persisted_variable.h File Reference

#include <stddef.h>
#include <map>
#include <string>
#include <unordered_set>
#include "map_helpers.h"
#include "my_alloc.h"
#include "my_inttypes.h"
#include "my_psi_config.h"
#include "mysql/components/services/bits/mysql_mutex_bits.h"
#include "mysql/components/services/bits/psi_bits.h"
#include "mysql/psi/mysql_mutex.h"
#include "sql/psi_memory_key.h"
#include "sql_string.h"

Go to the source code of this file.

Classes
struct	st_persist_var
	STRUCT st_persist_var. More...
struct	st_persist_var_hash
	STRUCT st_persist_var_hash. More...
class	Persisted_variables_cache
struct	Persisted_variables_cache::Key_info

Typedefs
using	Persisted_variables_umap = malloc_unordered_map< std::string, st_persist_var >
using	Persisted_variables_uset = malloc_unordered_set< st_persist_var, st_persist_var_hash >

Functions
void	my_init_persist_psi_keys (void)
	CLASS Persisted_variables_cache Holds <name,value> pair of all options which needs to be persisted to a file. More...

Typedef Documentation

Persisted_variables_umap

using Persisted_variables_umap = malloc_unordered_map<std::string, st_persist_var>

Persisted_variables_uset

using Persisted_variables_uset = malloc_unordered_set<st_persist_var, st_persist_var_hash>

Function Documentation

my_init_persist_psi_keys()

void my_init_persist_psi_keys

(

void

)

CLASS Persisted_variables_cache Holds <name,value> pair of all options which needs to be persisted to a file.

OVERVIEW

When first SET PERSIST statement is executed we instantiate Persisted_variables_cache which loads the config file if present into m_persisted_dynamic_variables set. This is a singleton operation. m_persisted_dynamic_variables is an in-memory copy of config file itself. If the SET statement passes then this in-memory is updated and flushed to file as an atomic operation.

Next SET PERSIST statement would only update the in-memory copy and sync to config file instead of loading the file again.