Cpl::Persistent::Chunk Class Reference

This abstract class defines the interface for a Chunk. More...

Detailed Description

This abstract class defines the interface for a Chunk.

A Chunk is responsible for managing the meta-data (e.g. CRC) associated with a Record's data. There is one-to-one relationship between a Chunk and Record instances.

#include <Chunk.h>

Inheritance diagram for Cpl::Persistent::Chunk:

Public Member Functions
virtual void	start (Cpl::Dm::MailboxServer &myMbox) noexcept=0
	This method is to start/initialize the chunk.
virtual void	stop () noexcept=0
	This method is to stop/shutdown the chunk.
virtual bool	loadData (Payload &dstHandler, size_t index=0) noexcept=0
	This method is used to initiate the sequence to retrieve a Record's data from persistent storage.
virtual bool	updateData (Payload &srcHandler, size_t index=0, bool invalidate=false) noexcept=0
	This method is used to update persistent storage with new data for the Record.
virtual size_t	getMetadataLength () const noexcept=0
	This method returns the size, in bytes, of any/all metadata that is included with the record.
virtual	~Chunk ()
	Virtual destructor.

Constructor & Destructor Documentation

~Chunk()

virtual Cpl::Persistent::Chunk::~Chunk ( )

inlinevirtual

Virtual destructor.

Member Function Documentation

getMetadataLength()

virtual size_t Cpl::Persistent::Chunk::getMetadataLength ( ) const

pure virtualnoexcept

This method returns the size, in bytes, of any/all metadata that is included with the record.

Implemented in Cpl::Persistent::CrcChunk, and Cpl::Persistent::MirroredChunk.

loadData()

virtual bool Cpl::Persistent::Chunk::loadData ( Payload &  dstHandler, size_t  index = 0  )

pure virtualnoexcept

This method is used to initiate the sequence to retrieve a Record's data from persistent storage.

This method should ONLY be called once (after start() has been called) to load its data into RAM.

The 'index' offset can be used by the Chunk client to 'index into' the Chunk's region instead of starting at offset zero. This argument should only be used when multiple instances of a Record is being stored in a single region.

The method returns true if the read operation was successful and that the CRC for the data is valid; else false is returned

Implemented in Cpl::Persistent::CrcChunk, and Cpl::Persistent::MirroredChunk.

start()

virtual void Cpl::Persistent::Chunk::start ( Cpl::Dm::MailboxServer &  myMbox )

pure virtualnoexcept

This method is to start/initialize the chunk.

It is typically only called once at the startup of the application. However, start() can be called after a previous call to the stop() method.

This method is called when the corresponding Record instance is 'started'

The 'myMbox' is reference to the RecordServer's DM/ITC mailbox, i.e. the mailbox for the thread that the Chunk executes in.

Implemented in Cpl::Persistent::CrcChunk, and Cpl::Persistent::MirroredChunk.

stop()

virtual void Cpl::Persistent::Chunk::stop ( )

pure virtualnoexcept

This method is to stop/shutdown the chunk.

It is typically only called once during an orderly shutdown of the application. However, start() can be after a previous call to the stop() method.

Implemented in Cpl::Persistent::CrcChunk, and Cpl::Persistent::MirroredChunk.

updateData()

virtual bool Cpl::Persistent::Chunk::updateData ( Payload &  srcHandler, size_t  index = 0, bool  invalidate = false  )

pure virtualnoexcept

This method is used to update persistent storage with new data for the Record.

The entire record is written/updated when this call is made. The method does not return until the write operation has completed.

If the 'invalidate' argument is true, the instead of writing the new data to persistent storage, all binary zero's are written AND in incorrect CRC is written. This effectively erases the Record, i.e. the next time the record is loaded, it will fail because the chunk data is NOT valid.

The 'index' offset can be used by the Chunk client to 'index into' the Chunk's region instead of starting at offset zero. This argument should only be used when multiple instances of a Record is being stored in a single region.

The method returns true if successful; else false is returned. It is the responsibility of the Record/Application to decided what to do when there is error (e.g. ignored, a log entry generated, etc.)

Implemented in Cpl::Persistent::CrcChunk, and Cpl::Persistent::MirroredChunk.

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The documentation for this class was generated from the following file:

• Cpl/Persistent/Chunk.h