1 /////////////////////////////////////////////////////////////////////////////
4 // Author: Guilhem Lavaux
5 // Modified by: Vadim Zeitlin (modifications partly inspired by omnithreads
6 // package from Olivetti & Oracle Research Laboratory)
9 // Copyright: (c) Guilhem Lavaux
10 // Licence: wxWindows licence
11 /////////////////////////////////////////////////////////////////////////////
16 // ----------------------------------------------------------------------------
18 // ----------------------------------------------------------------------------
20 // get the value of wxUSE_THREADS configuration flag
25 // Windows headers define it
30 // ----------------------------------------------------------------------------
32 // ----------------------------------------------------------------------------
36 wxMUTEX_NO_ERROR
= 0, // operation completed successfully
37 wxMUTEX_INVALID
, // mutex hasn't been initialized
38 wxMUTEX_DEAD_LOCK
, // mutex is already locked by the calling thread
39 wxMUTEX_BUSY
, // mutex is already locked by another thread
40 wxMUTEX_UNLOCKED
, // attempt to unlock a mutex which is not locked
41 wxMUTEX_MISC_ERROR
// any other error
48 wxCOND_TIMEOUT
, // WaitTimeout() has timed out
55 wxSEMA_INVALID
, // semaphore hasn't been initialized successfully
56 wxSEMA_BUSY
, // returned by TryWait() if Wait() would block
57 wxSEMA_TIMEOUT
, // returned by WaitTimeout()
58 wxSEMA_OVERFLOW
, // Post() would increase counter past the max
64 wxTHREAD_NO_ERROR
= 0, // No error
65 wxTHREAD_NO_RESOURCE
, // No resource left to create a new thread
66 wxTHREAD_RUNNING
, // The thread is already running
67 wxTHREAD_NOT_RUNNING
, // The thread isn't running
68 wxTHREAD_KILLED
, // Thread we waited for had to be killed
69 wxTHREAD_MISC_ERROR
// Some other error
78 // defines the interval of priority
81 WXTHREAD_MIN_PRIORITY
= 0u,
82 WXTHREAD_DEFAULT_PRIORITY
= 50u,
83 WXTHREAD_MAX_PRIORITY
= 100u
86 // There are 2 types of mutexes: normal mutexes and recursive ones. The attempt
87 // to lock a normal mutex by a thread which already owns it results in
88 // undefined behaviour (it always works under Windows, it will almost always
89 // result in a deadlock under Unix). Locking a recursive mutex in such
90 // situation always succeeds and it must be unlocked as many times as it has
93 // However recursive mutexes have several important drawbacks: first, in the
94 // POSIX implementation, they're less efficient. Second, and more importantly,
95 // they CAN NOT BE USED WITH CONDITION VARIABLES under Unix! Using them with
96 // wxCondition will work under Windows and some Unices (notably Linux) but will
97 // deadlock under other Unix versions (e.g. Solaris). As it might be difficult
98 // to ensure that a recursive mutex is not used with wxCondition, it is a good
99 // idea to avoid using recursive mutexes at all. Also, the last problem with
100 // them is that some (older) Unix versions don't support this at all -- which
101 // results in a configure warning when building and a deadlock when using them.
104 // normal mutex: try to always use this one
107 // recursive mutex: don't use these ones with wxCondition
111 // forward declarations
112 class WXDLLIMPEXP_BASE wxThreadHelper
;
113 class WXDLLIMPEXP_BASE wxConditionInternal
;
114 class WXDLLIMPEXP_BASE wxMutexInternal
;
115 class WXDLLIMPEXP_BASE wxSemaphoreInternal
;
116 class WXDLLIMPEXP_BASE wxThreadInternal
;
118 // ----------------------------------------------------------------------------
119 // A mutex object is a synchronization object whose state is set to signaled
120 // when it is not owned by any thread, and nonsignaled when it is owned. Its
121 // name comes from its usefulness in coordinating mutually-exclusive access to
122 // a shared resource. Only one thread at a time can own a mutex object.
123 // ----------------------------------------------------------------------------
125 // you should consider wxMutexLocker whenever possible instead of directly
126 // working with wxMutex class - it is safer
127 class WXDLLIMPEXP_BASE wxMutex
130 // constructor & destructor
131 // ------------------------
133 // create either default (always safe) or recursive mutex
134 wxMutex(wxMutexType mutexType
= wxMUTEX_DEFAULT
);
136 // destroys the mutex kernel object
139 // test if the mutex has been created successfully
145 // Lock the mutex, blocking on it until it is unlocked by the other thread.
146 // The result of locking a mutex already locked by the current thread
147 // depend on the mutex type.
149 // The caller must call Unlock() later if Lock() returned wxMUTEX_NO_ERROR.
152 // Try to lock the mutex: if it is currently locked, return immediately
153 // with an error. Otherwise the caller must call Unlock().
154 wxMutexError
TryLock();
156 // Unlock the mutex. It is an error to unlock an already unlocked mutex
157 wxMutexError
Unlock();
160 wxMutexInternal
*m_internal
;
162 friend class wxConditionInternal
;
164 DECLARE_NO_COPY_CLASS(wxMutex
)
167 // a helper class which locks the mutex in the ctor and unlocks it in the dtor:
168 // this ensures that mutex is always unlocked, even if the function returns or
169 // throws an exception before it reaches the end
170 class WXDLLIMPEXP_BASE wxMutexLocker
173 // lock the mutex in the ctor
174 wxMutexLocker(wxMutex
& mutex
)
175 : m_isOk(false), m_mutex(mutex
)
176 { m_isOk
= ( m_mutex
.Lock() == wxMUTEX_NO_ERROR
); }
178 // returns true if mutex was successfully locked in ctor
182 // unlock the mutex in dtor
184 { if ( IsOk() ) m_mutex
.Unlock(); }
187 // no assignment operator nor copy ctor
188 wxMutexLocker(const wxMutexLocker
&);
189 wxMutexLocker
& operator=(const wxMutexLocker
&);
195 // ----------------------------------------------------------------------------
196 // Critical section: this is the same as mutex but is only visible to the
197 // threads of the same process. For the platforms which don't have native
198 // support for critical sections, they're implemented entirely in terms of
201 // NB: wxCriticalSection object does not allocate any memory in its ctor
202 // which makes it possible to have static globals of this class
203 // ----------------------------------------------------------------------------
205 // in order to avoid any overhead under platforms where critical sections are
206 // just mutexes make all wxCriticalSection class functions inline
207 #if !defined(__WXMSW__) && !defined(__WXMAC__)
208 #define wxCRITSECT_IS_MUTEX 1
210 #define wxCRITSECT_INLINE inline
212 #define wxCRITSECT_IS_MUTEX 0
214 #define wxCRITSECT_INLINE
217 // you should consider wxCriticalSectionLocker whenever possible instead of
218 // directly working with wxCriticalSection class - it is safer
219 class WXDLLIMPEXP_BASE wxCriticalSection
223 wxCRITSECT_INLINE
wxCriticalSection();
224 wxCRITSECT_INLINE
~wxCriticalSection();
226 // enter the section (the same as locking a mutex)
227 wxCRITSECT_INLINE
void Enter();
229 // leave the critical section (same as unlocking a mutex)
230 wxCRITSECT_INLINE
void Leave();
233 #if wxCRITSECT_IS_MUTEX
235 #elif defined(__WXMSW__)
236 // we can't allocate any memory in the ctor, so use placement new -
237 // unfortunately, we have to hardcode the sizeof() here because we can't
238 // include windows.h from this public header and we also have to use the
239 // union to force the correct (i.e. maximal) alignment
241 // if CRITICAL_SECTION size changes in Windows, you'll get an assert from
242 // thread.cpp and will need to increase the buffer size
244 // finally, we need this typedef instead of declaring m_buffer directly
245 // because otherwise the assert mentioned above wouldn't compile with some
246 // compilers (notably CodeWarrior 8)
248 typedef char wxCritSectBuffer
[40];
250 typedef char wxCritSectBuffer
[24];
254 unsigned long m_dummy1
;
257 wxCritSectBuffer m_buffer
;
259 #elif defined(__WXMAC__)
261 #endif // Unix&OS2/Win32
263 DECLARE_NO_COPY_CLASS(wxCriticalSection
)
266 #if wxCRITSECT_IS_MUTEX
267 // implement wxCriticalSection using mutexes
268 inline wxCriticalSection::wxCriticalSection() { }
269 inline wxCriticalSection::~wxCriticalSection() { }
271 inline void wxCriticalSection::Enter() { (void)m_mutex
.Lock(); }
272 inline void wxCriticalSection::Leave() { (void)m_mutex
.Unlock(); }
273 #endif // wxCRITSECT_IS_MUTEX
275 #undef wxCRITSECT_INLINE
276 #undef wxCRITSECT_IS_MUTEX
278 // wxCriticalSectionLocker is the same to critical sections as wxMutexLocker is
280 class WXDLLIMPEXP_BASE wxCriticalSectionLocker
283 wxCriticalSectionLocker(wxCriticalSection
& cs
)
289 ~wxCriticalSectionLocker()
295 wxCriticalSection
& m_critsect
;
297 DECLARE_NO_COPY_CLASS(wxCriticalSectionLocker
)
300 // ----------------------------------------------------------------------------
301 // wxCondition models a POSIX condition variable which allows one (or more)
302 // thread(s) to wait until some condition is fulfilled
303 // ----------------------------------------------------------------------------
305 class WXDLLIMPEXP_BASE wxCondition
308 // Each wxCondition object is associated with a (single) wxMutex object.
309 // The mutex object MUST be locked before calling Wait()
310 wxCondition(wxMutex
& mutex
);
312 // dtor is not virtual, don't use this class polymorphically
315 // return true if the condition has been created successfully
318 // NB: the associated mutex MUST be locked beforehand by the calling thread
320 // it atomically releases the lock on the associated mutex
321 // and starts waiting to be woken up by a Signal()/Broadcast()
322 // once its signaled, then it will wait until it can reacquire
323 // the lock on the associated mutex object, before returning.
326 // exactly as Wait() except that it may also return if the specified
327 // timeout ellapses even if the condition hasn't been signalled: in this
328 // case, the return value is false, otherwise (i.e. in case of a normal
329 // return) it is true
331 // the timeeout parameter specifies a interval that needs to be waited in
333 wxCondError
WaitTimeout(unsigned long milliseconds
);
335 // NB: the associated mutex may or may not be locked by the calling thread
337 // this method unblocks one thread if any are blocking on the condition.
338 // if no thread is blocking in Wait(), then the signal is NOT remembered
339 // The thread which was blocking on Wait(), will then reacquire the lock
340 // on the associated mutex object before returning
341 wxCondError
Signal();
343 // NB: the associated mutex may or may not be locked by the calling thread
345 // this method unblocks all threads if any are blocking on the condition.
346 // if no thread is blocking in Wait(), then the signal is NOT remembered
347 // The threads which were blocking on Wait(), will then reacquire the lock
348 // on the associated mutex object before returning.
349 wxCondError
Broadcast();
352 // deprecated version, don't use
353 bool Wait(unsigned long milliseconds
)
354 { return WaitTimeout(milliseconds
) == wxCOND_NO_ERROR
; }
357 wxConditionInternal
*m_internal
;
359 DECLARE_NO_COPY_CLASS(wxCondition
)
362 // ----------------------------------------------------------------------------
363 // wxSemaphore: a counter limiting the number of threads concurrently accessing
365 // ----------------------------------------------------------------------------
367 class WXDLLIMPEXP_BASE wxSemaphore
370 // specifying a maxcount of 0 actually makes wxSemaphore behave as if there
371 // is no upper limit, if maxcount is 1 the semaphore behaves as a mutex
372 wxSemaphore( int initialcount
= 0, int maxcount
= 0 );
374 // dtor is not virtual, don't use this class polymorphically
377 // return true if the semaphore has been created successfully
380 // wait indefinitely, until the semaphore count goes beyond 0
381 // and then decrement it and return (this method might have been called
385 // same as Wait(), but does not block, returns wxSEMA_NO_ERROR if
386 // successful and wxSEMA_BUSY if the count is currently zero
387 wxSemaError
TryWait();
389 // same as Wait(), but as a timeout limit, returns wxSEMA_NO_ERROR if the
390 // semaphore was acquired and wxSEMA_TIMEOUT if the timeout has ellapsed
391 wxSemaError
WaitTimeout(unsigned long milliseconds
);
393 // increments the semaphore count and signals one of the waiting threads
397 wxSemaphoreInternal
*m_internal
;
399 DECLARE_NO_COPY_CLASS(wxSemaphore
)
402 // ----------------------------------------------------------------------------
403 // wxThread: class encapsulating a thread of execution
404 // ----------------------------------------------------------------------------
406 // there are two different kinds of threads: joinable and detached (default)
407 // ones. Only joinable threads can return a return code and only detached
408 // threads auto-delete themselves - the user should delete the joinable
411 // NB: in the function descriptions the words "this thread" mean the thread
412 // created by the wxThread object while "main thread" is the thread created
413 // during the process initialization (a.k.a. the GUI thread)
415 // On VMS thread pointers are 64 bits (also needed for other systems???
417 typedef unsigned long long wxThreadIdType
;
419 typedef unsigned long wxThreadIdType
;
422 class WXDLLIMPEXP_BASE wxThread
425 // the return type for the thread function
426 typedef void *ExitCode
;
429 // Returns the wxThread object for the calling thread. NULL is returned
430 // if the caller is the main thread (but it's recommended to use
431 // IsMain() and only call This() for threads other than the main one
432 // because NULL is also returned on error). If the thread wasn't
433 // created with wxThread class, the returned value is undefined.
434 static wxThread
*This();
436 // Returns true if current thread is the main thread.
437 static bool IsMain();
439 // Release the rest of our time slice leting the other threads run
442 // Sleep during the specified period of time in milliseconds
444 // NB: at least under MSW worker threads can not call ::wxSleep()!
445 static void Sleep(unsigned long milliseconds
);
447 // get the number of system CPUs - useful with SetConcurrency()
448 // (the "best" value for it is usually number of CPUs + 1)
450 // Returns -1 if unknown, number of CPUs otherwise
451 static int GetCPUCount();
453 // Get the platform specific thread ID and return as a long. This
454 // can be used to uniquely identify threads, even if they are not
455 // wxThreads. This is used by wxPython.
456 static wxThreadIdType
GetCurrentId();
458 // sets the concurrency level: this is, roughly, the number of threads
459 // the system tries to schedule to run in parallel. 0 means the
460 // default value (usually acceptable, but may not yield the best
461 // performance for this process)
463 // Returns true on success, false otherwise (if not implemented, for
465 static bool SetConcurrency(size_t level
);
467 // constructor only creates the C++ thread object and doesn't create (or
468 // start) the real thread
469 wxThread(wxThreadKind kind
= wxTHREAD_DETACHED
);
471 // functions that change the thread state: all these can only be called
472 // from _another_ thread (typically the thread that created this one, e.g.
473 // the main thread), not from the thread itself
475 // create a new thread and optionally set the stack size on
476 // platforms that support that - call Run() to start it
477 // (special cased for watcom which won't accept 0 default)
479 wxThreadError
Create(unsigned int stackSize
= 0);
481 // starts execution of the thread - from the moment Run() is called
482 // the execution of wxThread::Entry() may start at any moment, caller
483 // shouldn't suppose that it starts after (or before) Run() returns.
486 // stops the thread if it's running and deletes the wxThread object if
487 // this is a detached thread freeing its memory - otherwise (for
488 // joinable threads) you still need to delete wxThread object
491 // this function only works if the thread calls TestDestroy()
492 // periodically - the thread will only be deleted the next time it
495 // will fill the rc pointer with the thread exit code if it's !NULL
496 wxThreadError
Delete(ExitCode
*rc
= (ExitCode
*)NULL
);
498 // waits for a joinable thread to finish and returns its exit code
500 // Returns (ExitCode)-1 on error (for example, if the thread is not
504 // kills the thread without giving it any chance to clean up - should
505 // not be used in normal circumstances, use Delete() instead. It is a
506 // dangerous function that should only be used in the most extreme
509 // The wxThread object is deleted by Kill() if the thread is
510 // detachable, but you still have to delete it manually for joinable
512 wxThreadError
Kill();
514 // pause a running thread: as Delete(), this only works if the thread
515 // calls TestDestroy() regularly
516 wxThreadError
Pause();
518 // resume a paused thread
519 wxThreadError
Resume();
522 // Sets the priority to "prio": see WXTHREAD_XXX_PRIORITY constants
524 // NB: the priority can only be set before the thread is created
525 void SetPriority(unsigned int prio
);
527 // Get the current priority.
528 unsigned int GetPriority() const;
530 // thread status inquiries
531 // Returns true if the thread is alive: i.e. running or suspended
532 bool IsAlive() const;
533 // Returns true if the thread is running (not paused, not killed).
534 bool IsRunning() const;
535 // Returns true if the thread is suspended
536 bool IsPaused() const;
538 // is the thread of detached kind?
539 bool IsDetached() const { return m_isDetached
; }
541 // Get the thread ID - a platform dependent number which uniquely
542 // identifies a thread inside a process
543 wxThreadIdType
GetId() const;
545 // called when the thread exits - in the context of this thread
547 // NB: this function will not be called if the thread is Kill()ed
548 virtual void OnExit() { }
550 // Returns true if the thread was asked to terminate: this function should
551 // be called by the thread from time to time, otherwise the main thread
552 // will be left forever in Delete()!
553 virtual bool TestDestroy();
555 // dtor is public, but the detached threads should never be deleted - use
556 // Delete() instead (or leave the thread terminate by itself)
560 // exits from the current thread - can be called only from this thread
561 void Exit(ExitCode exitcode
= 0);
563 // entry point for the thread - called by Run() and executes in the context
565 virtual void *Entry() = 0;
568 // no copy ctor/assignment operator
569 wxThread(const wxThread
&);
570 wxThread
& operator=(const wxThread
&);
572 friend class wxThreadInternal
;
574 // the (platform-dependent) thread class implementation
575 wxThreadInternal
*m_internal
;
577 // protects access to any methods of wxThreadInternal object
578 wxCriticalSection m_critsect
;
580 // true if the thread is detached, false if it is joinable
584 // wxThreadHelperThread class
585 // --------------------------
587 class WXDLLIMPEXP_BASE wxThreadHelperThread
: public wxThread
590 // constructor only creates the C++ thread object and doesn't create (or
591 // start) the real thread
592 wxThreadHelperThread(wxThreadHelper
& owner
)
593 : wxThread(wxTHREAD_JOINABLE
), m_owner(owner
)
597 // entry point for the thread -- calls Entry() in owner.
598 virtual void *Entry();
601 // the owner of the thread
602 wxThreadHelper
& m_owner
;
604 // no copy ctor/assignment operator
605 wxThreadHelperThread(const wxThreadHelperThread
&);
606 wxThreadHelperThread
& operator=(const wxThreadHelperThread
&);
609 // ----------------------------------------------------------------------------
610 // wxThreadHelper: this class implements the threading logic to run a
611 // background task in another object (such as a window). It is a mix-in: just
612 // derive from it to implement a threading background task in your class.
613 // ----------------------------------------------------------------------------
615 class WXDLLIMPEXP_BASE wxThreadHelper
628 // constructor only initializes m_thread to NULL
629 wxThreadHelper() : m_thread(NULL
) { }
631 // destructor deletes m_thread
632 virtual ~wxThreadHelper() { KillThread(); }
634 // create a new thread (and optionally set the stack size on platforms that
635 // support/need that), call Run() to start it
636 wxThreadError
Create(unsigned int stackSize
= 0)
640 m_thread
= new wxThreadHelperThread(*this);
642 return m_thread
->Create(stackSize
);
645 // entry point for the thread - called by Run() and executes in the context
647 virtual void *Entry() = 0;
649 // returns a pointer to the thread which can be used to call Run()
650 wxThread
*GetThread() const { return m_thread
; }
656 // call Entry() in owner, put it down here to avoid circular declarations
657 inline void *wxThreadHelperThread::Entry()
659 return m_owner
.Entry();
662 // ----------------------------------------------------------------------------
663 // Automatic initialization
664 // ----------------------------------------------------------------------------
666 // GUI mutex handling.
667 void WXDLLIMPEXP_BASE
wxMutexGuiEnter();
668 void WXDLLIMPEXP_BASE
wxMutexGuiLeave();
670 // macros for entering/leaving critical sections which may be used without
671 // having to take them inside "#if wxUSE_THREADS"
672 #define wxENTER_CRIT_SECT(cs) (cs).Enter()
673 #define wxLEAVE_CRIT_SECT(cs) (cs).Leave()
674 #define wxCRIT_SECT_DECLARE(cs) static wxCriticalSection cs
675 #define wxCRIT_SECT_DECLARE_MEMBER(cs) wxCriticalSection cs
676 #define wxCRIT_SECT_LOCKER(name, cs) wxCriticalSectionLocker name(cs)
678 // function for checking if we're in the main thread which may be used whether
679 // wxUSE_THREADS is 0 or 1
680 inline bool wxIsMainThread() { return wxThread::IsMain(); }
682 #else // !wxUSE_THREADS
685 inline void WXDLLIMPEXP_BASE
wxMutexGuiEnter() { }
686 inline void WXDLLIMPEXP_BASE
wxMutexGuiLeave() { }
688 // macros for entering/leaving critical sections which may be used without
689 // having to take them inside "#if wxUSE_THREADS"
690 #define wxENTER_CRIT_SECT(cs)
691 #define wxLEAVE_CRIT_SECT(cs)
692 #define wxCRIT_SECT_DECLARE(cs)
693 #define wxCRIT_SECT_DECLARE_MEMBER(cs)
694 #define wxCRIT_SECT_LOCKER(name, cs)
696 // if there is only one thread, it is always the main one
697 inline bool wxIsMainThread() { return true; }
699 #endif // wxUSE_THREADS/!wxUSE_THREADS
701 // mark part of code as being a critical section: this macro declares a
702 // critical section with the given name and enters it immediately and leaves
703 // it at the end of the current scope
709 // static int s_counter = 0;
711 // wxCRITICAL_SECTION(counter);
713 // return ++s_counter;
716 // this function is MT-safe in presence of the threads but there is no
717 // overhead when the library is compiled without threads
718 #define wxCRITICAL_SECTION(name) \
719 wxCRIT_SECT_DECLARE(s_cs##name); \
720 wxCRIT_SECT_LOCKER(cs##name##Locker, s_cs##name)
722 // automatically lock GUI mutex in ctor and unlock it in dtor
723 class WXDLLIMPEXP_BASE wxMutexGuiLocker
726 wxMutexGuiLocker() { wxMutexGuiEnter(); }
727 ~wxMutexGuiLocker() { wxMutexGuiLeave(); }
730 // -----------------------------------------------------------------------------
731 // implementation only until the end of file
732 // -----------------------------------------------------------------------------
736 #if defined(__WXMSW__) || defined(__WXMAC__) || defined(__OS2__) || defined(__EMX__)
737 // unlock GUI if there are threads waiting for and lock it back when
738 // there are no more of them - should be called periodically by the main
740 extern void WXDLLIMPEXP_BASE
wxMutexGuiLeaveOrEnter();
742 // returns true if the main thread has GUI lock
743 extern bool WXDLLIMPEXP_BASE
wxGuiOwnedByMainThread();
745 // wakes up the main thread if it's sleeping inside ::GetMessage()
746 extern void WXDLLIMPEXP_BASE
wxWakeUpMainThread();
748 // return true if the main thread is waiting for some other to terminate:
749 // wxApp then should block all "dangerous" messages
750 extern bool WXDLLIMPEXP_BASE
wxIsWaitingForThread();
751 #endif // MSW, Mac, OS/2
753 #endif // wxUSE_THREADS
755 #endif // _WX_THREAD_H_