Alexandre Lision | ddd731e | 2014-01-31 11:50:08 -0500 | [diff] [blame] | 1 | // Copyright (C) 2006-2010 David Sugar, Tycho Softworks. |
| 2 | // |
| 3 | // This file is part of GNU uCommon C++. |
| 4 | // |
| 5 | // GNU uCommon C++ is free software: you can redistribute it and/or modify |
| 6 | // it under the terms of the GNU Lesser General Public License as published |
| 7 | // by the Free Software Foundation, either version 3 of the License, or |
| 8 | // (at your option) any later version. |
| 9 | // |
| 10 | // GNU uCommon C++ is distributed in the hope that it will be useful, |
| 11 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | // GNU Lesser General Public License for more details. |
| 14 | // |
| 15 | // You should have received a copy of the GNU Lesser General Public License |
| 16 | // along with GNU uCommon C++. If not, see <http://www.gnu.org/licenses/>. |
| 17 | |
| 18 | /** |
| 19 | * Locking protocol classes for member function automatic operations. |
| 20 | * This header covers ucommon access related classes. These are used to |
| 21 | * provide automatic management of locks and synchronization objects through |
| 22 | * common virtual base classes which can be used with automatic objects. |
| 23 | * These classes are related to "protocols" and are used in conjunction |
| 24 | * with smart pointer/referencing classes. The access interface supports |
| 25 | * member functions to acquire a lock when entered and automatically |
| 26 | * release the lock when the member function returns that are used in |
| 27 | * conjunction with special referencing smart pointers. |
| 28 | * @file ucommon/access.h |
| 29 | */ |
| 30 | |
| 31 | // we do this twice because of some bizarre issue in just this file that |
| 32 | // otherwise breaks doxygen and lists all items outside the namespace... |
| 33 | #include <ucommon/platform.h> |
| 34 | |
| 35 | #ifndef _UCOMMON_ACCESS_H_ |
| 36 | #define _UCOMMON_ACCESS_H_ |
| 37 | |
| 38 | #ifndef _UCOMMON_CPR_H_ |
| 39 | #include <ucommon/cpr.h> |
| 40 | #endif |
| 41 | |
| 42 | #ifndef _UCOMMON_PROTOCOLS_H_ |
| 43 | #include <ucommon/protocols.h> |
| 44 | #endif |
| 45 | |
| 46 | NAMESPACE_UCOMMON |
| 47 | |
| 48 | /** |
| 49 | * Common unlock protocol for locking protocol interface classes. |
| 50 | * This is to assure _unlock is a common base virtual method. |
| 51 | * @author David Sugar <dyfet@gnutelephony.org> |
| 52 | */ |
| 53 | class __EXPORT UnlockAccess |
| 54 | { |
| 55 | public: |
| 56 | virtual ~UnlockAccess(); |
| 57 | |
| 58 | protected: |
| 59 | virtual void _unlock(void) = 0; |
| 60 | }; |
| 61 | |
| 62 | /** |
| 63 | * An exclusive locking protocol interface base. |
| 64 | * This is an abstract class to form objects that will operate under an |
| 65 | * exclusive lock while being actively referenced by a smart pointer. |
| 66 | * @author David Sugar <dyfet@gnutelephony.org> |
| 67 | */ |
| 68 | class __EXPORT ExclusiveAccess : public UnlockAccess |
| 69 | { |
| 70 | protected: |
| 71 | virtual ~ExclusiveAccess(); |
| 72 | |
| 73 | virtual void _lock(void) = 0; |
| 74 | |
| 75 | public: |
| 76 | /** |
| 77 | * Access interface to exclusive lock the object. |
| 78 | */ |
| 79 | inline void exclusive_lock(void) |
| 80 | {return _lock();} |
| 81 | |
| 82 | /** |
| 83 | * Access interface to release a lock. |
| 84 | */ |
| 85 | inline void release_exclusive(void) |
| 86 | {return _unlock();} |
| 87 | }; |
| 88 | |
| 89 | /** |
| 90 | * An exclusive locking access interface base. |
| 91 | * This is an abstract class to form objects that will operate under an |
| 92 | * exclusive lock while being actively referenced by a smart pointer. |
| 93 | * @author David Sugar <dyfet@gnutelephony.org> |
| 94 | */ |
| 95 | class __EXPORT SharedAccess : protected UnlockAccess |
| 96 | { |
| 97 | protected: |
| 98 | virtual ~SharedAccess(); |
| 99 | |
| 100 | protected: |
| 101 | /** |
| 102 | * Access interface to share lock the object. |
| 103 | */ |
| 104 | virtual void _share(void) = 0; |
| 105 | |
| 106 | public: |
| 107 | /** |
| 108 | * Share the lock with other referencers. Many of our shared locking |
| 109 | * objects support the ability to switch between shared and exclusive |
| 110 | * mode. This derived protocol member allows one to restore the lock |
| 111 | * to shared mode after it has been made exclusive. |
| 112 | */ |
| 113 | virtual void share(void); |
| 114 | |
| 115 | /** |
| 116 | * Convert object to an exclusive lock. Many of our shared locking |
| 117 | * objects such as the "conditional lock" support the ability to switch |
| 118 | * between shared and exclusive locking modes. This derived protocol |
| 119 | * member allows one to temporarily assert exclusive locking when tied |
| 120 | * to such methods. |
| 121 | */ |
| 122 | virtual void exclusive(void); |
| 123 | |
| 124 | inline void shared_lock(void) |
| 125 | {return _share();} |
| 126 | |
| 127 | inline void release_share(void) |
| 128 | {return _unlock();} |
| 129 | }; |
| 130 | |
| 131 | /** |
| 132 | * A kind of smart pointer object to support exclusive locking protocol. |
| 133 | * This object initiates an exclusive lock for the object being referenced when |
| 134 | * it is instantiated, and releases the exclusive lock when it is destroyed. |
| 135 | * You would pass the pointer an object that has the Exclusive as a base class. |
| 136 | * @author David Sugar <dyfet@gnutelephony.org> |
| 137 | */ |
| 138 | class __EXPORT exclusive_access |
| 139 | { |
| 140 | private: |
| 141 | ExclusiveAccess *lock; |
| 142 | |
| 143 | public: |
| 144 | /** |
| 145 | * Create an instance of an exclusive object reference. |
| 146 | * @param object containing Exclusive base class protocol to lock. |
| 147 | */ |
| 148 | exclusive_access(ExclusiveAccess *object); |
| 149 | |
| 150 | /** |
| 151 | * Destroy reference to exclusively locked object, release lock. |
| 152 | */ |
| 153 | ~exclusive_access(); |
| 154 | |
| 155 | /** |
| 156 | * Test if the reference holds an active lock. |
| 157 | * @return true if is not locking an object. |
| 158 | */ |
| 159 | inline bool operator!() const |
| 160 | {return lock == NULL;}; |
| 161 | |
| 162 | /** |
| 163 | * Test if the reference holds an active lock. |
| 164 | * @return true if locking an object. |
| 165 | */ |
| 166 | inline operator bool() const |
| 167 | {return lock != NULL;}; |
| 168 | |
| 169 | /** |
| 170 | * Release a held lock programmatically. This can be used to de-reference |
| 171 | * the object being exclusively locked without having to wait for the |
| 172 | * destructor to be called when the exclusive_lock falls out of scope. |
| 173 | */ |
| 174 | void release(void); |
| 175 | }; |
| 176 | |
| 177 | /** |
| 178 | * A kind of smart pointer object to support shared locking protocol. |
| 179 | * This object initiates a shared lock for the object being referenced when |
| 180 | * it is instantiated, and releases the shared lock when it is destroyed. |
| 181 | * You would pass the pointer an object that has the Shared as a base class. |
| 182 | * @author David Sugar <dyfet@gnutelephony.org> |
| 183 | */ |
| 184 | class __EXPORT shared_access |
| 185 | { |
| 186 | private: |
| 187 | SharedAccess *lock; |
| 188 | int state; |
| 189 | bool modify; |
| 190 | |
| 191 | public: |
| 192 | /** |
| 193 | * Create an instance of an exclusive object reference. |
| 194 | * @param object containing Exclusive base class protocol to lock. |
| 195 | */ |
| 196 | shared_access(SharedAccess *object); |
| 197 | |
| 198 | /** |
| 199 | * Destroy reference to shared locked object, release lock. |
| 200 | */ |
| 201 | ~shared_access(); |
| 202 | |
| 203 | /** |
| 204 | * Test if the reference holds an active lock. |
| 205 | * @return true if is not locking an object. |
| 206 | */ |
| 207 | inline bool operator!() const |
| 208 | {return lock == NULL;}; |
| 209 | |
| 210 | /** |
| 211 | * Test if the reference holds an active lock. |
| 212 | * @return true if locking an object. |
| 213 | */ |
| 214 | inline operator bool() const |
| 215 | {return lock != NULL;}; |
| 216 | |
| 217 | /** |
| 218 | * Release a held lock programmatically. This can be used to de-reference |
| 219 | * the object being share locked without having to wait for the |
| 220 | * destructor to be called when the shared_lock falls out of scope. |
| 221 | */ |
| 222 | void release(void); |
| 223 | |
| 224 | /** |
| 225 | * Call exclusive access on referenced objects protocol. |
| 226 | */ |
| 227 | void exclusive(void); |
| 228 | |
| 229 | /** |
| 230 | * Restore shared access on referenced objects protocol. |
| 231 | */ |
| 232 | void share(void); |
| 233 | }; |
| 234 | |
| 235 | /** |
| 236 | * Convenience function to exclusively lock an object through it's protocol. |
| 237 | * @param object to lock. |
| 238 | */ |
| 239 | inline void lock(ExclusiveAccess& object) |
| 240 | {object.exclusive_lock();} |
| 241 | |
| 242 | /** |
| 243 | * Convenience function to unlock an exclusive object through it's protocol. |
| 244 | * @param object to unlock. |
| 245 | */ |
| 246 | inline void unlock(ExclusiveAccess& object) |
| 247 | {object.release_exclusive();} |
| 248 | |
| 249 | /** |
| 250 | * Convenience function to access (lock) shared object through it's protocol. |
| 251 | * @param object to share lock. |
| 252 | */ |
| 253 | inline void access(SharedAccess& object) |
| 254 | {object.shared_lock();} |
| 255 | |
| 256 | /** |
| 257 | * Convenience function to unlock shared object through it's protocol. |
| 258 | * @param object to unlock. |
| 259 | */ |
| 260 | inline void release(SharedAccess& object) |
| 261 | {object.release_share();} |
| 262 | |
| 263 | /** |
| 264 | * Convenience function to exclusive lock shared object through it's protocol. |
| 265 | * @param object to exclusive lock. |
| 266 | */ |
| 267 | inline void exclusive(SharedAccess& object) |
| 268 | {object.exclusive();} |
| 269 | |
| 270 | /** |
| 271 | * Convenience function to restore shared locking for object through it's protocol. |
| 272 | * @param object to restore shared locking. |
| 273 | */ |
| 274 | inline void share(SharedAccess& object) |
| 275 | {object.share();} |
| 276 | |
| 277 | /** |
| 278 | * Convenience type to use for object referencing an exclusive object. |
| 279 | */ |
| 280 | typedef exclusive_access exlock_t; |
| 281 | |
| 282 | /** |
| 283 | * Convenience type to use for object referencing a shared object. |
| 284 | */ |
| 285 | typedef shared_access shlock_t; |
| 286 | |
| 287 | /** |
| 288 | * Convenience function to release a reference to an exclusive lock. |
| 289 | * @param reference to object referencing exclusive locked object. |
| 290 | */ |
| 291 | inline void release(exlock_t &reference) |
| 292 | {reference.release();} |
| 293 | |
| 294 | /** |
| 295 | * Convenience function to release a reference to a shared lock. |
| 296 | * @param reference to object referencing shared locked object. |
| 297 | */ |
| 298 | inline void release(shlock_t &reference) |
| 299 | {reference.release();} |
| 300 | |
| 301 | // Special macros to allow member functions of an object with a protocol |
| 302 | // to create self locking states while the member functions are called by |
| 303 | // placing an exclusive_lock or shared_lock smart object on their stack |
| 304 | // frame to reference their self. |
| 305 | |
| 306 | #define exclusive_object() exlock_t __autolock__ = this |
| 307 | #define protected_object() shlock_t __autolock__ = this |
| 308 | #define exclusive_locking(x) exlock_t __autolock__ = &x |
| 309 | #define protected_locking(x) shlock_t __autolock__ = &x |
| 310 | |
| 311 | END_NAMESPACE |
| 312 | |
| 313 | #endif |