mysql::csa::Event_set_fetchable Class Reference

Represents metadata of a set of events, capable of being fetched from a storage. More...

#include <event_set_fetchable.h>

Inheritance diagram for mysql::csa::Event_set_fetchable:

Public Types
using	Fde_type = Format_description_log_event
using	Fde_ptr = Fde_type *
using	Log_event_ptr = std::shared_ptr< Log_event >

Public Member Functions
virtual bool	wait_next ()=0
	Waits until the next event can be fetched. More...
virtual std::optional< Managed_event >	fetch_next ()=0
	Fetches the next event if possible. More...
virtual bool	is_done () const =0
	Checks if the event set has been fully fetched successfully. More...
virtual bool	is_error () const =0
	Checks if an error occurred during fetching. More...
virtual const std::string &	get_error_str () const =0
	Retrieves the error message if an error occurred. More...
virtual void	reset (bool reset_events)=0
	Resets the state to allow fetching the event set again, also clearing any error state. More...
virtual bool	is_trx () const =0
	Checks if this event set represents a complete transaction. More...
virtual Fde_ptr	get_fde ()=0
	Obtains non-owning pointer to current transaction FDE. More...
virtual	~Event_set_fetchable ()=default
	Sets the end of the stream if needed. More...
virtual void	set_success ()
	Callback on success, default - do nothing. More...

Detailed Description

Represents metadata of a set of events, capable of being fetched from a storage.

Typically, one event set will contain metadata of a part of, or a whole transaction. Event_set_fetchable supplies a function to fetch consecutive Log_event objects. If needed, it decompresses the underlying event stream. A transaction contains one or many fetchable event sets; this is decided by a specific implementation of a storage reader (e.g., relay log storage reader will keep separate event sets for parts of transaction kept in separate files). The specific implementation of a fetchable event set is driven by the implementation of the storage type (see Event_set_fetchable_relay_log).

Member Typedef Documentation

Fde_ptr

using mysql::csa::Event_set_fetchable::Fde_ptr = Fde_type *

Fde_type

using mysql::csa::Event_set_fetchable::Fde_type = Format_description_log_event

Log_event_ptr

using mysql::csa::Event_set_fetchable::Log_event_ptr = std::shared_ptr<Log_event>

Constructor & Destructor Documentation

~Event_set_fetchable()

virtual mysql::csa::Event_set_fetchable::~Event_set_fetchable ( )

virtualdefault

Sets the end of the stream if needed.

Empty by default.

Virtual destructor.

Member Function Documentation

fetch_next()

virtual std::optional< Managed_event > mysql::csa::Event_set_fetchable::fetch_next ( )

pure virtual

Fetches the next event if possible.

Callers are expected to wait for availability with wait_next() first when the underlying implementation supports streaming updates.

Returns

Managed_event object or an empty optional if the stream ended (with or without error).

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

get_error_str()

virtual const std::string & mysql::csa::Event_set_fetchable::get_error_str ( ) const

pure virtual

Retrieves the error message if an error occurred.

Returns

A reference to the error message string (empty if no error).

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

get_fde()

virtual Fde_ptr mysql::csa::Event_set_fetchable::get_fde ( )

pure virtual

Obtains non-owning pointer to current transaction FDE.

Returns

Non-owning pointer to FDE.

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

is_done()

virtual bool mysql::csa::Event_set_fetchable::is_done ( ) const

pure virtual

Checks if the event set has been fully fetched successfully.

Returns

true if the event set finished successfully, false otherwise.

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

is_error()

virtual bool mysql::csa::Event_set_fetchable::is_error ( ) const

pure virtual

Checks if an error occurred during fetching.

Returns

true if an error occurred, false otherwise.

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

is_trx()

virtual bool mysql::csa::Event_set_fetchable::is_trx ( ) const

pure virtual

Checks if this event set represents a complete transaction.

Returns

true if it represents a transaction, false otherwise.

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

reset()

virtual void mysql::csa::Event_set_fetchable::reset ( bool  reset_events )

pure virtual

Resets the state to allow fetching the event set again, also clearing any error state.

Parameters

reset_events

When true events states need to be reset

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

set_success()

virtual void mysql::csa::Event_set_fetchable::set_success ( )

inlinevirtual

Callback on success, default - do nothing.

Reimplemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

wait_next()

virtual bool mysql::csa::Event_set_fetchable::wait_next ( )

pure virtual

Waits until the next event can be fetched.

Returns

true if the next event can be fetched, false on end/error.

Implemented in mysql::csa::Event_set_fetchable_cache, and mysql::csa::Event_set_fetchable_relay_log.

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

• sql/changestreams/apply/storage/common/event_set_fetchable.h