1 /* Copyright (c) 2016, 2020, Oracle and/or its affiliates. All rights reserved. 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 #ifndef MYSQL_SERVER_PERSISTENT_DYNAMIC_LOADER_H 24 #define MYSQL_SERVER_PERSISTENT_DYNAMIC_LOADER_H 25 26 #include <mysql/components/service_implementation.h> 27 #include <mysql/components/services/persistent_dynamic_loader.h> 28 #include <mysql/psi/mysql_mutex.h> 29 #include <atomic> 30 #include <map> 31 32 #include "my_inttypes.h" 33 34 /* 35 This header file is used in mysql_server component, which is not 36 server-enabled, and can't have following declaration acquired by including 37 mysql headers. 38 */ 39 40 bool persistent_dynamic_loader_init(void *thd); 41 void persistent_dynamic_loader_deinit(); 42 43 /** 44 Allows to wrap another Service Implementation of the Dynamic Loader service 45 and add ability to store a list of groups of loaded components. It reacts on 46 successful invocations of the underlying Dynamic Loader Service Implementation 47 methods load() and unload() and saves changes. It also loads during the start 48 of the MySQL Server all groups of the Components that were still loaded on 49 last MySQL Server shutdown, they are loaded in order of the original loads. 50 It assumes that components does not any not fully-deterministic loads of 51 another Components, which would break dependencies if they are decided to load 52 other Components than last time. The list of groups of Components is stored in 53 the 'mysql.component' table. It is valid to unload only part of the group of 54 the previously loaded group of Components. In such a situation, as long as all 55 dependencies are met, which is assured by the underlying Service 56 Implementation, the rest of Components in group should load successfully after 57 the MySQL Server restart. 58 */ 59 class mysql_persistent_dynamic_loader_imp { 60 public: 61 /** 62 Initializes persistence store, loads all groups of components registered in 63 component table. Shouldn't be called multiple times. We assume the order 64 specified by group ID is correct one. This should be assured by dynamic 65 loader as long as it will not allow to unload the component that has 66 dependency on, in case there would be a possibility to switch that 67 dependency to other component that is not to be unloaded. If this is 68 assured, then it will not be possible for components with lower group IDs 69 to have a dependency on component with higher group ID, even after state is 70 restored in this initialization method. 71 72 @param thdp Current thread execution context 73 @return Status of performed operation 74 @retval false success 75 @retval true failure 76 */ 77 static bool init(void *thdp); 78 /** 79 De-initializes persistence loader. 80 */ 81 static void deinit(); 82 83 /** 84 Initialisation status of persistence loader. An helper function. 85 */ 86 static bool initialized(); 87 88 public: /* service implementations */ 89 /** 90 Loads specified group of components by URN, initializes them and 91 registers all service implementations present in these components. 92 Assures all dependencies will be met after loading specified components. 93 The dependencies may be circular, in such case it's necessary to specify 94 all components on cycle to load in one batch. From URNs specified the 95 scheme part of URN (part before "://") is extracted and used to acquire 96 service implementation of scheme component loader service for specified 97 scheme. If the loading process successes then a group of Components by their 98 URN is added to the component table. 99 100 @param thd_ptr Current thread execution context. 101 @param urns List of URNs of Components to load. 102 @param component_count Number of Components on list to load. 103 @return Status of performed operation 104 @retval false success 105 @retval true failure 106 */ 107 static DEFINE_BOOL_METHOD(load, (void *thd_ptr, const char *urns[], 108 int component_count)); 109 110 /** 111 Unloads specified group of Components by URN, deinitializes them and 112 unregisters all service implementations present in these components. 113 Assumes, although does not check it, all dependencies of not unloaded 114 components will still be met after unloading specified components. 115 The dependencies may be circular, in such case it's necessary to specify 116 all components on cycle to unload in one batch. From URNs specified the 117 scheme part of URN (part before "://") is extracted and used to acquire 118 service implementation of scheme component loader service for specified 119 scheme. URN specified should be identical to ones specified in load() 120 method, i.e. all letters must have the same case. If the unloading process 121 successes then a group of Components by their URN is added to the component 122 table. 123 124 @param thd_ptr Current thread execution context. 125 @param urns List of URNs of components to unload. 126 @param component_count Number of components on list to unload. 127 @return Status of performed operation 128 @retval false success 129 @retval true failure 130 */ 131 static DEFINE_BOOL_METHOD(unload, (void *thd_ptr, const char *urns[], 132 int component_count)); 133 134 private: 135 /** 136 Stores last group ID used in component table. It is initialized on init() 137 on component table scan with maximum group ID used in table. 138 */ 139 static std::atomic<uint64> s_group_id; 140 /** 141 Stores mapping of component URNs to their component_id used in component 142 table, to ease row deletion. 143 */ 144 static std::map<std::string, uint64> component_id_by_urn; 145 /** 146 Indicates the initialization status of dynamic loader persistence. 147 */ 148 static bool is_initialized; 149 150 /** 151 Serializes access to @ref component_id_by_urn 152 */ 153 static mysql_mutex_t component_id_by_urn_mutex; 154 }; 155 156 #endif /* MYSQL_SERVER_PERSISTENT_DYNAMIC_LOADER_H */ 157