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	/***************************************************************************
2	* *
3	* LinuxSampler - modular, streaming capable sampler *
4	* *
5	* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	* Copyright (C) 2005 - 2007 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 __CONDITION_H__
25	#define __CONDITION_H__
26
27	#include "Mutex.h"
28
29	#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	namespace LinuxSampler {
57
58	/**
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	virtual ~Condition();
77
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	* @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	* without any timeout, or in other words: @e infinity!
89	*
90	* @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	* @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	* without any timeout, or in other words: @e infinity!
107	*
108	* @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	* awakened. (Note the condition will not be locked for the calling
122	* thread after this method returns!)
123	*
124	* @param bCondition - new condition
125	*/
126	void Set(bool bCondition);
127
128	/**
129	* 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	* @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	bool GetUnsafe();
138
139	protected:
140	#if defined(WIN32)
141	win32thread_cond_t __win32_true_condition;
142	win32thread_cond_t __win32_false_condition;
143	#else
144	pthread_cond_t __posix_true_condition;
145	pthread_cond_t __posix_false_condition;
146	#endif
147	bool bCondition;
148	};
149
150	} // namespace LinuxSampler
151
152	#endif // __CONDITION_H__