rewriter_plugin.cc File Reference

The plugin declaration part of the Rewriter plugin. More...

#include "plugin/rewriter/rewriter_plugin.h"
#include "my_config.h"
#include <assert.h>
#include <mysql/plugin_audit.h>
#include <mysql/psi/mysql_thread.h>
#include <stddef.h>
#include <algorithm>
#include <atomic>
#include <new>
#include <mysql/components/my_service.h>
#include <mysql/components/services/dynamic_privilege.h>
#include <mysql/components/services/log_builtins.h>
#include <mysql/components/services/mysql_current_thread_reader.h>
#include <mysql/components/services/mysql_thd_attributes.h>
#include <mysql/components/services/security_context.h>
#include "my_inttypes.h"
#include "my_psi_config.h"
#include "my_sys.h"
#include "mysql/psi/mysql_rwlock.h"
#include "mysqld_error.h"
#include "plugin/rewriter/rewriter.h"
#include "plugin/rewriter/rule.h"
#include "plugin/rewriter/services.h"
#include "template_utils.h"

Macros
#define	ACQUIRE_SERVICE(name)
#define	RELEASE_SERVICE(service)

Functions
template<class T >
T *	acquire_service (const char *service_name)
template<class T , class TNoConst >
void	release_service (T *service)
static void	update_verbose (MYSQL_THD, SYS_VAR *, void *, const void *save)
	Updater function for the status variable ..._verbose. More...
static void	update_enabled (MYSQL_THD, SYS_VAR *, void *, const void *value)
	Updater function for the status variable ..._enabled. More...
static void	update_enabled_for_threads_without_privilege_checks (MYSQL_THD, SYS_VAR *, void *, const void *value)
	Updater function for the status variable ..._enabled_for_threads_without_privilege_checks. More...
static	MYSQL_SYSVAR_INT (verbose, sys_var_verbose, PLUGIN_VAR_NOCMDARG, "Tells " PLUGIN_NAME " how verbose it should be.", nullptr, update_verbose, 1, 0, 2, 1)
static	MYSQL_SYSVAR_BOOL (enabled, sys_var_enabled, PLUGIN_VAR_NOCMDARG, "Whether queries should actually be rewritten.", nullptr, update_enabled, 1)
static	MYSQL_SYSVAR_BOOL (enabled_for_threads_without_privilege_checks, sys_var_enabled_for_threads_without_privilege_checks, PLUGIN_VAR_NOCMDARG, "Whether queries from threads which execute with privilege checks disabled" " should be rewritten.", nullptr, update_enabled_for_threads_without_privilege_checks, 1)
MYSQL_PLUGIN	get_rewriter_plugin_info ()
static void	init_rewriter_psi_keys ()
static bool	reload (MYSQL_THD thd)
	Reloads the rules into the in-memory table. More...
static bool	lock_and_reload (MYSQL_THD thd)
bool	refresh_rules_table ()
static string	shorten_query (MYSQL_LEX_STRING query)
static void	log_nonrewritten_query (MYSQL_THD thd, const uchar *digest_buf, Rewrite_result result)
	Writes a message in the log saying that the query did not get rewritten. More...
static bool	allow_rewrite ()
	Check if rewrite should be skipped for this query. More...

Variables
static bool	sys_var_enabled_for_threads_without_privilege_checks
	Enabled for threads with privilege checks disabled. More...
const mysql_service_mysql_thd_attributes_t *	mysql_thd_attributes = nullptr
const mysql_service_dynamic_privilege_register_t *	dynamic_privilege_register = nullptr
const mysql_service_mysql_current_thread_reader_t *	mysql_current_thread_reader
const mysql_service_global_grants_check_t *	global_grants_check = nullptr
static bool	needs_initial_load
	We handle recovery in a kind of lazy manner. More...
static const size_t	MAX_QUERY_LENGTH_IN_LOG = 100
static MYSQL_PLUGIN	plugin_info
static mysql_rwlock_t	LOCK_table
static Rewriter *	rewriter
static int	sys_var_verbose
	Verbose level. More...
static bool	sys_var_enabled
	Enabled. More...
static const mysql_service_registry_t *	reg_srv = nullptr
const mysql_service_log_builtins_t *	log_bi = nullptr
	accessor built-ins More...
const mysql_service_log_builtins_string_t *	log_bs = nullptr
	string built-ins More...
SYS_VAR *	rewriter_plugin_sys_vars []
PSI_rwlock_key	key_rwlock_LOCK_table_
static PSI_rwlock_info	all_rewrite_rwlocks []

Status variables for the plugin.
#define	PLUGIN_NAME   "Rewriter"
static std::atomic< long long >	status_var_number_rewritten_queries
	Number of queries that were rewritten. More...
static bool	status_var_reload_error
	Indicates if there was an error during the last reload. More...
static unsigned	status_var_number_loaded_rules
	Number of rules loaded in the in-memory table. More...
static long long	status_var_number_reloads
	Number of times the in-memory table was reloaded. More...
static SHOW_VAR	rewriter_plugin_status_vars []

Plugin declaration.
static struct st_mysql_audit	rewrite_query_descriptor
	mysql_declare_plugin_end
static int	rewrite_query_notify (MYSQL_THD thd, mysql_event_class_t event_class, const void *event)
	Entry point to the plugin. More...
static int	rewriter_plugin_init (MYSQL_PLUGIN plugin_ref)
static int	rewriter_plugin_deinit (void *)
	mysql_declare_plugin (audit_log)

Detailed Description

The plugin declaration part of the Rewriter plugin.

This file (alone) creates a post-parse query rewrite plugin. All of the functionality is brought in by including rewriter.h.

Macro Definition Documentation

ACQUIRE_SERVICE

#define ACQUIRE_SERVICE

(

name

)

Value:

  name = acquire_service<SERVICE_TYPE(name)>(#name); \
  if (name == nullptr) return 1;

PLUGIN_NAME

#define PLUGIN_NAME   "Rewriter"

RELEASE_SERVICE

#define RELEASE_SERVICE

(

service

)

Value:

  release_service<SERVICE_TYPE(service), SERVICE_TYPE_NO_CONST(service)>( \
      service);

Function Documentation

acquire_service()

template<class T >

T * acquire_service

(

const char *

service_name

)

allow_rewrite()

static bool allow_rewrite ( )

static

Check if rewrite should be skipped for this query.

Skip rewrites for

• init-thread queries and upgrade queries
• any query from a user who has the SKIP_QUERY_REWRITE privilege
• any replication applier query where the PRIVILEGE_CHECKS_USER has the SKIP_QUERY_REWRITE privilege
• any replication applier query where the PRIVILEGE_CHECKS_USER is null if the config var enabled_for_threads_without_privilege_checks=OFF. If the config var is ON, rewrites should be allowed.

Return values

true	if query should not skip rewrite
false	if query should skip rewrite

get_rewriter_plugin_info()

MYSQL_PLUGIN get_rewriter_plugin_info

(

)

init_rewriter_psi_keys()

static void init_rewriter_psi_keys ( )

static

lock_and_reload()

static bool lock_and_reload ( MYSQL_THD  thd )

static

log_nonrewritten_query()

static void log_nonrewritten_query ( MYSQL_THD  thd, const uchar *  digest_buf, Rewrite_result  result  )

static

Writes a message in the log saying that the query did not get rewritten.

(Only if verbose level is high enough.)

mysql_declare_plugin()

mysql_declare_plugin

(

audit_log

)

MYSQL_SYSVAR_BOOL() [1/2]

static MYSQL_SYSVAR_BOOL ( enabled  , sys_var_enabled  , PLUGIN_VAR_NOCMDARG  , "Whether queries should actually be rewritten."  , nullptr  , update_enabled  , 1    )

static

MYSQL_SYSVAR_BOOL() [2/2]

static MYSQL_SYSVAR_BOOL ( enabled_for_threads_without_privilege_checks  , sys_var_enabled_for_threads_without_privilege_checks  , PLUGIN_VAR_NOCMDARG  , "Whether queries from threads which execute with privilege checks disabled" " should be rewritten."  , nullptr  , update_enabled_for_threads_without_privilege_checks  , 1    )

static

MYSQL_SYSVAR_INT()

static MYSQL_SYSVAR_INT ( verbose  , sys_var_verbose  , PLUGIN_VAR_NOCMDARG  , "Tells " PLUGIN_NAME " how verbose it should be."  , nullptr  , update_verbose  , 1  , 0  , 2  , 1    )

static

refresh_rules_table()

bool refresh_rules_table

(

)

release_service()

template<class T , class TNoConst >

void release_service

(

T *

service

)

reload()

static bool reload ( MYSQL_THD  thd )

static

Reloads the rules into the in-memory table.

This function assumes that the appropriate lock is already taken and doesn't concern itself with locks.

rewrite_query_notify()

static int rewrite_query_notify ( MYSQL_THD  thd, mysql_event_class_t  event_class, const void *  event  )

static

Entry point to the plugin.

The server calls this function after each parsed query when the plugin is active. The function extracts the digest of the query. If the digest matches an existing rewrite rule, it is executed.

rewriter_plugin_deinit()

static int rewriter_plugin_deinit ( void *  )

static

rewriter_plugin_init()

static int rewriter_plugin_init ( MYSQL_PLUGIN  plugin_ref )

static

shorten_query()

static string shorten_query ( MYSQL_LEX_STRING  query )

static

update_enabled()

static void update_enabled ( MYSQL_THD  , SYS_VAR *  , void *  , const void *  value  )

static

Updater function for the status variable ..._enabled.

update_enabled_for_threads_without_privilege_checks()

static void update_enabled_for_threads_without_privilege_checks ( MYSQL_THD  , SYS_VAR *  , void *  , const void *  value  )

static

Updater function for the status variable ..._enabled_for_threads_without_privilege_checks.

update_verbose()

static void update_verbose ( MYSQL_THD  , SYS_VAR *  , void *  , const void *  save  )

static

Updater function for the status variable ..._verbose.

Variable Documentation

all_rewrite_rwlocks

PSI_rwlock_info all_rewrite_rwlocks[]

static

Initial value:

= {{&key_rwlock_LOCK_table_,
                                                 "LOCK_plugin_rewriter_table_",
                                                 0, 0, PSI_DOCUMENT_ME}}

dynamic_privilege_register

const mysql_service_dynamic_privilege_register_t* dynamic_privilege_register = nullptr

global_grants_check

const mysql_service_global_grants_check_t* global_grants_check = nullptr

key_rwlock_LOCK_table_

PSI_rwlock_key key_rwlock_LOCK_table_

LOCK_table

mysql_rwlock_t LOCK_table

static

log_bi

const mysql_service_log_builtins_t* log_bi = nullptr

accessor built-ins

accessor built-ins

log_bs

const mysql_service_log_builtins_string_t* log_bs = nullptr

string built-ins

MAX_QUERY_LENGTH_IN_LOG

const size_t MAX_QUERY_LENGTH_IN_LOG = 100

static

mysql_current_thread_reader

const mysql_service_mysql_current_thread_reader_t* mysql_current_thread_reader

Initial value:

=
    nullptr

mysql_declare_plugin_end

mysql_declare_plugin_end

mysql_thd_attributes

const mysql_service_mysql_thd_attributes_t* mysql_thd_attributes = nullptr

needs_initial_load

bool needs_initial_load

static

We handle recovery in a kind of lazy manner.

If the server was shut down with this plugin installed, we should ideally load the rules into memory right on the spot in rewriter_plugin_init() as the server comes to. But this plugin is relying on transactions to do that and unfortunately the transaction log is not set up at this point. (It's set up about 200 lines further down in init_server_components() at the time of writing.) That's why we simply set this flag in rewriter_plugin_init() and reload in rewrite_query_post_parse() if it is set.

plugin_info

MYSQL_PLUGIN plugin_info

static

reg_srv

const mysql_service_registry_t* reg_srv = nullptr

static

rewrite_query_descriptor

struct st_mysql_audit rewrite_query_descriptor

static

Initial value:

= {
    MYSQL_AUDIT_INTERFACE_VERSION, 
    nullptr,                       
    rewrite_query_notify,          
    {
        0,
        0,
        (unsigned long)MYSQL_AUDIT_PARSE_ALL,
    } 
}

rewriter

Rewriter* rewriter

static

rewriter_plugin_status_vars

SHOW_VAR rewriter_plugin_status_vars[]

static

Initial value:

= {
    {PLUGIN_NAME "_number_rewritten_queries",
     pointer_cast<char *>(&status_var_number_rewritten_queries), SHOW_LONGLONG,
     SHOW_SCOPE_GLOBAL},
    {PLUGIN_NAME "_reload_error",
     pointer_cast<char *>(&status_var_reload_error), SHOW_BOOL,
     SHOW_SCOPE_GLOBAL},
    {PLUGIN_NAME "_number_loaded_rules",
     pointer_cast<char *>(&status_var_number_loaded_rules), SHOW_INT,
     SHOW_SCOPE_GLOBAL},
    {PLUGIN_NAME "_number_reloads",
     pointer_cast<char *>(&status_var_number_reloads), SHOW_LONGLONG,
     SHOW_SCOPE_GLOBAL},
    {nullptr, nullptr, SHOW_BOOL, SHOW_SCOPE_GLOBAL}}

rewriter_plugin_sys_vars

SYS_VAR* rewriter_plugin_sys_vars[]

Initial value:

= {
    MYSQL_SYSVAR(verbose), MYSQL_SYSVAR(enabled),
    MYSQL_SYSVAR(enabled_for_threads_without_privilege_checks), nullptr}

status_var_number_loaded_rules

unsigned status_var_number_loaded_rules

static

Number of rules loaded in the in-memory table.

status_var_number_reloads

long long status_var_number_reloads

static

Number of times the in-memory table was reloaded.

status_var_number_rewritten_queries

std::atomic<long long> status_var_number_rewritten_queries

static

Number of queries that were rewritten.

status_var_reload_error

bool status_var_reload_error

static

Indicates if there was an error during the last reload.

sys_var_enabled

bool sys_var_enabled

static

Enabled.

sys_var_enabled_for_threads_without_privilege_checks

bool sys_var_enabled_for_threads_without_privilege_checks

static

Enabled for threads with privilege checks disabled.

sys_var_verbose

int sys_var_verbose

static

Verbose level.