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>
#endif

namespace LinuxSampler {

#if defined(WIN32)
class ConditionInternal;
#endif

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