MySQL 8.4.3
Source Code Documentation
sql_plugin_services.h
Go to the documentation of this file.
1/* Copyright (c) 2009, 2024, Oracle and/or its affiliates.
2
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License, version 2.0,
5 as published by the Free Software Foundation.
6
7 This program is designed to work with certain software (including
8 but not limited to OpenSSL) that is licensed under separate terms,
9 as designated in a particular file or component or in included license
10 documentation. The authors of MySQL hereby grant you an additional
11 permission to link the program and your derivative works with the
12 separately licensed software that they have either included with
13 the program or referenced in the documentation.
14
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License, version 2.0, for more details.
19
20 You should have received a copy of the GNU General Public License
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
23
24/* support for Services */
25#include "mysql/services.h"
26#include "service_versions.h"
27
28/**
29 @page page_ext_plugin_svc_new_service_howto How to add a new service
30
31 A "plugin service" is in its core a C struct containing one or more function
32 pointers.
33
34 If you want to export C++ class you need to provide an
35 extern "C" function that will create a new instance of your class,
36 and put it in a service. But be careful to also provide a destructor
37 method since the heaps of the server and the plugin may be different.
38
39 Data structures are not part of the service structure, but they are part
40 of the API you create and usually need to be declared in the same
41 service_*.h file.
42
43 To turn a **pre-existing** set of functions (foo_func1, foo_func2)
44 into a service "foo" you need to:
45
46 <ol>
47 <li>
48 Create a new file include/mysql/service_foo.h
49
50 The template is:
51
52 @include service_foo.h
53
54 The service_foo.h file should be self-contained, if it needs system headers -
55 include them in it, e.g. if you use `size_t`
56
57 ~~~~
58 #include <stdlib.h>
59 ~~~~
60
61 It should also declare all the accompanying data structures, as necessary
62 (e.g. ::thd_alloc_service declares ::MYSQL_LEX_STRING).
63</li><li>
64 Add the new file to include/mysql/services.h
65</li><li>
66 Increase the minor plugin ABI version in include/mysql/plugin.h:
67 ::MYSQL_PLUGIN_INTERFACE_VERSION = ::MYSQL_PLUGIN_INTERFACE_VERSION + 1
68</li><li>
69 Add the version of your service to include/service_versions.h:
70 ~~~~
71 #define VERSION_foo 0x0100
72 ~~~~
73</li><li>
74 Create a new file `libservices/foo_service.c` using the following template:
75 @include service_foo.cc
76</li><li>
77 Add the new file to libservices/CMakeLists.txt (MYSQLSERVICES_SOURCES)
78</li><li>
79 And finally, register your service for dynamic linking in
80 sql/sql_plugin_services.h
81 <ul><li>
82 Fill in the service structure:
83 ~~~
84 static struct foo_service_st foo_handler = {
85 foo_func1,
86 foo_func2
87 }
88 ~~~
89 </li><li>
90 Add it to the ::list_of_services
91
92 ~~~
93 { "foo_service", VERSION_foo, &foo_handler }
94 ~~~
95 </li></ul></li></ol>
96*/
97
98/**
99 @page page_ext_plugin_api_goodservices What defines a "good" plugin service ?
100
101 The following is an attempt to explain what is a good plugin service.
102 It is also an attempt to mention some bad practices that should be
103 avoided. The text is in no way conclusive and is a constant work in progress
104 to keep it updated.
105
106
107 Avoid exposing the definitions of complex server structure
108 ----------------------------------------------------------
109
110 @ref page_ext_plugin_svc_new_service_howto states that the service header
111 should be self-contained, i.e. all data structures used by the API need to be
112 defined by the service header.
113
114 The service headers are considered "public" and are packaged into the binary
115 packages for users of these binary packages to use when developing plugins
116 that are using the service.
117
118 When you combine the two together it becomes evident that complex server data
119 structures should definitely be avoided as parts of the API.
120
121 The main inconvenience is that a complex structure's definition should be
122 copied into the service's header. And if that is a frequently changed
123 structure all plugins using it will need to be recompiled every time it
124 changes.
125
126 That is the reason why it is always better to pass individual members of
127 these structures that are simpler. Even if this means passing more than just
128 a single argument.
129
130 If you absolutely must pass references to complex structure instances it is
131 better to do it as a "handle", i.e. a `void *`. For convenience, you can have
132 a named class for that, e.g.
133 ~~~~
134 typedef void *my_new_handle_t;
135 ~~~~
136
137 This isolates the layout of the server structure from the plugin code while
138 still allowing the plugins to operate on it via accessor and mutator methods.
139
140 Strive to make reusable services
141 --------------------------------
142
143 Services have some extra processing associated with them. So they should be
144 used only for functionality that more than one plugin will probably use.
145
146 How do we know if a service is reusable ?
147
148 If a service deals with complex structures related to a specific plugin API
149 or does not provide a logically complete set of operations chances are that
150 there will not be much re-use of this service.
151
152 Keep the identifier namespace clean
153 -----------------------------------
154
155 As discussed in @ref page_ext_plugin_svc_anathomy each function of each
156 service API is added to the global C/C++ namespace for all plugins via a set
157 of preprocessor defines.
158
159 So if you name your plugin service functions after single common words, e.g.
160 `get` or `put` etc you will strongly pollute the namespace that the plugin
161 authors will use. They will either have to refrain from using such methods or
162 go to the extra trouble of using either preprocessor or C++ namespace tricks.
163
164 Thus, prefix your APIs. We typically use the `my_` prefix for all MySQL
165 exported functions (note that the `mysql_` prefix is reserved for the C API
166 functions, e.g. ::mysql_real_connect()). We also add a subsystem prefix, e.g.
167 ::my_plugin_log_message() is the service API name for plugins to log messages
168 to the server's error log.
169
170 Use services for "published" APIs only
171 --------------------------------------
172
173 Plugin services are an element of the binary APIs that must be kept stable
174 to keep existing plugins operating.
175 Plugin service APIs are thus versioned to allow the server to check if the
176 plugins are using the right version of the particular service API.
177 The server's build scripts also package the service API headers in a
178 designated directory and are documented in a specific service API document.
179
180 This stability comes at a price. All of the above should be observed and the
181 versions should be increased accordingly.
182
183 Major should be bumped (and the minor reset) when there are incompatible
184 changes: signature change, meaning change etc.
185
186 Minor should be bumped when there are backward compatible changes: adding
187 new functions at the end of the API, adding new named constants to be used
188 by the API etc.
189
190 Use services to make plugins "clean"
191 ------------------------------------
192
193 A clean plugin is one that does not need to reference the symbols of the
194 server binary that loads it. Such plugin can be loaded by any binary and
195 it is guaranteed to operate in a predictable way as long as the right
196 plugin APIs are called and the relevant plugin service APIs are defined
197 by the loading binary.
198
199 Always make fully-formed plugin service APIs
200 --------------------------------------------
201
202 Follow strictly and completely the steps defined in
203 @ref page_ext_plugin_svc_new_service_howto.
204
205 Don't skip steps or you'll be decreasing the usability of the service API.
206*/
207
208/**
209 @defgroup group_ext_plugin_services MySQL Server Plugin Services
210
211 This is a group of all plugin service APIs.
212
213 See @ref page_ext_plugin_services for more details.
214*/
215
216/**
217 A server-side reference to a plugin service.
218
219 @sa plugin_add, list_of_services
220*/
222 /** The name of the service pointer symbol exported by the plugin */
223 const char *name;
224 /** The service version provided by the server */
226 /** The actual server side service structure pointer */
227 void *service;
228};
229
235
238};
239
246
250
253
256
259
266};
267
270
273
283
286};
287
291
294
300
303
306
308 {"srv_session_service", VERSION_srv_session_service,
310 {"command_service", VERSION_command, &command_handler},
311 {"srv_session_info_service", VERSION_srv_session_info_service,
313 {"thd_alloc_service", VERSION_thd_alloc, &thd_alloc_handler},
314 {"thd_wait_service", VERSION_thd_wait, &thd_wait_handler},
315 {"my_thread_scheduler_service", VERSION_my_thread_scheduler,
317 {"my_plugin_log_service", VERSION_my_plugin_log, &my_plugin_log_handler},
318 {"mysql_string_service", VERSION_mysql_string, &mysql_string_handler},
319 {"mysql_malloc_service", VERSION_mysql_malloc, &mysql_malloc_handler},
320 {"mysql_password_policy_service", VERSION_mysql_password_policy,
322 {"mysql_parser_service", VERSION_parser, &parser_handler},
323 {"rpl_transaction_ctx_service", VERSION_rpl_transaction_ctx_service,
325 {"transaction_write_set_service", VERSION_transaction_write_set_service,
327 {"security_context_service", VERSION_security_context_service,
329 {"mysql_locking_service", VERSION_locking_service,
331 {"mysql_keyring_service", VERSION_mysql_keyring_service,
333 {"plugin_registry_service", VERSION_plugin_registry_service,
335};
void * my_malloc(PSI_memory_key key, size_t size, int flags)
Allocates size bytes of memory.
Definition: my_memory.cc:57
void my_free(void *ptr)
Frees the memory pointed by the ptr.
Definition: my_memory.cc:81
int command_service_run_command(MYSQL_SESSION session, enum enum_server_command command, const union COM_DATA *data, const CHARSET_INFO *client_cs, const struct st_command_service_cbs *callbacks, enum cs_text_or_binary text_or_binary, void *service_callbacks_ctx)
Executes a server command in a session.
int mysql_acquire_locking_service_locks(MYSQL_THD opaque_thd, const char *lock_namespace, const char **lock_names, size_t lock_num, enum enum_locking_service_lock_type lock_type, uint64_t lock_timeout)
int mysql_release_locking_service_locks(MYSQL_THD opaque_thd, const char *lock_namespace)
Definition: locking_service.cc:186
int my_plugin_log_message(MYSQL_PLUGIN *plugin, enum plugin_log_level level, const char *format,...)
Definition: log.cc:2335
char * my_strdup(PSI_memory_key key, const char *from, myf_t flags)
Definition: my_malloc.cc:548
void * my_memdup(PSI_memory_key key, const void *from, size_t length, myf_t flags)
Definition: my_malloc.cc:540
void my_claim(const void *ptr, bool claim)
Definition: my_malloc.cc:458
char * my_strndup(PSI_memory_key key, const char *from, size_t length, myf_t flags)
Definition: my_malloc.cc:556
void * my_realloc(PSI_memory_key key, void *ptr, size_t size, myf_t flags)
Definition: my_malloc.cc:449
int my_key_fetch(const char *, char **, const char *, void **, size_t *)
Iterates over all active keyring plugins and calls the mysql_key_fetch API for the first one found.
Definition: keyring_service.cc:125
int my_key_store(const char *, const char *, const char *, const void *, size_t)
Iterates over all active keyring plugins calls the mysql_key_store API for the first one found.
Definition: keyring_service.cc:141
int my_key_generate(const char *, const char *, const char *, size_t)
Iterates over all active keyring plugins and calls the mysql_key_generate API for the first one found...
Definition: keyring_service.cc:166
int my_key_remove(const char *, const char *)
Iterates over all active keyring plugins and calls the mysql_key_remove API for the first one found.
Definition: keyring_service.cc:154
int my_calculate_password_strength(const char *, unsigned int)
Invoke the component/plugin to evalue the strength of a password.
Definition: password_policy_service.cc:132
int my_validate_password_policy(const char *, unsigned int)
Invoke the component/plugin to validate the input password.
Definition: password_policy_service.cc:74
mysql_string_handle mysql_string_to_lowercase(mysql_string_handle string_handle)
Definition: string_service.cc:148
int mysql_string_iterator_isdigit(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:138
void mysql_string_iterator_free(mysql_string_iterator_handle)
Definition: string_service.cc:78
void mysql_string_free(mysql_string_handle)
Definition: string_service.cc:68
mysql_string_iterator_handle mysql_string_get_iterator(mysql_string_handle string_handle)
Definition: string_service.cc:83
int mysql_string_iterator_islower(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:128
int mysql_string_iterator_next(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:95
int mysql_string_iterator_isupper(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:118
int mysql_string_convert_to_char_ptr(mysql_string_handle string_handle, const char *charset_name, char *buffer, unsigned int buffer_size, int *error)
Definition: string_service.cc:52
void mysql_parser_join_thread(struct my_thread_handle *thread_handle)
Definition: parser_service.cc:218
int mysql_parser_get_statement_type(MYSQL_THD thd)
Definition: parser_service.cc:284
int mysql_parser_parse(MYSQL_THD thd, const MYSQL_LEX_STRING query, unsigned char is_prepared, sql_condition_handler_function handle_condition, void *condition_handler_state)
Definition: parser_service.cc:233
int mysql_parser_get_statement_digest(MYSQL_THD thd, unsigned char *digest)
Definition: parser_service.cc:310
void mysql_parser_start_thread(MYSQL_THD thd, callback_function fun, void *arg, struct my_thread_handle *thread_handle)
MYSQL_THD mysql_parser_current_session()
Definition: parser_service.cc:139
void mysql_parser_set_current_database(MYSQL_THD thd, const MYSQL_LEX_STRING db)
Definition: parser_service.cc:222
int mysql_parser_visit_tree(MYSQL_THD thd, parse_node_visit_function processor, unsigned char *arg)
Definition: parser_service.cc:332
MYSQL_THD mysql_parser_open_session()
Definition: parser_service.cc:141
MYSQL_LEX_STRING mysql_parser_item_string(MYSQL_ITEM item)
Definition: parser_service.cc:338
int mysql_parser_extract_prepared_params(MYSQL_THD thd, int *positions)
Definition: parser_service.cc:324
int mysql_parser_get_number_params(MYSQL_THD thd)
Definition: parser_service.cc:320
MYSQL_LEX_STRING mysql_parser_get_normalized_query(MYSQL_THD thd)
Definition: parser_service.cc:358
MYSQL_LEX_STRING mysql_parser_get_query(MYSQL_THD thd)
Definition: parser_service.cc:352
void mysql_parser_free_string(MYSQL_LEX_STRING string)
Definition: parser_service.cc:350
const mysql_service_registry_t * mysql_plugin_registry_acquire()
Returns a new reference to the "registry" service.
Definition: plugin_registry_service.cc:47
int mysql_plugin_registry_release(const mysql_service_registry_t *)
Releases a registry service reference.
Definition: plugin_registry_service.cc:75
int set_transaction_ctx(Transaction_termination_ctx transaction_termination_ctx)
Definition: rpl_transaction_ctx.cc:96
void update_write_set_memory_size_limit(uint64 size_limit)
Definition: rpl_transaction_write_set_ctx.cc:173
void require_full_write_set(bool requires_ws)
Definition: rpl_transaction_write_set_ctx.cc:153
Transaction_write_set * get_transaction_write_set(unsigned long m_thread_id)
Definition: rpl_transaction_write_set_ctx.cc:193
void set_write_set_memory_size_limit(uint64 size_limit)
Definition: rpl_transaction_write_set_ctx.cc:168
my_svc_bool thd_get_security_context(MYSQL_THD, MYSQL_SECURITY_CONTEXT *out_ctx)
Gets the security context for the thread.
Definition: service_security_context.cc:55
my_svc_bool security_context_set_option(MYSQL_SECURITY_CONTEXT, const char *name, void *pvalue)
Sets a value for a named security context attribute Currently defined names are:
Definition: service_security_context.cc:304
my_svc_bool security_context_lookup(MYSQL_SECURITY_CONTEXT ctx, const char *user, const char *host, const char *ip, const char *db)
Looks up in the defined user accounts an account based on the user@host[ip] combo supplied and checks...
Definition: service_security_context.cc:177
my_svc_bool security_context_create(MYSQL_SECURITY_CONTEXT *out_ctx)
Creates a new security context and initializes it with the defaults (no access, no user etc).
Definition: service_security_context.cc:109
my_svc_bool security_context_get_option(MYSQL_SECURITY_CONTEXT, const char *name, void *inout_pvalue)
Reads a named security context attribute and returns its value.
Definition: service_security_context.cc:239
my_svc_bool security_context_copy(MYSQL_SECURITY_CONTEXT in_ctx, MYSQL_SECURITY_CONTEXT *out_ctx)
Duplicates a security context.
Definition: service_security_context.cc:146
my_svc_bool thd_set_security_context(MYSQL_THD, MYSQL_SECURITY_CONTEXT in_ctx)
Sets a new security context for the thread.
Definition: service_security_context.cc:80
my_svc_bool security_context_destroy(MYSQL_SECURITY_CONTEXT ctx)
Deallocates a security context.
Definition: service_security_context.cc:127
int srv_session_init_thread(const void *plugin)
Initializes the current physical thread to use with session service.
Definition: srv_session_service.cc:60
int srv_session_attach(MYSQL_SESSION session, MYSQL_THD *ret_previous_thd)
Attaches a session to current physical thread.
Definition: srv_session_service.cc:232
void srv_session_deinit_thread()
Deinitializes the current physical thread to use with session service.
Definition: srv_session_service.cc:67
int srv_session_server_is_available()
Returns if the server is available (not booting or shutting down)
Definition: srv_session_service.cc:221
int srv_session_close(MYSQL_SESSION session)
Closes a previously opened session.
MYSQL_SESSION srv_session_open(srv_session_error_cb error_cb, void *plugin_ctx)
Opens a server session.
Definition: srv_session_service.cc:145
int srv_session_detach(MYSQL_SESSION session)
Detaches a session from current physical thread.
MYSQL_THD srv_session_info_get_thd(MYSQL_SESSION session)
Returns the THD of a session.
uint16_t srv_session_info_get_client_port(MYSQL_SESSION session)
Returns the client port of a session.
unsigned int srv_session_info_thread_count(const void *plugin)
Returns the number opened sessions in thread initialized by srv_session service.
Definition: srv_session_info_service.cc:144
int srv_session_info_killed(MYSQL_SESSION session)
Returns whether the session was killed.
unsigned int srv_session_info_session_count()
Returns the number opened sessions in thread initialized by srv_session service.
Definition: srv_session_info_service.cc:133
int srv_session_info_set_client_port(MYSQL_SESSION session, uint16_t port)
Sets the client port of a session.
LEX_CSTRING srv_session_info_get_current_db(MYSQL_SESSION session)
Returns the current database of a session.
int srv_session_info_set_connection_type(MYSQL_SESSION session, enum enum_vio_type type)
Sets the connection type of a session.
my_thread_id srv_session_info_get_session_id(MYSQL_SESSION session)
Returns the ID of a session.
char * thd_strdup(MYSQL_THD thd, const char *str)
Definition: sql_thd_api.cc:613
void * thd_calloc(MYSQL_THD thd, size_t size)
Definition: sql_thd_api.cc:611
MYSQL_LEX_STRING * thd_make_lex_string(MYSQL_THD thd, MYSQL_LEX_STRING *lex_str, const char *str, size_t size, int allocate_lex_string)
Create a LEX_STRING in this connection's local memory pool.
Definition: sql_thd_api.cc:621
char * thd_strmake(MYSQL_THD thd, const char *str, size_t size)
Definition: sql_thd_api.cc:617
void * thd_memdup(MYSQL_THD thd, const void *str, size_t size)
Definition: sql_thd_api.cc:630
void * thd_alloc(MYSQL_THD thd, size_t size)
Allocate memory in the connection's local memory pool.
Definition: sql_thd_api.cc:609
void thd_wait_end(THD *thd)
void thd_wait_begin(THD *thd, int wait_type)
int my_connection_handler_reset()
Destroys the current connection handler and restores the previous.
Definition: connection_handler_manager.cc:304
int my_connection_handler_set(struct Connection_handler_functions *chf, struct THD_event_functions *tef)
Instantiates Plugin_connection_handler based on the supplied Conection_handler_functions and sets it ...
Definition: connection_handler_manager.cc:287
#define VERSION_mysql_malloc
Definition: service_versions.h:40
#define VERSION_my_plugin_log
Definition: service_versions.h:38
#define VERSION_locking_service
Definition: service_versions.h:46
#define VERSION_mysql_keyring_service
Definition: service_versions.h:49
#define VERSION_security_context_service
Definition: service_versions.h:45
#define VERSION_thd_alloc
Definition: service_versions.h:35
#define VERSION_my_thread_scheduler
Definition: service_versions.h:37
#define VERSION_rpl_transaction_ctx_service
Definition: service_versions.h:43
#define VERSION_transaction_write_set_service
Definition: service_versions.h:44
#define VERSION_plugin_registry_service
Definition: service_versions.h:50
#define VERSION_thd_wait
Definition: service_versions.h:36
#define VERSION_mysql_password_policy
Definition: service_versions.h:41
#define VERSION_srv_session_service
Definition: service_versions.h:48
#define VERSION_mysql_string
Definition: service_versions.h:39
#define VERSION_srv_session_info_service
Definition: service_versions.h:47
#define VERSION_command
Definition: service_versions.h:34
#define VERSION_parser
Definition: service_versions.h:42
static struct mysql_parser_service_st parser_handler
Definition: sql_plugin_services.h:274
static struct mysql_locking_service_st locking_service_handler
Definition: sql_plugin_services.h:292
static struct mysql_password_policy_service_st mysql_password_policy_handler
Definition: sql_plugin_services.h:271
static struct my_thread_scheduler_service my_thread_scheduler_handler
Definition: sql_plugin_services.h:254
static struct plugin_registry_service_st plugin_registry_handler
Definition: sql_plugin_services.h:304
static struct srv_session_info_service_st srv_session_info_handler
Definition: sql_plugin_services.h:240
static struct thd_alloc_service_st thd_alloc_handler
Definition: sql_plugin_services.h:247
static struct srv_session_service_st srv_session_service_handler
Definition: sql_plugin_services.h:230
static struct thd_wait_service_st thd_wait_handler
Definition: sql_plugin_services.h:251
static struct mysql_keyring_service_st mysql_keyring_handler
Definition: sql_plugin_services.h:301
static struct st_service_ref list_of_services[]
Definition: sql_plugin_services.h:307
static struct mysql_malloc_service_st mysql_malloc_handler
Definition: sql_plugin_services.h:268
static struct mysql_string_service_st mysql_string_handler
Definition: sql_plugin_services.h:260
static struct transaction_write_set_service_st transaction_write_set_handler
Definition: sql_plugin_services.h:288
static struct my_plugin_log_service my_plugin_log_handler
Definition: sql_plugin_services.h:257
static struct security_context_service_st security_context_handler
Definition: sql_plugin_services.h:295
static struct command_service_st command_handler
Definition: sql_plugin_services.h:236
static struct rpl_transaction_ctx_service_st rpl_transaction_ctx_handler
Definition: sql_plugin_services.h:284
Definition: service_command.h:394
Enables plugins to log messages into the server's error log.
Definition: service_my_plugin_log.h:51
Definition: service_thread_scheduler.h:36
This service allows plugins to interact with key store backends.
Definition: service_mysql_keyring.h:65
This service provides support for taking read/write locks.
Definition: service_locking.h:108
This service allows plugins to allocate and free memory through the server's memory handling routines...
Definition: service_mysql_alloc.h:59
Definition: service_parser.h:197
This service allows plugins to validate passwords based on a common policy.
Definition: service_mysql_password_policy.h:46
Definition: service_mysql_string.h:39
A bridge service allowing plugins to work with the registry.
Definition: service_plugin_registry.h:47
Definition: service_rpl_transaction_ctx.h:63
This service provides functions for plugins and storage engines to manipulate the thread's security c...
Definition: service_security_context.h:72
Definition: service_srv_session_info.h:43
Definition: service_srv_session.h:42
A server-side reference to a plugin service.
Definition: sql_plugin_services.h:221
void * service
The actual server side service structure pointer.
Definition: sql_plugin_services.h:227
uint version
The service version provided by the server.
Definition: sql_plugin_services.h:225
const char * name
The name of the service pointer symbol exported by the plugin.
Definition: sql_plugin_services.h:223
Definition: service_thd_alloc.h:47
Definition: service_thd_wait.h:143
Definition: service_rpl_transaction_write_set.h:62