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CSemaphore.h

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00001 /* +---------------------------------------------------------------------------+
00002    |          The Mobile Robot Programming Toolkit (MRPT) C++ library          |
00003    |                                                                           |
00004    |                   http://mrpt.sourceforge.net/                            |
00005    |                                                                           |
00006    |   Copyright (C) 2005-2011  University of Malaga                           |
00007    |                                                                           |
00008    |    This software was written by the Machine Perception and Intelligent    |
00009    |      Robotics Lab, University of Malaga (Spain).                          |
00010    |    Contact: Jose-Luis Blanco  <jlblanco@ctima.uma.es>                     |
00011    |                                                                           |
00012    |  This file is part of the MRPT project.                                   |
00013    |                                                                           |
00014    |     MRPT is free software: you can redistribute it and/or modify          |
00015    |     it under the terms of the GNU General Public License as published by  |
00016    |     the Free Software Foundation, either version 3 of the License, or     |
00017    |     (at your option) any later version.                                   |
00018    |                                                                           |
00019    |   MRPT is distributed in the hope that it will be useful,                 |
00020    |     but WITHOUT ANY WARRANTY; without even the implied warranty of        |
00021    |     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         |
00022    |     GNU General Public License for more details.                          |
00023    |                                                                           |
00024    |     You should have received a copy of the GNU General Public License     |
00025    |     along with MRPT.  If not, see <http://www.gnu.org/licenses/>.         |
00026    |                                                                           |
00027    +---------------------------------------------------------------------------+ */
00028 #ifndef  mrpt_synch_semaphore_H
00029 #define  mrpt_synch_semaphore_H
00030 
00031 #include <mrpt/utils/utils_defs.h>
00032 #include <mrpt/utils/CStream.h>
00033 #include <mrpt/utils/CReferencedMemBlock.h>
00034 
00035 /*---------------------------------------------------------------
00036         Class
00037   ---------------------------------------------------------------*/
00038 namespace mrpt
00039 {
00040         /** This namespace provides multitask, synchronization utilities.
00041          */
00042         namespace synch
00043         {
00044                 /** A semaphore for inter-thread synchronization.
00045                   * The state of a semaphore object is signaled when its count is greater than zero,
00046                   *  and nonsignaled when its count is equal to zero. The initialCount parameter specifies
00047                   *  the initial count. Each time a waiting thread is released because of the semaphore's
00048                   *  signaled state, the count of the semaphore is decreased by one. Use the release function
00049                   *  to increment a semaphore's count by a specified amount. The count can never be less
00050                   *   than zero or greater than the value specified in the maxCount parameter.
00051                   */
00052                 class BASE_IMPEXP CSemaphore
00053                 {
00054                 protected:
00055                         utils::CReferencedMemBlock              m_data;
00056 
00057         public:
00058             /** Creates a semaphore.
00059               */
00060             CSemaphore(
00061                 unsigned int    initialCount,
00062                 unsigned int    maxCount,
00063                 const std::string &name=std::string("") );
00064 
00065             /** Destructor
00066               */
00067             virtual ~CSemaphore();
00068 
00069             /** Blocks until the count of the semaphore to be non-zero.
00070               * \param timeout_ms The timeout in milliseconds, or set to zero to wait indefinidely.
00071               * \return true if the semaphore has been signaled, false on timeout or any other error.
00072               */
00073             bool waitForSignal( unsigned int timeout_ms = 0 );
00074 
00075             /** Increments the count of the semaphore by a given amount.
00076               */
00077             void release(unsigned int increaseCount = 1);
00078 
00079                 };
00080 
00081         } // End of namespace
00082 
00083 } // End of namespace
00084 
00085 #endif



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