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sun.jvm.hotspot.utilities

public Class MarkBits

extends Object
Class Inheritance
Imports
sun.jvm.hotspot.debugger.*, sun.jvm.hotspot.gc.shared.*, sun.jvm.hotspot.memory.*, sun.jvm.hotspot.oops.*, sun.jvm.hotspot.runtime.*
Helper class which covers the reserved area of the heap with an (object-external) set of mark bits, used for GC-like scans through the heap like liveness analysis.

Field Summary

Modifier and TypeField and Description
private BitMapInterface
bits

private Address
end

private Address
start

Constructor Summary

AccessConstructor and Description
public
MarkBits(CollectedHeap heap)

Method Summary

Modifier and TypeMethod and Description
public void
clear()

public void
clear(Oop obj)

Forces clearing of a given mark bit.

public boolean
mark(Oop obj)

Returns true if a mark was newly placed for the given Oop, or false if the Oop was already marked.

Inherited from java.lang.Object:
cloneequalsfinalizegetClasshashCodenotifynotifyAlltoStringwaitwaitwait

Field Detail

bitsback to summary
private BitMapInterface bits
endback to summary
private Address end
startback to summary
private Address start

Constructor Detail

MarkBitsback to summary
public MarkBits(CollectedHeap heap)

Method Detail

clearback to summary
public void clear()
clearback to summary
public void clear(Oop obj)

Forces clearing of a given mark bit.

markback to summary
public boolean mark(Oop obj)

Returns true if a mark was newly placed for the given Oop, or false if the Oop was already marked. If the Oop happens to lie outside the heap (should not happen), prints a warning and returns false.