Class MPagePool

MPagePool

Support

Supported from 5.0

Description

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

The interface is abstract and handles pages as TAny pointers. It is left to derived classes to implement page storage in a particular storage medium, such as memory or disk.

Defined in MPagePool:
AcquireL(), AllocL(), AssignL(), Delete(), DeleteL(), LockL(), Pop(), PushL(), Unlock(), UpdateL()

virtual TPageAbandonFunction AcquireL()=0;

Description

Returns a function that abandons all locked pages for this page pool.

Return value

TPageAbandonFunction A function that abandons all locked pages for this page pool.

virtual TAny* AllocL()=0;

Description

Allocates an unassigned page.

Return value

TAny* Newly allocated page.

virtual TPageRef AssignL(const TAny* aPage,TPageReclamation aReclamation=EPageDeleteOnly)=0;

Description

Assigns a reference to a new page and unlocks it.

Parameters

const TAny* aPage Page to assign TPageReclamation aReclamation=EPageDeleteOnly Flag for page reclaimation settings

Return value

TPageRef Reference to page

void Delete(TPageRef aRef);

Description

Deletes a page, ignoring any errors.

Parameters

TPageRef aRef Reference to the page to delete

void DeleteL(TPageRef aRef);

Description

Deletes a page, leaving if an error occurs.

Parameters

TPageRef aRef Reference to the page to delete

void Pop();

Description

Do a pop from the cleanup stack.

void PushL();

Description

Pushes this object onto the cleanup stack.

virtual TAny* LockL(TPageRef aRef)=0;

Description

Locks a page and returns a pointer to it.

Parameters

TPageRef aRef Reference to the page to lock

Return value

TAny* Locked page

virtual void Unlock(const TAny* aPage,TPageChange aChange=EPageNoChange)=0;

Description

Unlocks a page.

Parameters

const TAny* aPage Page to unlock TPageChange aChange=EPageNoChange How the page should be treated once it is unlocked

virtual void UpdateL(const TAny* aPage)=0;

Description

Updates a page.

This can be used for cached pages that may have become outdated.

Parameters

const TAny* aPage Page to update