AbstractPageFile (ELKI: Environment for DeveLoping KDD-Applications Supported by Index-Structures)

java.lang.Object
- elki.persistent.AbstractPageFile<P>

Type Parameters:

P - page type

All Implemented Interfaces:

PageFile<P>

Direct Known Subclasses:

AbstractStoringPageFile, LRUCache
```
public abstract class AbstractPageFile<P extends Page>
extends java.lang.Object
implements PageFile<P>
```
Abstract base class for the page file API for both caches and true page files (in-memory and on-disk).

Since:

0.4.0

Author:

Erich Schubert

Field Summary

Fields
Modifier and Type Field Description

private Counter readAccess
The read I/O-Access of this file.

private Counter writeAccess
The write I/O-Access of this file.

Constructor Summary

Constructors
Constructor Description

AbstractPageFile()
Constructor.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`close()`	Closes this file.
`protected void`	`countRead()`	Count a page read access.
`protected void`	`countWrite()`	Count a page write access.
`protected abstract Logging`	`getLogger()`	Get the class logger.
`void`	`logStatistics()`	Log some statistics to the appropriate logger.
`protected abstract void`	`writePage(int 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 elki.persistent.PageFile
clear, deletePage, getNextPageID, getPageSize, initialize, readPage, setNextPageID, setPageID

- Field Detail
  - readAccess
```
private Counter readAccess
```
    The read I/O-Access of this file.
  - writeAccess
```
private Counter writeAccess
```
    The write I/O-Access of this file.
- Constructor Detail
  - AbstractPageFile
```
public AbstractPageFile()
```
    Constructor.
- Method Detail
  - getLogger
```
protected abstract Logging getLogger()
```
    Get the class logger.
    
    Returns:
    
    Logger
  - 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(int 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>
  - logStatistics
```
public void logStatistics()
```
    Description copied from interface: PageFile
    
    Log some statistics to the appropriate logger.
    
    Specified by:
    
    logStatistics in interface PageFile<P extends Page>
  - countRead
```
protected void countRead()
```
    Count a page read access.
  - countWrite
```
protected void countWrite()
```
    Count a page write access.