Gcs_message Class Reference

Class that represents the data that is exchanged within a group. More...

#include <gcs_message.h>

Public Member Functions
	Gcs_message (const Gcs_member_identifier &origin, const Gcs_group_identifier &destination, Gcs_message_data *message_data)
	Gcs_message 1st constructor. More...
	Gcs_message (const Gcs_member_identifier &origin, Gcs_message_data *message_data)
	Gcs_message 2nd constructor. More...
virtual	~Gcs_message ()
const Gcs_member_identifier &	get_origin () const
const Gcs_group_identifier *	get_destination () const
Gcs_message_data &	get_message_data () const

Private Member Functions
void	init (const Gcs_member_identifier *origin, const Gcs_group_identifier *destination, Gcs_message_data *message_data)
	Gcs_message (Gcs_message const &)
Gcs_message &	operator= (Gcs_message const &)

Private Attributes
Gcs_member_identifier *	m_origin
Gcs_group_identifier *	m_destination
Gcs_message_data *	m_data

Detailed Description

Class that represents the data that is exchanged within a group.

It is sent by a member having the group as destination. It shall be received by all members that pertain to the group in that moment.

It is built using two major blocks: the header and the payload of the message. A user of Gcs_message can freely add data to the header and to the payload.

Each binding implementation might use these two fields at its own discretion but that data should be removed from the header/payload before its delivery to the client layer.

When the message is built, none of the data is passed unto it. One has to use the append_* methods in order to append data. Calling encode() at the end will provide a ready-to-send message.

On the receiver side, one shall use decode() in order to have the header and the payload restored in the original message fields.

A typical use case of sending a message is:

Gcs_control_interface       *gcs_ctrl_interface_instance;
Gcs_communication_interface *gcs_comm_interface_instance; // obtained
                                                          // previously
 
Gcs_member_identifier *myself=
  gcs_ctrl_interface_instance->get_local_information();
 
Gcs_group_identifier destination("the_group");
 
Gcs_message *msg= new Gcs_message(&myself, new Gcs_message_data(0, 3));
 
uchar[] some_data= {(uchar)0x12,
                    (uchar)0x24,
                    (uchar)0x00};
 
msg->get_message_data()->append_to_payload(&some_data,
                                           strlen(some_data));
 
gcs_comm_interface_instance->send_message(msg);

A typical use case of receiving a message is:

class my_Gcs_communication_event_listener : Gcs_communication_event_listener
{
  my_Gcs_communication_event_listener(my_Message_delegator *delegator)
  {
    this->delegator= delegator;
  }
 
  void on_message_received(Gcs_message &message)
  {
    // Do something when message arrives...
    delegator->process_gcs_message(message);
  }
 
  private:
    my_Message_delegator *delegator;
}

Constructor & Destructor Documentation

Gcs_message() [1/3]

Gcs_message::Gcs_message ( const Gcs_member_identifier &  origin, const Gcs_group_identifier &  destination, Gcs_message_data *  message_data  )

explicit

Gcs_message 1st constructor.

Gcs_message implementation.

This is used to build full messages.

Note that the Gcs_message will acquire ownership of the data, i.e. Gcs_message_data, and will be responsible for deleting it.

Parameters

[in]	origin	The group member that sent the message
[in]	destination	The group in which this message belongs
[in]	message_data	External message data object.

Gcs_message() [2/3]

Gcs_message::Gcs_message ( const Gcs_member_identifier &  origin, Gcs_message_data *  message_data  )

explicit

Gcs_message 2nd constructor.

This is used to send messages but with an external Gcs_message_data object.

Note that the Gcs_message will acquire ownership of the data, i.e. Gcs_message_data, and will be responsible for deleting it.

Parameters

[in]	origin	The group member that sent the message
[in]	message_data	External message data object.

~Gcs_message()

Gcs_message::~Gcs_message ( )

virtual

Gcs_message() [3/3]

Gcs_message::Gcs_message ( Gcs_message const &  )

private

Member Function Documentation

get_destination()

const Gcs_group_identifier * Gcs_message::get_destination

(

)

const

Returns

the destination of this message. It might be NULL.

get_message_data()

Gcs_message_data & Gcs_message::get_message_data

(

)

const

Returns

the message data to be filled.

get_origin()

const Gcs_member_identifier & Gcs_message::get_origin

(

)

const

Returns

the origin of this message

init()

void Gcs_message::init ( const Gcs_member_identifier *  origin, const Gcs_group_identifier *  destination, Gcs_message_data *  message_data  )

private

operator=()

Gcs_message & Gcs_message::operator= ( Gcs_message const &  )

private

Member Data Documentation

m_data

Gcs_message_data* Gcs_message::m_data

private

m_destination

Gcs_group_identifier* Gcs_message::m_destination

private

m_origin

Gcs_member_identifier* Gcs_message::m_origin

private

---

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

• plugin/group_replication/libmysqlgcs/include/mysql/gcs/gcs_message.h
• plugin/group_replication/libmysqlgcs/src/interface/gcs_message.cc