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.

The internal static initializer also detects whether the methods unique to the Unsafe class in JDK8 are present; if not, methods that are compatible with JDK7 are substituted using an internal interface. In order for this to work with jdk7, this library must be compiled using jdk8 and it must be done with both source and target versions of jdk7 specified in pom.xml. The resultant jar will work on jdk7 and jdk8.

This may work with jdk9 but might require the JVM arg -permit-illegal-access, –illegal-access=permit or equivalent. Proper operation with jdk9 or above is not guaranteed and has not been tested.

Author:

Lee Rhodes

Field Summary

Fields

Modifier and Type	Field and Description
static int	ADDRESS_SIZE
static long	ARRAY_BOOLEAN_BASE_OFFSET
static int	ARRAY_BOOLEAN_INDEX_SCALE
static long	ARRAY_BYTE_BASE_OFFSET
static int	ARRAY_BYTE_INDEX_SCALE
static long	ARRAY_CHAR_BASE_OFFSET
static long	ARRAY_CHAR_INDEX_SCALE
static long	ARRAY_DOUBLE_BASE_OFFSET
static long	ARRAY_DOUBLE_INDEX_SCALE
static long	ARRAY_FLOAT_BASE_OFFSET
static long	ARRAY_FLOAT_INDEX_SCALE
static long	ARRAY_INT_BASE_OFFSET
static long	ARRAY_INT_INDEX_SCALE
static long	ARRAY_LONG_BASE_OFFSET
static long	ARRAY_LONG_INDEX_SCALE
static long	ARRAY_OBJECT_BASE_OFFSET
static long	ARRAY_OBJECT_INDEX_SCALE
static long	ARRAY_SHORT_BASE_OFFSET
static long	ARRAY_SHORT_INDEX_SCALE
static int	BOOLEAN_SHIFT
static int	BYTE_SHIFT
static long	CHAR_SHIFT
static long	DOUBLE_SHIFT
static long	FLOAT_SHIFT
static long	INT_SHIFT
static String	JDK
static long	LONG_SHIFT
static String	LS
static long	OBJECT_SHIFT
static long	SHORT_SHIFT
static sun.misc.Unsafe	unsafe

Method Summary

Modifier and Type	Method and Description
static void	assertBounds(long reqOff, long reqLen, long allocSize) Assert 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.

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

JDK

public static final String JDK

ADDRESS_SIZE

public static final int ADDRESS_SIZE

ARRAY_BOOLEAN_BASE_OFFSET

public static final long ARRAY_BOOLEAN_BASE_OFFSET

ARRAY_BYTE_BASE_OFFSET

public static final long ARRAY_BYTE_BASE_OFFSET

ARRAY_SHORT_BASE_OFFSET

public static final long ARRAY_SHORT_BASE_OFFSET

ARRAY_CHAR_BASE_OFFSET

public static final long ARRAY_CHAR_BASE_OFFSET

ARRAY_INT_BASE_OFFSET

public static final long ARRAY_INT_BASE_OFFSET

ARRAY_LONG_BASE_OFFSET

public static final long ARRAY_LONG_BASE_OFFSET

ARRAY_FLOAT_BASE_OFFSET

public static final long ARRAY_FLOAT_BASE_OFFSET

ARRAY_DOUBLE_BASE_OFFSET

public static final long ARRAY_DOUBLE_BASE_OFFSET

ARRAY_OBJECT_BASE_OFFSET

public static final long ARRAY_OBJECT_BASE_OFFSET

ARRAY_BOOLEAN_INDEX_SCALE

public static final int ARRAY_BOOLEAN_INDEX_SCALE

See Also:

Constant Field Values

ARRAY_BYTE_INDEX_SCALE

public static final int ARRAY_BYTE_INDEX_SCALE

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Constant Field Values

ARRAY_SHORT_INDEX_SCALE

public static final long ARRAY_SHORT_INDEX_SCALE

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Constant Field Values

ARRAY_CHAR_INDEX_SCALE

public static final long ARRAY_CHAR_INDEX_SCALE

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Constant Field Values

ARRAY_INT_INDEX_SCALE

public static final long ARRAY_INT_INDEX_SCALE

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Constant Field Values

ARRAY_LONG_INDEX_SCALE

public static final long ARRAY_LONG_INDEX_SCALE

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Constant Field Values

ARRAY_FLOAT_INDEX_SCALE

public static final long ARRAY_FLOAT_INDEX_SCALE

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Constant Field Values

ARRAY_DOUBLE_INDEX_SCALE

public static final long ARRAY_DOUBLE_INDEX_SCALE

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Constant Field Values

ARRAY_OBJECT_INDEX_SCALE

public static final long ARRAY_OBJECT_INDEX_SCALE

BOOLEAN_SHIFT

public static final int BOOLEAN_SHIFT

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Constant Field Values

BYTE_SHIFT

public static final int BYTE_SHIFT

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Constant Field Values

SHORT_SHIFT

public static final long SHORT_SHIFT

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Constant Field Values

CHAR_SHIFT

public static final long CHAR_SHIFT

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Constant Field Values

INT_SHIFT

public static final long INT_SHIFT

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Constant Field Values

LONG_SHIFT

public static final long LONG_SHIFT

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Constant Field Values

FLOAT_SHIFT

public static final long FLOAT_SHIFT

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Constant Field Values

DOUBLE_SHIFT

public static final long DOUBLE_SHIFT

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Constant Field Values

OBJECT_SHIFT

public static final long OBJECT_SHIFT

LS

public static final String LS

Method Detail

assertBounds

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

Assert the requested offset and length against the allocated size. The invariants equation is: 0 <= reqOff <= reqLen <= reqOff + reqLen <= allocSize. If this equation is violated and assertions are enabled, an AssertionError 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. The invariants equation is: 0 <= reqOff <= reqLen <= reqOff + reqLen <= allocSize. If this equation is violated an IllegalArgumentException will be thrown.

Parameters:

reqOff - the requested offset

reqLen - the requested length

allocSize - the allocated size.