MIncrementalCollector in System Libraries Store

class MIncrementalCollector;

Description

Interface for incrementally reclaiming or compacting space in a stream store. The interface allows these actions to be performed in small steps, so that applications can remain responsive while doing these potentially long-running tasks.

An instance of a class derived from this interface is returned by StreamStore::DoReclaimL() and DoCompactL(). Each step is carried out in response to a call of MIncrementalCollector::DoNextL(TInt &,TInt &) and the object is released on completion of the last step.

Notes:

One-step reclaim using CStreamStore::ReclaimL() is actually implemented in terms of the incremental collector.

A CStreamStore implementation will only need to implement a collector class if it supports reclamation or compaction.

Members

Defined in MIncrementalCollector:

Close()Closes the collector after it is no longer required. The object should not be re...
DoNextL(TInt &,TInt &)Implementation of the public synchronous MIncrementalCollector::NextL(TInt &...
DoNextL(TPckgBuf< TInt > &,TRequestStatus &,TPckgBuf< TInt > &)Implementation of the public asynchronous MIncrementalCollector::NextL(TInt &...
DoRelease()Implementation of the public MIncrementalCollector::Release() function. This sig...
DoResetL(TInt &)Implementation of the public MIncrementalCollector::ResetL(TInt &) function....
MIncrementalCollector()Protected constructor. Protecting the constructor ensures that this abstract cla...
NextL(TInt &,TInt &)Does the next step in the reclaim synchronously.
NextL(TPckgBuf< TInt > &,TRequestStatus &,TPckgBuf< TInt > &)Does the next step in the reclaim asynchronously.
Release()Releases the collector after it is no longer required. The object should not be ...
ResetL(TInt &)Resets the collector. This leaves the collector in a state ready to start or res...

protected: inline MIncrementalCollector();

Description

Protected constructor. Protecting the constructor ensures that this abstract class cannot be instantiated.

MIncrementalCollector::MIncrementalCollector(const MIncrementalCollector &);

MIncrementalCollector& MIncrementalCollector::operator=(const MIncrementalCollector &);

Private copy constructor and copy assignment to prevent

inline void Close();

Description

Closes the collector after it is no longer required. The object should not be referenced after calling this function. The semantics for this function and MIncrementalCollector::Release() are effectively the same.

inline void Release();

Description

Releases the collector after it is no longer required. The object should not be referenced after calling this function. The semantics for this function and MIncrementalCollector::Close() are effectively the same.

Description

Resets the collector. This leaves the collector in a state ready to start or restart reclaiming/compacting. On return aCount contains a value that can be used to determine the progress of the operation the same value should be passed in to subsequent calls to MIncrementalCollector::NextL(TInt &,TInt &) until it reaches 0.

Parameters


                                 						TInt &aCount

A progress count for the reclamation/compaction process.

Description

Does the next step in the reclaim synchronously.

aStep contains a progress value, which decreases every time the function is called. aTotal contains the running total of free-space that remains in the store.

Parameters


                                 						TInt &aStep

The progress value from either the last MIncrementalCollector::NextL(TInt &,TInt &) increment of from MIncrementalCollector::ResetL(TInt &) if the reclamation/compaction was restarted. On return, contains the new progress value, which can be used in subsequent calls to MIncrementalCollector::NextL(TInt &,TInt &). This will be equal to, or less than, the previous value a zero value indicates that the operation is complete.


                                 						TInt &aTotal

On return, contains the total amount of free space in the store. This should increase every time the function is called.

Description

Does the next step in the reclaim asynchronously.

aStep contains a progress value, which decreases every time the function is called. aTotal contains the running total of free-space that remains in the store. These parameters are asynchronous equivalents of the other MIncrementalCollector::NextL(TInt &,TInt &) overload.

Parameters

`TPckgBuf< TInt > &aStep`	The progress value from either the last `MIncrementalCollector::NextL(TInt &,TInt &)` increment of from `MIncrementalCollector::ResetL(TInt &)` if the reclamation/compaction was restarted. On return, contains the new progress value, which can be used in subsequent calls to `MIncrementalCollector::NextL(TInt &,TInt &)`. This will be equal to, or less than, the previous value a zero value indicates that the operation is complete.
`TRequestStatus &aStatus`	A status variable. KErrNone on successful completion, otherwise another of the system-wide error codes.
`TPckgBuf< TInt > &aTotal`	On return, contains the total amount of free space in the store. This should increase every time the function is called.

Description

Implementation of the public MIncrementalCollector::Release() function. This signals that client has no further need of the object and all necessary clean-up should be done. e.g. if the implementation object is allocated on the heap, it could be deleted.

private: virtual void DoResetL(TInt &aCount)=0;

Description

Implementation of the public MIncrementalCollector::ResetL(TInt &) function. This signals that the client wants to start or retsart the operation from the beginning. A new progress count should be returned in aCount.

Parameters


                                 						TInt &aCount

On return, contains a progress count for the reclamation/compaction process.

private: virtual void DoNextL(TInt &aStep, TInt &aTotal)=0;

Description

Implementation of the public synchronous MIncrementalCollector::NextL(TInt &,TInt &) function. The next step in the reclamation should be done, reporting progress in aStep and aTotal.

Parameters


                                 						TInt &aStep

The progress value from either the last MIncrementalCollector::NextL(TInt &,TInt &) increment of from MIncrementalCollector::ResetL(TInt &) if the reclamation/compaction was restarted. On return, should contain the new progress value, which can be used in subsequent calls to MIncrementalCollector::NextL(TInt &,TInt &). This must be equal to, or less than, the previous valueÂ â€” a zero value must be used to indicate that the operation is complete.


                                 						TInt &aTotal

On return, should contain the total amount of free space in the store.

private: IMPORT_C virtual void DoNextL(TPckgBuf< TInt > &aStep, TRequestStatus &aStatus, TPckgBuf< TInt > &aTotal);

Description

Implementation of the public asynchronous MIncrementalCollector::NextL(TInt &,TInt &) function. The default implementation invokes the synchronous form of MIncrementalCollector::DoNextL(TInt &,TInt &) and then reports the result by signalling the request status.

Parameters

`TPckgBuf< TInt > &aStep`	The progress value from either the last `MIncrementalCollector::NextL(TInt &,TInt &)` increment of from `MIncrementalCollector::ResetL(TInt &)` if the reclamation/compaction was restarted. On return, should contain the new progress value, which can be used in subsequent calls to `MIncrementalCollector::NextL(TInt &,TInt &)`. This must be equal to, or less than, the previous value a zero value must be used to indicate that the operation is complete.
`TRequestStatus &aStatus`	A status variable. KErrNone on successful completion, otherwise another of the system-wide error codes.
`TPckgBuf< TInt > &aTotal`	On return, should contain the total amount of free space in the store.

Class `MIncrementalCollector`

Description

Members

Construction and destruction