org.mmtk.utility

Class Treadmill

java.lang.Object

org.mmtk.utility.Treadmill

public final class Treadmill
extends Object

FIXME The DoublyLinkedList class, upon which this depends, must be re-written as it makes the assumption that the implementation language (Java) and the language being implemented are the same. This is true in the case of Jikes RVM, but it is not true for any VM implementing a language other than Java.

Each instance of this class is a doubly-linked list, in which each item or node is a piece of memory. The first two words of each node contains the forward and backward links. The third word contains the treadmill. The remaining portion is the payload.

The treadmill object itself must not be moved.

Access to the instances may be synchronized depending on the constructor argument.

Field Summary

Fields

Modifier and Type	Field and Description
private DoublyLinkedList	allocNursery
private DoublyLinkedList	collectNursery
private DoublyLinkedList	fromSpace
private DoublyLinkedList	toSpace

Constructor Summary

Constructors

Constructor and Description
Treadmill(int granularity, boolean shared)

Method Summary

Modifier and Type	Method and Description
void	addToTreadmill(Address node, boolean nursery) Adds a node to the treadmill.
void	copy(Address node, boolean isInNursery) Copies a node (during gc tracing).
void	flip(boolean fullHeap) Flips the roles of the spaces in preparation for a collection.
boolean	fromSpaceEmpty()
void	gcspyGatherData(int event, TreadmillDriver tmDriver) Gather data for GCSpy from the nursery
void	gcspyGatherData(int event, TreadmillDriver tmDriver, boolean tospace) Gather data for GCSpy
static int	headerSize()
static Address	midPayloadToNode(Address payload)
static Address	nodeToPayload(Address payload)
boolean	nurseryEmpty()
Address	pop() Removes a node from the mature list.
Address	popNursery() Removes a node from the nursery list.
boolean	toSpaceEmpty()

Methods inherited from class java.lang.Object

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

Field Detail

fromSpace

private DoublyLinkedList fromSpace

toSpace

private DoublyLinkedList toSpace

collectNursery

private DoublyLinkedList collectNursery

allocNursery

private DoublyLinkedList allocNursery

Constructor Detail

Treadmill

public Treadmill(int granularity,
                 boolean shared)

Parameters:

granularity - TODO needs documentation

shared - true if the created instance will be shared between threads. If it is shared, accesses will be synchronized using locks.

Method Detail

addToTreadmill

public void addToTreadmill(Address node,
                           boolean nursery)

Adds a node to the treadmill. This is usually performed on allocation.

Parameters:

node - the node to add

nursery - whether to add to the nursery or to the to-space

popNursery

public Address popNursery()

Removes a node from the nursery list.

Returns:

the removed node

pop

public Address pop()

Removes a node from the mature list.

Returns:

the removed node

copy

public void copy(Address node,
                 boolean isInNursery)

Copies a node (during gc tracing).

Parameters:

node - the node to copy

isInNursery - whether the node is in the nursery or the from-space

toSpaceEmpty

public boolean toSpaceEmpty()

Returns:

whether the to-space is empty

fromSpaceEmpty

public boolean fromSpaceEmpty()

Returns:

whether the from-space is empty

nurseryEmpty

public boolean nurseryEmpty()

Returns:

whether the nursery is empty

flip

public void flip(boolean fullHeap)

Flips the roles of the spaces in preparation for a collection.

Parameters:

fullHeap - whether the collection is full heap

headerSize

public static int headerSize()

Returns:

the header size

nodeToPayload

public static Address nodeToPayload(Address payload)

midPayloadToNode

public static Address midPayloadToNode(Address payload)

gcspyGatherData

public void gcspyGatherData(int event,
                            TreadmillDriver tmDriver)

Gather data for GCSpy from the nursery

Parameters:

event - the gc event

tmDriver - the GCSpy space driver

gcspyGatherData

public void gcspyGatherData(int event,
                            TreadmillDriver tmDriver,
                            boolean tospace)

Gather data for GCSpy

Parameters:

event - the gc event

tmDriver - the GCSpy space driver

tospace - gather from tospace?