This is a stage in the pipeline that processes messages when they are put through the send and receive code paths. More...

#include <gcs_message_stages.h>

Inheritance diagram for Gcs_message_stage:

[legend]

Public Types
enum class	stage_status : unsigned int { apply , skip , abort }

Public Member Functions
virtual stage_status	skip_apply (uint64_t const &original_payload_size) const =0
	Check if the apply operation which affects outgoing packets should be executed (i.e. More...

virtual std::unique_ptr< Gcs_stage_metadata >	get_stage_header ()=0

	Gcs_message_stage ()

	Gcs_message_stage (bool enabled)

virtual	~Gcs_message_stage ()=default

virtual Stage_code	get_stage_code () const =0
	Return the unique stage code. More...

std::pair< bool, std::vector< Gcs_packet > >	apply (Gcs_packet &&packet)
	Apply some transformation to the outgoing packet, and return a set of one, or more, transformed packets. More...

std::pair< Gcs_pipeline_incoming_result, Gcs_packet >	revert (Gcs_packet &&packet)
	Revert some transformation from the incoming packet, and return one, or none, transformed packet. More...

bool	is_enabled () const
	Return whether the message stage is enabled or not. More...

virtual bool	update_members_information (const Gcs_member_identifier &, const Gcs_xcom_nodes &)
	Update the list of members in the group as this may be required by some stages in the communication pipeline. More...

virtual Gcs_xcom_synode_set	get_snapshot () const

void	set_enabled (bool is_enabled)
	Enable or disable the message stage. More...

Protected Member Functions
virtual stage_status	skip_revert (const Gcs_packet &packet) const =0
	Check if the revert operation which affects incoming packets should be executed (i.e. More...

virtual std::pair< bool, std::vector< Gcs_packet > >	apply_transformation (Gcs_packet &&packet)=0
	Implements the logic of this stage's transformation to the packet, and returns a set of one, or more, transformed packets. More...

virtual std::pair< Gcs_pipeline_incoming_result, Gcs_packet >	revert_transformation (Gcs_packet &&packet)=0
	Implements the logic to revert this stage's transformation to the packet, and returns one, or none, transformed packet. More...

void	encode (unsigned char *header, unsigned short header_length, unsigned long long old_payload_length)
	Encode the fixed part of the associated dynamic header information into the header buffer. More...

void	decode (const unsigned char header, unsigned short header_length, unsigned long long *old_payload_length)
	Decode the fixed part of the associated dynamic header information from the header buffer. More...

Private Attributes
bool	m_is_enabled

Detailed Description

This is a stage in the pipeline that processes messages when they are put through the send and receive code paths.

A stage may apply a transformation to the payload of the message that it is handling. If it does morph the message, it will append a stage header to the message and change the payload accordingly. On the receiving side the GCS receiver thread will revert the transformation before delivering the message to the application.

An example of a stage is the LZ4 stage that compresses the payload.

Developers willing to create a new stage have to inherit from this class and implement six virtual methods that are self-explanatory. Note, however, that the current semantics assume that each new stage added to the pipeline will allocate a new buffer and copy the payload, which may be transformed or not, to it.

This copy assumption makes it easier to create a simple infra-structure to add new stages. Currently, this does not represent a performance bottleneck but we may revisit this design if it becomes a problem. Note that a quick, but maybe not so simple way to overcome this limitation, is through the redefinition of the apply and revert methods.

Member Enumeration Documentation

◆ stage_status

enum class Gcs_message_stage::stage_status : unsigned int

strong

Enumerator
apply
skip
abort

Constructor & Destructor Documentation

◆ Gcs_message_stage() [1/2]

Gcs_message_stage::Gcs_message_stage ( )

inlineexplicit

◆ Gcs_message_stage() [2/2]

Gcs_message_stage::Gcs_message_stage ( bool enabled )

inlineexplicit

◆ ~Gcs_message_stage()

virtual Gcs_message_stage::~Gcs_message_stage ( )

virtualdefault

Member Function Documentation

◆ apply()

std::pair< bool, std::vector< Gcs_packet > > Gcs_message_stage::apply ( Gcs_packet && packet )

Apply some transformation to the outgoing packet, and return a set of one, or more, transformed packets.

Parameters

[in] packet The packet upon which the transformation should be applied

Return values

{true,_}	If there was an error applying the transformation
{false,P}	If the transformation was successful, and produced the set of transformed packets P

◆ apply_transformation()

virtual std::pair< bool, std::vector< Gcs_packet > > Gcs_message_stage::apply_transformation ( Gcs_packet && packet )

protectedpure virtual

Implements the logic of this stage's transformation to the packet, and returns a set of one, or more, transformed packets.

Parameters

[in] packet The packet upon which the transformation should be applied

Return values

{true,_}	If there was an error applying the transformation
{false,P}	If the transformation was successful, and produced the set of transformed packets P

Implemented in Gcs_message_stage_lz4, and Gcs_message_stage_split_v2.

◆ decode()

void Gcs_message_stage::decode	(	const unsigned char *	header,
		unsigned short *	header_length,
		unsigned long long *	old_payload_length
	)

protected

Decode the fixed part of the associated dynamic header information from the header buffer.

Parameters

	header	Pointer to the header buffer
[out]	header_length	Pointer to the length of the header information
[out]	old_payload_length	Pointer to the length of previous stage payload

◆ encode()

void Gcs_message_stage::encode	(	unsigned char *	header,
		unsigned short	header_length,
		unsigned long long	old_payload_length
	)

protected

Encode the fixed part of the associated dynamic header information into the header buffer.

Parameters

header	Pointer to the header buffer.
header_length	Length of the header information.
old_payload_length	Length of previous stage payload.

◆ get_snapshot()

virtual Gcs_xcom_synode_set Gcs_message_stage::get_snapshot ( ) const

inlinevirtual

Reimplemented in Gcs_message_stage_split_v2.

◆ get_stage_code()

virtual Stage_code Gcs_message_stage::get_stage_code ( ) const

pure virtual

Return the unique stage code.

Returns: the stage code.

Implemented in Gcs_message_stage_lz4, Gcs_message_stage_lz4_v2, Gcs_message_stage_lz4_v3, Gcs_message_stage_split_v2, and Gcs_message_stage_split_v3.

◆ get_stage_header()

virtual std::unique_ptr< Gcs_stage_metadata > Gcs_message_stage::get_stage_header ( )

pure virtual

Implemented in Gcs_message_stage_lz4, and Gcs_message_stage_split_v2.

◆ is_enabled()

bool Gcs_message_stage::is_enabled ( ) const

inline

Return whether the message stage is enabled or not.

◆ revert()

std::pair< Gcs_pipeline_incoming_result, Gcs_packet > Gcs_message_stage::revert ( Gcs_packet && packet )

Revert some transformation from the incoming packet, and return one, or none, transformed packet.

Parameters

[in] packet The packet upon which the transformation should be reverted

Return values

{ERROR,_}	If there was an error reverting the transformation
{OK_NO_PACKET,NP}	If the transformation was reverted, but produced no packet
{OK_PACKET,P}	If the transformation was reverted, and produced the packet P

◆ revert_transformation()

virtual std::pair< Gcs_pipeline_incoming_result, Gcs_packet > Gcs_message_stage::revert_transformation ( Gcs_packet && packet )

protectedpure virtual

Implements the logic to revert this stage's transformation to the packet, and returns one, or none, transformed packet.

Parameters

[in] packet The packet upon which the transformation should be reverted

Return values

{ERROR,_}	If there was an error reverting the transformation
{OK_NO_PACKET,NP}	If the transformation was reverted, but produced no packet
{OK_PACKET,P}	If the transformation was reverted, and produced the packet P

Implemented in Gcs_message_stage_lz4, and Gcs_message_stage_split_v2.

◆ set_enabled()

void Gcs_message_stage::set_enabled ( bool is_enabled )

inline

Enable or disable the message stage.

Parameters

is_enabled Whether the message stage is enabled or disabled.

◆ skip_apply()

virtual stage_status Gcs_message_stage::skip_apply ( uint64_t const & original_payload_size ) const

pure virtual

Check if the apply operation which affects outgoing packets should be executed (i.e.

applied), skipped or aborted.

If the outcome is code apply or code skip, the stage will process or skip the message, respectively. However, if the outcome is code abort, the message will be discarded and an error will be reported thus stopping the pipeline execution.

For example, if a packet's length is less than a pre-defined threshold the packet is not compressed.

Parameters

original_payload_size The size of the packet to which the transformation should be applied.

Returns: a status specifying whether the transformation should be executed, skipped or aborted

Implemented in Gcs_message_stage_lz4, and Gcs_message_stage_split_v2.

◆ skip_revert()

virtual stage_status Gcs_message_stage::skip_revert ( const Gcs_packet & packet ) const

protectedpure virtual

Check if the revert operation which affects incoming packets should be executed (i.e.

applied), skipped or aborted.

If the outcome is code apply or code skip, the stage will process or skip the message, respectively. However, if the outcome is code abort, the message will be discarded and an error will be reported thus stopping the pipeline execution.

For example, if the packet length is greater than the maximum allowed compressed information an error is returned.

Parameters

packet The packet upon which the transformation should be applied

Returns: a status specifying whether the transformation should be executed, skipped or aborted

Implemented in Gcs_message_stage_lz4, and Gcs_message_stage_split_v2.

◆ update_members_information()

virtual bool Gcs_message_stage::update_members_information	(	const Gcs_member_identifier &	,
		const Gcs_xcom_nodes &
	)

inlinevirtual

Update the list of members in the group as this may be required by some stages in the communication pipeline.

By default though, the call is simply ignored.

Returns: If there is an error, true is returned. Otherwise, false is returned.

Reimplemented in Gcs_message_stage_split_v2.

Member Data Documentation

◆ m_is_enabled

bool Gcs_message_stage::m_is_enabled

private

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

plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_message_stages.h
plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_message_stages.cc

Public Types

Public Member Functions

Protected Member Functions

Private Attributes

Detailed Description

Member Enumeration Documentation

◆ stage_status

Constructor & Destructor Documentation

◆ Gcs_message_stage() [1/2]

◆ Gcs_message_stage() [2/2]

◆ ~Gcs_message_stage()

Member Function Documentation

◆ apply()

◆ apply_transformation()

◆ decode()

◆ encode()

◆ get_snapshot()

◆ get_stage_code()

◆ get_stage_header()

◆ is_enabled()

◆ revert()

◆ revert_transformation()

◆ set_enabled()

◆ skip_apply()

◆ skip_revert()

◆ update_members_information()

Member Data Documentation

◆ m_is_enabled