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