com.sun.electric.database.geometry.btree
Class PageStorage

java.lang.Object
  com.sun.electric.database.geometry.btree.PageStorage

Direct Known Subclasses:

CachingPageStorage, FilePageStorage, OverflowPageStorage

public abstract class PageStorage
extends java.lang.Object

Stores and retrieves fixed-size byte sequences indexed by a page number; page numbers are guaranteed to be contiguous starting at zero.

Constructor Summary

PageStorage(int pageSize)

Method Summary

abstract void	close() close the PageStorage; invocation of any other methods after close() has undefined results
abstract int	createPage() creates a new page with undefined contents; returns its pageid
abstract void	fsync() ensure that the all pages are written to nonvolatile storage
abstract void	fsync(int pageid) ensure that the designated page is written to nonvolatile storage
abstract int	getNumPages() returns the number of pages; all pageids strictly less than this are valid
int	getPageSize() returns the size, in bytes, of each page
abstract void	readPage(int pageid, byte[] buf, int ofs) reads a page
abstract void	writePage(int pageid, byte[] buf, int ofs) writes a page; throws an exception if the page did not exist

Methods inherited from class java.lang.Object

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

Constructor Detail

PageStorage

public PageStorage(int pageSize)

Method Detail

getPageSize

public final int getPageSize()

returns the size, in bytes, of each page

createPage

public abstract int createPage()

creates a new page with undefined contents; returns its pageid

getNumPages

public abstract int getNumPages()

returns the number of pages; all pageids strictly less than this are valid

writePage

public abstract void writePage(int pageid,
                               byte[] buf,
                               int ofs)

writes a page; throws an exception if the page did not exist

readPage

public abstract void readPage(int pageid,
                              byte[] buf,
                              int ofs)

reads a page

fsync

public abstract void fsync(int pageid)

ensure that the designated page is written to nonvolatile storage

fsync

public abstract void fsync()

ensure that the all pages are written to nonvolatile storage

close

public abstract void close()

close the PageStorage; invocation of any other methods after close() has undefined results