mdf::IDataGroup Class Reference

Interface to a data group (DG) block. More...

#include <idatagroup.h>

Inheritance diagram for mdf::IDataGroup:

Collaboration diagram for mdf::IDataGroup:

Public Member Functions
virtual void	Description (const std::string &desc)
	Sets the descriptive text for the measurement.
virtual std::string	Description () const
	Return the descriptive text.
virtual void	RecordIdSize (uint8_t id_size)
	Sets size of the record ID (bytes). Note that record ID and its size, is automatically set when writing MDF files.
virtual uint8_t	RecordIdSize () const
	Returns the record ID size in bytes.
virtual std::vector< IChannelGroup * >	ChannelGroups () const =0
	Returns a list of channel groups.
virtual IChannelGroup *	CreateChannelGroup ()=0
	Create a new empty channel group.
IChannelGroup *	CreateChannelGroup (const std::string_view &name)
	Create a new channel group or return the existing group.
IChannelGroup *	GetChannelGroup (const std::string_view &name) const
	Returns the existing group by its name.
IChannelGroup *	GetChannelGroup (uint64_t record_id) const
	Return a channel group by its record id.
virtual IMetaData *	CreateMetaData ()
	Create or return the existing meta-data (MD) block.
virtual IMetaData *	MetaData () const
	Returns the existing meta-data (MD) block if it exist.
void	AttachSampleObserver (ISampleObserver *observer) const
	Internal function that attach a sample observer to the measurement block.
void	DetachSampleObserver (const ISampleObserver *observer) const
	Detach an observer from the measurement.
void	DetachAllSampleObservers () const
	Detaches all observers from the measurement.
bool	NotifySampleObservers (size_t sample, uint64_t record_id, const std::vector< uint8_t > &record) const
	Notifies the observer that a new sample record have been read.
virtual void	ClearData ()
	Clear all temporary sample and data buffers.
void	SetAsRead (bool mark_as_read=true) const
	Set the DG blocks data as read.
bool	IsEmpty () const
	Returns true if no samples has been stored yet.
bool	IsRead () const
	Return true if the DG blocks data has been read not the DG block itself.
virtual IChannelGroup *	FindParentChannelGroup (const IChannel &channel) const =0
	Support function that return the first CG block that contains a specific CN block.
bool	IsSubscribingOnRecord (uint64_t record_id) const
	Checks if this data group subscribes on a specific record.
bool	IsSubscribingOnChannel (const IChannel &channel) const
	Checks if this data group subscribes on a specific channel.
bool	IsSubscribingOnChannelVlsd (const IChannel &channel) const
	Checks if this data group subscribes on a specific channels VLSD raw data.
Public Member Functions inherited from mdf::IBlock
virtual	~IBlock ()=default
	Default destructor.
virtual int64_t	Index () const =0
	File position within the file.
virtual std::string	BlockType () const =0
	Returns the block type.

Protected Member Functions
	~IDataGroup () override=default
	Default destructor.
void	InitFastObserverList ()
	The function optimize the observer list before reading data.

Protected Attributes
std::vector< ISampleObserver * >	observer_list_
	List of observers.
std::map< uint64_t, std::vector< ISampleObserver * > >	fast_observer_list_
	The fast observer list is used internally when reading data.

Detailed Description

The data group block is the entry point for a measurement. The header (HD) block is the entry point for a test. A test consist of one or more measurements (DG).

Each measurement is defined by one or more channel groups (CG). The channel group in turn, consist of one or more channels. The group have an unique record ID.

A record is a byte array with fixed length and hold one sample for each channel in the group. The DG block also points to the data blocks (DT) which is an array of sample records.

In MDF version 3, data was always stored as raw bytes in a DT block. In version 4 the DT block may be split, reorganized and compressed.

Member Function Documentation

ClearData()

virtual void mdf::IDataGroup::ClearData ( )

virtual

Clear all sample and signal data buffers. Call this function when no need of any signal data (SD) or sample reduction (SR) data are needed. This reduce memory usage if more DG blocks should read in data bytes.

InitFastObserverList()

void mdf::IDataGroup::InitFastObserverList ( )

protected

The function is called before reading any data in the file. The purpose is optimize the read speed of files with many sample. The function is used internally only.

IsSubscribingOnChannel()

bool mdf::IDataGroup::IsSubscribingOnChannel ( const IChannel & channel ) const

nodiscard

Parameters

channel

Reference to the channel.

Returns

True if the observer list subscribe on this channel.

IsSubscribingOnChannelVlsd()

bool mdf::IDataGroup::IsSubscribingOnChannelVlsd ( const IChannel & channel ) const

nodiscard

Parameters

channel

Reference to the channel.

Returns

True if the observer list subscribe on this channels VLSD raw data .

IsSubscribingOnRecord()

bool mdf::IDataGroup::IsSubscribingOnRecord ( uint64_t record_id ) const

nodiscard

Parameters

record_id

Record ID of the channel group

Returns

True if the observer list subscribe on this channel group.

---

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

• include/mdf/idatagroup.h