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