| // Copyright (C) 2006-2010 David Sugar, Tycho Softworks. |
| // |
| // This file is part of GNU uCommon C++. |
| // |
| // GNU uCommon C++ is free software: you can redistribute it and/or modify |
| // it under the terms of the GNU Lesser General Public License as published |
| // by the Free Software Foundation, either version 3 of the License, or |
| // (at your option) any later version. |
| // |
| // GNU uCommon C++ is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| // GNU Lesser General Public License for more details. |
| // |
| // You should have received a copy of the GNU Lesser General Public License |
| // along with GNU uCommon C++. If not, see <http://www.gnu.org/licenses/>. |
| |
| /** |
| * Locking protocol classes for member function automatic operations. |
| * This header covers ucommon access related classes. These are used to |
| * provide automatic management of locks and synchronization objects through |
| * common virtual base classes which can be used with automatic objects. |
| * These classes are related to "protocols" and are used in conjunction |
| * with smart pointer/referencing classes. The access interface supports |
| * member functions to acquire a lock when entered and automatically |
| * release the lock when the member function returns that are used in |
| * conjunction with special referencing smart pointers. |
| * @file ucommon/access.h |
| */ |
| |
| // we do this twice because of some bizarre issue in just this file that |
| // otherwise breaks doxygen and lists all items outside the namespace... |
| #include <ucommon/platform.h> |
| |
| #ifndef _UCOMMON_ACCESS_H_ |
| #define _UCOMMON_ACCESS_H_ |
| |
| #ifndef _UCOMMON_CPR_H_ |
| #include <ucommon/cpr.h> |
| #endif |
| |
| #ifndef _UCOMMON_PROTOCOLS_H_ |
| #include <ucommon/protocols.h> |
| #endif |
| |
| NAMESPACE_UCOMMON |
| |
| /** |
| * Common unlock protocol for locking protocol interface classes. |
| * This is to assure _unlock is a common base virtual method. |
| * @author David Sugar <dyfet@gnutelephony.org> |
| */ |
| class __EXPORT UnlockAccess |
| { |
| public: |
| virtual ~UnlockAccess(); |
| |
| protected: |
| virtual void _unlock(void) = 0; |
| }; |
| |
| /** |
| * An exclusive locking protocol interface base. |
| * This is an abstract class to form objects that will operate under an |
| * exclusive lock while being actively referenced by a smart pointer. |
| * @author David Sugar <dyfet@gnutelephony.org> |
| */ |
| class __EXPORT ExclusiveAccess : public UnlockAccess |
| { |
| protected: |
| virtual ~ExclusiveAccess(); |
| |
| virtual void _lock(void) = 0; |
| |
| public: |
| /** |
| * Access interface to exclusive lock the object. |
| */ |
| inline void exclusive_lock(void) |
| {return _lock();} |
| |
| /** |
| * Access interface to release a lock. |
| */ |
| inline void release_exclusive(void) |
| {return _unlock();} |
| }; |
| |
| /** |
| * An exclusive locking access interface base. |
| * This is an abstract class to form objects that will operate under an |
| * exclusive lock while being actively referenced by a smart pointer. |
| * @author David Sugar <dyfet@gnutelephony.org> |
| */ |
| class __EXPORT SharedAccess : protected UnlockAccess |
| { |
| protected: |
| virtual ~SharedAccess(); |
| |
| protected: |
| /** |
| * Access interface to share lock the object. |
| */ |
| virtual void _share(void) = 0; |
| |
| public: |
| /** |
| * Share the lock with other referencers. Many of our shared locking |
| * objects support the ability to switch between shared and exclusive |
| * mode. This derived protocol member allows one to restore the lock |
| * to shared mode after it has been made exclusive. |
| */ |
| virtual void share(void); |
| |
| /** |
| * Convert object to an exclusive lock. Many of our shared locking |
| * objects such as the "conditional lock" support the ability to switch |
| * between shared and exclusive locking modes. This derived protocol |
| * member allows one to temporarily assert exclusive locking when tied |
| * to such methods. |
| */ |
| virtual void exclusive(void); |
| |
| inline void shared_lock(void) |
| {return _share();} |
| |
| inline void release_share(void) |
| {return _unlock();} |
| }; |
| |
| /** |
| * A kind of smart pointer object to support exclusive locking protocol. |
| * This object initiates an exclusive lock for the object being referenced when |
| * it is instantiated, and releases the exclusive lock when it is destroyed. |
| * You would pass the pointer an object that has the Exclusive as a base class. |
| * @author David Sugar <dyfet@gnutelephony.org> |
| */ |
| class __EXPORT exclusive_access |
| { |
| private: |
| ExclusiveAccess *lock; |
| |
| public: |
| /** |
| * Create an instance of an exclusive object reference. |
| * @param object containing Exclusive base class protocol to lock. |
| */ |
| exclusive_access(ExclusiveAccess *object); |
| |
| /** |
| * Destroy reference to exclusively locked object, release lock. |
| */ |
| ~exclusive_access(); |
| |
| /** |
| * Test if the reference holds an active lock. |
| * @return true if is not locking an object. |
| */ |
| inline bool operator!() const |
| {return lock == NULL;}; |
| |
| /** |
| * Test if the reference holds an active lock. |
| * @return true if locking an object. |
| */ |
| inline operator bool() const |
| {return lock != NULL;}; |
| |
| /** |
| * Release a held lock programmatically. This can be used to de-reference |
| * the object being exclusively locked without having to wait for the |
| * destructor to be called when the exclusive_lock falls out of scope. |
| */ |
| void release(void); |
| }; |
| |
| /** |
| * A kind of smart pointer object to support shared locking protocol. |
| * This object initiates a shared lock for the object being referenced when |
| * it is instantiated, and releases the shared lock when it is destroyed. |
| * You would pass the pointer an object that has the Shared as a base class. |
| * @author David Sugar <dyfet@gnutelephony.org> |
| */ |
| class __EXPORT shared_access |
| { |
| private: |
| SharedAccess *lock; |
| int state; |
| bool modify; |
| |
| public: |
| /** |
| * Create an instance of an exclusive object reference. |
| * @param object containing Exclusive base class protocol to lock. |
| */ |
| shared_access(SharedAccess *object); |
| |
| /** |
| * Destroy reference to shared locked object, release lock. |
| */ |
| ~shared_access(); |
| |
| /** |
| * Test if the reference holds an active lock. |
| * @return true if is not locking an object. |
| */ |
| inline bool operator!() const |
| {return lock == NULL;}; |
| |
| /** |
| * Test if the reference holds an active lock. |
| * @return true if locking an object. |
| */ |
| inline operator bool() const |
| {return lock != NULL;}; |
| |
| /** |
| * Release a held lock programmatically. This can be used to de-reference |
| * the object being share locked without having to wait for the |
| * destructor to be called when the shared_lock falls out of scope. |
| */ |
| void release(void); |
| |
| /** |
| * Call exclusive access on referenced objects protocol. |
| */ |
| void exclusive(void); |
| |
| /** |
| * Restore shared access on referenced objects protocol. |
| */ |
| void share(void); |
| }; |
| |
| /** |
| * Convenience function to exclusively lock an object through it's protocol. |
| * @param object to lock. |
| */ |
| inline void lock(ExclusiveAccess& object) |
| {object.exclusive_lock();} |
| |
| /** |
| * Convenience function to unlock an exclusive object through it's protocol. |
| * @param object to unlock. |
| */ |
| inline void unlock(ExclusiveAccess& object) |
| {object.release_exclusive();} |
| |
| /** |
| * Convenience function to access (lock) shared object through it's protocol. |
| * @param object to share lock. |
| */ |
| inline void access(SharedAccess& object) |
| {object.shared_lock();} |
| |
| /** |
| * Convenience function to unlock shared object through it's protocol. |
| * @param object to unlock. |
| */ |
| inline void release(SharedAccess& object) |
| {object.release_share();} |
| |
| /** |
| * Convenience function to exclusive lock shared object through it's protocol. |
| * @param object to exclusive lock. |
| */ |
| inline void exclusive(SharedAccess& object) |
| {object.exclusive();} |
| |
| /** |
| * Convenience function to restore shared locking for object through it's protocol. |
| * @param object to restore shared locking. |
| */ |
| inline void share(SharedAccess& object) |
| {object.share();} |
| |
| /** |
| * Convenience type to use for object referencing an exclusive object. |
| */ |
| typedef exclusive_access exlock_t; |
| |
| /** |
| * Convenience type to use for object referencing a shared object. |
| */ |
| typedef shared_access shlock_t; |
| |
| /** |
| * Convenience function to release a reference to an exclusive lock. |
| * @param reference to object referencing exclusive locked object. |
| */ |
| inline void release(exlock_t &reference) |
| {reference.release();} |
| |
| /** |
| * Convenience function to release a reference to a shared lock. |
| * @param reference to object referencing shared locked object. |
| */ |
| inline void release(shlock_t &reference) |
| {reference.release();} |
| |
| // Special macros to allow member functions of an object with a protocol |
| // to create self locking states while the member functions are called by |
| // placing an exclusive_lock or shared_lock smart object on their stack |
| // frame to reference their self. |
| |
| #define exclusive_object() exlock_t __autolock__ = this |
| #define protected_object() shlock_t __autolock__ = this |
| #define exclusive_locking(x) exlock_t __autolock__ = &x |
| #define protected_locking(x) shlock_t __autolock__ = &x |
| |
| END_NAMESPACE |
| |
| #endif |