org.tmatesoft.sqljet.core.internal.pager
Class SqlJetPageCache

java.lang.Object
  org.tmatesoft.sqljet.core.internal.pager.SqlJetPageCache

All Implemented Interfaces:

ISqlJetPageCache

public class SqlJetPageCache
extends java.lang.Object
implements ISqlJetPageCache

A complete page cache is an instance of this structure.

Field Summary

static int	PAGE_CACHE_SIZE_DEFAULT
static int	PAGE_CACHE_SIZE_MINIMUM
static java.lang.String	SQLJET_PAGE_CACHE_SIZE System property name for cache size configuration.

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 pgno, 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 iter) 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 newPgno) Change a page number.
void	open(int szPage, boolean purgeable, ISqlJetPageCallback stress) Create a new pager cache.
void	release(ISqlJetPage page) Dereference a page.
void	setCacheSize(int mxPage) 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 pgno) Remove all pages with page numbers more than pageNumber.

Methods inherited from class java.lang.Object

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

Field Detail

SQLJET_PAGE_CACHE_SIZE

public static final java.lang.String SQLJET_PAGE_CACHE_SIZE

System property name for cache size configuration.

See Also:

Constant Field Values

PAGE_CACHE_SIZE_DEFAULT

public static final int PAGE_CACHE_SIZE_DEFAULT

See Also:

Constant Field Values

PAGE_CACHE_SIZE_MINIMUM

public static final int PAGE_CACHE_SIZE_MINIMUM

See Also:

Constant Field Values

Method Detail

open

public void open(int szPage,
                 boolean purgeable,
                 ISqlJetPageCallback stress)

Description copied from interface: ISqlJetPageCache

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

Specified by:

open in interface ISqlJetPageCache

Parameters:

szPage - Size of every page

purgeable - True if pages are on backing store

stress - Call to try to make pages clean

setPageSize

public void setPageSize(int pageSize)

Description copied from interface: ISqlJetPageCache

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.

Specified by:

setPageSize in interface ISqlJetPageCache

fetch

public ISqlJetPage fetch(int pgno,
                         boolean createFlag)
                  throws SqlJetException

Description copied from interface: ISqlJetPageCache

Try to obtain a page from the cache.

Specified by:

fetch in interface ISqlJetPageCache

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

Returns:

Throws:

SqlJetException

release

public void release(ISqlJetPage page)

Description copied from interface: ISqlJetPageCache

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.

Specified by:

release in interface ISqlJetPageCache

drop

public void drop(ISqlJetPage page)

Description copied from interface: ISqlJetPageCache

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.

Specified by:

drop in interface ISqlJetPageCache

makeDirty

public void makeDirty(ISqlJetPage page)

Description copied from interface: ISqlJetPageCache

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

Specified by:

makeDirty in interface ISqlJetPageCache

makeClean

public void makeClean(ISqlJetPage page)

Description copied from interface: ISqlJetPageCache

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

Specified by:

makeClean in interface ISqlJetPageCache

cleanAll

public void cleanAll()

Description copied from interface: ISqlJetPageCache

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

Specified by:

cleanAll in interface ISqlJetPageCache

clearSyncFlags

public void clearSyncFlags()

Description copied from interface: ISqlJetPageCache

Clear flags from pages of the page cache

Specified by:

clearSyncFlags in interface ISqlJetPageCache

move

public void move(ISqlJetPage page,
                 int newPgno)

Description copied from interface: ISqlJetPageCache

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.

Specified by:

move in interface ISqlJetPageCache

truncate

public void truncate(int pgno)

Description copied from interface: ISqlJetPageCache

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".

Specified by:

truncate in interface ISqlJetPageCache

close

public void close()

Description copied from interface: ISqlJetPageCache

Reset and close the cache object

Specified by:

close in interface ISqlJetPageCache

clear

public void clear()

Description copied from interface: ISqlJetPageCache

Discard the contents of the cache

Specified by:

clear in interface ISqlJetPageCache

getDirtyList

public ISqlJetPage getDirtyList()

Description copied from interface: ISqlJetPageCache

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

Specified by:

getDirtyList in interface ISqlJetPageCache

Returns:

getRefCount

public int getRefCount()

Description copied from interface: ISqlJetPageCache

Return the total number of outstanding page references

Specified by:

getRefCount in interface ISqlJetPageCache

getPageCount

public int getPageCount()

Description copied from interface: ISqlJetPageCache

Return the total number of pages stored in the cache

Specified by:

getPageCount in interface ISqlJetPageCache

getCachesize

public int getCachesize()

Description copied from interface: ISqlJetPageCache

Get the cache-size for the pager-cache.

Specified by:

getCachesize in interface ISqlJetPageCache

Returns:

setCacheSize

public void setCacheSize(int mxPage)

Description copied from interface: ISqlJetPageCache

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.

Specified by:

setCacheSize in interface ISqlJetPageCache

iterate

public void iterate(ISqlJetPageCallback iter)
             throws SqlJetException

Description copied from interface: ISqlJetPageCache

Iterate through all pages currently stored in the cache.

Specified by:

iterate in interface ISqlJetPageCache

Throws:

SqlJetException