src/common/Mutex.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 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__

#include <pthread.h>

/** @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:
        pthread_mutex_t     __posix_mutex;
        pthread_mutexattr_t __posix_mutexattr;
};

#endif // __MUTEX_H__
1	/***************************************************************************
2	* *
3	* LinuxSampler - modular, streaming capable sampler *
4	* *
5	* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	* Copyright (C) 2005 Christian Schoenebeck *
7	* *
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	#include <pthread.h>
28
29	/** @brief Mutual exclusive objects
30	*
31	* This class provides the classical thread / process synchronisation
32	* technique called Mutex. It is used to protect critical sections, that is
33	* resources (typically data structures) from being used at the same time by
34	* different threads or processes which otherwise might turn into undefined
35	* and of course undesired behavior.
36	*
37	* Note: as this technique might block the calling thread and also implies
38	* a system call, this should not be used directly in realtime sensitive
39	* threads!
40	*/
41	class Mutex {
42	public:
43	/**
44	* Constructor
45	*/
46	Mutex();
47
48	/**
49	* Destructor
50	*/
51	virtual ~Mutex();
52
53	/** @brief Lock this Mutex.
54	*
55	* If this Mutex object is currently be locked by another thread,
56	* then the calling thread will be blocked until the other thread
57	* unlocks this Mutex object. The calling thread though can safely
58	* call this method several times without danger to be blocked
59	* himself.
60	*
61	* The calling thread should call Unlock() as soon as the critical
62	* section was left.
63	*/
64	void Lock();
65
66	/** @brief Try to lock this Mutex.
67	*
68	* Same as Lock() except that this method won't block the calling
69	* thread in case this Mutex object is currently locked by another
70	* thread. So this call will always immediately return and the
71	* return value has to be checked if the locking request was
72	* successful or not.
73	*
74	* @returns true if the Mutex object could be locked, false if the
75	* Mutex is currently locked by another thread
76	*/
77	bool Trylock();
78
79	/** @brief Unlock this Mutex.
80	*
81	* If other threads are currently blocked and waiting due to a
82	* Lock() call, one of them will be awaken.
83	*/
84	void Unlock();
85
86	protected:
87	pthread_mutex_t __posix_mutex;
88	pthread_mutexattr_t __posix_mutexattr;
89	};
90
91	#endif // __MUTEX_H__