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java.lang.Object de.lmu.ifi.dbs.elki.persistent.AbstractPageFile<P> de.lmu.ifi.dbs.elki.persistent.AbstractStoringPageFile<P> de.lmu.ifi.dbs.elki.persistent.OnDiskArrayPageFile<P>
P
- Page typepublic class OnDiskArrayPageFile<P extends Page>
A OnDiskArrayPageFile stores objects persistently that implement the
Page
interface. For convenience each page is represented by a
single file. All pages are stored in a specified directory.
Field Summary | |
---|---|
private static int |
EMPTY_PAGE
Indicates an empty page. |
private boolean |
existed
Whether or not the file originally existed |
private OnDiskArray |
file
The file storing the pages. |
private File |
filename
The file name to use |
private static int |
FILLED_PAGE
Indicates a filled page. |
protected PageHeader |
header
The header of this page file. |
Fields inherited from class de.lmu.ifi.dbs.elki.persistent.AbstractStoringPageFile |
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emptyPages, nextPageID, pageSize |
Fields inherited from class de.lmu.ifi.dbs.elki.persistent.AbstractPageFile |
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readAccess, writeAccess |
Constructor Summary | |
---|---|
OnDiskArrayPageFile(int pageSize,
String fileName)
Creates a new OnDiskArrayPageFile from an existing file. |
Method Summary | |
---|---|
private P |
byteBufferToPage(ByteBuffer buffer)
Reconstruct a serialized object from the specified byte array. |
void |
clear()
Clears this PageFile. |
void |
close()
Closes this file. |
void |
deletePage(int pageID)
Deletes the node with the specified id from this file. |
boolean |
initialize(PageHeader header)
Initialize the page file with the given header - return "true" if the file already existed. |
private byte[] |
pageToByteArray(P page)
Serializes an object into a byte array. |
P |
readPage(int pageID)
Reads the page with the given id from this file. |
void |
writePage(Integer pageID,
P page)
Write page to disk. |
Methods inherited from class de.lmu.ifi.dbs.elki.persistent.AbstractStoringPageFile |
---|
getInnerStatistics, getNextPageID, getPageSize, setNextPageID, setPageID |
Methods inherited from class de.lmu.ifi.dbs.elki.persistent.AbstractPageFile |
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getReadOperations, getWriteOperations, resetPageAccess, writePage |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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private static final int EMPTY_PAGE
private static final int FILLED_PAGE
private File filename
private OnDiskArray file
protected PageHeader header
private final boolean existed
Constructor Detail |
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public OnDiskArrayPageFile(int pageSize, String fileName)
pageSize
- page sizefileName
- the name of the fileMethod Detail |
---|
public P readPage(int pageID)
pageID
- the id of the page to be returned
public void deletePage(int pageID)
deletePage
in interface PageFile<P extends Page>
deletePage
in class AbstractStoringPageFile<P extends Page>
pageID
- the id of the node to be deletedpublic void writePage(Integer pageID, P page)
writePage
in class AbstractPageFile<P extends Page>
pageID
- page idpage
- the page which has to be written to diskpublic void close()
close
in interface PageFile<P extends Page>
close
in class AbstractPageFile<P extends Page>
public void clear()
private P byteBufferToPage(ByteBuffer buffer)
buffer
- the buffer from which the object should be reconstructed
private byte[] pageToByteArray(P page)
page
- the object to be serialized
public boolean initialize(PageHeader header)
AbstractStoringPageFile
initialize
in interface PageFile<P extends Page>
initialize
in class AbstractStoringPageFile<P extends Page>
header
- Header
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