monq.stuff

Class Sizeof

java.lang.Object

monq.stuff.Sizeof

public class Sizeof
extends java.lang.Object

estimator for the size of data structures. The sizes of individual elements used to compute the overall size of a data structure are estimates only derived on 1.4.2 on a 32bit Linux.

The implementation will be changed to java.lang.instrument.Instrumentation as soon as we switch to Java 5.

Author:

© 2005 Harald Kirsch

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Sizeof.Pair a pair of count and size describing use and size of a data type.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MEM_ARRAY_OVERHEAD
static int	MEM_CHAR_INARRAY
static int	MEM_OBJ_OVERHEAD
static int	MEM_PTR_SIZE

Method Summary

Modifier and Type	Method and Description
static int	charArrayMemEstimate(int numElems)
static int	objectArrayMemEstimate(int numElems)
static void	printTypes(java.io.PrintStream out, java.util.Map<java.lang.Class<?>,java.util.Map<java.lang.Class<?>,Sizeof.Pair>> types) prints the result produced with sizeof().
static int	roundUp(int l)
static java.util.Map<java.lang.Class<?>,java.util.Map<java.lang.Class<?>,Sizeof.Pair>>	sizeof(java.lang.Object o) recursively delves into the object graph o and returns a Hashtable with information about object sizes and counts.

Methods inherited from class java.lang.Object

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

Field Detail

MEM_ARRAY_OVERHEAD

public static final int MEM_ARRAY_OVERHEAD

MEM_PTR_SIZE

public static final int MEM_PTR_SIZE

MEM_CHAR_INARRAY

public static final int MEM_CHAR_INARRAY

MEM_OBJ_OVERHEAD

public static int MEM_OBJ_OVERHEAD

Method Detail

charArrayMemEstimate

public static int charArrayMemEstimate(int numElems)

objectArrayMemEstimate

public static int objectArrayMemEstimate(int numElems)

roundUp

public static int roundUp(int l)

sizeof

public static java.util.Map<java.lang.Class<?>,java.util.Map<java.lang.Class<?>,Sizeof.Pair>> sizeof(java.lang.Object o)

recursively delves into the object graph o and returns a Hashtable with information about object sizes and counts. The keys used in the result are java.lang.Class objects. Each key k is mapped to a java.util.Map object which pairs a class object r and a Sizeof.Pair. The Pair describes how often k appears as a field in an object of type r. In other words: within the object graph, objects of type r are parents of objects of type k.

printTypes

public static void printTypes(java.io.PrintStream out,
                              java.util.Map<java.lang.Class<?>,java.util.Map<java.lang.Class<?>,Sizeof.Pair>> types)

prints the result produced with sizeof().