src/common/ConditionServer.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005 - 2008 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 __CONDITIONSERVER_H__
#define __CONDITIONSERVER_H__

#include "Mutex.h"
#include "SynchronizedConfig.h"

namespace LinuxSampler {

/**
 * Thread safe condition for semi real time operation
 *
 * Sense behind the ConditionServer is to sync a boolean condition between
 * one real time thread (RTT) and n non real time threads (NRTT).
 *
 *   1 Real Time Thread <--> Condition Object <--> n Non Real Time Threads
 *
 * The non real time threads set the condition by calling Push(), this
 * method will immediately return if the current condition already equals
 * the desired condition given with Push(), if it's not equal then Push()
 * will cause a request to change the condition and will block until the
 * condition actually changed, which happens when the RTT is outside its
 * critical region, or has called the Pop() method, which will also return
 * the new condition to the RTT.
 *
 * Advantage of this technique is that the RTT doesn't has to execute system
 * calls whenever it wants to check for a condition change. Disadvantage on
 * the other hand is that the NRTTs might be blocked for some time, but this
 * is usually unproblematic for NRTTs.
 */
class ConditionServer {
    public:
        ConditionServer();


        // methods for non realtime threads (0..n NRTTs)

        /**
         * Set condition to \a bCondition. If current condition already
         * equals \a bCondition, then this method will immediately return,
         * if not it will block the calling thread until the condition
         * actually changed to the requested condition (which happens when
         * Pop() has been called by the real time thread, or when the real
         * time thread is outside its critical region). If there are multiple
         * non real time threads calling Push() only one by one will be
         * served, all others blocked meanwhile. When the calling thread
         * returns from Push() the Push() method will still be blocked
         * against other NRTTs, so the thread can safely enter a critical
         * section and has to Unlock() right after it left it's critical
         * section, so other NRTTs can pass Push().
         *
         * @param bCondition         - condition to set
         * @param TimeoutSeconds     - optional: max. wait time in seconds
         *                             (default: 0s)
         * @param TimeoutNanoSeconds - optional: max wait time in nano
         *                             seconds (default: 0ns)
         * @returns  bool pointer with condition before Push() call, NULL if
         *           timeout exceeded
         * @see Unlock()
         */
        bool* Push(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L);

        /**
         * Same as Push(), except that PushAndUnlock() will unlock the
         * ConditionServer right after so that other NRTTs can follow to
         * pass push. You should only call this method if you're sure that
         * no other NRTT will change the condition, otherwise you should
         * call Push() instead, execute the critical section and manually
         * unlock at the end of the critical section.
         *
         * @param bCondition         - condition to set
         * @param TimeoutSeconds     - optional: max. wait time in seconds
         *                             (default: 0s)
         * @param TimeoutNanoSeconds - optional: max wait time in nano
         *                             seconds (default: 0ns)
         * @param bAlreadyLocked     - optional: you must set this to true if
         *                             you have called Push() before and are
         *                             using PushAndUnlock to end the
         *                             critical region (default: false)
         * @returns  bool pointer with condition before PushAndUnlock()
         *           call, NULL if timeout exceeded
         */
        bool* PushAndUnlock(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L, bool bAlreadyLocked = false);

        void PushAndUnlock2(bool bCondition);

        /**
         * Should be called by the NRTT after it left it's critical section
         * to unlock the ConditionServer and give other NRTTs the chance to
         * pass Push().
         */
        void Unlock();

        /**
         * Returns unsafely the current condition. This method will not
         * block and should only be used in a not thread critical context.
         *
         * @returns  current condition (unsafe)
         */
        bool GetUnsafe();


        // method for real time thread (1 RTT)

        /**
         * Should be called by the real time thread (RTT) at the
         * beginning of the critical region to check for a condition
         * change. If an NRTT requested a condition change by calling
         * Push() or PushAndUnlock() the NRTT will be blocked until
         * it knows that the RTT will not go into its critical region
         * without being notified about the condition change.
         *
         * @returns  current condition
         */
        bool Pop() {
            return Reader.Lock();
        }

        /**
         * Should be called by the real time thread (RTT) at the end of
         * the critical region.
         */
        void RttDone() {
            Reader.Unlock();
        }

    protected:
        SynchronizedConfig<bool> Condition;
        SynchronizedConfig<bool>::Reader Reader;
        bool      bOldCondition;
        Mutex     PushMutex;
};

} // namespace LinuxSampler

#endif // __CONDITIONSERVER_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	persson	1764	* Copyright (C) 2005 - 2008 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 __CONDITIONSERVER_H__
25			#define __CONDITIONSERVER_H__
26
27			#include "Mutex.h"
28	persson	1764	#include "SynchronizedConfig.h"
29	schoenebeck	53
30	schoenebeck	880	namespace LinuxSampler {
31
32	schoenebeck	53	/**
33			* Thread safe condition for semi real time operation
34			*
35			* Sense behind the ConditionServer is to sync a boolean condition between
36			* one real time thread (RTT) and n non real time threads (NRTT).
37			*
38			* 1 Real Time Thread <--> Condition Object <--> n Non Real Time Threads
39			*
40			* The non real time threads set the condition by calling Push(), this
41			* method will immediately return if the current condition already equals
42			* the desired condition given with Push(), if it's not equal then Push()
43			* will cause a request to change the condition and will block until the
44	persson	1764	* condition actually changed, which happens when the RTT is outside its
45			* critical region, or has called the Pop() method, which will also return
46			* the new condition to the RTT.
47	schoenebeck	53	*
48			* Advantage of this technique is that the RTT doesn't has to execute system
49	persson	1764	* calls whenever it wants to check for a condition change. Disadvantage on
50			* the other hand is that the NRTTs might be blocked for some time, but this
51			* is usually unproblematic for NRTTs.
52	schoenebeck	53	*/
53			class ConditionServer {
54			public:
55			ConditionServer();
56
57
58			// methods for non realtime threads (0..n NRTTs)
59
60			/**
61			* Set condition to \a bCondition. If current condition already
62			* equals \a bCondition, then this method will immediately return,
63			* if not it will block the calling thread until the condition
64			* actually changed to the requested condition (which happens when
65	persson	1764	* Pop() has been called by the real time thread, or when the real
66			* time thread is outside its critical region). If there are multiple
67	schoenebeck	53	* non real time threads calling Push() only one by one will be
68			* served, all others blocked meanwhile. When the calling thread
69			* returns from Push() the Push() method will still be blocked
70			* against other NRTTs, so the thread can safely enter a critical
71			* section and has to Unlock() right after it left it's critical
72			* section, so other NRTTs can pass Push().
73			*
74			* @param bCondition - condition to set
75			* @param TimeoutSeconds - optional: max. wait time in seconds
76			* (default: 0s)
77			* @param TimeoutNanoSeconds - optional: max wait time in nano
78			* seconds (default: 0ns)
79			* @returns bool pointer with condition before Push() call, NULL if
80			* timeout exceeded
81			* @see Unlock()
82			*/
83			bool* Push(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L);
84
85			/**
86			* Same as Push(), except that PushAndUnlock() will unlock the
87			* ConditionServer right after so that other NRTTs can follow to
88			* pass push. You should only call this method if you're sure that
89			* no other NRTT will change the condition, otherwise you should
90			* call Push() instead, execute the critical section and manually
91			* unlock at the end of the critical section.
92			*
93			* @param bCondition - condition to set
94			* @param TimeoutSeconds - optional: max. wait time in seconds
95			* (default: 0s)
96			* @param TimeoutNanoSeconds - optional: max wait time in nano
97			* seconds (default: 0ns)
98	persson	1933	* @param bAlreadyLocked - optional: you must set this to true if
99			* you have called Push() before and are
100			* using PushAndUnlock to end the
101			* critical region (default: false)
102	schoenebeck	53	* @returns bool pointer with condition before PushAndUnlock()
103			* call, NULL if timeout exceeded
104			*/
105	persson	1933	bool* PushAndUnlock(bool bCondition, long TimeoutSeconds = 0L, long TimeoutNanoSeconds = 0L, bool bAlreadyLocked = false);
106	schoenebeck	53
107	persson	1933	void PushAndUnlock2(bool bCondition);
108
109	schoenebeck	53	/**
110			* Should be called by the NRTT after it left it's critical section
111			* to unlock the ConditionServer and give other NRTTs the chance to
112			* pass Push().
113			*/
114			void Unlock();
115
116			/**
117			* Returns unsafely the current condition. This method will not
118			* block and should only be used in a not thread critical context.
119			*
120			* @returns current condition (unsafe)
121			*/
122			bool GetUnsafe();
123
124
125
126			// method for real time thread (1 RTT)
127
128			/**
129	persson	1764	* Should be called by the real time thread (RTT) at the
130			* beginning of the critical region to check for a condition
131			* change. If an NRTT requested a condition change by calling
132			* Push() or PushAndUnlock() the NRTT will be blocked until
133			* it knows that the RTT will not go into its critical region
134			* without being notified about the condition change.
135	schoenebeck	53	*
136			* @returns current condition
137			*/
138	persson	1764	bool Pop() {
139			return Reader.Lock();
140			}
141	schoenebeck	53
142	persson	1764	/**
143			* Should be called by the real time thread (RTT) at the end of
144			* the critical region.
145			*/
146			void RttDone() {
147			Reader.Unlock();
148			}
149
150	schoenebeck	53	protected:
151	persson	1764	SynchronizedConfig<bool> Condition;
152			SynchronizedConfig<bool>::Reader Reader;
153	schoenebeck	53	bool bOldCondition;
154			Mutex PushMutex;
155			};
156
157	schoenebeck	880	} // namespace LinuxSampler
158
159	schoenebeck	53	#endif // __CONDITIONSERVER_H__