de.lmu.ifi.dbs.elki.persistent
Class AbstractPageFile<P extends Page>

java.lang.Object
  de.lmu.ifi.dbs.elki.persistent.AbstractPageFile<P>

Type Parameters:

P - page type

All Implemented Interfaces:

PageFile<P>, PageFileStatistics

Direct Known Subclasses:

AbstractStoringPageFile, LRUCache

public abstract class AbstractPageFile<P extends Page>
extends Object
implements PageFile<P>

Abstract base class for the page file API for both caches and true page files (in-memory and on-disk).

Field Summary

protected long	readAccess The read I/O-Access of this file.
protected long	writeAccess The write I/O-Access of this file.

Constructor Summary

AbstractPageFile()
Constructor.

Method Summary

void	close() Closes this file.
long	getReadOperations() Returns the read I/O-Accesses of this file.
long	getWriteOperations() Returns the write I/O-Accesses of this file.
void	resetPageAccess() Resets the counters for page accesses of this file and flushes the cache.
protected abstract void	writePage(Integer pageid, P page) Perform the actual page write operation.
int	writePage(P page) Writes a page into this file.

Methods inherited from class java.lang.Object

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

Methods inherited from interface de.lmu.ifi.dbs.elki.persistent.PageFile

clear, deletePage, getNextPageID, getPageSize, initialize, readPage, setNextPageID, setPageID

Methods inherited from interface de.lmu.ifi.dbs.elki.persistent.PageFileStatistics

getInnerStatistics

Field Detail

readAccess

protected long readAccess

The read I/O-Access of this file.

writeAccess

protected long writeAccess

The write I/O-Access of this file.

Constructor Detail

AbstractPageFile

public AbstractPageFile()

Constructor.

Method Detail

writePage

public final int writePage(P page)

Writes a page into this file. The method tests if the page has already an id, otherwise a new id is assigned and returned.

Specified by:

writePage in interface PageFile<P extends Page>

Parameters:

page - the page to be written

Returns:

the id of the page

writePage

protected abstract void writePage(Integer pageid,
                                  P page)

Perform the actual page write operation.

Parameters:

pageid - Page id

page - Page to write

close

public void close()

Description copied from interface: PageFile

Closes this file.

Specified by:

close in interface PageFile<P extends Page>

getReadOperations

public final long getReadOperations()

Description copied from interface: PageFileStatistics

Returns the read I/O-Accesses of this file.

Specified by:

getReadOperations in interface PageFileStatistics

Returns:

Number of physical read I/O accesses

getWriteOperations

public final long getWriteOperations()

Description copied from interface: PageFileStatistics

Returns the write I/O-Accesses of this file.

Specified by:

getWriteOperations in interface PageFileStatistics

Returns:

Number of physical write I/O accesses

resetPageAccess

public final void resetPageAccess()

Description copied from interface: PageFileStatistics

Resets the counters for page accesses of this file and flushes the cache.

Specified by:

resetPageAccess in interface PageFileStatistics