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Eclipse eCAL™

class eCAL::CPayloadWriter

Base payload writer class to allow zero copy memory operations.

This class serves as the base class for payload writers, allowing zero-copy memory operations. The WriteFull and WriteModified calls may operate on the target memory file directly in zero-copy mode.

A partial writing / modification of the memory file is only possible when zero-copy mode is activated. If zero-copy is not enabled, the WriteModified method is ignored and the WriteFull method is always executed (see CPublisher::ShmEnableZeroCopy)

Members

public CPayloadWriter() = default

Default constructor for CPayloadWriter.

public virtual ~CPayloadWriter() = default

Virtual destructor for CPayloadWriter.

public CPayloadWriter(const CPayloadWriter &) = default

Copy constructor (deleted).

public CPayloadWriter(CPayloadWriter &&) = default

Move constructor (deleted).

public CPayloadWriter&operator=(const CPayloadWriter &) = default

Copy assignment operator (deleted).

public CPayloadWriter&operator=(CPayloadWriter &&) = default

Move assignment operator (deleted).

public bool WriteFull(void * buffer_,size_t size_)

Perform a full write operation on uninitialized memory.

This virtual function allows derived classes to perform a full write operation when the provisioned memory is uninitialized. Typically, this is the case when a memory file had to be recreated or its size had to be changed.

Parameters

  • buffer_ Pointer to the buffer containing the data to be written.

  • size_ Size of the data to be written.

Returns

True if the write operation is successful, false otherwise.

public inline virtual bool WriteModified(void * buffer_,size_t size_)

Perform a partial write operation to modify existing data.

This virtual function allows derived classes to modify existing data when the provisioned memory is already initialized by a WriteFull call (i.e. contains the data from that full write operation).

The memory can be partially modified and does not have to be completely rewritten, which leads to significantly higher performance (lower latency).

If not implemented (by default), this operation will just call the WriteFull function.

Parameters

  • buffer_ Pointer to the buffer containing the data to be modified.

  • size_ Size of the data to be modified.

Returns

True if the write/update operation is successful, false otherwise.

public size_t GetSize()

Get the size of the required memory.

This virtual function allows derived classes to provide the size of the memory that eCAL needs to allocate.

Returns

The size of the required memory.