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 // only for wxUSE_THREADS - otherwise we'd get undefined symbols
26 #if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
27 #pragma interface "thread.h"
30 // Windows headers define it
35 // ----------------------------------------------------------------------------
37 // ----------------------------------------------------------------------------
41 wxMUTEX_NO_ERROR
= 0, // operation completed successfully
42 wxMUTEX_INVALID
, // mutex hasn't been initialized
43 wxMUTEX_DEAD_LOCK
, // mutex is already locked by the calling thread
44 wxMUTEX_BUSY
, // mutex is already locked by another thread
45 wxMUTEX_UNLOCKED
, // attempt to unlock a mutex which is not locked
46 wxMUTEX_MISC_ERROR
// any other error
53 wxCOND_TIMEOUT
, // WaitTimeout() has timed out
60 wxSEMA_INVALID
, // semaphore hasn't been initialized successfully
61 wxSEMA_BUSY
, // returned by TryWait() if Wait() would block
62 wxSEMA_TIMEOUT
, // returned by WaitTimeout()
63 wxSEMA_OVERFLOW
, // Post() would increase counter past the max
69 wxTHREAD_NO_ERROR
= 0, // No error
70 wxTHREAD_NO_RESOURCE
, // No resource left to create a new thread
71 wxTHREAD_RUNNING
, // The thread is already running
72 wxTHREAD_NOT_RUNNING
, // The thread isn't running
73 wxTHREAD_KILLED
, // Thread we waited for had to be killed
74 wxTHREAD_MISC_ERROR
// Some other error
83 // defines the interval of priority
86 WXTHREAD_MIN_PRIORITY
= 0u,
87 WXTHREAD_DEFAULT_PRIORITY
= 50u,
88 WXTHREAD_MAX_PRIORITY
= 100u
91 // There are 2 types of mutexes: normal mutexes and recursive ones. The attempt
92 // to lock a normal mutex by a thread which already owns it results in
93 // undefined behaviour (it always works under Windows, it will almost always
94 // result in a deadlock under Unix). Locking a recursive mutex in such
95 // situation always succeeds and it must be unlocked as many times as it has
98 // However recursive mutexes have several important drawbacks: first, in the
99 // POSIX implementation, they're less efficient. Second, and more importantly,
100 // they CAN NOT BE USED WITH CONDITION VARIABLES under Unix! Using them with
101 // wxCondition will work under Windows and some Unices (notably Linux) but will
102 // deadlock under other Unix versions (e.g. Solaris). As it might be difficult
103 // to ensure that a recursive mutex is not used with wxCondition, it is a good
104 // idea to avoid using recursive mutexes at all. Also, the last problem with
105 // them is that some (older) Unix versions don't support this at all -- which
106 // results in a configure warning when building and a deadlock when using them.
109 // normal mutex: try to always use this one
112 // recursive mutex: don't use these ones with wxCondition
116 // forward declarations
117 class WXDLLIMPEXP_BASE wxThreadHelper
;
118 class WXDLLIMPEXP_BASE wxConditionInternal
;
119 class WXDLLIMPEXP_BASE wxMutexInternal
;
120 class WXDLLIMPEXP_BASE wxSemaphoreInternal
;
121 class WXDLLIMPEXP_BASE wxThreadInternal
;
123 // ----------------------------------------------------------------------------
124 // A mutex object is a synchronization object whose state is set to signaled
125 // when it is not owned by any thread, and nonsignaled when it is owned. Its
126 // name comes from its usefulness in coordinating mutually-exclusive access to
127 // a shared resource. Only one thread at a time can own a mutex object.
128 // ----------------------------------------------------------------------------
130 // you should consider wxMutexLocker whenever possible instead of directly
131 // working with wxMutex class - it is safer
132 class WXDLLIMPEXP_BASE wxMutex
135 // constructor & destructor
136 // ------------------------
138 // create either default (always safe) or recursive mutex
139 wxMutex(wxMutexType mutexType
= wxMUTEX_DEFAULT
);
141 // destroys the mutex kernel object
144 // test if the mutex has been created successfully
150 // Lock the mutex, blocking on it until it is unlocked by the other thread.
151 // The result of locking a mutex already locked by the current thread
152 // depend on the mutex type.
154 // The caller must call Unlock() later if Lock() returned wxMUTEX_NO_ERROR.
157 // Try to lock the mutex: if it is currently locked, return immediately
158 // with an error. Otherwise the caller must call Unlock().
159 wxMutexError
TryLock();
161 // Unlock the mutex. It is an error to unlock an already unlocked mutex
162 wxMutexError
Unlock();
165 wxMutexInternal
*m_internal
;
167 friend class wxConditionInternal
;
169 DECLARE_NO_COPY_CLASS(wxMutex
)
172 // a helper class which locks the mutex in the ctor and unlocks it in the dtor:
173 // this ensures that mutex is always unlocked, even if the function returns or
174 // throws an exception before it reaches the end
175 class WXDLLIMPEXP_BASE wxMutexLocker
178 // lock the mutex in the ctor
179 wxMutexLocker(wxMutex
& mutex
)
180 : m_isOk(false), m_mutex(mutex
)
181 { m_isOk
= ( m_mutex
.Lock() == wxMUTEX_NO_ERROR
); }
183 // returns true if mutex was successfully locked in ctor
187 // unlock the mutex in dtor
189 { if ( IsOk() ) m_mutex
.Unlock(); }
192 // no assignment operator nor copy ctor
193 wxMutexLocker(const wxMutexLocker
&);
194 wxMutexLocker
& operator=(const wxMutexLocker
&);
200 // ----------------------------------------------------------------------------
201 // Critical section: this is the same as mutex but is only visible to the
202 // threads of the same process. For the platforms which don't have native
203 // support for critical sections, they're implemented entirely in terms of
206 // NB: wxCriticalSection object does not allocate any memory in its ctor
207 // which makes it possible to have static globals of this class
208 // ----------------------------------------------------------------------------
210 // in order to avoid any overhead under platforms where critical sections are
211 // just mutexes make all wxCriticalSection class functions inline
212 #if !defined(__WXMSW__)
213 #define wxCRITSECT_IS_MUTEX 1
215 #define wxCRITSECT_INLINE inline
217 #define wxCRITSECT_IS_MUTEX 0
219 #define wxCRITSECT_INLINE
222 // you should consider wxCriticalSectionLocker whenever possible instead of
223 // directly working with wxCriticalSection class - it is safer
224 class WXDLLIMPEXP_BASE wxCriticalSection
228 wxCRITSECT_INLINE
wxCriticalSection();
229 wxCRITSECT_INLINE
~wxCriticalSection();
231 // enter the section (the same as locking a mutex)
232 wxCRITSECT_INLINE
void Enter();
234 // leave the critical section (same as unlocking a mutex)
235 wxCRITSECT_INLINE
void Leave();
238 #if wxCRITSECT_IS_MUTEX
240 #elif defined(__WXMSW__)
241 // we can't allocate any memory in the ctor, so use placement new -
242 // unfortunately, we have to hardcode the sizeof() here because we can't
243 // include windows.h from this public header and we also have to use the
244 // union to force the correct (i.e. maximal) alignment
246 // if CRITICAL_SECTION size changes in Windows, you'll get an assert from
247 // thread.cpp and will need to increase the buffer size
249 // finally, we need this typedef instead of declaring m_buffer directly
250 // because otherwise the assert mentioned above wouldn't compile with some
251 // compilers (notably CodeWarrior 8)
253 typedef char wxCritSectBuffer
[40];
255 typedef char wxCritSectBuffer
[24];
259 unsigned long m_dummy1
;
262 wxCritSectBuffer m_buffer
;
264 #endif // Unix&OS2/Win32
266 DECLARE_NO_COPY_CLASS(wxCriticalSection
)
269 #if wxCRITSECT_IS_MUTEX
270 // implement wxCriticalSection using mutexes
271 inline wxCriticalSection::wxCriticalSection() { }
272 inline wxCriticalSection::~wxCriticalSection() { }
274 inline void wxCriticalSection::Enter() { (void)m_mutex
.Lock(); }
275 inline void wxCriticalSection::Leave() { (void)m_mutex
.Unlock(); }
276 #endif // wxCRITSECT_IS_MUTEX
278 #undef wxCRITSECT_INLINE
279 #undef wxCRITSECT_IS_MUTEX
281 // wxCriticalSectionLocker is the same to critical sections as wxMutexLocker is
283 class WXDLLIMPEXP_BASE wxCriticalSectionLocker
286 wxCriticalSectionLocker(wxCriticalSection
& cs
)
292 ~wxCriticalSectionLocker()
298 wxCriticalSection
& m_critsect
;
300 DECLARE_NO_COPY_CLASS(wxCriticalSectionLocker
)
303 // ----------------------------------------------------------------------------
304 // wxCondition models a POSIX condition variable which allows one (or more)
305 // thread(s) to wait until some condition is fulfilled
306 // ----------------------------------------------------------------------------
308 class WXDLLIMPEXP_BASE wxCondition
311 // Each wxCondition object is associated with a (single) wxMutex object.
312 // The mutex object MUST be locked before calling Wait()
313 wxCondition(wxMutex
& mutex
);
315 // dtor is not virtual, don't use this class polymorphically
318 // return true if the condition has been created successfully
321 // NB: the associated mutex MUST be locked beforehand by the calling thread
323 // it atomically releases the lock on the associated mutex
324 // and starts waiting to be woken up by a Signal()/Broadcast()
325 // once its signaled, then it will wait until it can reacquire
326 // the lock on the associated mutex object, before returning.
329 // exactly as Wait() except that it may also return if the specified
330 // timeout ellapses even if the condition hasn't been signalled: in this
331 // case, the return value is false, otherwise (i.e. in case of a normal
332 // return) it is true
334 // the timeeout parameter specifies a interval that needs to be waited in
336 wxCondError
WaitTimeout(unsigned long milliseconds
);
338 // NB: the associated mutex may or may not be locked by the calling thread
340 // this method unblocks one thread if any are blocking on the condition.
341 // if no thread is blocking in Wait(), then the signal is NOT remembered
342 // The thread which was blocking on Wait(), will then reacquire the lock
343 // on the associated mutex object before returning
344 wxCondError
Signal();
346 // NB: the associated mutex may or may not be locked by the calling thread
348 // this method unblocks all threads if any are blocking on the condition.
349 // if no thread is blocking in Wait(), then the signal is NOT remembered
350 // The threads which were blocking on Wait(), will then reacquire the lock
351 // on the associated mutex object before returning.
352 wxCondError
Broadcast();
355 // deprecated version, don't use
356 bool Wait(unsigned long milliseconds
)
357 { return WaitTimeout(milliseconds
) == wxCOND_NO_ERROR
; }
360 wxConditionInternal
*m_internal
;
362 DECLARE_NO_COPY_CLASS(wxCondition
)
365 // ----------------------------------------------------------------------------
366 // wxSemaphore: a counter limiting the number of threads concurrently accessing
368 // ----------------------------------------------------------------------------
370 class WXDLLIMPEXP_BASE wxSemaphore
373 // specifying a maxcount of 0 actually makes wxSemaphore behave as if there
374 // is no upper limit, if maxcount is 1 the semaphore behaves as a mutex
375 wxSemaphore( int initialcount
= 0, int maxcount
= 0 );
377 // dtor is not virtual, don't use this class polymorphically
380 // return true if the semaphore has been created successfully
383 // wait indefinitely, until the semaphore count goes beyond 0
384 // and then decrement it and return (this method might have been called
388 // same as Wait(), but does not block, returns wxSEMA_NO_ERROR if
389 // successful and wxSEMA_BUSY if the count is currently zero
390 wxSemaError
TryWait();
392 // same as Wait(), but as a timeout limit, returns wxSEMA_NO_ERROR if the
393 // semaphore was acquired and wxSEMA_TIMEOUT if the timeout has ellapsed
394 wxSemaError
WaitTimeout(unsigned long milliseconds
);
396 // increments the semaphore count and signals one of the waiting threads
400 wxSemaphoreInternal
*m_internal
;
402 DECLARE_NO_COPY_CLASS(wxSemaphore
)
405 // ----------------------------------------------------------------------------
406 // wxThread: class encpasulating a thread of execution
407 // ----------------------------------------------------------------------------
409 // there are two different kinds of threads: joinable and detached (default)
410 // ones. Only joinable threads can return a return code and only detached
411 // threads auto-delete themselves - the user should delete the joinable
414 // NB: in the function descriptions the words "this thread" mean the thread
415 // created by the wxThread object while "main thread" is the thread created
416 // during the process initialization (a.k.a. the GUI thread)
418 // On VMS thread pointers are 64 bits (also needed for other systems???
420 typedef unsigned long long wxThreadIdType
;
422 typedef unsigned long wxThreadIdType
;
425 class WXDLLIMPEXP_BASE wxThread
428 // the return type for the thread function
429 typedef void *ExitCode
;
432 // Returns the wxThread object for the calling thread. NULL is returned
433 // if the caller is the main thread (but it's recommended to use
434 // IsMain() and only call This() for threads other than the main one
435 // because NULL is also returned on error). If the thread wasn't
436 // created with wxThread class, the returned value is undefined.
437 static wxThread
*This();
439 // Returns true if current thread is the main thread.
440 static bool IsMain();
442 // Release the rest of our time slice leting the other threads run
445 // Sleep during the specified period of time in milliseconds
447 // NB: at least under MSW worker threads can not call ::wxSleep()!
448 static void Sleep(unsigned long milliseconds
);
450 // get the number of system CPUs - useful with SetConcurrency()
451 // (the "best" value for it is usually number of CPUs + 1)
453 // Returns -1 if unknown, number of CPUs otherwise
454 static int GetCPUCount();
456 // Get the platform specific thread ID and return as a long. This
457 // can be used to uniquely identify threads, even if they are not
458 // wxThreads. This is used by wxPython.
459 static wxThreadIdType
GetCurrentId();
461 // sets the concurrency level: this is, roughly, the number of threads
462 // the system tries to schedule to run in parallel. 0 means the
463 // default value (usually acceptable, but may not yield the best
464 // performance for this process)
466 // Returns true on success, false otherwise (if not implemented, for
468 static bool SetConcurrency(size_t level
);
470 // constructor only creates the C++ thread object and doesn't create (or
471 // start) the real thread
472 wxThread(wxThreadKind kind
= wxTHREAD_DETACHED
);
474 // functions that change the thread state: all these can only be called
475 // from _another_ thread (typically the thread that created this one, e.g.
476 // the main thread), not from the thread itself
478 // create a new thread and optionally set the stack size on
479 // platforms that support that - call Run() to start it
480 // (special cased for watcom which won't accept 0 default)
482 wxThreadError
Create(unsigned int stackSize
= 0);
484 // starts execution of the thread - from the moment Run() is called
485 // the execution of wxThread::Entry() may start at any moment, caller
486 // shouldn't suppose that it starts after (or before) Run() returns.
489 // stops the thread if it's running and deletes the wxThread object if
490 // this is a detached thread freeing its memory - otherwise (for
491 // joinable threads) you still need to delete wxThread object
494 // this function only works if the thread calls TestDestroy()
495 // periodically - the thread will only be deleted the next time it
498 // will fill the rc pointer with the thread exit code if it's !NULL
499 wxThreadError
Delete(ExitCode
*rc
= (ExitCode
*)NULL
);
501 // waits for a joinable thread to finish and returns its exit code
503 // Returns (ExitCode)-1 on error (for example, if the thread is not
507 // kills the thread without giving it any chance to clean up - should
508 // not be used in normal circumstances, use Delete() instead. It is a
509 // dangerous function that should only be used in the most extreme
512 // The wxThread object is deleted by Kill() if the thread is
513 // detachable, but you still have to delete it manually for joinable
515 wxThreadError
Kill();
517 // pause a running thread: as Delete(), this only works if the thread
518 // calls TestDestroy() regularly
519 wxThreadError
Pause();
521 // resume a paused thread
522 wxThreadError
Resume();
525 // Sets the priority to "prio": see WXTHREAD_XXX_PRIORITY constants
527 // NB: the priority can only be set before the thread is created
528 void SetPriority(unsigned int prio
);
530 // Get the current priority.
531 unsigned int GetPriority() const;
533 // thread status inquiries
534 // Returns true if the thread is alive: i.e. running or suspended
535 bool IsAlive() const;
536 // Returns true if the thread is running (not paused, not killed).
537 bool IsRunning() const;
538 // Returns true if the thread is suspended
539 bool IsPaused() const;
541 // is the thread of detached kind?
542 bool IsDetached() const { return m_isDetached
; }
544 // Get the thread ID - a platform dependent number which uniquely
545 // identifies a thread inside a process
546 wxThreadIdType
GetId() const;
548 // called when the thread exits - in the context of this thread
550 // NB: this function will not be called if the thread is Kill()ed
551 virtual void OnExit() { }
553 // Returns true if the thread was asked to terminate: this function should
554 // be called by the thread from time to time, otherwise the main thread
555 // will be left forever in Delete()!
556 virtual bool TestDestroy();
558 // dtor is public, but the detached threads should never be deleted - use
559 // Delete() instead (or leave the thread terminate by itself)
563 // exits from the current thread - can be called only from this thread
564 void Exit(ExitCode exitcode
= 0);
566 // entry point for the thread - called by Run() and executes in the context
568 virtual void *Entry() = 0;
571 // no copy ctor/assignment operator
572 wxThread(const wxThread
&);
573 wxThread
& operator=(const wxThread
&);
575 friend class wxThreadInternal
;
577 // the (platform-dependent) thread class implementation
578 wxThreadInternal
*m_internal
;
580 // protects access to any methods of wxThreadInternal object
581 wxCriticalSection m_critsect
;
583 // true if the thread is detached, false if it is joinable
587 // wxThreadHelperThread class
588 // --------------------------
590 class WXDLLIMPEXP_BASE wxThreadHelperThread
: public wxThread
593 // constructor only creates the C++ thread object and doesn't create (or
594 // start) the real thread
595 wxThreadHelperThread(wxThreadHelper
& owner
)
596 : wxThread(wxTHREAD_JOINABLE
), m_owner(owner
)
600 // entry point for the thread -- calls Entry() in owner.
601 virtual void *Entry();
604 // the owner of the thread
605 wxThreadHelper
& m_owner
;
607 // no copy ctor/assignment operator
608 wxThreadHelperThread(const wxThreadHelperThread
&);
609 wxThreadHelperThread
& operator=(const wxThreadHelperThread
&);
612 // ----------------------------------------------------------------------------
613 // wxThreadHelper: this class implements the threading logic to run a
614 // background task in another object (such as a window). It is a mix-in: just
615 // derive from it to implement a threading background task in your class.
616 // ----------------------------------------------------------------------------
618 class WXDLLIMPEXP_BASE wxThreadHelper
631 // constructor only initializes m_thread to NULL
632 wxThreadHelper() : m_thread(NULL
) { }
634 // destructor deletes m_thread
635 virtual ~wxThreadHelper() { KillThread(); }
637 // create a new thread (and optionally set the stack size on platforms that
638 // support/need that), call Run() to start it
639 wxThreadError
Create(unsigned int stackSize
= 0)
643 m_thread
= new wxThreadHelperThread(*this);
645 return m_thread
->Create(stackSize
);
648 // entry point for the thread - called by Run() and executes in the context
650 virtual void *Entry() = 0;
652 // returns a pointer to the thread which can be used to call Run()
653 wxThread
*GetThread() const { return m_thread
; }
659 // call Entry() in owner, put it down here to avoid circular declarations
660 inline void *wxThreadHelperThread::Entry()
662 return m_owner
.Entry();
665 // ----------------------------------------------------------------------------
666 // Automatic initialization
667 // ----------------------------------------------------------------------------
669 // GUI mutex handling.
670 void WXDLLIMPEXP_BASE
wxMutexGuiEnter();
671 void WXDLLIMPEXP_BASE
wxMutexGuiLeave();
673 // macros for entering/leaving critical sections which may be used without
674 // having to take them inside "#if wxUSE_THREADS"
675 #define wxENTER_CRIT_SECT(cs) (cs).Enter()
676 #define wxLEAVE_CRIT_SECT(cs) (cs).Leave()
677 #define wxCRIT_SECT_DECLARE(cs) static wxCriticalSection cs
678 #define wxCRIT_SECT_DECLARE_MEMBER(cs) wxCriticalSection cs
679 #define wxCRIT_SECT_LOCKER(name, cs) wxCriticalSectionLocker name(cs)
681 // function for checking if we're in the main thread which may be used whether
682 // wxUSE_THREADS is 0 or 1
683 inline bool wxIsMainThread() { return wxThread::IsMain(); }
685 #else // !wxUSE_THREADS
688 inline void WXDLLIMPEXP_BASE
wxMutexGuiEnter() { }
689 inline void WXDLLIMPEXP_BASE
wxMutexGuiLeave() { }
691 // macros for entering/leaving critical sections which may be used without
692 // having to take them inside "#if wxUSE_THREADS"
693 #define wxENTER_CRIT_SECT(cs)
694 #define wxLEAVE_CRIT_SECT(cs)
695 #define wxCRIT_SECT_DECLARE(cs)
696 #define wxCRIT_SECT_DECLARE_MEMBER(cs)
697 #define wxCRIT_SECT_LOCKER(name, cs)
699 // if there is only one thread, it is always the main one
700 inline bool wxIsMainThread() { return true; }
702 #endif // wxUSE_THREADS/!wxUSE_THREADS
704 // mark part of code as being a critical section: this macro declares a
705 // critical section with the given name and enters it immediately and leaves
706 // it at the end of the current scope
712 // static int s_counter = 0;
714 // wxCRITICAL_SECTION(counter);
716 // return ++s_counter;
719 // this function is MT-safe in presence of the threads but there is no
720 // overhead when the library is compiled without threads
721 #define wxCRITICAL_SECTION(name) \
722 wxCRIT_SECT_DECLARE(s_cs##name); \
723 wxCRIT_SECT_LOCKER(cs##name##Locker, s_cs##name)
725 // automatically lock GUI mutex in ctor and unlock it in dtor
726 class WXDLLIMPEXP_BASE wxMutexGuiLocker
729 wxMutexGuiLocker() { wxMutexGuiEnter(); }
730 ~wxMutexGuiLocker() { wxMutexGuiLeave(); }
733 // -----------------------------------------------------------------------------
734 // implementation only until the end of file
735 // -----------------------------------------------------------------------------
739 #if defined(__WXMSW__) || defined(__WXMAC__) || defined(__WXPM__) || defined(__EMX__)
740 // unlock GUI if there are threads waiting for and lock it back when
741 // there are no more of them - should be called periodically by the main
743 extern void WXDLLIMPEXP_BASE
wxMutexGuiLeaveOrEnter();
745 // returns true if the main thread has GUI lock
746 extern bool WXDLLIMPEXP_BASE
wxGuiOwnedByMainThread();
749 // wakes up the main thread if it's sleeping inside ::GetMessage()
750 extern void WXDLLIMPEXP_BASE
wxWakeUpMainThread();
753 // return true if the main thread is waiting for some other to terminate:
754 // wxApp then should block all "dangerous" messages
755 extern bool WXDLLIMPEXP_BASE
wxIsWaitingForThread();
756 #endif // MSW, Mac, OS/2
758 #endif // wxUSE_THREADS
760 #endif // _WX_THREAD_H_