| /************************************************************** |
| * |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * |
| *************************************************************/ |
| |
| |
| |
| #ifndef __FRAMEWORK_THREADHELP_WRITEGUARD_HXX_ |
| #define __FRAMEWORK_THREADHELP_WRITEGUARD_HXX_ |
| |
| //_________________________________________________________________________________________________________________ |
| // my own includes |
| //_________________________________________________________________________________________________________________ |
| |
| #include <threadhelp/inoncopyable.h> |
| #include <threadhelp/irwlock.h> |
| |
| //#ifndef __FRAMEWORK_THREADHELP_THREADHELPBASE_HXX_ |
| //#include <threadhelp/threadhelpbase.hxx> |
| //#endif |
| |
| //_________________________________________________________________________________________________________________ |
| // interface includes |
| //_________________________________________________________________________________________________________________ |
| |
| //_________________________________________________________________________________________________________________ |
| // other includes |
| //_________________________________________________________________________________________________________________ |
| |
| //_________________________________________________________________________________________________________________ |
| // namespace |
| //_________________________________________________________________________________________________________________ |
| |
| namespace framework{ |
| |
| //_________________________________________________________________________________________________________________ |
| // const |
| //_________________________________________________________________________________________________________________ |
| |
| //_________________________________________________________________________________________________________________ |
| // declarations |
| //_________________________________________________________________________________________________________________ |
| |
| /*-************************************************************************************************************//** |
| @short implement a guard to set write locks |
| @descr This guard should be used to set a lock for reading AND writing object internal member. |
| We never need a own mutex to safe our internal member access - because |
| a guard is used as function-local member only. There exist no multithreaded access to it realy ... |
| |
| @attention a) To prevent us against wrong using, the default ctor, copy ctor and the =operator are maked private! |
| b) Use interface "IRWLock" of set LockHelper only - because we must support a finer granularity of locking. |
| Interface "IMutex" should be used by easier guard implementations ... like "ResetableGuard"! |
| |
| @implements - |
| @base INonCopyable |
| |
| @devstatus ready to use |
| *//*-*************************************************************************************************************/ |
| class WriteGuard : private INonCopyable |
| { |
| //------------------------------------------------------------------------------------------------------------- |
| // public methods |
| //------------------------------------------------------------------------------------------------------------- |
| public: |
| |
| /*-****************************************************************************************************//** |
| @short ctor |
| @descr These ctors initialize the guard with a reference to used lock member of object to protect. |
| Null isn't allowed as value! |
| |
| @seealso - |
| |
| @param "pLock" ,reference to used lock member of object to protect |
| @param "rLock" ,reference to used lock member of object to protect |
| @return - |
| |
| @onerror - |
| *//*-*****************************************************************************************************/ |
| inline WriteGuard( IRWLock* pLock ) |
| : m_pLock ( pLock ) |
| , m_eMode ( E_NOLOCK ) |
| { |
| lock(); |
| } |
| |
| //********************************************************************************************************* |
| inline WriteGuard( IRWLock& rLock ) |
| : m_pLock ( &rLock ) |
| , m_eMode ( E_NOLOCK ) |
| { |
| lock(); |
| } |
| |
| /*-****************************************************************************************************//** |
| @short dtor |
| @descr We unlock the used lock member automaticly if user forget it. |
| |
| @seealso - |
| |
| @param - |
| @return - |
| |
| @onerror - |
| *//*-*****************************************************************************************************/ |
| inline ~WriteGuard() |
| { |
| unlock(); |
| } |
| |
| /*-****************************************************************************************************//** |
| @short set write lock |
| @descr Call this method to set the write lock. The call will block till all current threads are synchronized! |
| |
| @seealso method unlock() |
| |
| @param - |
| @return - |
| |
| @onerror - |
| *//*-*****************************************************************************************************/ |
| inline void lock() |
| { |
| switch( m_eMode ) |
| { |
| case E_NOLOCK : { |
| // Acquire write access and set return state. |
| // Mode is set later if it was successful! |
| m_pLock->acquireWriteAccess(); |
| m_eMode = E_WRITELOCK; |
| } |
| break; |
| case E_READLOCK : { |
| // User has downgrade to read access before! |
| // We must release it before we can set a new write access! |
| m_pLock->releaseReadAccess(); |
| m_pLock->acquireWriteAccess(); |
| m_eMode = E_WRITELOCK; |
| } |
| break; |
| default: break; // nothing to do |
| } |
| } |
| |
| /*-****************************************************************************************************//** |
| @short unset write lock |
| @descr Call this method to unlock the rw-lock temp.! |
| Normaly we do it at dtor automaticly for you ... |
| |
| @seealso method lock() |
| |
| @param - |
| @return - |
| |
| @onerror - |
| *//*-*****************************************************************************************************/ |
| inline void unlock() |
| { |
| switch( m_eMode ) |
| { |
| case E_READLOCK : { |
| // User has downgraded to a read lock before! |
| // => There isn't realy a write lock ... |
| m_pLock->releaseReadAccess(); |
| m_eMode = E_NOLOCK; |
| } |
| break; |
| case E_WRITELOCK : { |
| m_pLock->releaseWriteAccess(); |
| m_eMode = E_NOLOCK; |
| } |
| break; |
| default: break; // nothing to do |
| } |
| } |
| |
| /*-****************************************************************************************************//** |
| @short downgrade write access to read access without new blocking! |
| @descr If this write lock is set you can change it to a "read lock". |
| An "upgrade" is the same like new calling "lock()"! |
| |
| @seealso - |
| |
| @param - |
| @return - |
| |
| @onerror - |
| *//*-*****************************************************************************************************/ |
| inline void downgrade() |
| { |
| if( m_eMode == E_WRITELOCK ) |
| { |
| m_pLock->downgradeWriteAccess(); |
| m_eMode = E_READLOCK; |
| } |
| } |
| |
| /*-****************************************************************************************************//** |
| @short return internal states |
| @descr For user they dont know what they are doing ... |
| |
| @seealso - |
| |
| @param - |
| @return Current set lock mode. |
| |
| @onerror No error should occure. |
| *//*-*****************************************************************************************************/ |
| inline ELockMode getMode() const |
| { |
| return m_eMode; |
| } |
| |
| //------------------------------------------------------------------------------------------------------------- |
| // private methods |
| //------------------------------------------------------------------------------------------------------------- |
| private: |
| |
| /*-****************************************************************************************************//** |
| @short disable using of these functions! |
| @descr It's not allowed to use this methods. Different problem can occure otherwise. |
| Thats why we disable it by make it private. |
| |
| @seealso other ctor |
| |
| @param - |
| @return - |
| |
| @onerror - |
| *//*-*****************************************************************************************************/ |
| WriteGuard(); |
| |
| //------------------------------------------------------------------------------------------------------------- |
| // private member |
| //------------------------------------------------------------------------------------------------------------- |
| private: |
| |
| IRWLock* m_pLock ; /// reference to lock-member of protected object |
| ELockMode m_eMode ; /// protection against multiple lock calls without unlock and difference between supported lock modi |
| |
| }; // class WriteGuard |
| |
| } // namespace framework |
| |
| #endif // #ifndef __FRAMEWORK_THREADHELP_WRITEGUARD_HXX_ |