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

Interface OPageCache

All Known Implementing Classes:

OLruPageCache, OPassthroughPageCache, OTinyPageCache

public interface OPageCache

Defines the contract for page caches which act as a buffer between some page source and the consumer of the pages. Typically instances of this interface are backed by the underlying OReadCache and OWriteCache instances.

Author:

Sergey Sitnikov

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.

Method Detail

loadPage

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

Loads the page.

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

void releasePage(OCacheEntry cacheEntry,
                 OWriteCache writeCache)

Releases the page.

Parameters:

cacheEntry - the page to release.

writeCache - the underlying write cache instance.

See Also:

OReadCache.release(OCacheEntry, OWriteCache)

releaseFilePages

void releaseFilePages(long fileId,
                      OWriteCache writeCache)

Releases the pages associated with the given file.

Parameters:

fileId - the file id of the file.

writeCache - the underlying write cache instance.

purgePage

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

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.

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

void reset(OWriteCache writeCache)

Resets this page cache by releasing all cached pages.

Parameters:

writeCache - the underlying write cache instance.