Class CBufStore

class CBufStore : public CStreamStore;

Description

In-memory non-persistent store. The buffer store does not have a root stream and cannot be closed without losing all the data.

It implements many of the operations defined by the store abstract framework. Specifically, streams in this store can be: overwritten, replaced, appended, deleted, and created in advance of being written to. However the class does not support commit and revert operations.

Overwriting an existing stream can result in a shorter stream; however, a stream cannot be extended beyond its original length. Replacing a stream can result in a stream which is longer or shorter than the original. The order in which streams are written to a memory store is not important as streams can be changed and rewritten.

Derivation

• CBase - Base class for all classes to be instantiated on the heap

• CStreamStore - Provides the core abstract framework for stores allowing streams to be created and manipulated

• CBufStore - In-memory non-persistent store

Members

Defined in CBufStore:
CBufStore(), DoCreateL(), DoDeleteL(), DoExtendL(), DoReadL(), DoReplaceL(), DoWriteL(), NewL(), NewLC(), ~CBufStore()

Inherited from CBase:
Extension_(), operator new()

Inherited from CStreamStore:
Commit(), CommitL(), CompactL(), Delete(), DeleteL(), DoCommitL(), DoCompactL(), DoReclaimL(), DoRevertL(), ExtendL(), ReclaimL(), Revert(), RevertL()

static IMPORT_C CBufStore *NewL(TInt anExpandSize);

Description

Allocates and constructs a new in-memory store and returns a pointer to it.

Parameters

TInt anExpandSize The granularity of the buffers used in the implementation of the store. Each stream is contained in a separate CBufSeg buffer.

Return value

CBufStore * A pointer to the memory store object.

static IMPORT_C CBufStore *NewLC(TInt anExpandSize);

Description

Allocates and constructs a new in-memory store and returns a pointer to it, putting a pointer to the object onto the cleanup stack.

Putting a pointer to the object on the cleanup stack allows the object and allocated resources to be cleaned up if a subsequent leave occurs.

Parameters

TInt anExpandSize The granularity of the buffers used in the implementation of the store. Each stream is contained in a separate CBufSeg buffer.

Return value

CBufStore * A pointer to the memory store object.

IMPORT_C CBufStore(TInt anExpandSize);

Description

Parameters

TInt anExpandSize

IMPORT_C ~CBufStore();

Description

Frees resources owned by the object, prior to its destruction.

protected: virtual IMPORT_C TStreamId DoExtendL();

Description

Generates a new stream within this store, and returns its id. This function is intended to create a new stream in advance of being written to.

This is called by ExtendL().

Return value

TStreamId The new stream id.

See also:

• CStreamStore::ExtendL()

protected: virtual IMPORT_C void DoDeleteL(TStreamId anId);

Description

Parameters

TStreamId anId

protected: virtual IMPORT_C MStreamBuf *DoReadL(TStreamId anId) const;

Description

Opens the requested stream for reading. The function should return a stream buffer positioned at the beginning of this stream.

This function is called by the OpenL() and OpenLC() member functions of RStoreReadStream.

Parameters

TStreamId anId The stream to be read.

Return value

MStreamBuf * A stream buffer positioned at the beginning of the stream to be read.

See also:

• RStoreReadStream::OpenL()
• RStoreReadStream::OpenLC()

protected: virtual IMPORT_C MStreamBuf *DoCreateL(TStreamId &anId);

Description

Creates a new stream in the store. The function gets the allocated stream id in the anId parameter. A stream buffer for the stream should be returned, ready to write into the new stream. This provides the implementation for the RStoreWriteStream::CreateL() functions.

Parameters

TStreamId &anId On return, contains the allocated stream id.

Return value

MStreamBuf * The stream buffer to be written to.

protected: virtual IMPORT_C MStreamBuf *DoWriteL(TStreamId anId);

Description

Parameters

TStreamId anId

Return value

MStreamBuf *

protected: virtual IMPORT_C MStreamBuf *DoReplaceL(TStreamId anId);

Description

Parameters

TStreamId anId

Return value

MStreamBuf *