MySQL 8.3.0
Source Code Documentation
sql_plugin_services.h
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1/* Copyright (c) 2009, 2023, 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 also distributed 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 included with MySQL.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License, version 2.0, for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
22
23/* support for Services */
24#include "mysql/services.h"
25#include "service_versions.h"
26
27/**
28 @page page_ext_plugin_svc_new_service_howto How to add a new service
29
30 A "plugin service" is in its core a C struct containing one or more function
31 pointers.
32
33 If you want to export C++ class you need to provide an
34 extern "C" function that will create a new instance of your class,
35 and put it in a service. But be careful to also provide a destructor
36 method since the heaps of the server and the plugin may be different.
37
38 Data structures are not part of the service structure, but they are part
39 of the API you create and usually need to be declared in the same
40 service_*.h file.
41
42 To turn a **pre-existing** set of functions (foo_func1, foo_func2)
43 into a service "foo" you need to:
44
45 <ol>
46 <li>
47 Create a new file include/mysql/service_foo.h
48
49 The template is:
50
51 @include service_foo.h
52
53 The service_foo.h file should be self-contained, if it needs system headers -
54 include them in it, e.g. if you use `size_t`
55
56 ~~~~
57 #include <stdlib.h>
58 ~~~~
59
60 It should also declare all the accompanying data structures, as necessary
61 (e.g. ::thd_alloc_service declares ::MYSQL_LEX_STRING).
62</li><li>
63 Add the new file to include/mysql/services.h
64</li><li>
65 Increase the minor plugin ABI version in include/mysql/plugin.h:
66 ::MYSQL_PLUGIN_INTERFACE_VERSION = ::MYSQL_PLUGIN_INTERFACE_VERSION + 1
67</li><li>
68 Add the version of your service to include/service_versions.h:
69 ~~~~
70 #define VERSION_foo 0x0100
71 ~~~~
72</li><li>
73 Create a new file `libservices/foo_service.c` using the following template:
74 @include service_foo.cc
75</li><li>
76 Add the new file to libservices/CMakeLists.txt (MYSQLSERVICES_SOURCES)
77</li><li>
78 And finally, register your service for dynamic linking in
79 sql/sql_plugin_services.h
80 <ul><li>
81 Fill in the service structure:
82 ~~~
83 static struct foo_service_st foo_handler = {
84 foo_func1,
85 foo_func2
86 }
87 ~~~
88 </li><li>
89 Add it to the ::list_of_services
90
91 ~~~
92 { "foo_service", VERSION_foo, &foo_handler }
93 ~~~
94 </li></ul></li></ol>
95*/
96
97/**
98 @page page_ext_plugin_api_goodservices What defines a "good" plugin service ?
99
100 The following is an attempt to explain what is a good plugin service.
101 It is also an attempt to mention some bad practices that should be
102 avoided. The text is in no way conclusive and is a constant work in progress
103 to keep it updated.
104
105
106 Avoid exposing the definitions of complex server structure
107 ----------------------------------------------------------
108
109 @ref page_ext_plugin_svc_new_service_howto states that the service header
110 should be self-contained, i.e. all data structures used by the API need to be
111 defined by the service header.
112
113 The service headers are considered "public" and are packaged into the binary
114 packages for users of these binary packages to use when developing plugins
115 that are using the service.
116
117 When you combine the two together it becomes evident that complex server data
118 structures should definitely be avoided as parts of the API.
119
120 The main inconvenience is that a complex structure's definition should be
121 copied into the service's header. And if that is a frequently changed
122 structure all plugins using it will need to be recompiled every time it
123 changes.
124
125 That is the reason why it is always better to pass individual members of
126 these structures that are simpler. Even if this means passing more than just
127 a single argument.
128
129 If you absolutely must pass references to complex structure instances it is
130 better to do it as a "handle", i.e. a `void *`. For convenience, you can have
131 a named class for that, e.g.
132 ~~~~
133 typedef void *my_new_handle_t;
134 ~~~~
135
136 This isolates the layout of the server structure from the plugin code while
137 still allowing the plugins to operate on it via accessor and mutator methods.
138
139 Strive to make reusable services
140 --------------------------------
141
142 Services have some extra processing associated with them. So they should be
143 used only for functionality that more than one plugin will probably use.
144
145 How do we know if a service is reusable ?
146
147 If a service deals with complex structures related to a specific plugin API
148 or does not provide a logically complete set of operations chances are that
149 there will not be much re-use of this service.
150
151 Keep the identifier namespace clean
152 -----------------------------------
153
154 As discussed in @ref page_ext_plugin_svc_anathomy each function of each
155 service API is added to the global C/C++ namespace for all plugins via a set
156 of preprocessor defines.
157
158 So if you name your plugin service functions after single common words, e.g.
159 `get` or `put` etc you will strongly pollute the namespace that the plugin
160 authors will use. They will either have to refrain from using such methods or
161 go to the extra trouble of using either preprocessor or C++ namespace tricks.
162
163 Thus, prefix your APIs. We typically use the `my_` prefix for all MySQL
164 exported functions (note that the `mysql_` prefix is reserved for the C API
165 functions, e.g. ::mysql_real_connect()). We also add a subsystem prefix, e.g.
166 ::my_plugin_log_message() is the service API name for plugins to log messages
167 to the server's error log.
168
169 Use services for "published" APIs only
170 --------------------------------------
171
172 Plugin services are an element of the binary APIs that must be kept stable
173 to keep existing plugins operating.
174 Plugin service APIs are thus versioned to allow the server to check if the
175 plugins are using the right version of the particular service API.
176 The server's build scripts also package the service API headers in a
177 designated directory and are documented in a specific service API document.
178
179 This stability comes at a price. All of the above should be observed and the
180 versions should be increased accordingly.
181
182 Major should be bumped (and the minor reset) when there are incompatible
183 changes: signature change, meaning change etc.
184
185 Minor should be bumped when there are backward compatible changes: adding
186 new functions at the end of the API, adding new named constants to be used
187 by the API etc.
188
189 Use services to make plugins "clean"
190 ------------------------------------
191
192 A clean plugin is one that does not need to reference the symbols of the
193 server binary that loads it. Such plugin can be loaded by any binary and
194 it is guaranteed to operate in a predictable way as long as the right
195 plugin APIs are called and the relevant plugin service APIs are defined
196 by the loading binary.
197
198 Always make fully-formed plugin service APIs
199 --------------------------------------------
200
201 Follow strictly and completely the steps defined in
202 @ref page_ext_plugin_svc_new_service_howto.
203
204 Don't skip steps or you'll be decreasing the usability of the service API.
205*/
206
207/**
208 @defgroup group_ext_plugin_services MySQL Server Plugin Services
209
210 This is a group of all plugin service APIs.
211
212 See @ref page_ext_plugin_services for more details.
213*/
214
215/**
216 A server-side reference to a plugin service.
217
218 @sa plugin_add, list_of_services
219*/
221 /** The name of the service pointer symbol exported by the plugin */
222 const char *name;
223 /** The service version provided by the server */
225 /** The actual server side service structure pointer */
226 void *service;
227};
228
234
237};
238
245
249
252
255
258
265};
266
269
272
282
285};
286
290
293
299
302
305
307 {"srv_session_service", VERSION_srv_session_service,
309 {"command_service", VERSION_command, &command_handler},
310 {"srv_session_info_service", VERSION_srv_session_info_service,
312 {"thd_alloc_service", VERSION_thd_alloc, &thd_alloc_handler},
313 {"thd_wait_service", VERSION_thd_wait, &thd_wait_handler},
314 {"my_thread_scheduler_service", VERSION_my_thread_scheduler,
316 {"my_plugin_log_service", VERSION_my_plugin_log, &my_plugin_log_handler},
317 {"mysql_string_service", VERSION_mysql_string, &mysql_string_handler},
318 {"mysql_malloc_service", VERSION_mysql_malloc, &mysql_malloc_handler},
319 {"mysql_password_policy_service", VERSION_mysql_password_policy,
321 {"mysql_parser_service", VERSION_parser, &parser_handler},
322 {"rpl_transaction_ctx_service", VERSION_rpl_transaction_ctx_service,
324 {"transaction_write_set_service", VERSION_transaction_write_set_service,
326 {"security_context_service", VERSION_security_context_service,
328 {"mysql_locking_service", VERSION_locking_service,
330 {"mysql_keyring_service", VERSION_mysql_keyring_service,
332 {"plugin_registry_service", VERSION_plugin_registry_service,
334};
void * my_malloc(PSI_memory_key key, size_t size, int flags)
Allocates size bytes of memory.
Definition: my_memory.cc:56
void my_free(void *ptr)
Frees the memory pointed by the ptr.
Definition: my_memory.cc:80
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:185
int my_plugin_log_message(MYSQL_PLUGIN *plugin, enum plugin_log_level level, const char *format,...)
Definition: log.cc:2334
char * my_strdup(PSI_memory_key key, const char *from, myf_t flags)
Definition: my_malloc.cc:547
void * my_memdup(PSI_memory_key key, const void *from, size_t length, myf_t flags)
Definition: my_malloc.cc:539
void my_claim(const void *ptr, bool claim)
Definition: my_malloc.cc:457
char * my_strndup(PSI_memory_key key, const char *from, size_t length, myf_t flags)
Definition: my_malloc.cc:555
void * my_realloc(PSI_memory_key key, void *ptr, size_t size, myf_t flags)
Definition: my_malloc.cc:448
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:124
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:140
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:165
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:153
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:131
int my_validate_password_policy(const char *, unsigned int)
Invoke the component/plugin to validate the input password.
Definition: password_policy_service.cc:73
mysql_string_handle mysql_string_to_lowercase(mysql_string_handle string_handle)
Definition: string_service.cc:147
int mysql_string_iterator_isdigit(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:137
void mysql_string_iterator_free(mysql_string_iterator_handle)
Definition: string_service.cc:77
void mysql_string_free(mysql_string_handle)
Definition: string_service.cc:67
mysql_string_iterator_handle mysql_string_get_iterator(mysql_string_handle string_handle)
Definition: string_service.cc:82
int mysql_string_iterator_islower(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:127
int mysql_string_iterator_next(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:94
int mysql_string_iterator_isupper(mysql_string_iterator_handle iterator_handle)
Definition: string_service.cc:117
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:51
void mysql_parser_join_thread(struct my_thread_handle *thread_handle)
Definition: parser_service.cc:217
int mysql_parser_get_statement_type(MYSQL_THD thd)
Definition: parser_service.cc:283
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:232
int mysql_parser_get_statement_digest(MYSQL_THD thd, unsigned char *digest)
Definition: parser_service.cc:309
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:138
void mysql_parser_set_current_database(MYSQL_THD thd, const MYSQL_LEX_STRING db)
Definition: parser_service.cc:221
int mysql_parser_visit_tree(MYSQL_THD thd, parse_node_visit_function processor, unsigned char *arg)
Definition: parser_service.cc:331
MYSQL_THD mysql_parser_open_session()
Definition: parser_service.cc:140
MYSQL_LEX_STRING mysql_parser_item_string(MYSQL_ITEM item)
Definition: parser_service.cc:337
int mysql_parser_extract_prepared_params(MYSQL_THD thd, int *positions)
Definition: parser_service.cc:323
int mysql_parser_get_number_params(MYSQL_THD thd)
Definition: parser_service.cc:319
MYSQL_LEX_STRING mysql_parser_get_normalized_query(MYSQL_THD thd)
Definition: parser_service.cc:357
MYSQL_LEX_STRING mysql_parser_get_query(MYSQL_THD thd)
Definition: parser_service.cc:351
void mysql_parser_free_string(MYSQL_LEX_STRING string)
Definition: parser_service.cc:349
const mysql_service_registry_t * mysql_plugin_registry_acquire()
Returns a new reference to the "registry" service.
Definition: plugin_registry_service.cc:46
int mysql_plugin_registry_release(const mysql_service_registry_t *)
Releases a registry service reference.
Definition: plugin_registry_service.cc:74
int set_transaction_ctx(Transaction_termination_ctx transaction_termination_ctx)
Definition: rpl_transaction_ctx.cc:95
void update_write_set_memory_size_limit(uint64 size_limit)
Definition: rpl_transaction_write_set_ctx.cc:172
void require_full_write_set(bool requires_ws)
Definition: rpl_transaction_write_set_ctx.cc:152
Transaction_write_set * get_transaction_write_set(unsigned long m_thread_id)
Definition: rpl_transaction_write_set_ctx.cc:192
void set_write_set_memory_size_limit(uint64 size_limit)
Definition: rpl_transaction_write_set_ctx.cc:167
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:54
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:303
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:176
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:108
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:238
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:145
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:79
my_svc_bool security_context_destroy(MYSQL_SECURITY_CONTEXT ctx)
Deallocates a security context.
Definition: service_security_context.cc:126
int srv_session_init_thread(const void *plugin)
Initializes the current physical thread to use with session service.
Definition: srv_session_service.cc:59
int srv_session_attach(MYSQL_SESSION session, MYSQL_THD *ret_previous_thd)
Attaches a session to current physical thread.
Definition: srv_session_service.cc:231
void srv_session_deinit_thread()
Deinitializes the current physical thread to use with session service.
Definition: srv_session_service.cc:66
int srv_session_server_is_available()
Returns if the server is available (not booting or shutting down)
Definition: srv_session_service.cc:220
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:144
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:143
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:132
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:612
void * thd_calloc(MYSQL_THD thd, size_t size)
Definition: sql_thd_api.cc:610
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:620
char * thd_strmake(MYSQL_THD thd, const char *str, size_t size)
Definition: sql_thd_api.cc:616
void * thd_memdup(MYSQL_THD thd, const void *str, size_t size)
Definition: sql_thd_api.cc:629
void * thd_alloc(MYSQL_THD thd, size_t size)
Allocate memory in the connection's local memory pool.
Definition: sql_thd_api.cc:608
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:301
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:284
#define VERSION_mysql_malloc
Definition: service_versions.h:39
#define VERSION_my_plugin_log
Definition: service_versions.h:37
#define VERSION_locking_service
Definition: service_versions.h:45
#define VERSION_mysql_keyring_service
Definition: service_versions.h:48
#define VERSION_security_context_service
Definition: service_versions.h:44
#define VERSION_thd_alloc
Definition: service_versions.h:34
#define VERSION_my_thread_scheduler
Definition: service_versions.h:36
#define VERSION_rpl_transaction_ctx_service
Definition: service_versions.h:42
#define VERSION_transaction_write_set_service
Definition: service_versions.h:43
#define VERSION_plugin_registry_service
Definition: service_versions.h:49
#define VERSION_thd_wait
Definition: service_versions.h:35
#define VERSION_mysql_password_policy
Definition: service_versions.h:40
#define VERSION_srv_session_service
Definition: service_versions.h:47
#define VERSION_mysql_string
Definition: service_versions.h:38
#define VERSION_srv_session_info_service
Definition: service_versions.h:46
#define VERSION_command
Definition: service_versions.h:33
#define VERSION_parser
Definition: service_versions.h:41
static struct mysql_parser_service_st parser_handler
Definition: sql_plugin_services.h:273
static struct mysql_locking_service_st locking_service_handler
Definition: sql_plugin_services.h:291
static struct mysql_password_policy_service_st mysql_password_policy_handler
Definition: sql_plugin_services.h:270
static struct my_thread_scheduler_service my_thread_scheduler_handler
Definition: sql_plugin_services.h:253
static struct plugin_registry_service_st plugin_registry_handler
Definition: sql_plugin_services.h:303
static struct srv_session_info_service_st srv_session_info_handler
Definition: sql_plugin_services.h:239
static struct thd_alloc_service_st thd_alloc_handler
Definition: sql_plugin_services.h:246
static struct srv_session_service_st srv_session_service_handler
Definition: sql_plugin_services.h:229
static struct thd_wait_service_st thd_wait_handler
Definition: sql_plugin_services.h:250
static struct mysql_keyring_service_st mysql_keyring_handler
Definition: sql_plugin_services.h:300
static struct st_service_ref list_of_services[]
Definition: sql_plugin_services.h:306
static struct mysql_malloc_service_st mysql_malloc_handler
Definition: sql_plugin_services.h:267
static struct mysql_string_service_st mysql_string_handler
Definition: sql_plugin_services.h:259
static struct transaction_write_set_service_st transaction_write_set_handler
Definition: sql_plugin_services.h:287
static struct my_plugin_log_service my_plugin_log_handler
Definition: sql_plugin_services.h:256
static struct security_context_service_st security_context_handler
Definition: sql_plugin_services.h:294
static struct command_service_st command_handler
Definition: sql_plugin_services.h:235
static struct rpl_transaction_ctx_service_st rpl_transaction_ctx_handler
Definition: sql_plugin_services.h:283
Definition: service_command.h:393
Enables plugins to log messages into the server's error log.
Definition: service_my_plugin_log.h:50
Definition: service_thread_scheduler.h:35
This service allows plugins to interact with key store backends.
Definition: service_mysql_keyring.h:64
This service provides support for taking read/write locks.
Definition: service_locking.h:107
This service allows plugins to allocate and free memory through the server's memory handling routines...
Definition: service_mysql_alloc.h:58
Definition: service_parser.h:196
This service allows plugins to validate passwords based on a common policy.
Definition: service_mysql_password_policy.h:45
Definition: service_mysql_string.h:38
A bridge service allowing plugins to work with the registry.
Definition: service_plugin_registry.h:46
Definition: service_rpl_transaction_ctx.h:62
This service provides functions for plugins and storage engines to manipulate the thread's security c...
Definition: service_security_context.h:71
Definition: service_srv_session_info.h:42
Definition: service_srv_session.h:41
A server-side reference to a plugin service.
Definition: sql_plugin_services.h:220
void * service
The actual server side service structure pointer.
Definition: sql_plugin_services.h:226
uint version
The service version provided by the server.
Definition: sql_plugin_services.h:224
const char * name
The name of the service pointer symbol exported by the plugin.
Definition: sql_plugin_services.h:222
Definition: service_thd_alloc.h:46
Definition: service_thd_wait.h:142
Definition: service_rpl_transaction_write_set.h:61