/[svn]/linuxsampler/trunk/src/common/Mutex.h
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Contents of /linuxsampler/trunk/src/common/Mutex.h

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Revision 2500 - (show annotations) (download) (as text)
Fri Jan 10 12:20:05 2014 UTC (5 years, 10 months ago) by schoenebeck
File MIME type: text/x-c++hdr
File size: 4628 byte(s)
* Added support for multiple MIDI input ports per sampler channel (added
  various new C++ API methods for this new feature/design, old C++ API
  methods are now marked as deprecated but should still provide full
  behavior backward compatibility).
* LSCP Network interface: Added the following new LSCP commands for the new
  feature mentioned above: "ADD CHANNEL MIDI_INPUT",
  "REMOVE CHANNEL MIDI_INPUT" and "LIST CHANNEL MIDI_INPUTS". As with the
  C++ API changes, the old LSCP commands for MIDI input management are now
  marked as deprecated, but are still there and should provide full behavior
  backward compatibility.
* New LSCP specification document (LSCP v1.6).
* AbstractEngine::GSCheckSum(): don't allocate memory on the stack (was
  unsafe and caused compilation error with old clang 2.x).
* Bumped version (1.0.0.svn25).

1 /***************************************************************************
2 * *
3 * LinuxSampler - modular, streaming capable sampler *
4 * *
5 * Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6 * Copyright (C) 2005 - 2014 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 #if defined(WIN32)
28 #include <windows.h>
29 #else
30 #include <pthread.h>
31 #endif
32
33 namespace LinuxSampler {
34
35 /** @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 class Mutex {
48 public:
49 /**
50 * Constructor
51 */
52 Mutex();
53
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 void Lock();
71
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 bool Trylock();
84
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 void Unlock();
91
92 protected:
93 #if defined(WIN32)
94 HANDLE hMutex;
95 #else
96 pthread_mutex_t __posix_mutex;
97 pthread_mutexattr_t __posix_mutexattr;
98 #endif
99 };
100
101 // Lock guard for exception safe locking
102 class LockGuard {
103 public:
104 LockGuard(Mutex& m) : pm(&m) {
105 m.Lock();
106 }
107
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 LockGuard(LockGuard& g) : pm(g.pm) {
121 if (pm) pm->Lock();
122 }
123
124 ~LockGuard() {
125 if (pm) pm->Unlock();
126 }
127 private:
128 Mutex* pm;
129 };
130
131 } // namespace LinuxSampler
132
133 #endif // __MUTEX_H__

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