Interface ISqlJetPageCache

  • All Known Implementing Classes:
    SqlJetPageCache

    public interface ISqlJetPageCache
    The page cache subsystem
    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      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
      • 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 -