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package sun.jvm.hotspot.gc.shared;

import java.io.*;
import java.util.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.types.*;

A Space describes a heap area. Class Space is an abstract base class.

Space supports allocation, size computation and GC support is provided.

Invariant: bottom() and end() are on page_size boundaries and:

bottom() <= top() <= end()

top() is inclusive and end() is exclusive.

/** <P> A Space describes a heap area. Class Space is an abstract base class. </P> <P> Space supports allocation, size computation and GC support is provided. </P> <P> Invariant: bottom() and end() are on page_size boundaries and: </P> <P> bottom() <= top() <= end() </P> <P> top() is inclusive and end() is exclusive. </P> */
public abstract class Space extends VMObject { private static AddressField bottomField; private static AddressField endField; static { VM.registerVMInitializedObserver(new Observer() { public void update(Observable o, Object data) { initialize(VM.getVM().getTypeDataBase()); } }); } private static synchronized void initialize(TypeDataBase db) { Type type = db.lookupType("Space"); bottomField = type.getAddressField("_bottom"); endField = type.getAddressField("_end"); } public Space(Address addr) { super(addr); } public Address bottom() { return bottomField.getValue(addr); } public Address end() { return endField.getValue(addr); }
Returns a subregion of the space containing all the objects in the space.
/** Returns a subregion of the space containing all the objects in the space. */
public MemRegion usedRegion() { return new MemRegion(bottom(), end()); }
Support for iteration over heap -- not sure how this will interact with GC in reflective system, but necessary for the debugging mechanism
/** Support for iteration over heap -- not sure how this will interact with GC in reflective system, but necessary for the debugging mechanism */
public OopHandle bottomAsOopHandle() { return bottomField.getOopHandle(addr); }
Support for iteration over heap -- not sure how this will interact with GC in reflective system, but necessary for the debugging mechanism
/** Support for iteration over heap -- not sure how this will interact with GC in reflective system, but necessary for the debugging mechanism */
public OopHandle nextOopHandle(OopHandle handle, long size) { return handle.addOffsetToAsOopHandle(size); }
returns all MemRegions where live objects are
/** returns all MemRegions where live objects are */
public abstract List/*<MemRegion>*/ getLiveRegions();
Returned value is in bytes
/** Returned value is in bytes */
public long capacity() { return end().minus(bottom()); }
Returned value is in bytes
/** Returned value is in bytes */
public abstract long used();
Returned value is in bytes
/** Returned value is in bytes */
public abstract long free();
Testers
/** Testers */
public boolean contains(Address p) { return (bottom().lessThanOrEqual(p) && end().greaterThan(p)); } public void print() { printOn(System.out); } public void printOn(PrintStream tty) { tty.print(" space capacity = "); tty.print(capacity()); tty.print(", "); tty.print((double) used() * 100.0/ capacity()); tty.print(" used"); } }