CCriticalSection.h

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */
#ifndef  mrpt_synch_criticalsection_H
#define  mrpt_synch_criticalsection_H

#include <mrpt/utils/CReferencedMemBlock.h>
#include <mrpt/utils/mrpt_macros.h>
#include <string>

namespace mrpt
{
        namespace utils { class CStream; }

        /** @defgroup synch_grp Synchronization, multi-threading synch tools
          * \ingroup mrpt_base_grp */


        /** This namespace provides multitask, synchronization utilities. \ingroup synch_grp
         */
        namespace synch
        {
                class BASE_IMPEXP CAbstractMutex
                {
                public:
                        virtual ~CAbstractMutex();
                        virtual void  enter() const =0;
                        virtual void  leave() const =0;
                        virtual bool  try_enter() const = 0; //!< Returns true if adquired; false otherwise.
                };

                /** This class provides simple critical sections functionality.
                  * \sa CCriticalSectionLocker
                  * \ingroup synch_grp
                  */
                class BASE_IMPEXP CCriticalSection : public CAbstractMutex
                {
                private:
                        void *m_data;  //!< std::mutex*. Opaque ptr until MRPT 2.0.0 in which we could expose C++11 to user headers
                        std::string             m_name;
                public:
                        CCriticalSection(const char *name = NULL);   //!< Ctor
                        virtual  ~CCriticalSection();   //!< Dtor

                        void  enter() const MRPT_OVERRIDE; //!< Enter. \exception If the calling thread already possesses this critical section (it would be a dead-lock).
                        void  leave() const MRPT_OVERRIDE; //!< Leave. \exception If the calling thread is not the current owner of the critical section.
                        bool  try_enter() const MRPT_OVERRIDE;

                        /** Returns the name used in the constructor. */
                        std::string getName() const { return m_name; }

                        /** If set to a non-NULL value, debug messages regarding the calling threads IDs will be output.  */
                        utils::CStream          *m_debugOut;
                };

                /** Recursive mutex: allow recursive locks by the owner thread.
                  * \sa CCriticalSectionLocker, CCriticalSection
                  * \note [New in MRPT 1.5.0]
                  * \ingroup synch_grp
                  */
                class BASE_IMPEXP CCriticalSectionRecursive : public CAbstractMutex
                {
                private:
                        void *m_data;  //!< std::recursive_mutex*. Opaque ptr until MRPT 2.0.0 in which we could expose C++11 to user headers
                public:
                        CCriticalSectionRecursive();
                        virtual ~CCriticalSectionRecursive();

                        void  enter() const MRPT_OVERRIDE; //!< Enter. \exception If the calling thread already possesses this critical section (it would be a dead-lock).
                        void  leave() const MRPT_OVERRIDE; //!< Leave. \exception If the calling thread is not the current owner of the critical section.
                        bool  try_enter() const MRPT_OVERRIDE;
                };

                /** A class acquiring a CCriticalSection at its constructor, and releasing it at destructor.
                  *   It is a better idea to always use CCriticalSectionLocker, since it is more secure in the case of possible exceptions, many different exit points from a function, etc.. : it will always release the critical section at the destructor.
                  *    Example:
                  *  \code
                  *             {  // Code in this scope is protected by critical section
                  *                     CCriticalSectionLocker  myCSLocker( &myCS );
                  *                     ...
                  *             }  // End of code protected by critical section
                  *  \endcode
                  *  \sa CCriticalSection, THREADSAFE_OPERATION
                  */
                class BASE_IMPEXP CCriticalSectionLocker
                {
                protected:
                        const CAbstractMutex    *m_cs; // it's safe for copy ctor & =op to copy this ptr

                public:
                        /** Constructor: enters the critical section.
                          * \note [Since MRPT 0.9.6] The pointer can be NULL, in which case no action at all will be taken.
                          */
                        CCriticalSectionLocker( const CAbstractMutex *cs  );

                        CCriticalSectionLocker(const CCriticalSectionLocker &o) : m_cs(o.m_cs) {}

                        /** Destructor: leaves the critical section. */
                        ~CCriticalSectionLocker();

                }; // end of CCriticalSectionLocker



                /** A macro for protecting a given piece of code with a critical section; for example:
                  *  \code
                  *    CCriticalSection  cs;
                  *    MyObject  obj;
                  *    ...
                  *
                  *    THREADSAFE_OPERATION(cs,  obj.foo(); )
                  *    ...
                  *    THREADSAFE_OPERATION(cs,  obj.foo(); obj.bar(); }
                  *
                  *  \endcode
                  *
                  * \sa CCriticalSectionLocker, CThreadSafeVariable
                  */
                #define  THREADSAFE_OPERATION(_CRITSECT_OBJ, CODE_TO_EXECUTE )  \
                                { \
                                        mrpt::synch::CCriticalSectionLocker lock(&_CRITSECT_OBJ); \
                                        CODE_TO_EXECUTE \
                                }


        } // End of namespace
} // End of namespace

#endif