com.orientechnologies.orient.core.storage.cache.pages

Class OTinyPageCache

java.lang.Object

com.orientechnologies.orient.core.storage.cache.pages.OTinyPageCache

All Implemented Interfaces:

OPageCache

public class OTinyPageCache
extends Object
implements OPageCache

The implementation of a page cache suitable for page caches of a very tiny size, like 1-8 pages. Built on arrays, on a page load request always evicts the page with the lowest observed hits.

Author:

Sergey Sitnikov

Constructor Summary

Constructors

Constructor and Description
OTinyPageCache(OReadCache readCache, int maximumSize) Constructs a new tiny page cache instance.

Method Summary

Modifier and Type	Method and Description
OCacheEntry	loadPage(long fileId, long pageIndex, boolean checkPinnedPages, OWriteCache writeCache, int pageCount) Loads the page.
OCacheEntry	purgePage(long fileId, long pageIndex, OWriteCache writeCache) Purges the page from this page cache, but not from the underlying read cache.
void	releaseFilePages(long fileId, OWriteCache writeCache) Releases the pages associated with the given file.
void	releasePage(OCacheEntry cacheEntry, OWriteCache writeCache) Releases the page.
void	reset(OWriteCache writeCache) Resets this page cache by releasing all cached pages.

Methods inherited from class java.lang.Object

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

Constructor Detail

OTinyPageCache

public OTinyPageCache(OReadCache readCache,
                      int maximumSize)

Constructs a new tiny page cache instance.

Parameters:

readCache - the underlying read cache.

maximumSize - the maximum cache size in pages.

Method Detail

loadPage

public OCacheEntry loadPage(long fileId,
                            long pageIndex,
                            boolean checkPinnedPages,
                            OWriteCache writeCache,
                            int pageCount)
                     throws IOException

Description copied from interface: OPageCache

Loads the page.

Specified by:

loadPage in interface OPageCache

Parameters:

fileId - the page's file id to load from.

pageIndex - the page's index in the file.

checkPinnedPages - true to inspect the pinned pages in the underlying OReadCache, false to skip them.

writeCache - the underlying write cache.

pageCount - the number of pages to load.

Returns:

the loaded page or null if page is not found neither in this page cache nor underlying OReadCache.

Throws:

IOException - if there was an I/O error.

See Also:

OReadCache#load(long, long, boolean, OWriteCache, int)

releasePage

public void releasePage(OCacheEntry cacheEntry,
                        OWriteCache writeCache)

Description copied from interface: OPageCache

Releases the page.

Specified by:

releasePage in interface OPageCache

Parameters:

cacheEntry - the page to release.

writeCache - the underlying write cache instance.

See Also:

OReadCache.release(OCacheEntry, OWriteCache)

releaseFilePages

public void releaseFilePages(long fileId,
                             OWriteCache writeCache)

Description copied from interface: OPageCache

Releases the pages associated with the given file.

Specified by:

releaseFilePages in interface OPageCache

Parameters:

fileId - the file id of the file.

writeCache - the underlying write cache instance.

purgePage

public OCacheEntry purgePage(long fileId,
                             long pageIndex,
                             OWriteCache writeCache)

Description copied from interface: OPageCache

Purges the page from this page cache, but not from the underlying read cache. On return, there are no references to the purged page in a context of this page cache, but the page is still present in the underlying read cache.

Specified by:

purgePage in interface OPageCache

Parameters:

fileId - the page's file id.

pageIndex - the page's index in the file.

writeCache - the underlying write cache instance.

Returns:

the purged page or null if the page is not cached by this page cache.

reset

public void reset(OWriteCache writeCache)

Description copied from interface: OPageCache

Resets this page cache by releasing all cached pages.

Specified by:

reset in interface OPageCache

Parameters:

writeCache - the underlying write cache instance.