X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/414c639cc20a68e7021019dbbcecfd39210fb10a..43a997b6e2064a189fa73ca1816908fb740ce297:/src/msw/thread.cpp diff --git a/src/msw/thread.cpp b/src/msw/thread.cpp index 8320440d20..d93d017704 100644 --- a/src/msw/thread.cpp +++ b/src/msw/thread.cpp @@ -1,12 +1,12 @@ ///////////////////////////////////////////////////////////////////////////// -// Name: thread.cpp +// Name: src/msw/thread.cpp // Purpose: wxThread Implementation // Author: Original from Wolfram Gloger/Guilhem Lavaux // Modified by: Vadim Zeitlin to make it work :-) // Created: 04/22/98 // RCS-ID: $Id$ -// Copyright: (c) Wolfram Gloger (1996, 1997); Guilhem Lavaux (1998), -// Vadim Zeitlin (1999) +// Copyright: (c) Wolfram Gloger (1996, 1997), Guilhem Lavaux (1998); +// Vadim Zeitlin (1999-2002) // Licence: wxWindows licence ///////////////////////////////////////////////////////////////////////////// @@ -32,14 +32,11 @@ #if wxUSE_THREADS #include "wx/msw/private.h" +#include "wx/msw/missing.h" #include "wx/module.h" #include "wx/thread.h" -#ifdef Yield -# undef Yield -#endif - // must have this symbol defined to get _beginthread/_endthread declarations #ifndef _MT #define _MT @@ -62,7 +59,7 @@ #if defined(__VISUALC__) || \ (defined(__BORLANDC__) && (__BORLANDC__ >= 0x500)) || \ (defined(__GNUG__) && defined(__MSVCRT__)) || \ - defined(__WATCOMC__) + defined(__WATCOMC__) || defined(__MWERKS__) #undef wxUSE_BEGIN_THREAD #define wxUSE_BEGIN_THREAD @@ -127,252 +124,353 @@ static size_t gs_nWaitingForGui = 0; static bool gs_waitingForThread = FALSE; // ============================================================================ -// Windows implementation of thread classes +// Windows implementation of thread and related classes // ============================================================================ // ---------------------------------------------------------------------------- -// wxMutex implementation +// wxCriticalSection +// ---------------------------------------------------------------------------- + +wxCriticalSection::wxCriticalSection() +{ + wxCOMPILE_TIME_ASSERT( sizeof(CRITICAL_SECTION) <= sizeof(wxCritSectBuffer), + wxCriticalSectionBufferTooSmall ); + + ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer); +} + +wxCriticalSection::~wxCriticalSection() +{ + ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer); +} + +void wxCriticalSection::Enter() +{ + ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer); +} + +void wxCriticalSection::Leave() +{ + ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer); +} + +// ---------------------------------------------------------------------------- +// wxMutex // ---------------------------------------------------------------------------- class wxMutexInternal { public: - wxMutexInternal() - { - m_mutex = ::CreateMutex(NULL, FALSE, NULL); - if ( !m_mutex ) - { - wxLogSysError(_("Can not create mutex")); - } - } + wxMutexInternal(wxMutexType mutexType); + ~wxMutexInternal(); - ~wxMutexInternal() { if ( m_mutex ) CloseHandle(m_mutex); } + bool IsOk() const { return m_mutex != NULL; } + + wxMutexError Lock() { return LockTimeout(INFINITE); } + wxMutexError TryLock() { return LockTimeout(0); } + wxMutexError Unlock(); + +private: + wxMutexError LockTimeout(DWORD milliseconds); -public: HANDLE m_mutex; }; -wxMutex::wxMutex() +// all mutexes are recursive under Win32 so we don't use mutexType +wxMutexInternal::wxMutexInternal(wxMutexType WXUNUSED(mutexType)) { - m_internal = new wxMutexInternal; - - m_locked = 0; + // create a nameless (hence intra process and always private) mutex + m_mutex = ::CreateMutex + ( + NULL, // default secutiry attributes + FALSE, // not initially locked + NULL // no name + ); + + if ( !m_mutex ) + { + wxLogLastError(_T("CreateMutex()")); + } } -wxMutex::~wxMutex() +wxMutexInternal::~wxMutexInternal() { - if ( m_locked > 0 ) + if ( m_mutex ) { - wxLogDebug(_T("Warning: freeing a locked mutex (%d locks)."), m_locked); + if ( !::CloseHandle(m_mutex) ) + { + wxLogLastError(_T("CloseHandle(mutex)")); + } } - - delete m_internal; } -wxMutexError wxMutex::Lock() +wxMutexError wxMutexInternal::LockTimeout(DWORD milliseconds) { - DWORD ret; - - ret = WaitForSingleObject(m_internal->m_mutex, INFINITE); - switch ( ret ) + DWORD rc = ::WaitForSingleObject(m_mutex, milliseconds); + if ( rc == WAIT_ABANDONED ) { - case WAIT_ABANDONED: - return wxMUTEX_BUSY; + // the previous caller died without releasing the mutex, but now we can + // really lock it + wxLogDebug(_T("WaitForSingleObject() returned WAIT_ABANDONED")); + + // use 0 timeout, normally we should always get it + rc = ::WaitForSingleObject(m_mutex, 0); + } + switch ( rc ) + { case WAIT_OBJECT_0: // ok break; - case WAIT_FAILED: - wxLogSysError(_("Couldn't acquire a mutex lock")); - return wxMUTEX_MISC_ERROR; - case WAIT_TIMEOUT: + return wxMUTEX_BUSY; + + case WAIT_ABANDONED: // checked for above default: wxFAIL_MSG(wxT("impossible return value in wxMutex::Lock")); - } + // fall through - m_locked++; - return wxMUTEX_NO_ERROR; -} - -wxMutexError wxMutex::TryLock() -{ - DWORD ret; - - ret = WaitForSingleObject(m_internal->m_mutex, 0); - if (ret == WAIT_TIMEOUT || ret == WAIT_ABANDONED) - return wxMUTEX_BUSY; + case WAIT_FAILED: + wxLogLastError(_T("WaitForSingleObject(mutex)")); + return wxMUTEX_MISC_ERROR; + } - m_locked++; return wxMUTEX_NO_ERROR; } -wxMutexError wxMutex::Unlock() +wxMutexError wxMutexInternal::Unlock() { - if (m_locked > 0) - m_locked--; - - BOOL ret = ReleaseMutex(m_internal->m_mutex); - if ( ret == 0 ) + if ( !::ReleaseMutex(m_mutex) ) { - wxLogSysError(_("Couldn't release a mutex")); + wxLogLastError(_("ReleaseMutex()")); + return wxMUTEX_MISC_ERROR; } return wxMUTEX_NO_ERROR; } -// ---------------------------------------------------------------------------- -// wxCondition implementation -// ---------------------------------------------------------------------------- +// -------------------------------------------------------------------------- +// wxSemaphore +// -------------------------------------------------------------------------- -class wxConditionInternal +// a trivial wrapper around Win32 semaphore +class wxSemaphoreInternal { public: - wxConditionInternal() - { - m_hEvent = ::CreateEvent( - NULL, // default secutiry - FALSE, // not manual reset - FALSE, // nonsignaled initially - NULL // nameless event - ); - if ( !m_hEvent ) - { - wxLogSysError(_("Can not create event object.")); - } + wxSemaphoreInternal(int initialcount, int maxcount); + ~wxSemaphoreInternal(); - // nobody waits for us yet - m_nWaiters = 0; - } + bool IsOk() const { return m_semaphore != NULL; } - bool Wait(DWORD timeout) - { - // as m_nWaiters variable is accessed from multiple waiting threads - // (and possibly from the broadcasting thread), we need to change its - // value atomically - ::InterlockedIncrement(&m_nWaiters); + wxSemaError Wait() { return WaitTimeout(INFINITE); } + wxSemaError TryWait() { return WaitTimeout(0); } + wxSemaError WaitTimeout(unsigned long milliseconds); - // FIXME this should be MsgWaitForMultipleObjects() as we want to keep - // processing Windows messages while waiting (or don't we?) - DWORD rc = ::WaitForSingleObject(m_hEvent, timeout); + wxSemaError Post(); - ::InterlockedDecrement(&m_nWaiters); +private: + HANDLE m_semaphore; +}; - return rc != WAIT_TIMEOUT; +wxSemaphoreInternal::wxSemaphoreInternal(int initialcount, int maxcount) +{ + if ( maxcount == 0 ) + { + // make it practically infinite + maxcount = INT_MAX; } - void Signal() + m_semaphore = ::CreateSemaphore + ( + NULL, // default security attributes + initialcount, + maxcount, + NULL // no name + ); + + if ( !m_semaphore ) { - // set the event to signaled: if a thread is already waiting on it, it - // will be woken up, otherwise the event will remain in the signaled - // state until someone waits on it. In any case, the system will return - // it to a non signalled state afterwards. If multiple threads are - // waiting, only one will be woken up. - if ( !::SetEvent(m_hEvent) ) - { - wxLogLastError(wxT("SetEvent")); - } + wxLogLastError(_T("CreateSemaphore()")); } +} - void Broadcast() +wxSemaphoreInternal::~wxSemaphoreInternal() +{ + if ( m_semaphore ) { - // we need to save the original value as m_nWaiters is goign to be - // decreased by the signalled thread resulting in the loop being - // executed less times than needed - LONG nWaiters = m_nWaiters; - - // this works because all these threads are already waiting and so each - // SetEvent() inside Signal() is really a PulseEvent() because the - // event state is immediately returned to non-signaled - for ( LONG n = 0; n < nWaiters; n++ ) + if ( !::CloseHandle(m_semaphore) ) { - Signal(); + wxLogLastError(_T("CloseHandle(semaphore)")); } } +} + +wxSemaError wxSemaphoreInternal::WaitTimeout(unsigned long milliseconds) +{ + DWORD rc = ::WaitForSingleObject( m_semaphore, milliseconds ); - ~wxConditionInternal() + switch ( rc ) { - if ( m_hEvent ) - { - if ( !::CloseHandle(m_hEvent) ) - { - wxLogLastError(wxT("CloseHandle(event)")); - } - } - } + case WAIT_OBJECT_0: + return wxSEMA_NO_ERROR; -private: - // the Win32 synchronization object corresponding to this event - HANDLE m_hEvent; + case WAIT_TIMEOUT: + return wxSEMA_BUSY; - // number of threads waiting for this condition - LONG m_nWaiters; -}; + default: + wxLogLastError(_T("WaitForSingleObject(semaphore)")); + } -wxCondition::wxCondition() -{ - m_internal = new wxConditionInternal; + return wxSEMA_MISC_ERROR; } -wxCondition::~wxCondition() +wxSemaError wxSemaphoreInternal::Post() { - delete m_internal; + if ( !::ReleaseSemaphore(m_semaphore, 1, NULL /* ptr to previous count */) ) + { + wxLogLastError(_T("ReleaseSemaphore")); + + return wxSEMA_MISC_ERROR; + } + + return wxSEMA_NO_ERROR; } -void wxCondition::Wait() +// -------------------------------------------------------------------------- +// wxCondition +// -------------------------------------------------------------------------- + +// Win32 doesn't have explicit support for the POSIX condition variables and +// the Win32 events have quite different semantics, so we reimplement the +// conditions from scratch using the mutexes and semaphores +class wxConditionInternal { - (void)m_internal->Wait(INFINITE); -} +public: + wxConditionInternal(wxMutex& mutex); + + bool IsOk() const { return m_mutex.IsOk() && m_semaphore.IsOk(); } + + wxCondError Wait(); + wxCondError WaitTimeout(unsigned long milliseconds); -bool wxCondition::Wait(unsigned long sec, - unsigned long nsec) + 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; +}; + +wxConditionInternal::wxConditionInternal(wxMutex& mutex) + : m_mutex(mutex) { - return m_internal->Wait(sec*1000 + nsec/1000000); + // another thread can't access it until we return from ctor, so no need to + // protect access to m_numWaiters here + m_numWaiters = 0; } -void wxCondition::Signal() +wxCondError wxConditionInternal::Wait() { - m_internal->Signal(); + // increment the number of waiters + ::InterlockedIncrement(&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; } -void wxCondition::Broadcast() +wxCondError wxConditionInternal::WaitTimeout(unsigned long milliseconds) { - m_internal->Broadcast(); -} + ::InterlockedIncrement(&m_numWaiters); -// ---------------------------------------------------------------------------- -// wxCriticalSection implementation -// ---------------------------------------------------------------------------- + m_mutex.Unlock(); -wxCriticalSection::wxCriticalSection() -{ -#ifdef __WXDEBUG__ - // Done this way to stop warnings during compilation about statement - // always being false - int csSize = sizeof(CRITICAL_SECTION); - int bSize = sizeof(m_buffer); - wxASSERT_MSG( csSize <= bSize, - _T("must increase buffer size in wx/thread.h") ); -#endif + // a race condition can occur at this point in the code + // + // please see the comments in Wait(), for details - ::InitializeCriticalSection((CRITICAL_SECTION *)m_buffer); -} + wxSemaError err = m_semaphore.WaitTimeout(milliseconds); -wxCriticalSection::~wxCriticalSection() -{ - ::DeleteCriticalSection((CRITICAL_SECTION *)m_buffer); + if ( err == wxSEMA_BUSY ) + { + // another potential race condition exists here it is caused when a + // 'waiting' thread timesout, and returns from WaitForSingleObject, but + // has not yet decremented 'nwaiters'. + // + // 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 + // 'nwaiters_mutex'. 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); + + err = m_semaphore.WaitTimeout(0); + + if ( err != wxSEMA_NO_ERROR ) + { + m_numWaiters--; + } + } + + m_mutex.Lock(); + + return err == wxSEMA_NO_ERROR ? wxCOND_NO_ERROR : wxCOND_MISC_ERROR; } -void wxCriticalSection::Enter() +wxCondError wxConditionInternal::Signal() { - ::EnterCriticalSection((CRITICAL_SECTION *)m_buffer); + 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; } -void wxCriticalSection::Leave() +wxCondError wxConditionInternal::Broadcast() { - ::LeaveCriticalSection((CRITICAL_SECTION *)m_buffer); + 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; } // ---------------------------------------------------------------------------- @@ -647,6 +745,11 @@ int wxThread::GetCPUCount() return si.dwNumberOfProcessors; } +unsigned long wxThread::GetCurrentId() +{ + return (unsigned long)::GetCurrentThreadId(); +} + bool wxThread::SetConcurrency(size_t level) { wxASSERT_MSG( IsMain(), _T("should only be called from the main thread") ); @@ -869,10 +972,6 @@ wxThreadError wxThread::Delete(ExitCode *pRc) { // set flag for wxIsWaitingForThread() gs_waitingForThread = TRUE; - -#if wxUSE_GUI - wxBeginBusyCursor(); -#endif // wxUSE_GUI } // ask the thread to terminate @@ -887,16 +986,27 @@ wxThreadError wxThread::Delete(ExitCode *pRc) // we can't just wait for the thread to terminate because it might be // calling some GUI functions and so it will never terminate before we // process the Windows messages that result from these functions - DWORD result; + DWORD result = 0; // suppress warnings from broken compilers do { + if ( IsMain() ) + { + // give the thread we're waiting for chance to do the GUI call + // it might be in + if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() ) + { + wxMutexGuiLeave(); + } + } + result = ::MsgWaitForMultipleObjects ( 1, // number of objects to wait for &hThread, // the objects FALSE, // don't wait for all objects INFINITE, // no timeout - QS_ALLEVENTS // return as soon as there are any events + QS_ALLINPUT | // return as soon as there are any events + QS_ALLPOSTMESSAGE ); switch ( result ) @@ -920,17 +1030,6 @@ wxThreadError wxThread::Delete(ExitCode *pRc) return wxTHREAD_KILLED; } - - if ( IsMain() ) - { - // give the thread we're waiting for chance to exit - // from the GUI call it might have been in - if ( (gs_nWaitingForGui > 0) && wxGuiOwnedByMainThread() ) - { - wxMutexGuiLeave(); - } - } - break; default: @@ -951,19 +1050,21 @@ wxThreadError wxThread::Delete(ExitCode *pRc) if ( IsMain() ) { gs_waitingForThread = FALSE; - -#if wxUSE_GUI - wxEndBusyCursor(); -#endif // wxUSE_GUI } } - if ( !::GetExitCodeThread(hThread, (LPDWORD)&rc) ) + // although the thread might be already in the EXITED state it might not + // have terminated yet and so we are not sure that it has actually + // terminated if the "if" above hadn't been taken + do { - wxLogLastError(wxT("GetExitCodeThread")); + if ( !::GetExitCodeThread(hThread, (LPDWORD)&rc) ) + { + wxLogLastError(wxT("GetExitCodeThread")); - rc = (ExitCode)-1; - } + rc = (ExitCode)-1; + } + } while ( (DWORD)rc == STILL_ACTIVE ); if ( IsDetached() ) { @@ -974,9 +1075,6 @@ wxThreadError wxThread::Delete(ExitCode *pRc) delete this; } - wxASSERT_MSG( (DWORD)rc != STILL_ACTIVE, - wxT("thread must be already terminated.") ); - if ( pRc ) *pRc = rc; @@ -1247,6 +1345,11 @@ bool WXDLLEXPORT wxIsWaitingForThread() return gs_waitingForThread; } +// ---------------------------------------------------------------------------- +// include common implementation code +// ---------------------------------------------------------------------------- + +#include "wx/thrimpl.cpp" + #endif // wxUSE_THREADS -// vi:sts=4:sw=4:et