src/common/Condition.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 - 2007 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 __CONDITION_H__
#define __CONDITION_H__

#include "Mutex.h"

#if defined(WIN32)
#include <windows.h>
typedef HANDLE win32thread_mutex_t;

typedef struct
{
    int waiters_count_;
    // Number of waiting threads.

    CRITICAL_SECTION waiters_count_lock_;
    // Serialize access to <waiters_count_>.

    HANDLE sema_;
    // Semaphore used to queue up threads waiting for the condition to
    // become signaled. 

    HANDLE waiters_done_;
    // An auto-reset event used by the broadcast/signal thread to wait
    // for all the waiting thread(s) to wake up and be released from the
    // semaphore. 

    size_t was_broadcast_;
    // Keeps track of whether we were broadcasting or signaling.  This
    // allows us to optimize the code if we're just signaling.
} win32thread_cond_t;
#endif

namespace LinuxSampler {

/**
 * Thread safe boolean condition.
 *
 * This is not meant to be used for real time operation!
 */
class Condition : public Mutex {
    public:
        /**
         * Constructor
         *
         * @param bInitialCondition - optional: starting condition
         *                            (default = false)
         */
        Condition(bool bInitialCondition = false);

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

        /**
         * Blocks the calling thread if current condition equals
         * \a bCondition, in this case the calling thread will be blocked
         * until condition turns. Upon successful return the Condition
         * object is locked, so the calling thread can safely run it's
         * critical section and has to explicitly call Unlock() right after
         * it left it's critcal section.
         *
         * @e Note: If you don't provide a timeout value or if you provide a
         * timeout value of exactly 0s and 0ns, then this call will block
         * without any timeout, or in other words: @e infinity!
         *
         * @param bCondition         - block in case of this condition
         * @param TimeoutSeconds     - optional: max. wait time in seconds
         *                             (default: 0s)
         * @param TimeoutNanoSeconds - optional: max wait time in nano
         *                             seconds (default: 0ns)
         * @returns  0 on success, a value less than 0 if timeout exceeded
         */
        int WaitIf(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L);

        /**
         * Same as WaitIf(), except that WaitAndUnlockIf() will unlock the
         * Condition object, so only use this call if you don't need to
         * enter a thread critical section, otherwise use WaitIf() instead!
         *
         * @e Note: If you don't provide a timeout value or if you provide a
         * timeout value of exactly 0s and 0ns, then this call will block
         * without any timeout, or in other words: @e infinity!
         *
         * @param bCondition         - block in case of this condition
         * @param TimeoutSeconds     - optional: max. wait time in seconds
         *                             (default: 0s)
         * @param TimeoutNanoSeconds - optional: max wait time in nano
         *                             seconds (default: 0ns)
         * @returns  0 on success, a value less than 0 if timeout exceeded
         * @see WaitIf()
         */
        int WaitAndUnlockIf(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L);

        /**
         * Set Condition object to \a bCondition. Upon change of the
         * condition, other threads waiting for \a bCondition will be
         * awakened. (Note the condition will not be locked for the calling
         * thread after this method returns!)
         *
         * @param bCondition - new condition
         */
        void Set(bool bCondition);

        /**
         * Returns the current boolean state of this condition object. This
         * method never blocks, it returns immediately and doesn't use any
         * system calls.
         *
         * @e Caution: this method is not thread safe! If you need to use
         * the condition state in a thread critical context you must call
         * @c Lock() and @c Unlock() respectively by yourself!
         */
        bool GetUnsafe();

    protected:
    #if defined(WIN32)
        win32thread_cond_t __win32_true_condition;
        win32thread_cond_t __win32_false_condition;
    #else
        pthread_cond_t __posix_true_condition;
        pthread_cond_t __posix_false_condition;
    #endif
        bool bCondition;
};

} // namespace LinuxSampler

#endif // __CONDITION_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	1221	* Copyright (C) 2005 - 2007 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 __CONDITION_H__
25			#define __CONDITION_H__
26
27			#include "Mutex.h"
28
29	senoner	1481	#if defined(WIN32)
30			#include <windows.h>
31			typedef HANDLE win32thread_mutex_t;
32
33			typedef struct
34			{
35			int waiters_count_;
36			// Number of waiting threads.
37
38			CRITICAL_SECTION waiters_count_lock_;
39			// Serialize access to <waiters_count_>.
40
41			HANDLE sema_;
42			// Semaphore used to queue up threads waiting for the condition to
43			// become signaled.
44
45			HANDLE waiters_done_;
46			// An auto-reset event used by the broadcast/signal thread to wait
47			// for all the waiting thread(s) to wake up and be released from the
48			// semaphore.
49
50			size_t was_broadcast_;
51			// Keeps track of whether we were broadcasting or signaling. This
52			// allows us to optimize the code if we're just signaling.
53			} win32thread_cond_t;
54			#endif
55
56	schoenebeck	880	namespace LinuxSampler {
57
58	schoenebeck	53	/**
59			* Thread safe boolean condition.
60			*
61			* This is not meant to be used for real time operation!
62			*/
63			class Condition : public Mutex {
64			public:
65			/**
66			* Constructor
67			*
68			* @param bInitialCondition - optional: starting condition
69			* (default = false)
70			*/
71			Condition(bool bInitialCondition = false);
72
73			/**
74			* Destructor
75			*/
76	letz	502	virtual ~Condition();
77	schoenebeck	53
78			/**
79			* Blocks the calling thread if current condition equals
80			* \a bCondition, in this case the calling thread will be blocked
81			* until condition turns. Upon successful return the Condition
82			* object is locked, so the calling thread can safely run it's
83			* critical section and has to explicitly call Unlock() right after
84			* it left it's critcal section.
85			*
86	schoenebeck	1221	* @e Note: If you don't provide a timeout value or if you provide a
87			* timeout value of exactly 0s and 0ns, then this call will block
88	schoenebeck	1319	* without any timeout, or in other words: @e infinity!
89	schoenebeck	1221	*
90	schoenebeck	53	* @param bCondition - block in case of this condition
91			* @param TimeoutSeconds - optional: max. wait time in seconds
92			* (default: 0s)
93			* @param TimeoutNanoSeconds - optional: max wait time in nano
94			* seconds (default: 0ns)
95			* @returns 0 on success, a value less than 0 if timeout exceeded
96			*/
97			int WaitIf(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L);
98
99			/**
100			* Same as WaitIf(), except that WaitAndUnlockIf() will unlock the
101			* Condition object, so only use this call if you don't need to
102			* enter a thread critical section, otherwise use WaitIf() instead!
103			*
104	schoenebeck	1221	* @e Note: If you don't provide a timeout value or if you provide a
105			* timeout value of exactly 0s and 0ns, then this call will block
106	schoenebeck	1319	* without any timeout, or in other words: @e infinity!
107	schoenebeck	1221	*
108	schoenebeck	53	* @param bCondition - block in case of this condition
109			* @param TimeoutSeconds - optional: max. wait time in seconds
110			* (default: 0s)
111			* @param TimeoutNanoSeconds - optional: max wait time in nano
112			* seconds (default: 0ns)
113			* @returns 0 on success, a value less than 0 if timeout exceeded
114			* @see WaitIf()
115			*/
116			int WaitAndUnlockIf(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L);
117
118			/**
119			* Set Condition object to \a bCondition. Upon change of the
120			* condition, other threads waiting for \a bCondition will be
121	schoenebeck	63	* awakened. (Note the condition will not be locked for the calling
122			* thread after this method returns!)
123	schoenebeck	53	*
124			* @param bCondition - new condition
125			*/
126			void Set(bool bCondition);
127
128	schoenebeck	1221	/**
129	schoenebeck	1319	* Returns the current boolean state of this condition object. This
130			* method never blocks, it returns immediately and doesn't use any
131			* system calls.
132			*
133	schoenebeck	1231	* @e Caution: this method is not thread safe! If you need to use
134			* the condition state in a thread critical context you must call
135			* @c Lock() and @c Unlock() respectively by yourself!
136			*/
137	schoenebeck	1221	bool GetUnsafe();
138
139	schoenebeck	53	protected:
140	senoner	1481	#if defined(WIN32)
141			win32thread_cond_t __win32_true_condition;
142			win32thread_cond_t __win32_false_condition;
143			#else
144	schoenebeck	53	pthread_cond_t __posix_true_condition;
145			pthread_cond_t __posix_false_condition;
146	senoner	1481	#endif
147	schoenebeck	53	bool bCondition;
148			};
149
150	schoenebeck	880	} // namespace LinuxSampler
151
152	schoenebeck	53	#endif // __CONDITION_H__