reverseBytes(val);
}
if (buf.isDirect()) {
theUnsafe.putShort(((DirectBuffer) buf).address() + offset, val);
} else {
theUnsafe.putShort(buf.array(), BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset, val);
}
return offset + Bytes.SIZEOF_SHORT;
}
/**
* Put a long value out to the specified BB position in big-endian format.
* @param buf the byte buffer
* @param offset position in the buffer
* @param val long to write out
* @return incremented offset
*/
public static int putLong(ByteBuffer buf, int offset, long val) {
if (littleEndian) {
val = Long.reverseBytes(val);
}
if (buf.isDirect()) {
theUnsafe.putLong(((DirectBuffer) buf).address() + offset, val);
} else {
theUnsafe.putLong(buf.array(), BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset, val);
}
return offset + Bytes.SIZEOF_LONG;
}
/**
* Put a byte value out to the specified BB position in big-endian format.
* @param buf the byte buffer
* @param offset position in the buffer
* @param b byte to write out
* @return incremented offset
*/
public static int putByte(ByteBuffer buf, int offset, byte b) {
if (buf.isDirect()) {
theUnsafe.putByte(((DirectBuffer) buf).address() + offset, b);
} else {
theUnsafe.putByte(buf.array(),
BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset, b);
}
return offset + 1;
}
/**
* Returns the byte at the given offset
* @param buf the buffer to read
* @param offset the offset at which the byte has to be read
* @return the byte at the given offset
*/
public static byte toByte(ByteBuffer buf, int offset) {
if (buf.isDirect()) {
return theUnsafe.getByte(((DirectBuffer) buf).address() + offset);
} else {
return theUnsafe.getByte(buf.array(), BYTE_ARRAY_BASE_OFFSET + buf.arrayOffset() + offset);
}
}
/**
* Returns the byte at the given offset of the object
* @param ref
* @param offset
* @return the byte at the given offset
*/
public static byte toByte(Object ref, long offset) {
return theUnsafe.getByte(ref, offset);
}
}