Allows to wrap another Service Implementation of the Dynamic Loader service and add ability to store a list of groups of loaded components. More...

#include <persistent_dynamic_loader_imp.h>

Static Public Member Functions
static bool	init (void *thdp)
	Initializes persistence store, loads all groups of components registered in component table. More...

static void	deinit ()
	De-initializes persistence loader. More...

static bool	initialized ()
	Initialisation status of persistence loader. More...

static mysql_service_status_t	load (void thd_ptr, const char urns[], int component_count) noexcept
	Loads specified group of components by URN, initializes them and registers all service implementations present in these components. More...

static mysql_service_status_t	unload (void thd_ptr, const char urns[], int component_count) noexcept
	Unloads specified group of Components by URN, deinitializes them and unregisters all service implementations present in these components. More...

static int	remove_from_cache (const char *urns[], int component_count)
	Removes the entries from the in-memory cache. More...

Static Private Attributes
static std::atomic< uint64 >	s_group_id
	Stores last group ID used in component table. More...

static std::map< std::string, uint64 >	component_id_by_urn
	Stores mapping of component URNs to their component_id used in component table, to ease row deletion. More...

static bool	is_initialized = false
	Indicates the initialization status of dynamic loader persistence. More...

static mysql_mutex_t	component_id_by_urn_mutex
	Serializes access to component_id_by_urn. More...

Detailed Description

Allows to wrap another Service Implementation of the Dynamic Loader service and add ability to store a list of groups of loaded components.

It reacts on successful invocations of the underlying Dynamic Loader Service Implementation methods load() and unload() and saves changes. It also loads during the start of the MySQL Server all groups of the Components that were still loaded on last MySQL Server shutdown, they are loaded in order of the original loads. It assumes that components does not any not fully-deterministic loads of another Components, which would break dependencies if they are decided to load other Components than last time. The list of groups of Components is stored in the 'mysql.component' table. It is valid to unload only part of the group of the previously loaded group of Components. In such a situation, as long as all dependencies are met, which is assured by the underlying Service Implementation, the rest of Components in group should load successfully after the MySQL Server restart.

Member Function Documentation

◆ deinit()

void mysql_persistent_dynamic_loader_imp::deinit ( void )

static

De-initializes persistence loader.

◆ init()

bool mysql_persistent_dynamic_loader_imp::init ( void * thdp )

static

Initializes persistence store, loads all groups of components registered in component table.

Shouldn't be called multiple times. We assume the order specified by group ID is correct one. This should be assured by dynamic loader as long as it will not allow to unload the component that has dependency on, in case there would be a possibility to switch that dependency to other component that is not to be unloaded. If this is assured, then it will not be possible for components with lower group IDs to have a dependency on component with higher group ID, even after state is restored in this initialization method.

Parameters

thdp	Current thread execution context

Returns: Status of performed operation

Return values

false	success
true	failure

◆ initialized()

bool mysql_persistent_dynamic_loader_imp::initialized ( )

static

Initialisation status of persistence loader.

An helper function.

Returns: Status of performed operation

Return values

true	initialization is done
false	initialization is not done

◆ load()

mysql_service_status_t mysql_persistent_dynamic_loader_imp::load	(	void *	thd_ptr,
		const char *	urns[],
		int	component_count
	)

staticnoexcept

Loads specified group of components by URN, initializes them and registers all service implementations present in these components.

Assures all dependencies will be met after loading specified components. The dependencies may be circular, in such case it's necessary to specify all components on cycle to load in one batch. From URNs specified the scheme part of URN (part before "://") is extracted and used to acquire service implementation of scheme component loader service for specified scheme. If the loading process successes then a group of Components by their URN is added to the component table.

Parameters

thd_ptr	Current thread execution context.
urns	List of URNs of Components to load.
component_count	Number of Components on list to load.

Returns: Status of performed operation

Return values

false	success
true	failure

◆ remove_from_cache()

int mysql_persistent_dynamic_loader_imp::remove_from_cache	(	const char *	urns[],
		int	component_count
	)

static

Removes the entries from the in-memory cache.

This is a "private method" of the persisted loader that's used in the same component.

Parameters

urns	the entries to remove
component_count	the count of entries to remove.

Return values

number of entried actually erased from the memory cache

◆ unload()

mysql_service_status_t mysql_persistent_dynamic_loader_imp::unload	(	void *	thd_ptr,
		const char *	urns[],
		int	component_count
	)

staticnoexcept

Unloads specified group of Components by URN, deinitializes them and unregisters all service implementations present in these components.

Assumes, although does not check it, all dependencies of not unloaded components will still be met after unloading specified components. The dependencies may be circular, in such case it's necessary to specify all components on cycle to unload in one batch. From URNs specified the scheme part of URN (part before "://") is extracted and used to acquire service implementation of scheme component loader service for specified scheme. URN specified should be identical to ones specified in load() method, i.e. all letters must have the same case. If the unloading process successes then a group of Components by their URN is added to the component table.

Parameters

thd_ptr	Current thread execution context.
urns	List of URNs of components to unload.
component_count	Number of components on list to unload.

Returns: Status of performed operation

Return values

false	success
true	failure

Member Data Documentation

◆ component_id_by_urn

std::map< my_string, uint64 > mysql_persistent_dynamic_loader_imp::component_id_by_urn

staticprivate

Stores mapping of component URNs to their component_id used in component table, to ease row deletion.

◆ component_id_by_urn_mutex

mysql_mutex_t mysql_persistent_dynamic_loader_imp::component_id_by_urn_mutex

staticprivate

Serializes access to component_id_by_urn.

◆ is_initialized

bool mysql_persistent_dynamic_loader_imp::is_initialized = false

staticprivate

Indicates the initialization status of dynamic loader persistence.

◆ s_group_id

std::atomic< uint64 > mysql_persistent_dynamic_loader_imp::s_group_id

staticprivate

Stores last group ID used in component table.

It is initialized on init() on component table scan with maximum group ID used in table.

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

sql/server_component/persistent_dynamic_loader_imp.h
sql/server_component/persistent_dynamic_loader.cc

Static Public Member Functions

Static Private Attributes

Detailed Description

Member Function Documentation

◆ deinit()

◆ init()

◆ initialized()

◆ load()

◆ remove_from_cache()

◆ unload()

Member Data Documentation

◆ component_id_by_urn

◆ component_id_by_urn_mutex

◆ is_initialized

◆ s_group_id