dolphin/Externals/wxWidgets/include/wx/thrimpl.cpp

331 lines
8.3 KiB
C++

/////////////////////////////////////////////////////////////////////////////
// Name: include/wx/thrimpl.cpp
// Purpose: common part of wxThread Implementations
// Author: Vadim Zeitlin
// Modified by:
// Created: 04.06.02 (extracted from src/*/thread.cpp files)
// RCS-ID: $Id: thrimpl.cpp 42206 2006-10-21 16:06:11Z VZ $
// Copyright: (c) Vadim Zeitlin (2002)
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
// this file is supposed to be included only by the various thread.cpp
// ----------------------------------------------------------------------------
// wxMutex
// ----------------------------------------------------------------------------
wxMutex::wxMutex(wxMutexType mutexType)
{
m_internal = new wxMutexInternal(mutexType);
if ( !m_internal->IsOk() )
{
delete m_internal;
m_internal = NULL;
}
}
wxMutex::~wxMutex()
{
delete m_internal;
}
bool wxMutex::IsOk() const
{
return m_internal != NULL;
}
wxMutexError wxMutex::Lock()
{
wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
_T("wxMutex::Lock(): not initialized") );
return m_internal->Lock();
}
wxMutexError wxMutex::TryLock()
{
wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
_T("wxMutex::TryLock(): not initialized") );
return m_internal->TryLock();
}
wxMutexError wxMutex::Unlock()
{
wxCHECK_MSG( m_internal, wxMUTEX_INVALID,
_T("wxMutex::Unlock(): not initialized") );
return m_internal->Unlock();
}
// --------------------------------------------------------------------------
// wxConditionInternal
// --------------------------------------------------------------------------
// Win32 and OS/2 don't have explicit support for the POSIX condition
// variables and their events/event semaphores have quite different semantics,
// so we reimplement the conditions from scratch using the mutexes and
// semaphores
#if defined(__WXMSW__) || defined(__OS2__) || defined(__EMX__)
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
LONG 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
{
wxCriticalSectionLocker lock(m_csWaiters);
m_numWaiters++;
}
m_mutex.Unlock();
// a potential race condition can occur here
//
// after a thread increments m_numWaiters, 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 m_numWaiters 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();
if ( err == wxSEMA_NO_ERROR )
return wxCOND_NO_ERROR;
else if ( err == wxSEMA_TIMEOUT )
return wxCOND_TIMEOUT;
else
return wxCOND_MISC_ERROR;
}
wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds)
{
{
wxCriticalSectionLocker lock(m_csWaiters);
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);
if ( err == wxSEMA_TIMEOUT )
{
// another potential race condition exists here it is caused when a
// 'waiting' thread times out, and returns from WaitForSingleObject,
// but has not yet decremented m_numWaiters
//
// at this point if another thread calls signal() then the semaphore
// will be incremented, but the waiting thread will miss it.
//
// to handle this particular case, the waiting thread calls
// WaitForSingleObject again with a timeout of 0, after locking
// m_csWaiters. This call does not block because of the zero
// timeout, but will allow the waiting thread to catch the missed
// signals.
wxCriticalSectionLocker lock(m_csWaiters);
wxSemaError err2 = m_semaphore.WaitTimeout(0);
if ( err2 != wxSEMA_NO_ERROR )
{
m_numWaiters--;
}
}
m_mutex.Lock();
return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR
: err == wxSEMA_TIMEOUT ? wxCOND_TIMEOUT
: wxCOND_MISC_ERROR;
}
wxCondError wxConditionInternal::Signal()
{
wxCriticalSectionLocker lock(m_csWaiters);
if ( m_numWaiters > 0 )
{
// increment the semaphore by 1
if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
return wxCOND_MISC_ERROR;
m_numWaiters--;
}
return wxCOND_NO_ERROR;
}
wxCondError wxConditionInternal::Broadcast()
{
wxCriticalSectionLocker lock(m_csWaiters);
while ( m_numWaiters > 0 )
{
if ( m_semaphore.Post() != wxSEMA_NO_ERROR )
return wxCOND_MISC_ERROR;
m_numWaiters--;
}
return wxCOND_NO_ERROR;
}
#endif // MSW or OS2
// ----------------------------------------------------------------------------
// wxCondition
// ----------------------------------------------------------------------------
wxCondition::wxCondition(wxMutex& mutex)
{
m_internal = new wxConditionInternal(mutex);
if ( !m_internal->IsOk() )
{
delete m_internal;
m_internal = NULL;
}
}
wxCondition::~wxCondition()
{
delete m_internal;
}
bool wxCondition::IsOk() const
{
return m_internal != NULL;
}
wxCondError wxCondition::Wait()
{
wxCHECK_MSG( m_internal, wxCOND_INVALID,
_T("wxCondition::Wait(): not initialized") );
return m_internal->Wait();
}
wxCondError wxCondition::WaitTimeout(unsigned long milliseconds)
{
wxCHECK_MSG( m_internal, wxCOND_INVALID,
_T("wxCondition::Wait(): not initialized") );
return m_internal->WaitTimeout(milliseconds);
}
wxCondError wxCondition::Signal()
{
wxCHECK_MSG( m_internal, wxCOND_INVALID,
_T("wxCondition::Signal(): not initialized") );
return m_internal->Signal();
}
wxCondError wxCondition::Broadcast()
{
wxCHECK_MSG( m_internal, wxCOND_INVALID,
_T("wxCondition::Broadcast(): not initialized") );
return m_internal->Broadcast();
}
// --------------------------------------------------------------------------
// wxSemaphore
// --------------------------------------------------------------------------
wxSemaphore::wxSemaphore(int initialcount, int maxcount)
{
m_internal = new wxSemaphoreInternal( initialcount, maxcount );
if ( !m_internal->IsOk() )
{
delete m_internal;
m_internal = NULL;
}
}
wxSemaphore::~wxSemaphore()
{
delete m_internal;
}
bool wxSemaphore::IsOk() const
{
return m_internal != NULL;
}
wxSemaError wxSemaphore::Wait()
{
wxCHECK_MSG( m_internal, wxSEMA_INVALID,
_T("wxSemaphore::Wait(): not initialized") );
return m_internal->Wait();
}
wxSemaError wxSemaphore::TryWait()
{
wxCHECK_MSG( m_internal, wxSEMA_INVALID,
_T("wxSemaphore::TryWait(): not initialized") );
return m_internal->TryWait();
}
wxSemaError wxSemaphore::WaitTimeout(unsigned long milliseconds)
{
wxCHECK_MSG( m_internal, wxSEMA_INVALID,
_T("wxSemaphore::WaitTimeout(): not initialized") );
return m_internal->WaitTimeout(milliseconds);
}
wxSemaError wxSemaphore::Post()
{
wxCHECK_MSG( m_internal, wxSEMA_INVALID,
_T("wxSemaphore::Post(): not initialized") );
return m_internal->Post();
}