org.aksw.jena_sparql_api.io.binseach

Class PageManagerForFileChannel

java.lang.Object

org.aksw.jena_sparql_api.io.binseach.PageManagerForFileChannel

All Implemented Interfaces:

PageManager

public class PageManagerForFileChannel
extends Object
implements PageManager

Field Summary

Fields

Modifier and Type	Field and Description
protected FileChannel	channel
protected long	channelSize We rely on the channel's size being constant.
protected com.google.common.cache.Cache<Long,Reference<Page>>	pageCache The cache is crucial to the implementation.
protected int	pageSize

Constructor Summary

Constructors

Constructor and Description
PageManagerForFileChannel(FileChannel channel, long channelSize, int pageSize)

Method Summary

Modifier and Type	Method and Description
static PageManagerForFileChannel	create(FileChannel channel)
static PageManagerForFileChannel	create(FileChannel channel, int pageSize)
long	getEndPos()
int	getPageSize() The pageSize.
Reference<Page>	getRefForPage(long page)
Reference<Page>	requestBufferForPage(long page)

Methods inherited from class java.lang.Object

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

Field Detail

pageCache

protected com.google.common.cache.Cache<Long,Reference<Page>> pageCache

The cache is crucial to the implementation. Setting its size to 0 will cause excessive allocation of pages and thus a timely OutOfMemory error.

channel

protected FileChannel channel

channelSize

protected long channelSize

We rely on the channel's size being constant. A growing size should work, a shrinking one will cause exceptions.

pageSize

protected int pageSize

Constructor Detail

PageManagerForFileChannel

public PageManagerForFileChannel(FileChannel channel,
                                 long channelSize,
                                 int pageSize)

Method Detail

create

public static PageManagerForFileChannel create(FileChannel channel)
                                        throws IOException

Throws:

IOException

create

public static PageManagerForFileChannel create(FileChannel channel,
                                               int pageSize)
                                        throws IOException

Throws:

IOException

getPageSize

public int getPageSize()

Description copied from interface: PageManager

The pageSize. Must never change during the life time of a page manager.

Specified by:

getPageSize in interface PageManager

Returns:

requestBufferForPage

public Reference<Page> requestBufferForPage(long page)

Specified by:

requestBufferForPage in interface PageManager

getEndPos

public long getEndPos()

Specified by:

getEndPos in interface PageManager

getRefForPage

public Reference<Page> getRefForPage(long page)
                              throws IOException

Throws:

IOException