Class RStorePagePool

class RStorePagePool : public TCachePagePool;

Description

Uses a store to implement the page pool interface MPagePool.

Pages can be reclaimable (tracked by the page pool, so that they can be freed when required) or not (in which case they must be deleted explicitly): this is indicated by a flag of type TPageReclamation. Non-reclaimable pages each have their own stream in the store; reclaimable pages are bundled 15 to a stream. To track the reclaimable pages, the page pool has a separate token, type TStorePagePoolToken, that must be saved by the user of the pool.

The store used must support CStreamStore::ExtendL(), CStreamStore::DeleteL(TStreamId) and allow streams to be re-written. CPermanentFileStore meets these conditions.

A store page pool uses a cache to store pages in-memory and to cache frequently accessed pages. You should provide a cache object (CPageCache) to the pool for this purpose.

Derivation

• MPagePool - Interface to a page pool, the storage abstraction used by the B-trees API.

• TCachePagePool - Provides a page pool with cached pages.

• RStorePagePool - Uses a store to implement the page pool interface MPagePool.

Members

Defined in RStorePagePool:

• Close()Flushes and purges the page cache and stops using the stream store.
• Create(CStreamStore &)Creates a new pool.
• Discard()Invalidates the list of free pages in the reclaimable set.
• DoDeleteL(TPageRef)
• ExtendL(const TAny *,TPageReclamation)
• HasAvailable()constTests if there is a free page in the pool.
• IsDirty()constTests if the dirty flag has been set on the page pool.
• IsEmpty()constTests if the page pool is empty.
• MarkCurrent()Clears the dirty flag.
• MarkDirty()Sets the dirty flag on the pool.
• Open(CStreamStore &,const TStorePagePoolToken &)Opens an existing pool.
• RStorePagePool()Default constructor.
• RStorePagePool(CPageCache &)Constructor with a page cache for the pool.
• RStorePagePool(CStreamStore &)Constructor with a stream store to use for the pool.
• RStorePagePool(CStreamStore &,const TStorePagePoolToken &)Constructor with a stream store and settings to use for the pool.
• ReadL(TPageRef,TAny *)
• ReclaimAllL()Deletes all streams in the store.
• ReclaimL()Deletes the first stream that stores reclaimable pages in the store.
• Release()Purges the page cache and stops using the stream store.
• Token()constGets an object that encapsulates the page pool settings.
• WriteL(TPageRef,const TAny *,TPageChange)

Inherited from MPagePool:

• Delete(TPageRef)Deletes a page, ignoring any errors.
• DeleteL(TPageRef)Deletes a page, leaving if an error occurs.
• Pop()Do a pop from the cleanup stack.
• PushL()Pushes this object onto the cleanup stack.

Inherited from TCachePagePool:

• AcquireL()Returns a function that abandons all locked pages for this page pool.
• AllocL()Allocates an unassigned page.
• AssignL(const TAny *,TPageReclamation)Assigns a reference to a new page and unlocks it.
• Flush()Flush all pages in this pool from the cache.
• FlushL()Flushes all pages in this pool from the cache, leaving with a system-wide error ...
• LockL(TPageRef)Locks a page and returns a pointer to it.
• Purge()Purge all pages in this pool from the cache.
• Set(CPageCache &)Sets the page cache for the pool.
• TCachePagePool(CPageCache &)
• Unlock(const TAny *,TPageChange)Unlocks a page.
• UpdateL(const TAny *)Updates a page.

See also:

• CStreamStore...

IMPORT_C RStorePagePool();

Description

Default constructor.

IMPORT_C RStorePagePool(CPageCache &aCache);

Description

Constructor with a page cache for the pool.

Parameters

IMPORT_C RStorePagePool(CStreamStore &aStore);

Description

Constructor with a stream store to use for the pool.

Parameters

IMPORT_C RStorePagePool(CStreamStore &aStore, const TStorePagePoolToken &aToken);

Description

Constructor with a stream store and settings to use for the pool.

Parameters

IMPORT_C void Create(CStreamStore &aStore);

Description

Creates a new pool.

Parameters

IMPORT_C void Open(CStreamStore &aStore, const TStorePagePoolToken &aToken);

Description

Opens an existing pool.

Parameters

IMPORT_C TStorePagePoolToken Token() const;

Description

Gets an object that encapsulates the page pool settings.

That object can then be used to externalise the settings.

Return value

IMPORT_C void Close();

Description

Flushes and purges the page cache and stops using the stream store.

inline void Release();

Description

Purges the page cache and stops using the stream store.

inline TBool IsDirty() const;

Description

Tests if the dirty flag has been set on the page pool.

Return value

inline void MarkCurrent();

Description

Clears the dirty flag.

inline void MarkDirty();

Description

Sets the dirty flag on the pool.

inline TBool HasAvailable() const;

Description

Tests if there is a free page in the pool.

Return value

inline void Discard();

Description

Invalidates the list of free pages in the reclaimable set.

This should be done if there has been a failure in updating the BTree, as this list is possibly corrupt now. The reclaimable set can be deleted using RStorePagePool::ReclaimAllL(), and the BTree then repaired.

inline TBool IsEmpty() const;

Description

Tests if the page pool is empty.

Return value

IMPORT_C TBool ReclaimL();

Description

Deletes the first stream that stores reclaimable pages in the store.

Return value

IMPORT_C void ReclaimAllL();

Description

Deletes all streams in the store.

protected: IMPORT_C virtual TPageRef ExtendL(const TAny *aPage, TPageReclamation aReclamation);

Description

Parameters

Return value

protected: IMPORT_C virtual void WriteL(TPageRef aRef, const TAny *aPage, TPageChange aChange);

Description

Parameters

protected: IMPORT_C virtual void ReadL(TPageRef aRef, TAny *aPage);

Description

Parameters

protected: IMPORT_C virtual void DoDeleteL(TPageRef aRef);

Description

Parameters