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/*========================================================================= |
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Program: Insight Segmentation & Registration Toolkit |
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Module: $RCSfile: itkSemaphore.h.html,v $ |
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Language: C++ |
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Date: $Date: 2006/01/17 19:15:47 $ |
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Version: $Revision: 1.4 $ |
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Copyright (c) Insight Software Consortium. All rights reserved. |
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See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details. |
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This software is distributed WITHOUT ANY WARRANTY; without even |
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
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PURPOSE. See the above copyright notices for more information. |
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=========================================================================*/ |
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DEF |
#ifndef __itkSemaphore_h_ |
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DEF |
#define __itkSemaphore_h_ |
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#include "itkObjectFactory.h" |
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#include "itkLightObject.h" |
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#include "itkConfigure.h" |
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#include <string> |
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#ifdef ITK_USE_UNIX_IPC_SEMAPHORES |
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#include "itkMutexLock.h" |
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#include <stdio.h> |
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#include <sys/types.h> |
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#include <sys/ipc.h> |
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#include <sys/sem.h> |
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#include <errno.h> |
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#endif |
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#ifndef ITK_USE_UNIX_IPC_SEMAPHORES |
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#ifdef ITK_USE_SPROC |
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#include "itkMultiThreader.h" |
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#include <ulocks.h> |
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#endif |
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#ifdef ITK_USE_PTHREADS |
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#ifdef sun |
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#include <synch.h> |
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#else |
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#include <semaphore.h> |
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#endif |
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#endif |
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#endif |
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#ifdef ITK_USE_WIN32_THREADS |
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#include "itkWindows.h" |
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#endif |
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namespace itk { |
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#ifdef ITK_USE_UNIX_IPC_SEMAPHORES |
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**typedef int SemaphoreType; |
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#endif |
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#ifndef ITK_USE_UNIX_IPC_SEMAPHORES |
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#ifdef ITK_USE_SPROC |
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typedef usema_t * SemaphoreType; |
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#endif |
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#ifdef ITK_USE_PTHREADS |
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#ifdef sun |
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typedef sema_t SemaphoreType; |
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#else |
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#ifdef __APPLE__ |
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typedef sem_t *SemaphoreType; |
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#else |
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typedef sem_t SemaphoreType; |
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#endif |
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#endif |
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#endif |
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#endif |
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#ifdef ITK_USE_WIN32_THREADS |
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typedef HANDLE SemaphoreType; |
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#endif |
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#ifndef ITK_USE_UNIX_IPC_SEMAPHORES |
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#ifndef ITK_USE_SPROC |
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#ifndef ITK_USE_PTHREADS |
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#ifndef ITK_USE_WIN32_THREADS |
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typedef int SemaphoreType; |
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#endif |
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#endif |
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#endif |
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#endif |
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/** \class Semaphore |
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* \brief The semaphore class is used to synchronize execution between threads. |
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* |
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* Semaphore objects maintain a counter value that can be incremented and |
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* decremented by atomic calls to Up() and Down(). Semaphores are commonly used |
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* to manage the use of a limited pool of system resources among several |
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* threads. If Down() is called when the value of the semaphore is zero, the |
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* calling thread will block until the semaphore value goes above zero again. |
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* When a blocked thread is released, it decrements the Semaphore counter |
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* before continuing to execute. |
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* |
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* The Up() and Down() operations are standard as defined by E.W. Dijkstra. |
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* The Initialize( num ) operation creates the system semaphore object with an |
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* initial counter value of num. Initialize must be called before the |
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* Semaphore can be used. The Remove() method destroys the system semaphore |
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* object. It is not necessary to call Remove() unless you want to |
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* re-Initialize() the object. |
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* |
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* This class supports 3 types of semaphores on Unix systems, POSIX semaphores, |
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* IPC semaphores, and IRIX semaphores from the SGI Sproc library. On Windows |
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* systems, POSIX semaphores and WIN32 thread library semaphores are supported. |
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* |
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*/ |
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class ITKCommon_EXPORT Semaphore : public LightObject |
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{ |
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public: |
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/** Standard class typedefs. */ |
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typedef Semaphore Self; |
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typedef LightObject Superclass; |
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typedef SmartPointer<Self> Pointer; |
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typedef SmartPointer<const Self> ConstPointer; |
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/** Method for creation through the object factory. */ |
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itkNewMacro(Self); |
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/** Run-time type information (and related methods). */ |
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itkTypeMacro(Semaphore, LightObject); |
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/** Initialize the semaphore with a count of value. */ |
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void Initialize(unsigned int value); |
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/** Increment the semaphore count, unblocking up to one thread that may be |
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******blocked in the down() method. */ |
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void Up(); |
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/** Decrement the semaphore count. If the count is zero, this thread will be |
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******blocked until another thread calls the up() method. The order in which |
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******threads will be unblocked is not defined, but implementors should give |
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******preference to those threads that have waited the longest. |
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***/ |
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void Down(); |
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/** Remove the semaphore from the system. */ |
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void Remove (); |
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protected: |
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Semaphore (); |
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~Semaphore(); |
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private: |
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#ifdef ITK_USE_UNIX_IPC_SEMAPHORES |
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/** Every IPC semaphore must be created with a unique key. This variable |
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* increments with each new ITK Semaphore created to give a unique key. */ |
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static int m_IPCSemaphoreKey; |
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/** Mutex to lock increment operation on m_IPCSemaphoreKey */ |
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static SimpleMutexLock m_Mutex; |
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int UnixIpcSemaphoreCreate (int unix_semaphore_key); |
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void UnixIpcSemaphoreRemove (int sid); |
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void UnixIpcSemaphoreCall (int sid, int op); |
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void UnixIpcSemaphoreDown (int sid); |
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void UnixIpcSemaphoreUp (int sid); |
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#endif |
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char Pad1[128]; // to avoid false sharing in case of shared memory multiprocessor systems |
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SemaphoreType m_Sema; |
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char Pad2[128]; // to avoid false sharing in case of shared memory multiprocessor systems |
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#ifdef __APPLE__ |
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std::string GetUniqueName(); |
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static int m_SemaphoreCount; |
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std::string m_SemaphoreName; |
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#endif |
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/** When using pthread the semaphore cannot be removed twice so we use a flag */ |
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#ifdef ITK_USE_PTHREADS |
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bool m_PThreadsSemaphoreRemoved; |
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#endif |
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}; |
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}//itk |
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#endif |
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