org.github.jamm

Class MemoryLayoutSpecification

java.lang.Object

org.github.jamm.MemoryLayoutSpecification

public abstract class MemoryLayoutSpecification
extends Object

Field Summary

Fields

Modifier and Type	Field and Description
static MemoryLayoutSpecification	SPEC

Constructor Summary

Constructors

Constructor and Description
MemoryLayoutSpecification()

Method Summary

Modifier and Type	Method and Description
abstract int	getArrayHeaderSize()
abstract int	getObjectHeaderSize()
abstract int	getObjectPadding()
abstract int	getReferenceSize()
abstract int	getSuperclassFieldPadding()
static boolean	hasUnsafe()
static int	sizeOf(Field field)
static long	sizeOf(Object obj)
static long	sizeOfArray(int length, Class<?> type) Memory an array
static long	sizeOfArray(int length, long elementSize) Memory an array will consume
static long	sizeOfArray(Object instance, Class<?> type)
static int	sizeOfField(Class<?> type)
static long	sizeOfInstance(Class<?> type)
static long	sizeOfInstanceWithUnsafe(Class<?> type)
static long	sizeOfWithUnsafe(Object obj)

Methods inherited from class java.lang.Object

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

Field Detail

SPEC

public static final MemoryLayoutSpecification SPEC

Constructor Detail

MemoryLayoutSpecification

public MemoryLayoutSpecification()

Method Detail

getArrayHeaderSize

public abstract int getArrayHeaderSize()

getObjectHeaderSize

public abstract int getObjectHeaderSize()

getObjectPadding

public abstract int getObjectPadding()

getReferenceSize

public abstract int getReferenceSize()

getSuperclassFieldPadding

public abstract int getSuperclassFieldPadding()

hasUnsafe

public static boolean hasUnsafe()

sizeOf

public static int sizeOf(Field field)

Returns:

sizeOfField(field.getType())

sizeOfField

public static int sizeOfField(Class<?> type)

Returns:

The memory size of a field of a class of the provided type; for Objects this is the size of the reference only

sizeOf

public static long sizeOf(Object obj)

Returns:

The size of the provided instance as defined by the detected MemoryLayoutSpecification. For an array this is dependent on the size of the array, but for an object this is fixed for all instances

sizeOfWithUnsafe

public static long sizeOfWithUnsafe(Object obj)

Returns:

this allocated heap size of the instance provided; for arrays this is equivalent to sizeOf(obj), which uses the memory layout specification, however for objects this method uses

sizeOfInstance

public static long sizeOfInstance(Class<?> type)

sizeOfInstanceWithUnsafe

public static long sizeOfInstanceWithUnsafe(Class<?> type)

sizeOfArray

public static long sizeOfArray(Object instance,
                               Class<?> type)

sizeOfArray

public static long sizeOfArray(int length,
                               Class<?> type)

Memory an array

Parameters:

length - Number of elements in the array

type - the array class type

Returns:

In-memory size of the array

sizeOfArray

public static long sizeOfArray(int length,
                               long elementSize)

Memory an array will consume

Parameters:

length - Number of elements in the array

elementSize - In-memory size of each element's primitive stored

Returns:

In-memory size of the array