com.oracle.svm.core.genscavenge

Class Space

java.lang.Object

com.oracle.svm.core.genscavenge.Space

public class Space
extends Object

A Space is a collection of HeapChunks. Each Space keeps two collections: one of AlignedHeapChunks and one of UnalignedHeapChunks. The Space for the YoungGeneration is special because it keeps Pointers to the "top" and "end" of the current aligned allocation chunk for fast-path allocation without any indirections. The complication is the "top" pointer has to be flushed back to the chunk to make the heap parsable.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Space.Accounting Keep whatever accounting is required.
static interface	Space.Verifier

Field Summary

Fields

Modifier and Type	Field and Description
protected String	name The name of this Space.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Space(String name, boolean isFrom, int age) Constructor for sub-classes.

Method Summary

Modifier and Type	Method and Description
Space.Accounting	getAccounting() The accounting for this Space.
String	getName() The name of this Space.
boolean	isEmpty() Keep whatever accounting is required.
void	release() Release all the memory in this Space.
Log	report(Log log, boolean traceHeapChunks) Report some statistics about this Space.
void	tearDown() Return all allocated virtual memory chunks to HeapChunkProvider.
void	verifyDirtyCards()
boolean	walkDirtyObjects(ObjectVisitor visitor, boolean clean) Walk the dirty Objects in this Space, passing each to a Visitor.
boolean	walkObjects(ObjectVisitor visitor) Walk the Objects in this Space, passing each to a Visitor.

Methods inherited from class java.lang.Object

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

Field Detail

name

protected final String name

The name of this Space.

Constructor Detail

Space

protected Space(String name,
                boolean isFrom,
                int age)

Constructor for sub-classes. Spaces are HOSTED_ONLY because all the Spaces should be constructed during native image generation so they end up in the native image heap rather than the garbage-collected heap because they need to be accessed during collections so they should not move. See, for example, HeapChunk.getSpace() which keeps a reference to the containing Space for the HeapChunk, which reference is not updated by collections. Having all the Spaces as compile-time constants also means I can ask if a Space is the Space of the YoungGeneration with a simple, fast, constant check.

Method Detail

getAccounting

public Space.Accounting getAccounting()

The accounting for this Space.

getName

public String getName()

The name of this Space. This method is used in logging and so should not require any work.

isEmpty

public boolean isEmpty()

Keep whatever accounting is required. Note that I can not keep track of all the objects allocated in this Space, because many of them are fast-path allocated, which bypasses all any accounting. What I can keep track of is all the chunks that are allocated in this Space, and the bytes reserved (but maybe not allocated) for objects.

tearDown

public final void tearDown()

Return all allocated virtual memory chunks to HeapChunkProvider.

walkObjects

public boolean walkObjects(ObjectVisitor visitor)

Walk the Objects in this Space, passing each to a Visitor.

walkDirtyObjects

public boolean walkDirtyObjects(ObjectVisitor visitor,
                                boolean clean)

Walk the dirty Objects in this Space, passing each to a Visitor.

Parameters:

visitor - An ObjectVisitor.

Returns:

True if all visits returned true, false otherwise.

report

public Log report(Log log,
                  boolean traceHeapChunks)

Report some statistics about this Space.

release

public void release()

Release all the memory in this Space.

verifyDirtyCards

public void verifyDirtyCards()