+ while ( --n );
+
+ return wxCOND_NO_ERROR;
+}
+
+#else
+class wxConditionInternal
+{
+public:
+ wxConditionInternal( wxMutex& mutex );
+
+ bool IsOk() const
+ { return m_mutex.IsOk() && m_semaphore.IsOk(); }
+
+ wxCondError Wait();
+ wxCondError WaitTimeout( unsigned long milliseconds );
+
+ wxCondError Signal();
+ wxCondError Broadcast();
+
+private:
+ // the number of threads currently waiting for this condition
+ SInt32 m_numWaiters;
+
+ // the critical section protecting m_numWaiters
+ wxCriticalSection m_csWaiters;
+
+ wxMutex& m_mutex;
+ wxSemaphore m_semaphore;
+
+ DECLARE_NO_COPY_CLASS(wxConditionInternal)
+};
+
+wxConditionInternal::wxConditionInternal( wxMutex& mutex )
+ : m_mutex(mutex)
+{
+ // another thread can't access it until we return from ctor, so no need to
+ // protect access to m_numWaiters here
+ m_numWaiters = 0;
+}
+
+wxCondError wxConditionInternal::Wait()
+{
+ // increment the number of waiters
+ IncrementAtomic( &m_numWaiters );
+
+ m_mutex.Unlock();
+
+ // a potential race condition can occur here
+ //
+ // after a thread increments nwaiters, and unlocks the mutex and before the
+ // semaphore.Wait() is called, if another thread can cause a signal to be
+ // generated
+ //
+ // this race condition is handled by using a semaphore and incrementing the
+ // semaphore only if 'nwaiters' is greater that zero since the semaphore,
+ // can 'remember' signals the race condition will not occur
+
+ // wait ( if necessary ) and decrement semaphore
+ wxSemaError err = m_semaphore.Wait();
+ m_mutex.Lock();
+
+ return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR : wxCOND_MISC_ERROR;
+}
+
+wxCondError wxConditionInternal::WaitTimeout( unsigned long milliseconds )
+{
+ IncrementAtomic( &m_numWaiters );
+
+ m_mutex.Unlock();
+
+ // a race condition can occur at this point in the code
+ //
+ // please see the comments in Wait(), for details
+
+ wxSemaError err = m_semaphore.WaitTimeout(milliseconds);
projects / wxWidgets.git / blobdiff