include/wx/thread.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        thread.h
   3 // Purpose:     Thread API
   4 // Author:      Guilhem Lavaux
   5 // Modified by: Vadim Zeitlin (modifications partly inspired by omnithreads
   6 //              package from Olivetti & Oracle Research Laboratory)
   7 // Created:     04/13/98
   8 // RCS-ID:      $Id$
   9 // Copyright:   (c) Guilhem Lavaux
  10 // Licence:     wxWindows licence
  11 /////////////////////////////////////////////////////////////////////////////
  12
  13 #ifndef __THREADH__
  14 #define __THREADH__
  15
  16 #ifdef __GNUG__
  17     #pragma interface "thread.h"
  18 #endif
  19
  20 // ----------------------------------------------------------------------------
  21 // headers
  22 // ----------------------------------------------------------------------------
  23
  24 // get the value of wxUSE_THREADS configuration flag
  25 #include "wx/setup.h"
  26
  27 #if wxUSE_THREADS
  28
  29 // Windows headers define it
  30 #ifdef Yield
  31     #undef Yield
  32 #endif
  33
  34 #include "wx/module.h"
  35
  36 // ----------------------------------------------------------------------------
  37 // constants
  38 // ----------------------------------------------------------------------------
  39
  40 typedef enum
  41 {
  42   wxMUTEX_NO_ERROR = 0,
  43   wxMUTEX_DEAD_LOCK,      // Mutex has been already locked by THE CALLING thread
  44   wxMUTEX_BUSY,           // Mutex has been already locked by ONE thread
  45   wxMUTEX_UNLOCKED,
  46   wxMUTEX_MISC_ERROR
  47 } wxMutexError;
  48
  49 typedef enum
  50 {
  51   wxTHREAD_NO_ERROR = 0,      // No error
  52   wxTHREAD_NO_RESOURCE,       // No resource left to create a new thread
  53   wxTHREAD_RUNNING,           // The thread is already running
  54   wxTHREAD_NOT_RUNNING,       // The thread isn't running
  55   wxTHREAD_MISC_ERROR         // Some other error
  56 } wxThreadError;
  57
  58 // defines the interval of priority
  59 #define WXTHREAD_MIN_PRIORITY     0u
  60 #define WXTHREAD_DEFAULT_PRIORITY 50u
  61 #define WXTHREAD_MAX_PRIORITY     100u
  62
  63 // ----------------------------------------------------------------------------
  64 // A mutex object is a synchronization object whose state is set to signaled
  65 // when it is not owned by any thread, and nonsignaled when it is owned. Its
  66 // name comes from its usefulness in coordinating mutually-exclusive access to
  67 // a shared resource. Only one thread at a time can own a mutex object.
  68 // ----------------------------------------------------------------------------
  69
  70 // you should consider wxMutexLocker whenever possible instead of directly
  71 // working with wxMutex class - it is safer
  72 class WXDLLEXPORT wxMutexInternal;
  73 class WXDLLEXPORT wxMutex
  74 {
  75 public:
  76     // constructor & destructor
  77     wxMutex();
  78     ~wxMutex();
  79
  80     // Lock the mutex.
  81     wxMutexError Lock();
  82     // Try to lock the mutex: if it can't, returns immediately with an error.
  83     wxMutexError TryLock();
  84     // Unlock the mutex.
  85     wxMutexError Unlock();
  86
  87     // Returns true if the mutex is locked.
  88     bool IsLocked() const { return (m_locked > 0); }
  89
  90 protected:
  91     friend class wxCondition;
  92
  93     // no assignment operator nor copy ctor
  94     wxMutex(const wxMutex&);
  95     wxMutex& operator=(const wxMutex&);
  96
  97     int m_locked;
  98     wxMutexInternal *p_internal;
  99 };
 100
 101 // a helper class which locks the mutex in the ctor and unlocks it in the dtor:
 102 // this ensures that mutex is always unlocked, even if the function returns or
 103 // throws an exception before it reaches the end
 104 class WXDLLEXPORT wxMutexLocker
 105 {
 106 public:
 107     // lock the mutex in the ctor
 108     wxMutexLocker(wxMutex *mutex)
 109         { m_isOk = mutex && ((m_mutex = mutex)->Lock() == wxMUTEX_NO_ERROR); }
 110
 111     // returns TRUE if mutex was successfully locked in ctor
 112     bool IsOk() const { return m_isOk; }
 113
 114     // unlock the mutex in dtor
 115     ~wxMutexLocker() { if ( IsOk() ) m_mutex->Unlock(); }
 116
 117 private:
 118     // no assignment operator nor copy ctor
 119     wxMutexLocker(const wxMutexLocker&);
 120     wxMutexLocker& operator=(const wxMutexLocker&);
 121
 122     bool     m_isOk;
 123     wxMutex *m_mutex;
 124 };
 125
 126 // ----------------------------------------------------------------------------
 127 // Critical section: this is the same as mutex but is only visible to the
 128 // threads of the same process. For the platforms which don't have native
 129 // support for critical sections, they're implemented entirely in terms of
 130 // mutexes
 131 // ----------------------------------------------------------------------------
 132
 133 // in order to avoid any overhead under !MSW make all wxCriticalSection class
 134 // functions inline - but this can't be done under MSW
 135 #ifdef __WXMSW__
 136     class WXDLLEXPORT wxCriticalSectionInternal;
 137     #define WXCRITICAL_INLINE
 138 #else // !MSW
 139     #define WXCRITICAL_INLINE   inline
 140 #endif // MSW/!MSW
 141
 142 // you should consider wxCriticalSectionLocker whenever possible instead of
 143 // directly working with wxCriticalSection class - it is safer
 144 class WXDLLEXPORT wxCriticalSection
 145 {
 146 public:
 147     // ctor & dtor
 148     WXCRITICAL_INLINE wxCriticalSection();
 149     WXCRITICAL_INLINE ~wxCriticalSection();
 150
 151     // enter the section (the same as locking a mutex)
 152     void WXCRITICAL_INLINE Enter();
 153     // leave the critical section (same as unlocking a mutex)
 154     void WXCRITICAL_INLINE Leave();
 155
 156 private:
 157     // no assignment operator nor copy ctor
 158     wxCriticalSection(const wxCriticalSection&);
 159     wxCriticalSection& operator=(const wxCriticalSection&);
 160
 161 #ifdef __WXMSW__
 162     wxCriticalSectionInternal *m_critsect;
 163 #else // !MSW
 164     wxMutex m_mutex;
 165 #endif // MSW/!MSW
 166 };
 167
 168 // keep your preprocessor name space clean
 169 #undef WXCRITICAL_INLINE
 170
 171 // wxCriticalSectionLocker is the same to critical sections as wxMutexLocker is
 172 // to th mutexes
 173 class WXDLLEXPORT wxCriticalSectionLocker
 174 {
 175 public:
 176     wxCriticalSectionLocker(wxCriticalSection& critsect) : m_critsect(critsect)
 177         { m_critsect.Enter(); }
 178     ~wxCriticalSectionLocker()
 179         { m_critsect.Leave(); }
 180
 181 private:
 182     // no assignment operator nor copy ctor
 183     wxCriticalSectionLocker(const wxCriticalSectionLocker&);
 184     wxCriticalSectionLocker& operator=(const wxCriticalSectionLocker&);
 185
 186     wxCriticalSection& m_critsect;
 187 };
 188
 189 // ----------------------------------------------------------------------------
 190 // Condition handler.
 191 // ----------------------------------------------------------------------------
 192
 193 class wxConditionInternal;
 194 class WXDLLEXPORT wxCondition
 195 {
 196 public:
 197   // constructor & destructor
 198   wxCondition();
 199   ~wxCondition();
 200
 201   // Waits indefinitely.
 202   void Wait(wxMutex& mutex);
 203   // Waits until a signal is raised or the timeout is elapsed.
 204   bool Wait(wxMutex& mutex, unsigned long sec, unsigned long nsec);
 205   // Raises a signal: only one "Waiter" is released.
 206   void Signal();
 207   // Broadcasts to all "Waiters".
 208   void Broadcast();
 209
 210 private:
 211   wxConditionInternal *p_internal;
 212 };
 213
 214 // ----------------------------------------------------------------------------
 215 // Thread management class
 216 // ----------------------------------------------------------------------------
 217
 218 // FIXME Thread termination model is still unclear. Delete() should probably
 219 //       have a timeout after which the thread must be Kill()ed.
 220
 221 // NB: in the function descriptions the words "this thread" mean the thread
 222 //     created by the wxThread object while "main thread" is the thread created
 223 //     during the process initialization (a.k.a. the GUI thread)
 224 class wxThreadInternal;
 225 class WXDLLEXPORT wxThread
 226 {
 227 public:
 228     // the return type for the thread function
 229     typedef void *ExitCode;
 230
 231     // static functions
 232         // Returns the wxThread object for the calling thread. NULL is returned
 233         // if the caller is the main thread (but it's recommended to use
 234         // IsMain() and only call This() for threads other than the main one
 235         // because NULL is also returned on error). If the thread wasn't
 236         // created with wxThread class, the returned value is undefined.
 237     static wxThread *This();
 238
 239         // Returns true if current thread is the main thread.
 240     static bool IsMain();
 241
 242         // Release the rest of our time slice leting the other threads run
 243     static void Yield();
 244
 245         // Sleep during the specified period of time in milliseconds
 246         //
 247         // NB: at least under MSW worker threads can not call ::wxSleep()!
 248     static void Sleep(unsigned long milliseconds);
 249
 250     // default constructor
 251     wxThread();
 252
 253     // function that change the thread state
 254         // create a new thread - call Run() to start it
 255     wxThreadError Create();
 256
 257         // starts execution of the thread - from the moment Run() is called the
 258         // execution of wxThread::Entry() may start at any moment, caller
 259         // shouldn't suppose that it starts after (or before) Run() returns.
 260     wxThreadError Run();
 261
 262         // stops the thread if it's running and deletes the wxThread object
 263         // freeing its memory. This function should also be called if the
 264         // Create() or Run() fails to free memory (otherwise it will be done by
 265         // the thread itself when it terminates). The return value is the
 266         // thread exit code if the thread was gracefully terminated, 0 if it
 267         // wasn't running and -1 if an error occured.
 268     ExitCode Delete();
 269
 270         // kills the thread without giving it any chance to clean up - should
 271         // not be used in normal circumstances, use Delete() instead. It is a
 272         // dangerous function that should only be used in the most extreme
 273         // cases! The wxThread object is deleted by Kill() if thread was
 274         // killed (i.e. no errors occured).
 275     wxThreadError Kill();
 276
 277         // pause a running thread
 278     wxThreadError Pause();
 279
 280         // resume a paused thread
 281     wxThreadError Resume();
 282
 283     // priority
 284         // Sets the priority to "prio": see WXTHREAD_XXX_PRIORITY constants
 285         //
 286         // NB: the priority can only be set before the thread is created
 287     void SetPriority(unsigned int prio);
 288
 289         // Get the current priority.
 290     unsigned int GetPriority() const;
 291
 292     // Get the thread ID - a platform dependent number which uniquely
 293     // identifies a thread inside a process
 294     unsigned long GetID() const;
 295
 296     // thread status inquiries
 297         // Returns true if the thread is alive: i.e. running or suspended
 298     bool IsAlive() const;
 299         // Returns true if the thread is running (not paused, not killed).
 300     bool IsRunning() const;
 301         // Returns true if the thread is suspended
 302     bool IsPaused() const { return IsAlive() && !IsRunning(); }
 303
 304     // called when the thread exits - in the context of this thread
 305     //
 306     // NB: this function will not be called if the thread is Kill()ed
 307     virtual void OnExit() { }
 308
 309 protected:
 310     // Returns TRUE if the thread was asked to terminate: this function should
 311     // be called by the thread from time to time, otherwise the main thread
 312     // will be left forever in Delete()!
 313     bool TestDestroy() const;
 314
 315     // exits from the current thread - can be called only from this thread
 316     void Exit(void *exitcode = 0);
 317
 318     // destructor is private - user code can't delete thread objects, they will
 319     // auto-delete themselves (and thus must be always allocated on the heap).
 320     // Use Delete() or Kill() instead.
 321     //
 322     // NB: derived classes dtors shouldn't be public neither!
 323     virtual ~wxThread();
 324
 325     // entry point for the thread - called by Run() and executes in the context
 326     // of this thread.
 327     virtual void *Entry() = 0;
 328
 329 private:
 330     // no copy ctor/assignment operator
 331     wxThread(const wxThread&);
 332     wxThread& operator=(const wxThread&);
 333
 334     friend class wxThreadInternal;
 335
 336     // the (platform-dependent) thread class implementation
 337     wxThreadInternal *p_internal;
 338
 339     // protects access to any methods of wxThreadInternal object
 340     wxCriticalSection m_critsect;
 341 };
 342
 343 // ----------------------------------------------------------------------------
 344 // Automatic initialization
 345 // ----------------------------------------------------------------------------
 346
 347 // GUI mutex handling.
 348 void WXDLLEXPORT wxMutexGuiEnter();
 349 void WXDLLEXPORT wxMutexGuiLeave();
 350
 351 #else // !wxUSE_THREADS
 352
 353 // no thread support
 354 inline void WXDLLEXPORT wxMutexGuiEnter() { }
 355 inline void WXDLLEXPORT wxMutexGuiLeave() { }
 356
 357 #endif // wxUSE_THREADS
 358
 359 // automatically unlock GUI mutex in dtor
 360 class WXDLLEXPORT wxMutexGuiLocker
 361 {
 362 public:
 363     wxMutexGuiLocker() { wxMutexGuiEnter(); }
 364    ~wxMutexGuiLocker() { wxMutexGuiLeave(); }
 365 };
 366
 367 // -----------------------------------------------------------------------------
 368 // implementation only until the end of file
 369 // -----------------------------------------------------------------------------
 370 #ifdef wxUSE_THREADS
 371 #ifdef __WXMSW__
 372     // unlock GUI if there are threads waiting for and lock it back when
 373     // there are no more of them - should be called periodically by the main
 374     // thread
 375     extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter();
 376
 377     // returns TRUE if the main thread has GUI lock
 378     extern bool WXDLLEXPORT wxGuiOwnedByMainThread();
 379
 380     // wakes up the main thread if it's sleeping inside ::GetMessage()
 381     extern void WXDLLEXPORT wxWakeUpMainThread();
 382
 383     // return TRUE if the main thread is waiting for some other to terminate:
 384     // wxApp then should block all "dangerous" messages
 385     extern bool WXDLLEXPORT wxIsWaitingForThread();
 386 #else // !MSW
 387     // implement wxCriticalSection using mutexes
 388     inline wxCriticalSection::wxCriticalSection() { }
 389     inline wxCriticalSection::~wxCriticalSection() { }
 390
 391     inline void wxCriticalSection::Enter() { (void)m_mutex.Lock(); }
 392     inline void wxCriticalSection::Leave() { (void)m_mutex.Unlock(); }
 393 #endif // MSW/!MSW
 394 #endif // wxUSE_THREADS
 395
 396 #endif // __THREADH__