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 // ----------------------------------------------------------------------------
  17 // headers
  18 // ----------------------------------------------------------------------------
  19
  20 // get the value of wxUSE_THREADS configuration flag
  21 #include "wx/setup.h"
  22
  23 #if wxUSE_THREADS
  24 /* otherwise we get undefined references for non-thread case (KB)*/
  25 #ifdef __GNUG__
  26     #pragma interface "thread.h"
  27 #endif
  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) : m_mutex(mutex)
 109         { m_isOk = m_mutex.Lock() == wxMUTEX_NO_ERROR; }
 110
 111     // returns TRUE if mutex was successfully locked in ctor
 112     bool IsOk() const
 113         { return m_isOk; }
 114
 115     // unlock the mutex in dtor
 116     ~wxMutexLocker()
 117         { if ( IsOk() ) m_mutex.Unlock(); }
 118
 119 private:
 120     // no assignment operator nor copy ctor
 121     wxMutexLocker(const wxMutexLocker&);
 122     wxMutexLocker& operator=(const wxMutexLocker&);
 123
 124     bool     m_isOk;
 125     wxMutex& m_mutex;
 126 };
 127
 128 // ----------------------------------------------------------------------------
 129 // Critical section: this is the same as mutex but is only visible to the
 130 // threads of the same process. For the platforms which don't have native
 131 // support for critical sections, they're implemented entirely in terms of
 132 // mutexes
 133 // ----------------------------------------------------------------------------
 134
 135 // in order to avoid any overhead under !MSW make all wxCriticalSection class
 136 // functions inline - but this can't be done under MSW
 137 #if defined(__WXMSW__) || defined(__WXPM__)
 138     class WXDLLEXPORT wxCriticalSectionInternal;
 139     #define WXCRITICAL_INLINE
 140 #elif defined(__WXMAC__)
 141     class WXDLLEXPORT wxCriticalSectionInternal;
 142     #define WXCRITICAL_INLINE
 143 #else // !MSW && !PM
 144     #define WXCRITICAL_INLINE   inline
 145 #endif // MSW/!MSW
 146
 147 // you should consider wxCriticalSectionLocker whenever possible instead of
 148 // directly working with wxCriticalSection class - it is safer
 149 class WXDLLEXPORT wxCriticalSection
 150 {
 151 public:
 152     // ctor & dtor
 153     WXCRITICAL_INLINE wxCriticalSection();
 154     WXCRITICAL_INLINE ~wxCriticalSection();
 155
 156     // enter the section (the same as locking a mutex)
 157     WXCRITICAL_INLINE void Enter();
 158     // leave the critical section (same as unlocking a mutex)
 159     WXCRITICAL_INLINE void Leave();
 160
 161 private:
 162     // no assignment operator nor copy ctor
 163     wxCriticalSection(const wxCriticalSection&);
 164     wxCriticalSection& operator=(const wxCriticalSection&);
 165
 166 #if defined(__WXMSW__) || defined(__WXPM__) || defined(__WXMAC__)
 167     wxCriticalSectionInternal *m_critsect;
 168 #else // !MSW
 169     wxMutex m_mutex;
 170 #endif // MSW/!MSW
 171 };
 172
 173 // keep your preprocessor name space clean
 174 #undef WXCRITICAL_INLINE
 175
 176 // wxCriticalSectionLocker is the same to critical sections as wxMutexLocker is
 177 // to th mutexes
 178 class WXDLLEXPORT wxCriticalSectionLocker
 179 {
 180 public:
 181     inline wxCriticalSectionLocker(wxCriticalSection& critsect);
 182     inline ~wxCriticalSectionLocker();
 183
 184 private:
 185     // no assignment operator nor copy ctor
 186     wxCriticalSectionLocker(const wxCriticalSectionLocker&);
 187     wxCriticalSectionLocker& operator=(const wxCriticalSectionLocker&);
 188
 189     wxCriticalSection& m_critsect;
 190 };
 191
 192 // ----------------------------------------------------------------------------
 193 // Condition handler.
 194 // ----------------------------------------------------------------------------
 195
 196 class wxConditionInternal;
 197 class WXDLLEXPORT wxCondition
 198 {
 199 public:
 200   // constructor & destructor
 201   wxCondition();
 202   ~wxCondition();
 203
 204   // Waits indefinitely.
 205   void Wait(wxMutex& mutex);
 206   // Waits until a signal is raised or the timeout is elapsed.
 207   bool Wait(wxMutex& mutex, unsigned long sec, unsigned long nsec);
 208   // Raises a signal: only one "Waiter" is released.
 209   void Signal();
 210   // Broadcasts to all "Waiters".
 211   void Broadcast();
 212
 213 private:
 214   wxConditionInternal *p_internal;
 215 };
 216
 217 // ----------------------------------------------------------------------------
 218 // Thread management class
 219 // ----------------------------------------------------------------------------
 220
 221 // FIXME Thread termination model is still unclear. Delete() should probably
 222 //       have a timeout after which the thread must be Kill()ed.
 223
 224 // NB: in the function descriptions the words "this thread" mean the thread
 225 //     created by the wxThread object while "main thread" is the thread created
 226 //     during the process initialization (a.k.a. the GUI thread)
 227 class wxThreadInternal;
 228 class WXDLLEXPORT wxThread
 229 {
 230 public:
 231     // the return type for the thread function
 232     typedef void *ExitCode;
 233
 234     // static functions
 235         // Returns the wxThread object for the calling thread. NULL is returned
 236         // if the caller is the main thread (but it's recommended to use
 237         // IsMain() and only call This() for threads other than the main one
 238         // because NULL is also returned on error). If the thread wasn't
 239         // created with wxThread class, the returned value is undefined.
 240     static wxThread *This();
 241
 242         // Returns true if current thread is the main thread.
 243     static bool IsMain();
 244
 245         // Release the rest of our time slice leting the other threads run
 246     static void Yield();
 247
 248         // Sleep during the specified period of time in milliseconds
 249         //
 250         // NB: at least under MSW worker threads can not call ::wxSleep()!
 251     static void Sleep(unsigned long milliseconds);
 252
 253     // default constructor
 254     wxThread();
 255
 256     // function that change the thread state
 257         // create a new thread - call Run() to start it
 258     wxThreadError Create();
 259
 260         // starts execution of the thread - from the moment Run() is called the
 261         // execution of wxThread::Entry() may start at any moment, caller
 262         // shouldn't suppose that it starts after (or before) Run() returns.
 263     wxThreadError Run();
 264
 265         // stops the thread if it's running and deletes the wxThread object
 266         // freeing its memory. This function should also be called if the
 267         // Create() or Run() fails to free memory (otherwise it will be done by
 268         // the thread itself when it terminates). The return value is the
 269         // thread exit code if the thread was gracefully terminated, 0 if it
 270         // wasn't running and -1 if an error occured.
 271     ExitCode Delete();
 272
 273         // kills the thread without giving it any chance to clean up - should
 274         // not be used in normal circumstances, use Delete() instead. It is a
 275         // dangerous function that should only be used in the most extreme
 276         // cases! The wxThread object is deleted by Kill() if thread was
 277         // killed (i.e. no errors occured).
 278     wxThreadError Kill();
 279
 280         // pause a running thread
 281     wxThreadError Pause();
 282
 283         // resume a paused thread
 284     wxThreadError Resume();
 285
 286     // priority
 287         // Sets the priority to "prio": see WXTHREAD_XXX_PRIORITY constants
 288         //
 289         // NB: the priority can only be set before the thread is created
 290     void SetPriority(unsigned int prio);
 291
 292         // Get the current priority.
 293     unsigned int GetPriority() const;
 294
 295     // Get the thread ID - a platform dependent number which uniquely
 296     // identifies a thread inside a process
 297     unsigned long GetID() const;
 298
 299     // thread status inquiries
 300         // Returns true if the thread is alive: i.e. running or suspended
 301     bool IsAlive() const;
 302         // Returns true if the thread is running (not paused, not killed).
 303     bool IsRunning() const;
 304         // Returns true if the thread is suspended
 305     bool IsPaused() const;
 306
 307     // called when the thread exits - in the context of this thread
 308     //
 309     // NB: this function will not be called if the thread is Kill()ed
 310     virtual void OnExit() { }
 311
 312 protected:
 313     // Returns TRUE if the thread was asked to terminate: this function should
 314     // be called by the thread from time to time, otherwise the main thread
 315     // will be left forever in Delete()!
 316     bool TestDestroy();
 317
 318     // exits from the current thread - can be called only from this thread
 319     void Exit(void *exitcode = 0);
 320
 321     // destructor is private - user code can't delete thread objects, they will
 322     // auto-delete themselves (and thus must be always allocated on the heap).
 323     // Use Delete() or Kill() instead.
 324     //
 325     // NB: derived classes dtors shouldn't be public neither!
 326     virtual ~wxThread();
 327
 328     // entry point for the thread - called by Run() and executes in the context
 329     // of this thread.
 330     virtual void *Entry() = 0;
 331
 332 private:
 333     // no copy ctor/assignment operator
 334     wxThread(const wxThread&);
 335     wxThread& operator=(const wxThread&);
 336
 337     friend class wxThreadInternal;
 338
 339     // the (platform-dependent) thread class implementation
 340     wxThreadInternal *p_internal;
 341
 342     // protects access to any methods of wxThreadInternal object
 343     wxCriticalSection m_critsect;
 344 };
 345
 346 // ----------------------------------------------------------------------------
 347 // Automatic initialization
 348 // ----------------------------------------------------------------------------
 349
 350 // GUI mutex handling.
 351 void WXDLLEXPORT wxMutexGuiEnter();
 352 void WXDLLEXPORT wxMutexGuiLeave();
 353
 354 // macros for entering/leaving critical sections which may be used without
 355 // having to take them inside "#if wxUSE_THREADS"
 356 #define wxENTER_CRIT_SECT(cs)   (cs)->Enter()
 357 #define wxLEAVE_CRIT_SECT(cs)   (cs)->Leave()
 358 #define wxCRIT_SECT_LOCKER(name, cs)  wxCriticalSectionLocker name(*cs)
 359
 360 #else // !wxUSE_THREADS
 361
 362 #include "wx/defs.h" // for WXDLLEXPORT
 363
 364 // no thread support
 365 inline void WXDLLEXPORT wxMutexGuiEnter() { }
 366 inline void WXDLLEXPORT wxMutexGuiLeave() { }
 367
 368 // macros for entering/leaving critical sections which may be used without
 369 // having to take them inside "#if wxUSE_THREADS"
 370 #define wxENTER_CRIT_SECT(cs)
 371 #define wxLEAVE_CRIT_SECT(cs)
 372 #define wxCRIT_SECT_LOCKER(name, cs)
 373
 374 #endif // wxUSE_THREADS
 375
 376 // automatically unlock GUI mutex in dtor
 377 class WXDLLEXPORT wxMutexGuiLocker
 378 {
 379 public:
 380     wxMutexGuiLocker() { wxMutexGuiEnter(); }
 381    ~wxMutexGuiLocker() { wxMutexGuiLeave(); }
 382 };
 383
 384 // -----------------------------------------------------------------------------
 385 // implementation only until the end of file
 386 // -----------------------------------------------------------------------------
 387
 388 #if wxUSE_THREADS
 389
 390 #if defined(__WXMSW__)
 391     // unlock GUI if there are threads waiting for and lock it back when
 392     // there are no more of them - should be called periodically by the main
 393     // thread
 394     extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter();
 395
 396     // returns TRUE if the main thread has GUI lock
 397     extern bool WXDLLEXPORT wxGuiOwnedByMainThread();
 398
 399     // wakes up the main thread if it's sleeping inside ::GetMessage()
 400     extern void WXDLLEXPORT wxWakeUpMainThread();
 401
 402     // return TRUE if the main thread is waiting for some other to terminate:
 403     // wxApp then should block all "dangerous" messages
 404     extern bool WXDLLEXPORT wxIsWaitingForThread();
 405 #elif defined(__WXMAC__)
 406     extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter();
 407
 408     // returns TRUE if the main thread has GUI lock
 409     extern bool WXDLLEXPORT wxGuiOwnedByMainThread();
 410
 411     // wakes up the main thread if it's sleeping inside ::GetMessage()
 412     extern void WXDLLEXPORT wxWakeUpMainThread();
 413
 414     // return TRUE if the main thread is waiting for some other to terminate:
 415     // wxApp then should block all "dangerous" messages
 416     extern bool WXDLLEXPORT wxIsWaitingForThread();
 417 #elif defined(__WXPM__)
 418     // unlock GUI if there are threads waiting for and lock it back when
 419     // there are no more of them - should be called periodically by the main
 420     // thread
 421     extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter();
 422
 423     // returns TRUE if the main thread has GUI lock
 424     extern bool WXDLLEXPORT wxGuiOwnedByMainThread();
 425 #else // !MSW && !PM
 426     // implement wxCriticalSection using mutexes
 427     inline wxCriticalSection::wxCriticalSection() { }
 428     inline wxCriticalSection::~wxCriticalSection() { }
 429
 430     inline void wxCriticalSection::Enter() { (void)m_mutex.Lock(); }
 431     inline void wxCriticalSection::Leave() { (void)m_mutex.Unlock(); }
 432 #endif // MSW/!MSW
 433
 434     // we can define these inline functions now (they should be defined after
 435     // wxCriticalSection::Enter/Leave)
 436     inline
 437     wxCriticalSectionLocker:: wxCriticalSectionLocker(wxCriticalSection& cs)
 438         : m_critsect(cs) { m_critsect.Enter(); }
 439     inline
 440     wxCriticalSectionLocker::~wxCriticalSectionLocker() { m_critsect.Leave(); }
 441 #endif // wxUSE_THREADS
 442
 443 #endif // __THREADH__