src/common/Mutex.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 - 2014 Christian Schoenebeck                       *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program 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 General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __MUTEX_H__
#define __MUTEX_H__

#if defined(WIN32)
#include <windows.h>
#else
#include <pthread.h>
#endif

namespace LinuxSampler {

/** @brief Mutual exclusive objects
 *
 * This class provides the classical thread / process synchronisation
 * technique called Mutex. It is used to protect critical sections, that is
 * resources (typically data structures) from being used at the same time by
 * different threads or processes which otherwise might turn into undefined
 * and of course undesired behavior.
 *
 * Note: as this technique might block the calling thread and also implies
 * a system call, this should not be used directly in realtime sensitive
 * threads!
 */
class Mutex {
    public:
        /**
         * Constructor
         */    
        Mutex();

        /**
         * Destructor
         */
        virtual ~Mutex();

        /** @brief Lock this Mutex.
         *
         * If this Mutex object is currently be locked by another thread,
         * then the calling thread will be blocked until the other thread
         * unlocks this Mutex object. The calling thread though can safely
         * call this method several times without danger to be blocked
         * himself.
         *
         * The calling thread should call Unlock() as soon as the critical
         * section was left.
         */      
        void Lock();

        /** @brief Try to lock this Mutex.
         *
         * Same as Lock() except that this method won't block the calling
         * thread in case this Mutex object is currently locked by another
         * thread. So this call will always immediately return and the
         * return value has to be checked if the locking request was
         * successful or not.
         *
         * @returns  true if the Mutex object could be locked, false if the
         *           Mutex is currently locked by another thread
         */
        bool Trylock();

        /** @brief Unlock this Mutex.
         *
         * If other threads are currently blocked and waiting due to a
         * Lock() call, one of them will be awaken.
         */
        void Unlock();

    protected:
    #if defined(WIN32)
        HANDLE hMutex;
    #else
        pthread_mutex_t     __posix_mutex;
        pthread_mutexattr_t __posix_mutexattr;
    #endif
};

// Lock guard for exception safe locking
class LockGuard {
public:
    LockGuard(Mutex& m) : pm(&m) {
        m.Lock();
    }

    /**
     * Empty LockGuard. This constructor can be used to implement conditional
     * mutex protection like:
     * @code
     * Mutex m;
     * LockGuard g;
     * if (requiresMutexProtection()) g = LockGuard(m);
     * @endcode
     */
    LockGuard() : pm(NULL) {
    }

    LockGuard(const LockGuard& g) : pm(g.pm) {
        if (pm) pm->Lock();
    }

    ~LockGuard() {
        if (pm) pm->Unlock();
    }
private:
    Mutex* pm;
};

} // namespace LinuxSampler

#endif // __MUTEX_H__
1	schoenebeck	53	/***************************************************************************
2			* *
3			* LinuxSampler - modular, streaming capable sampler *
4			* *
5	schoenebeck	56	* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	schoenebeck	2500	* Copyright (C) 2005 - 2014 Christian Schoenebeck *
7	schoenebeck	53	* *
8			* This program is free software; you can redistribute it and/or modify *
9			* it under the terms of the GNU General Public License as published by *
10			* the Free Software Foundation; either version 2 of the License, or *
11			* (at your option) any later version. *
12			* *
13			* This program is distributed in the hope that it will be useful, *
14			* but WITHOUT ANY WARRANTY; without even the implied warranty of *
15			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16			* GNU General Public License for more details. *
17			* *
18			* You should have received a copy of the GNU General Public License *
19			* along with this program; if not, write to the Free Software *
20			* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
21			* MA 02111-1307 USA *
22			***************************************************************************/
23
24			#ifndef __MUTEX_H__
25			#define __MUTEX_H__
26
27	senoner	1481	#if defined(WIN32)
28			#include <windows.h>
29			#else
30	schoenebeck	53	#include <pthread.h>
31	senoner	1481	#endif
32	schoenebeck	53
33	schoenebeck	880	namespace LinuxSampler {
34
35	schoenebeck	550	/** @brief Mutual exclusive objects
36			*
37			* This class provides the classical thread / process synchronisation
38			* technique called Mutex. It is used to protect critical sections, that is
39			* resources (typically data structures) from being used at the same time by
40			* different threads or processes which otherwise might turn into undefined
41			* and of course undesired behavior.
42			*
43			* Note: as this technique might block the calling thread and also implies
44			* a system call, this should not be used directly in realtime sensitive
45			* threads!
46			*/
47	schoenebeck	53	class Mutex {
48			public:
49	schoenebeck	550	/**
50			* Constructor
51			*/
52	schoenebeck	53	Mutex();
53	schoenebeck	550
54			/**
55			* Destructor
56			*/
57			virtual ~Mutex();
58
59			/** @brief Lock this Mutex.
60			*
61			* If this Mutex object is currently be locked by another thread,
62			* then the calling thread will be blocked until the other thread
63			* unlocks this Mutex object. The calling thread though can safely
64			* call this method several times without danger to be blocked
65			* himself.
66			*
67			* The calling thread should call Unlock() as soon as the critical
68			* section was left.
69			*/
70	schoenebeck	53	void Lock();
71	schoenebeck	550
72			/** @brief Try to lock this Mutex.
73			*
74			* Same as Lock() except that this method won't block the calling
75			* thread in case this Mutex object is currently locked by another
76			* thread. So this call will always immediately return and the
77			* return value has to be checked if the locking request was
78			* successful or not.
79			*
80			* @returns true if the Mutex object could be locked, false if the
81			* Mutex is currently locked by another thread
82			*/
83	senkov	165	bool Trylock();
84	schoenebeck	550
85			/** @brief Unlock this Mutex.
86			*
87			* If other threads are currently blocked and waiting due to a
88			* Lock() call, one of them will be awaken.
89			*/
90	schoenebeck	53	void Unlock();
91	persson	2427
92	schoenebeck	53	protected:
93	senoner	1481	#if defined(WIN32)
94	persson	2427	HANDLE hMutex;
95	senoner	1481	#else
96	schoenebeck	53	pthread_mutex_t __posix_mutex;
97			pthread_mutexattr_t __posix_mutexattr;
98	senoner	1481	#endif
99	schoenebeck	53	};
100
101	persson	2427	// Lock guard for exception safe locking
102			class LockGuard {
103			public:
104	schoenebeck	2500	LockGuard(Mutex& m) : pm(&m) {
105	persson	2427	m.Lock();
106			}
107	schoenebeck	2500
108			/**
109			* Empty LockGuard. This constructor can be used to implement conditional
110			* mutex protection like:
111			* @code
112			* Mutex m;
113			* LockGuard g;
114			* if (requiresMutexProtection()) g = LockGuard(m);
115			* @endcode
116			*/
117			LockGuard() : pm(NULL) {
118			}
119
120	schoenebeck	2501	LockGuard(const LockGuard& g) : pm(g.pm) {
121	schoenebeck	2500	if (pm) pm->Lock();
122			}
123
124	persson	2427	~LockGuard() {
125	schoenebeck	2500	if (pm) pm->Unlock();
126	persson	2427	}
127			private:
128	schoenebeck	2500	Mutex* pm;
129	persson	2427	};
130
131	schoenebeck	880	} // namespace LinuxSampler
132
133	schoenebeck	53	#endif // __MUTEX_H__