com.yahoo.memory

Class UnsafeUtil

java.lang.Object

com.yahoo.memory.UnsafeUtil

public final class UnsafeUtil
extends Object

Provides access to the sun.misc.Unsafe class and its key static fields.

NOTE: Native/Direct memory acquired using Unsafe may have garbage in it. It is the responsibility of the using class to clear this memory, if required, and to call freeMemory() when done.

Author:

Lee Rhodes

Field Summary

Fields

Modifier and Type	Field and Description
static int	ADDRESS_SIZE
static int	ARRAY_BOOLEAN_BASE_OFFSET
static int	ARRAY_BOOLEAN_INDEX_SCALE
static int	ARRAY_BYTE_BASE_OFFSET
static int	ARRAY_BYTE_INDEX_SCALE
static int	ARRAY_CHAR_BASE_OFFSET
static int	ARRAY_CHAR_INDEX_SCALE
static int	ARRAY_DOUBLE_BASE_OFFSET
static int	ARRAY_DOUBLE_INDEX_SCALE
static int	ARRAY_FLOAT_BASE_OFFSET
static int	ARRAY_FLOAT_INDEX_SCALE
static int	ARRAY_INT_BASE_OFFSET
static int	ARRAY_INT_INDEX_SCALE
static int	ARRAY_LONG_BASE_OFFSET
static int	ARRAY_LONG_INDEX_SCALE
static int	ARRAY_OBJECT_BASE_OFFSET
static int	ARRAY_OBJECT_INDEX_SCALE
static int	ARRAY_SHORT_BASE_OFFSET
static int	ARRAY_SHORT_INDEX_SCALE
static int	BOOLEAN_SHIFT
static int	BYTE_SHIFT
static int	CHAR_SHIFT
static int	DOUBLE_SHIFT
static int	FLOAT_SHIFT
static int	INT_SHIFT
static int	LONG_SHIFT
static String	LS
static int	SHORT_SHIFT
static sun.misc.Unsafe	unsafe
static long	UNSAFE_COPY_THRESHOLD This number limits the number of bytes to copy per call to Unsafe's copyMemory method.

Method Summary

Modifier and Type	Method and Description
static void	assertBounds(long reqOff, long reqLen, long allocSize) Perform bounds checking using java assert (if enabled) checking the requested offset and length against the allocated size.
static void	checkBounds(long reqOff, long reqLen, long allocSize) Check the requested offset and length against the allocated size.
static boolean	checkOverlap(long srcOff, long dstOff, long length) Return true if the given offsets and length do not overlap.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

unsafe

public static final sun.misc.Unsafe unsafe

ADDRESS_SIZE

public static final int ADDRESS_SIZE

ARRAY_BOOLEAN_BASE_OFFSET

public static final int ARRAY_BOOLEAN_BASE_OFFSET

ARRAY_BYTE_BASE_OFFSET

public static final int ARRAY_BYTE_BASE_OFFSET

ARRAY_SHORT_BASE_OFFSET

public static final int ARRAY_SHORT_BASE_OFFSET

ARRAY_CHAR_BASE_OFFSET

public static final int ARRAY_CHAR_BASE_OFFSET

ARRAY_INT_BASE_OFFSET

public static final int ARRAY_INT_BASE_OFFSET

ARRAY_LONG_BASE_OFFSET

public static final int ARRAY_LONG_BASE_OFFSET

ARRAY_FLOAT_BASE_OFFSET

public static final int ARRAY_FLOAT_BASE_OFFSET

ARRAY_DOUBLE_BASE_OFFSET

public static final int ARRAY_DOUBLE_BASE_OFFSET

ARRAY_OBJECT_BASE_OFFSET

public static final int ARRAY_OBJECT_BASE_OFFSET

ARRAY_BOOLEAN_INDEX_SCALE

public static final int ARRAY_BOOLEAN_INDEX_SCALE

ARRAY_BYTE_INDEX_SCALE

public static final int ARRAY_BYTE_INDEX_SCALE

ARRAY_SHORT_INDEX_SCALE

public static final int ARRAY_SHORT_INDEX_SCALE

ARRAY_CHAR_INDEX_SCALE

public static final int ARRAY_CHAR_INDEX_SCALE

ARRAY_INT_INDEX_SCALE

public static final int ARRAY_INT_INDEX_SCALE

ARRAY_LONG_INDEX_SCALE

public static final int ARRAY_LONG_INDEX_SCALE

ARRAY_FLOAT_INDEX_SCALE

public static final int ARRAY_FLOAT_INDEX_SCALE

ARRAY_DOUBLE_INDEX_SCALE

public static final int ARRAY_DOUBLE_INDEX_SCALE

ARRAY_OBJECT_INDEX_SCALE

public static final int ARRAY_OBJECT_INDEX_SCALE

BOOLEAN_SHIFT

public static final int BOOLEAN_SHIFT

See Also:

Constant Field Values

BYTE_SHIFT

public static final int BYTE_SHIFT

See Also:

Constant Field Values

SHORT_SHIFT

public static final int SHORT_SHIFT

See Also:

Constant Field Values

CHAR_SHIFT

public static final int CHAR_SHIFT

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Constant Field Values

INT_SHIFT

public static final int INT_SHIFT

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Constant Field Values

LONG_SHIFT

public static final int LONG_SHIFT

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Constant Field Values

FLOAT_SHIFT

public static final int FLOAT_SHIFT

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Constant Field Values

DOUBLE_SHIFT

public static final int DOUBLE_SHIFT

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Constant Field Values

LS

public static final String LS

UNSAFE_COPY_THRESHOLD

public static final long UNSAFE_COPY_THRESHOLD

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.

See Also:

Constant Field Values

Method Detail

assertBounds

public static void assertBounds(long reqOff,
                                long reqLen,
                                long allocSize)

Perform bounds checking using java assert (if enabled) checking the requested offset and length against the allocated size. If reqOff + reqLen > allocSize or any of the parameters are negative an exception will be thrown.

Parameters:

reqOff - the requested offset

reqLen - the requested length

allocSize - the allocated size.

checkBounds

public static void checkBounds(long reqOff,
                               long reqLen,
                               long allocSize)

Check the requested offset and length against the allocated size. If reqOff + reqLen > allocSize or any of the parameters are negative an exception will be thrown.

Parameters:

reqOff - the requested offset

reqLen - the requested length

allocSize - the allocated size.

checkOverlap

public static boolean checkOverlap(long srcOff,
                                   long dstOff,
                                   long length)

Return true if the given offsets and length do not overlap.

Parameters:

srcOff - the start of the source region

dstOff - the start of the destination region

length - the length of both regions

Returns:

true if the given offsets and length do not overlap.