com.kenai.jffi

Class PageManager

java.lang.Object

com.kenai.jffi.PageManager

Direct Known Subclasses:

PageManager.Unix, PageManager.Windows

public abstract class PageManager
extends java.lang.Object

Manages allocation, disposal and protection of native memory pages

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	PageManager.SingletonHolder
(package private) static class	PageManager.Unix
(package private) static class	PageManager.Windows

Field Summary

Fields

Modifier and Type	Field and Description
private Foreign	foreign
private int	pageSize
static int	PROT_EXEC The memory should be executable
static int	PROT_READ The memory should be readable
static int	PROT_WRITE The memory should be writable

Constructor Summary

Constructors

Constructor and Description
PageManager()

Method Summary

Modifier and Type	Method and Description
abstract long	allocatePages(int npages, int protection) Allocates native memory pages.
private long	calculatePageSize()
abstract void	freePages(long address, int npages) Free pages allocated via allocatePages(int, int)
static PageManager	getInstance() Gets the page manager for the current platform.
long	pageSize() Gets the system page size.
abstract void	protectPages(long address, int npages, int protection) Sets the protection mask on a memory region.

Methods inherited from class java.lang.Object

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

Field Detail

PROT_EXEC

public static final int PROT_EXEC

The memory should be executable

See Also:

Constant Field Values

PROT_READ

public static final int PROT_READ

The memory should be readable

See Also:

Constant Field Values

PROT_WRITE

public static final int PROT_WRITE

The memory should be writable

See Also:

Constant Field Values

foreign

private final Foreign foreign

pageSize

private int pageSize

Constructor Detail

PageManager

public PageManager()

Method Detail

getInstance

public static PageManager getInstance()

Gets the page manager for the current platform.

Returns:

An instance of PageManager

pageSize

public final long pageSize()

Gets the system page size.

Returns:

The size of a page on the current system, in bytes.

calculatePageSize

private long calculatePageSize()

allocatePages

public abstract long allocatePages(int npages,
                                   int protection)

Allocates native memory pages. The memory allocated is aligned on a page boundary, and the size of the allocated memory is npages * pageSize.

Parameters:

npages - The number of pages to allocate.

protection - The initial protection for the page. This must be a bitmask of PROT_READ, PROT_WRITE and PROT_EXEC.

Returns:

The native address of the allocated memory.

freePages

public abstract void freePages(long address,
                               int npages)

Free pages allocated via allocatePages(int, int)

Parameters:

address - The memory address as returned from allocatePages(int, int)

npages - The number of pages to free.

protectPages

public abstract void protectPages(long address,
                                  int npages,
                                  int protection)

Sets the protection mask on a memory region.

Parameters:

address - The start of the memory region.

npages - The number of pages to protect.

protection - The protection mask.