Gcs_xcom_input_queue_impl< Queue >::Reply Class Reference

Wraps XCom's reply to a queued request. More...

#include <gcs_xcom_input_queue.h>

Public Member Functions
	Reply () noexcept
	~Reply ()
void	resolve (pax_msg *payload)
	Associates the payload of XCom's reply to this object. More...
future_reply	get_future ()
	Get the future that will hold a pointer to this object after it has been resolved. More...
pax_msg const *	get_payload ()
	Get XCom's reply. More...

Private Attributes
pax_msg *	m_payload
	XCom's reply. More...
std::promise< std::unique_ptr< Reply > >	m_promise
	Simultaneously holds the future's shared state and takes care of the lifetime of *this. More...

Detailed Description

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>
class Gcs_xcom_input_queue_impl< Queue >::Reply

Wraps XCom's reply to a queued request.

A request sent to XCom contains three important pieces of data:

1. The payload, i.e. what we want XCom to do
2. A function instructing XCom how to reply to the request
3. A Reply object (For more details please see xcom_input_request.)

When GCS pushes a request to XCom, GCS receives back a future pointer to the Reply object associated with the request. (future_reply) Basically, this future's result is equivalent to the reply GCS would get if it used a TCP socket to send the request to XCom. XCom will resolve this future when it receives and processes the request. When GCS retrieves the future's result, GCS obtains a std::unique_ptr to the Reply. Unless you do any shenanigans with this std::unique_ptr, when it goes out of scope the Reply object is destroyed. The Reply object owns the payload of XCom's reply (pax_msg), so the Reply object destroys the pax_msg when it is destroyed.

Constructor & Destructor Documentation

Reply()

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

Gcs_xcom_input_queue_impl< Queue >::Reply::Reply ( )

inlinenoexcept

~Reply()

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

Gcs_xcom_input_queue_impl< Queue >::Reply::~Reply ( )

inline

Member Function Documentation

get_future()

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

future_reply Gcs_xcom_input_queue_impl< Queue >::Reply::get_future ( )

inline

Get the future that will hold a pointer to this object after it has been resolved.

Returns

a future pointer to this object when it already contains XCom's reply

get_payload()

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

pax_msg const * Gcs_xcom_input_queue_impl< Queue >::Reply::get_payload ( )

inline

Get XCom's reply.

Returns

XCom's reply

resolve()

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

void Gcs_xcom_input_queue_impl< Queue >::Reply::resolve ( pax_msg *  payload )

inline

Associates the payload of XCom's reply to this object.

Resolves the future.

Parameters

payload

XCom's reply

Member Data Documentation

m_payload

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

pax_msg* Gcs_xcom_input_queue_impl< Queue >::Reply::m_payload

private

XCom's reply.

m_promise

template<typename Queue = Gcs_mpsc_queue<xcom_input_request, xcom_input_request_ptr_deleter>>

std::promise<std::unique_ptr<Reply> > Gcs_xcom_input_queue_impl< Queue >::Reply::m_promise

private

Simultaneously holds the future's shared state and takes care of the lifetime of *this.

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

• plugin/group_replication/libmysqlgcs/src/bindings/xcom/gcs_xcom_input_queue.h