// Written by Bernie Bright, started April 2001.
//
// Copyright (C) 2001 Bernard Bright - bbright@bigpond.net.au
+// Copyright (C) 2011 Mathias Froehlich
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
//
// 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
-// $Id$
#ifndef SGTHREAD_HXX_INCLUDED
#define SGTHREAD_HXX_INCLUDED 1
-#include <pthread.h>
-#include <cassert>
-#include <cerrno>
-
-class SGThread;
-
-extern "C" {
- void* start_handler( void* );
-};
+#include <simgear/compiler.h>
/**
* Encapsulate generic threading methods.
* Users derive a class from SGThread and implement the run() member function.
*/
-class SGThread
-{
+class SGThread {
public:
-
/**
- *
+ * Create a new thread object.
+ * When a SGThread object is created it does not begin execution
+ * immediately. It is started by calling the start() member function.
*/
SGThread();
/**
- *
- */
- virtual ~SGThread();
-
- /**
- *
- */
- int start();
-
- /**
- *
+ * Start the underlying thread of execution.
+ * @return Pthread error code if execution fails, otherwise returns 0.
*/
- void cancel();
+ bool start();
/**
- *
+ * Suspends the exection of the calling thread until this thread
+ * terminates.
*/
void join();
protected:
-
/**
- *
+ * Destroy a thread object.
+ * This is protected so that its illegal to simply delete a thread
+ * - it must return from its run() function.
*/
- virtual void run() = 0;
-
-private:
+ virtual ~SGThread();
/**
- *
+ * All threads execute by deriving the run() method of SGThread.
+ * If this function terminates then the thread also terminates.
*/
- pthread_t tid;
-
- friend void* start_handler( void* );
+ virtual void run() = 0;
private:
// Disable copying.
- SGThread( const SGThread& );
- SGThread& operator=( const SGThread& );
-};
-
-inline
-SGThread::SGThread()
-{
-}
-
-inline
-SGThread::~SGThread()
-{
-}
+ SGThread(const SGThread&);
+ SGThread& operator=(const SGThread&);
-inline int
-SGThread::start()
-{
- int status = pthread_create( &tid, 0, start_handler, this );
- assert( status == 0 );
- return status;
-}
+ struct PrivateData;
+ PrivateData* _privateData;
-inline void
-SGThread::join()
-{
- int status = pthread_join( tid, 0 );
- assert( status == 0 );
-}
+ friend struct PrivateData;
+};
-inline void
-SGThread::cancel()
-{
- int status = pthread_cancel( tid );
- assert( status == 0 );
-}
+class SGWaitCondition;
/**
* A mutex is used to protect a section of code such that at any time
* only a single thread can execute the code.
*/
-class SGMutex
-{
- friend class SGCondition;
-
+class SGMutex {
public:
-
/**
* Create a new mutex.
+ * Under Linux this is a 'fast' mutex.
*/
SGMutex();
/**
* Destroy a mutex object.
+ * Note: it is the responsibility of the caller to ensure the mutex is
+ * unlocked before destruction occurs.
*/
~SGMutex();
/**
- *
+ * Lock this mutex.
+ * If the mutex is currently unlocked, it becomes locked and owned by
+ * the calling thread. If the mutex is already locked by another thread,
+ * the calling thread is suspended until the mutex is unlocked. If the
+ * mutex is already locked and owned by the calling thread, the calling
+ * thread is suspended until the mutex is unlocked, effectively causing
+ * the calling thread to deadlock.
*/
void lock();
/**
- *
- */
- bool trylock();
-
- /**
- *
+ * Unlock this mutex.
+ * It is assumed that the mutex is locked and owned by the calling thread.
*/
void unlock();
-protected:
- pthread_mutex_t mutex;
-};
-
-inline SGMutex::SGMutex()
-{
- int status = pthread_mutex_init( &mutex, 0 );
- assert( status == 0 );
-}
-
-inline SGMutex::~SGMutex()
-{
- int status = pthread_mutex_destroy( &mutex );
- assert( status == 0 );
-}
-
-inline void SGMutex::lock()
-{
- int status = pthread_mutex_lock( &mutex );
- assert( status == 0 );
-}
+private:
+ struct PrivateData;
+ PrivateData* _privateData;
-inline void SGMutex::unlock()
-{
- int status = pthread_mutex_unlock( &mutex );
- assert( status == 0 );
-}
+ friend class SGWaitCondition;
+};
/**
- *
+ * A condition variable is a synchronization device that allows threads to
+ * suspend execution until some predicate on shared data is satisfied.
+ * A condition variable is always associated with a mutex to avoid race
+ * conditions.
*/
-class SGCondition
-{
+class SGWaitCondition {
public:
/**
* Create a new condition variable.
*/
- SGCondition();
+ SGWaitCondition();
/**
* Destroy the condition object.
*/
- ~SGCondition();
+ ~SGWaitCondition();
/**
* Wait for this condition variable to be signaled.
*
* @param SGMutex& reference to a locked mutex.
*/
- void wait( SGMutex& );
+ void wait(SGMutex&);
/**
* Wait for this condition variable to be signaled for at most
* 'ms' milliseconds.
*
- * @param SGMutex& reference to a locked mutex.
- * @param unsigned long milliseconds to wait for a signal.
+ * @param mutex reference to a locked mutex.
+ * @param ms milliseconds to wait for a signal.
*
- * @return
+ * @return
*/
- bool wait( SGMutex& mutex, unsigned long ms );
+ bool wait(SGMutex& mutex, unsigned msec);
/**
* Wake one thread waiting on this condition variable.
+ * Nothing happens if no threads are waiting.
+ * If several threads are waiting exactly one thread is restarted. It
+ * is not specified which.
*/
void signal();
/**
* Wake all threads waiting on this condition variable.
+ * Nothing happens if no threads are waiting.
*/
void broadcast();
private:
// Disable copying.
- SGCondition(const SGCondition& );
- SGCondition& operator=(const SGCondition& );
-
-private:
+ SGWaitCondition(const SGWaitCondition&);
+ SGWaitCondition& operator=(const SGWaitCondition&);
- pthread_cond_t cond;
+ struct PrivateData;
+ PrivateData* _privateData;
};
-inline SGCondition::SGCondition()
-{
- int status = pthread_cond_init( &cond, 0 );
- assert( status == 0 );
-}
-
-inline SGCondition::~SGCondition()
-{
- int status = pthread_cond_destroy( &cond );
- assert( status == 0 );
-}
-
-inline void SGCondition::signal()
-{
- int status = pthread_cond_signal( &cond );
- assert( status == 0 );
-}
-
-inline void SGCondition::broadcast()
-{
- int status = pthread_cond_broadcast( &cond );
- assert( status == 0 );
-}
-
-inline void SGCondition::wait( SGMutex& mutex )
-{
- int status = pthread_cond_wait( &cond, &mutex.mutex );
- assert( status == 0 );
-}
-
#endif /* SGTHREAD_HXX_INCLUDED */
projects / simgear.git / blobdiff