X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/9fc3ad34c5326856aeebf02335244ae315cef688..e8c6a69c9d700bbbc1b0d20fc2ecfad265f7a4da:/include/wx/thread.h diff --git a/include/wx/thread.h b/include/wx/thread.h index 016e2ff2b5..8652d6cbf8 100644 --- a/include/wx/thread.h +++ b/include/wx/thread.h @@ -1,5 +1,5 @@ ///////////////////////////////////////////////////////////////////////////// -// Name: thread.h +// Name: wx/thread.h // Purpose: Thread API // Author: Guilhem Lavaux // Modified by: Vadim Zeitlin (modifications partly inspired by omnithreads @@ -10,20 +10,20 @@ // Licence: wxWindows licence ///////////////////////////////////////////////////////////////////////////// -#ifndef __THREADH__ -#define __THREADH__ +#ifndef _WX_THREAD_H_ +#define _WX_THREAD_H_ // ---------------------------------------------------------------------------- // headers // ---------------------------------------------------------------------------- // get the value of wxUSE_THREADS configuration flag -#include "wx/setup.h" +#include "wx/defs.h" #if wxUSE_THREADS // only for wxUSE_THREADS - otherwise we'd get undefined symbols -#ifdef __GNUG__ +#if defined(__GNUG__) && !defined(__APPLE__) #pragma interface "thread.h" #endif @@ -40,11 +40,30 @@ enum wxMutexError { - wxMUTEX_NO_ERROR = 0, - wxMUTEX_DEAD_LOCK, // Mutex has been already locked by THE CALLING thread - wxMUTEX_BUSY, // Mutex has been already locked by ONE thread - wxMUTEX_UNLOCKED, - wxMUTEX_MISC_ERROR + wxMUTEX_NO_ERROR = 0, // operation completed successfully + wxMUTEX_INVALID, // mutex hasn't been initialized + wxMUTEX_DEAD_LOCK, // mutex is already locked by the calling thread + wxMUTEX_BUSY, // mutex is already locked by another thread + wxMUTEX_UNLOCKED, // attempt to unlock a mutex which is not locked + wxMUTEX_MISC_ERROR // any other error +}; + +enum wxCondError +{ + wxCOND_NO_ERROR = 0, + wxCOND_INVALID, + wxCOND_TIMEOUT, // WaitTimeout() has timed out + wxCOND_MISC_ERROR +}; + +enum wxSemaError +{ + wxSEMA_NO_ERROR = 0, + wxSEMA_INVALID, // semaphore hasn't been initialized successfully + wxSEMA_BUSY, // returned by TryWait() if Wait() would block + wxSEMA_TIMEOUT, // returned by WaitTimeout() + wxSEMA_OVERFLOW, // Post() would increase counter past the max + wxSEMA_MISC_ERROR }; enum wxThreadError @@ -71,6 +90,37 @@ enum WXTHREAD_MAX_PRIORITY = 100u }; +// There are 2 types of mutexes: normal mutexes and recursive ones. The attempt +// to lock a normal mutex by a thread which already owns it results in +// undefined behaviour (it always works under Windows, it will almost always +// result in a deadlock under Unix). Locking a recursive mutex in such +// situation always succeeds and it must be unlocked as many times as it has +// been locked. +// +// However recursive mutexes have several important drawbacks: first, in the +// POSIX implementation, they're less efficient. Second, and more importantly, +// they CAN NOT BE USED WITH CONDITION VARIABLES under Unix! Using them with +// wxCondition will work under Windows and some Unices (notably Linux) but will +// deadlock under other Unix versions (e.g. Solaris). As it might be difficult +// to ensure that a recursive mutex is not used with wxCondition, it is a good +// idea to avoid using recursive mutexes at all. Also, the last problem with +// them is that some (older) Unix versions don't support this at all -- which +// results in a configure warning when building and a deadlock when using them. +enum wxMutexType +{ + // normal mutex: try to always use this one + wxMUTEX_DEFAULT, + + // recursive mutex: don't use these ones with wxCondition + wxMUTEX_RECURSIVE +}; + +// forward declarations +class WXDLLEXPORT wxConditionInternal; +class WXDLLEXPORT wxMutexInternal; +class WXDLLEXPORT wxSemaphoreInternal; +class WXDLLEXPORT wxThreadInternal; + // ---------------------------------------------------------------------------- // A mutex object is a synchronization object whose state is set to signaled // when it is not owned by any thread, and nonsignaled when it is owned. Its @@ -80,33 +130,44 @@ enum // you should consider wxMutexLocker whenever possible instead of directly // working with wxMutex class - it is safer -class WXDLLEXPORT wxMutexInternal; class WXDLLEXPORT wxMutex { public: // constructor & destructor - wxMutex(); + // ------------------------ + + // create either default (always safe) or recursive mutex + wxMutex(wxMutexType mutexType = wxMUTEX_DEFAULT); + + // destroys the mutex kernel object ~wxMutex(); - // Lock the mutex. + // test if the mutex has been created successfully + bool IsOk() const; + + // mutex operations + // ---------------- + + // Lock the mutex, blocking on it until it is unlocked by the other thread. + // The result of locking a mutex already locked by the current thread + // depend on the mutex type. + // + // The caller must call Unlock() later if Lock() returned wxMUTEX_NO_ERROR. wxMutexError Lock(); - // Try to lock the mutex: if it can't, returns immediately with an error. + + // Try to lock the mutex: if it is currently locked, return immediately + // with an error. Otherwise the caller must call Unlock(). wxMutexError TryLock(); - // Unlock the mutex. - wxMutexError Unlock(); - // Returns true if the mutex is locked. - bool IsLocked() const { return (m_locked > 0); } + // Unlock the mutex. It is an error to unlock an already unlocked mutex + wxMutexError Unlock(); protected: - friend class wxCondition; + wxMutexInternal *m_internal; - // no assignment operator nor copy ctor - wxMutex(const wxMutex&); - wxMutex& operator=(const wxMutex&); + friend class wxConditionInternal; - int m_locked; - wxMutexInternal *m_internal; + DECLARE_NO_COPY_CLASS(wxMutex) }; // a helper class which locks the mutex in the ctor and unlocks it in the dtor: @@ -116,8 +177,9 @@ class WXDLLEXPORT wxMutexLocker { public: // lock the mutex in the ctor - wxMutexLocker(wxMutex& mutex) : m_mutex(mutex) - { m_isOk = m_mutex.Lock() == wxMUTEX_NO_ERROR; } + wxMutexLocker(wxMutex& mutex) + : m_isOk(FALSE), m_mutex(mutex) + { m_isOk = ( m_mutex.Lock() == wxMUTEX_NO_ERROR ); } // returns TRUE if mutex was successfully locked in ctor bool IsOk() const @@ -146,18 +208,16 @@ private: // which makes it possible to have static globals of this class // ---------------------------------------------------------------------------- -class WXDLLEXPORT wxCriticalSectionInternal; - // in order to avoid any overhead under platforms where critical sections are // just mutexes make all wxCriticalSection class functions inline -#if !defined(__WXMSW__) && !defined(__WXPM__) && !defined(__WXMAC__) - #define WXCRITICAL_INLINE inline - +#if !defined(__WXMSW__) && !defined(__WXPM__) #define wxCRITSECT_IS_MUTEX 1 -#else // MSW || Mac || OS2 - #define WXCRITICAL_INLINE + #define wxCRITSECT_INLINE inline +#else // MSW || OS2 #define wxCRITSECT_IS_MUTEX 0 + + #define wxCRITSECT_INLINE #endif // MSW/!MSW // you should consider wxCriticalSectionLocker whenever possible instead of @@ -166,83 +226,183 @@ class WXDLLEXPORT wxCriticalSection { public: // ctor & dtor - WXCRITICAL_INLINE wxCriticalSection(); - WXCRITICAL_INLINE ~wxCriticalSection(); + wxCRITSECT_INLINE wxCriticalSection(); + wxCRITSECT_INLINE ~wxCriticalSection(); // enter the section (the same as locking a mutex) - WXCRITICAL_INLINE void Enter(); + wxCRITSECT_INLINE void Enter(); + // leave the critical section (same as unlocking a mutex) - WXCRITICAL_INLINE void Leave(); + wxCRITSECT_INLINE void Leave(); private: - // no assignment operator nor copy ctor - wxCriticalSection(const wxCriticalSection&); - wxCriticalSection& operator=(const wxCriticalSection&); - #if wxCRITSECT_IS_MUTEX wxMutex m_mutex; #elif defined(__WXMSW__) // we can't allocate any memory in the ctor, so use placement new - // unfortunately, we have to hardcode the sizeof() here because we can't - // include windows.h from this public header - char m_buffer[24]; -#elif !defined(__WXPM__) - wxCriticalSectionInternal *m_critsect; + // include windows.h from this public header and we also have to use the + // union to force the correct (i.e. maximal) alignment + // + // if CRITICAL_SECTION size changes in Windows, you'll get an assert from + // thread.cpp and will need to increase the buffer size + // + // finally, we need this typedef instead of declaring m_buffer directly + // because otherwise the assert mentioned above wouldn't compile with some + // compilers (notably CodeWarrior 8) + typedef char wxCritSectBuffer[24]; + union + { + unsigned long m_dummy1; + void *m_dummy2; + + wxCritSectBuffer m_buffer; + }; #else // nothing for OS/2 -#endif // !Unix/Unix +#endif // Unix/Win32/OS2 + + DECLARE_NO_COPY_CLASS(wxCriticalSection) }; -// keep your preprocessor name space clean -#undef WXCRITICAL_INLINE +#if wxCRITSECT_IS_MUTEX + // implement wxCriticalSection using mutexes + inline wxCriticalSection::wxCriticalSection() { } + inline wxCriticalSection::~wxCriticalSection() { } + + inline void wxCriticalSection::Enter() { (void)m_mutex.Lock(); } + inline void wxCriticalSection::Leave() { (void)m_mutex.Unlock(); } +#endif // wxCRITSECT_IS_MUTEX + +#undef wxCRITSECT_INLINE +#undef wxCRITSECT_IS_MUTEX // wxCriticalSectionLocker is the same to critical sections as wxMutexLocker is // to th mutexes class WXDLLEXPORT wxCriticalSectionLocker { public: - inline wxCriticalSectionLocker(wxCriticalSection& critsect); - inline ~wxCriticalSectionLocker(); + wxCriticalSectionLocker(wxCriticalSection& cs) + : m_critsect(cs) + { + m_critsect.Enter(); + } -private: - // no assignment operator nor copy ctor - wxCriticalSectionLocker(const wxCriticalSectionLocker&); - wxCriticalSectionLocker& operator=(const wxCriticalSectionLocker&); + ~wxCriticalSectionLocker() + { + m_critsect.Leave(); + } +private: wxCriticalSection& m_critsect; + + DECLARE_NO_COPY_CLASS(wxCriticalSectionLocker) }; // ---------------------------------------------------------------------------- -// Condition variable: allows to block the thread execution until something -// happens (== condition is signaled) +// wxCondition models a POSIX condition variable which allows one (or more) +// thread(s) to wait until some condition is fulfilled // ---------------------------------------------------------------------------- -class wxConditionInternal; class WXDLLEXPORT wxCondition { public: - // constructor & destructor - wxCondition(); + // Each wxCondition object is associated with a (single) wxMutex object. + // The mutex object MUST be locked before calling Wait() + wxCondition(wxMutex& mutex); + + // dtor is not virtual, don't use this class polymorphically ~wxCondition(); - // wait until the condition is signaled - // waits indefinitely. - void Wait(); - // waits until a signal is raised or the timeout elapses - bool Wait(unsigned long sec, unsigned long nsec); + // return TRUE if the condition has been created successfully + bool IsOk() const; + + // NB: the associated mutex MUST be locked beforehand by the calling thread + // + // it atomically releases the lock on the associated mutex + // and starts waiting to be woken up by a Signal()/Broadcast() + // once its signaled, then it will wait until it can reacquire + // the lock on the associated mutex object, before returning. + wxCondError Wait(); + + // exactly as Wait() except that it may also return if the specified + // timeout ellapses even if the condition hasn't been signalled: in this + // case, the return value is FALSE, otherwise (i.e. in case of a normal + // return) it is TRUE + // + // the timeeout parameter specifies a interval that needs to be waited in + // milliseconds + wxCondError WaitTimeout(unsigned long milliseconds); + + // NB: the associated mutex may or may not be locked by the calling thread + // + // this method unblocks one thread if any are blocking on the condition. + // if no thread is blocking in Wait(), then the signal is NOT remembered + // The thread which was blocking on Wait(), will then reacquire the lock + // on the associated mutex object before returning + wxCondError Signal(); + + // NB: the associated mutex may or may not be locked by the calling thread + // + // this method unblocks all threads if any are blocking on the condition. + // if no thread is blocking in Wait(), then the signal is NOT remembered + // The threads which were blocking on Wait(), will then reacquire the lock + // on the associated mutex object before returning. + wxCondError Broadcast(); + - // signal the condition - // wakes up one (and only one) of the waiting threads - void Signal(); - // wakes up all threads waiting onthis condition - void Broadcast(); + // deprecated version, don't use + bool Wait(unsigned long milliseconds) + { return WaitTimeout(milliseconds) == wxCOND_NO_ERROR; } private: wxConditionInternal *m_internal; + + DECLARE_NO_COPY_CLASS(wxCondition) }; // ---------------------------------------------------------------------------- -// Thread class +// wxSemaphore: a counter limiting the number of threads concurrently accessing +// a shared resource +// ---------------------------------------------------------------------------- + +class WXDLLEXPORT wxSemaphore +{ +public: + // specifying a maxcount of 0 actually makes wxSemaphore behave as if there + // is no upper limit, if maxcount is 1 the semaphore behaves as a mutex + wxSemaphore( int initialcount = 0, int maxcount = 0 ); + + // dtor is not virtual, don't use this class polymorphically + ~wxSemaphore(); + + // return TRUE if the semaphore has been created successfully + bool IsOk() const; + + // wait indefinitely, until the semaphore count goes beyond 0 + // and then decrement it and return (this method might have been called + // Acquire()) + wxSemaError Wait(); + + // same as Wait(), but does not block, returns wxSEMA_NO_ERROR if + // successful and wxSEMA_BUSY if the count is currently zero + wxSemaError TryWait(); + + // same as Wait(), but as a timeout limit, returns wxSEMA_NO_ERROR if the + // semaphore was acquired and wxSEMA_TIMEOUT if the timeout has ellapsed + wxSemaError WaitTimeout(unsigned long milliseconds); + + // increments the semaphore count and signals one of the waiting threads + wxSemaError Post(); + +private: + wxSemaphoreInternal *m_internal; + + DECLARE_NO_COPY_CLASS(wxSemaphore) +}; + +// ---------------------------------------------------------------------------- +// wxThread: class encpasulating a thread of execution // ---------------------------------------------------------------------------- // there are two different kinds of threads: joinable and detached (default) @@ -254,7 +414,13 @@ private: // created by the wxThread object while "main thread" is the thread created // during the process initialization (a.k.a. the GUI thread) -class wxThreadInternal; +// On VMS thread pointers are 64 bits (also needed for other systems??? +#ifdef __VMS + typedef unsigned long long wxThreadIdType; +#else + typedef unsigned long wxThreadIdType; +#endif + class WXDLLEXPORT wxThread { public: @@ -280,6 +446,26 @@ public: // NB: at least under MSW worker threads can not call ::wxSleep()! static void Sleep(unsigned long milliseconds); + // get the number of system CPUs - useful with SetConcurrency() + // (the "best" value for it is usually number of CPUs + 1) + // + // Returns -1 if unknown, number of CPUs otherwise + static int GetCPUCount(); + + // Get the platform specific thread ID and return as a long. This + // can be used to uniquely identify threads, even if they are not + // wxThreads. This is used by wxPython. + static wxThreadIdType GetCurrentId(); + + // sets the concurrency level: this is, roughly, the number of threads + // the system tries to schedule to run in parallel. 0 means the + // default value (usually acceptable, but may not yield the best + // performance for this process) + // + // Returns TRUE on success, FALSE otherwise (if not implemented, for + // example) + static bool SetConcurrency(size_t level); + // constructor only creates the C++ thread object and doesn't create (or // start) the real thread wxThread(wxThreadKind kind = wxTHREAD_DETACHED); @@ -288,8 +474,11 @@ public: // from _another_ thread (typically the thread that created this one, e.g. // the main thread), not from the thread itself - // create a new thread - call Run() to start it - wxThreadError Create(); + // create a new thread and optionally set the stack size on + // platforms that support that - call Run() to start it + // (special cased for watcom which won't accept 0 default) + + wxThreadError Create(unsigned int stackSize = 0); // starts execution of the thread - from the moment Run() is called // the execution of wxThread::Entry() may start at any moment, caller @@ -353,7 +542,7 @@ public: // Get the thread ID - a platform dependent number which uniquely // identifies a thread inside a process - unsigned long GetId() const; + wxThreadIdType GetId() const; // called when the thread exits - in the context of this thread // @@ -406,12 +595,11 @@ void WXDLLEXPORT wxMutexGuiLeave(); // having to take them inside "#if wxUSE_THREADS" #define wxENTER_CRIT_SECT(cs) (cs).Enter() #define wxLEAVE_CRIT_SECT(cs) (cs).Leave() +#define wxCRIT_SECT_DECLARE(cs) static wxCriticalSection cs #define wxCRIT_SECT_LOCKER(name, cs) wxCriticalSectionLocker name(cs) #else // !wxUSE_THREADS -#include "wx/defs.h" // for WXDLLEXPORT - // no thread support inline void WXDLLEXPORT wxMutexGuiEnter() { } inline void WXDLLEXPORT wxMutexGuiLeave() { } @@ -420,11 +608,33 @@ inline void WXDLLEXPORT wxMutexGuiLeave() { } // having to take them inside "#if wxUSE_THREADS" #define wxENTER_CRIT_SECT(cs) #define wxLEAVE_CRIT_SECT(cs) +#define wxCRIT_SECT_DECLARE(cs) #define wxCRIT_SECT_LOCKER(name, cs) -#endif // wxUSE_THREADS +#endif // wxUSE_THREADS/!wxUSE_THREADS + +// mark part of code as being a critical section: this macro declares a +// critical section with the given name and enters it immediately and leaves +// it at the end of the current scope +// +// example: +// +// int Count() +// { +// static int s_counter = 0; +// +// wxCRITICAL_SECTION(counter); +// +// return ++s_counter; +// } +// +// this function is MT-safe in presence of the threads but there is no +// overhead when the library is compiled without threads +#define wxCRITICAL_SECTION(name) \ + wxCRIT_SECT_DECLARE(s_cs##name); \ + wxCRIT_SECT_LOCKER(cs##name##Locker, s_cs##name) -// automatically unlock GUI mutex in dtor +// automatically lock GUI mutex in ctor and unlock it in dtor class WXDLLEXPORT wxMutexGuiLocker { public: @@ -438,7 +648,7 @@ public: #if wxUSE_THREADS -#if defined(__WXMSW__) +#if defined(__WXMSW__) || defined(__WXMAC__) || defined(__WXPM__) // unlock GUI if there are threads waiting for and lock it back when // there are no more of them - should be called periodically by the main // thread @@ -447,53 +657,17 @@ public: // returns TRUE if the main thread has GUI lock extern bool WXDLLEXPORT wxGuiOwnedByMainThread(); +#ifndef __WXPM__ // wakes up the main thread if it's sleeping inside ::GetMessage() extern void WXDLLEXPORT wxWakeUpMainThread(); +#endif // !OS/2 // return TRUE if the main thread is waiting for some other to terminate: // wxApp then should block all "dangerous" messages extern bool WXDLLEXPORT wxIsWaitingForThread(); -#elif defined(__WXMAC__) - extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter(); +#endif // MSW, Mac, OS/2 - // returns TRUE if the main thread has GUI lock - extern bool WXDLLEXPORT wxGuiOwnedByMainThread(); - - // wakes up the main thread if it's sleeping inside ::GetMessage() - extern void WXDLLEXPORT wxWakeUpMainThread(); - - // return TRUE if the main thread is waiting for some other to terminate: - // wxApp then should block all "dangerous" messages - extern bool WXDLLEXPORT wxIsWaitingForThread(); -#elif defined(__WXPM__) - // unlock GUI if there are threads waiting for and lock it back when - // there are no more of them - should be called periodically by the main - // thread - extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter(); - - // returns TRUE if the main thread has GUI lock - extern bool WXDLLEXPORT wxGuiOwnedByMainThread(); - - // return TRUE if the main thread is waiting for some other to terminate: - // wxApp then should block all "dangerous" messages - extern bool WXDLLEXPORT wxIsWaitingForThread(); - -#else // !MSW && !PM - // implement wxCriticalSection using mutexes - inline wxCriticalSection::wxCriticalSection() { } - inline wxCriticalSection::~wxCriticalSection() { } - - inline void wxCriticalSection::Enter() { (void)m_mutex.Lock(); } - inline void wxCriticalSection::Leave() { (void)m_mutex.Unlock(); } -#endif // MSW/!MSW - - // we can define these inline functions now (they should be defined after - // wxCriticalSection::Enter/Leave) - inline - wxCriticalSectionLocker:: wxCriticalSectionLocker(wxCriticalSection& cs) - : m_critsect(cs) { m_critsect.Enter(); } - inline - wxCriticalSectionLocker::~wxCriticalSectionLocker() { m_critsect.Leave(); } #endif // wxUSE_THREADS -#endif // __THREADH__ +#endif // _WX_THREAD_H_ +