org.tmatesoft.sqljet.core.internal
Interface ISqlJetPageCache

All Known Implementing Classes:

SqlJetPageCache

public interface ISqlJetPageCache

The page cache subsystem

Method Summary

void	cleanAll() Mark all dirty list pages as clean Make every page in the cache clean.
void	clear() Discard the contents of the cache
void	clearSyncFlags() Clear flags from pages of the page cache
void	close() Reset and close the cache object
void	drop(ISqlJetPage page) Remove page from cache Drop a page from the cache.
ISqlJetPage	fetch(int pageNumber, boolean createFlag) Try to obtain a page from the cache.
int	getCachesize() Get the cache-size for the pager-cache.
ISqlJetPage	getDirtyList() Get a list of all dirty pages in the cache, sorted by page number
int	getPageCount() Return the total number of pages stored in the cache
int	getRefCount() Return the total number of outstanding page references
void	iterate(ISqlJetPageCallback xIter) Iterate through all pages currently stored in the cache.
void	makeClean(ISqlJetPage page) Make sure the page is marked as clean.
void	makeDirty(ISqlJetPage page) Make sure the page is marked as dirty.
void	move(ISqlJetPage page, int pageNumber) Change a page number.
void	open(int szPage, boolean bPurgeable, ISqlJetPageCallback xStress) Create a new pager cache.
void	release(ISqlJetPage page) Dereference a page.
void	setCacheSize(int cacheSize) Set the suggested cache-size for the pager-cache.
void	setPageSize(int pageSize) Modify the page-size after the cache has been created.
void	truncate(int pageNumber) Remove all pages with page numbers more than pageNumber.

Method Detail

open

void open(int szPage,
          boolean bPurgeable,
          ISqlJetPageCallback xStress)

Create a new pager cache. Under memory stress, invoke xStress to try to make pages clean. Only clean and unpinned pages can be reclaimed.

Parameters:

szPage - Size of every page

szExtra - Extra space associated with each page

bPurgeable - True if pages are on backing store

xDestroy - Called to destroy a page

xStress - Call to try to make pages clean

setPageSize

void setPageSize(int pageSize)

Modify the page-size after the cache has been created. Change the page size for PCache object. This can only happen when the cache is empty.

Parameters:

pageSize -

fetch

ISqlJetPage fetch(int pageNumber,
                  boolean createFlag)
                  throws SqlJetException

Try to obtain a page from the cache.

Parameters:

pgno - Page number to obtain

createFlag - If true, create page if it does not exist already

Returns:

Throws:

SqlJetException

release

void release(ISqlJetPage page)

Dereference a page. When the reference count reaches zero, move the page to the LRU list if it is clean. One release per successful fetch. Page is pinned until released. Reference counted.

Parameters:

page -

Throws:

SqlJetExceptionRemove

drop

void drop(ISqlJetPage page)

Remove page from cache Drop a page from the cache. There must be exactly one reference to the page. This function deletes that reference, so after it returns the page pointed to by p is invalid.

Parameters:

page -

Throws:

SqlJetExceptionRemove

makeDirty

void makeDirty(ISqlJetPage page)

Make sure the page is marked as dirty. If it isn't dirty already, make it so.

Parameters:

page -

Throws:

SqlJetExceptionRemove

makeClean

void makeClean(ISqlJetPage page)

Make sure the page is marked as clean. If it isn't clean already, make it so.

Parameters:

page -

Throws:

SqlJetExceptionRemove

cleanAll

void cleanAll()

Mark all dirty list pages as clean Make every page in the cache clean.

Throws:

SqlJetExceptionRemove

move

void move(ISqlJetPage page,
          int pageNumber)

Change a page number. Used by incr-vacuum. Change the page number of page p to newPgno. If newPgno is 0, then the page object is added to the clean-list and the PGHDR_REUSE_UNLIKELY flag set.

Parameters:

page -

pageNumber -

Throws:

SqlJetExceptionRemove

truncate

void truncate(int pageNumber)

Remove all pages with page numbers more than pageNumber. Reset the cache if pageNumber==0 Drop every cache entry whose page number is greater than "pgno".

Parameters:

pageNumber -

Throws:

SqlJetExceptionRemove

getDirtyList

ISqlJetPage getDirtyList()

Get a list of all dirty pages in the cache, sorted by page number

Returns:

close

void close()

Reset and close the cache object

clearSyncFlags

void clearSyncFlags()

Clear flags from pages of the page cache

Throws:

SqlJetExceptionRemove

clear

void clear()

Discard the contents of the cache

getRefCount

int getRefCount()

Return the total number of outstanding page references

getPageCount

int getPageCount()

Return the total number of pages stored in the cache

iterate

void iterate(ISqlJetPageCallback xIter)
             throws SqlJetException

Iterate through all pages currently stored in the cache.

Parameters:

xIter -

Throws:

SqlJetException

getCachesize

int getCachesize()

Get the cache-size for the pager-cache.

Returns:

setCacheSize

void setCacheSize(int cacheSize)

Set the suggested cache-size for the pager-cache. If no global maximum is configured, then the system attempts to limit the total number of pages cached by purgeable pager-caches to the sum of the suggested cache-sizes.

Parameters:

cacheSize -