wxWidgets/include/wx/thread.h
1999-12-06 12:31:04 +00:00

517 lines
18 KiB
C++

/////////////////////////////////////////////////////////////////////////////
// Name: thread.h
// Purpose: Thread API
// Author: Guilhem Lavaux
// Modified by: Vadim Zeitlin (modifications partly inspired by omnithreads
// package from Olivetti & Oracle Research Laboratory)
// Created: 04/13/98
// RCS-ID: $Id$
// Copyright: (c) Guilhem Lavaux
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
#ifndef __THREADH__
#define __THREADH__
// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------
// get the value of wxUSE_THREADS configuration flag
#include "wx/setup.h"
#if wxUSE_THREADS
// only for wxUSE_THREADS - otherwise we'd get undefined symbols
#ifdef __GNUG__
#pragma interface "thread.h"
#endif
// Windows headers define it
#ifdef Yield
#undef Yield
#endif
#include "wx/module.h"
// ----------------------------------------------------------------------------
// constants
// ----------------------------------------------------------------------------
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
};
enum wxThreadError
{
wxTHREAD_NO_ERROR = 0, // No error
wxTHREAD_NO_RESOURCE, // No resource left to create a new thread
wxTHREAD_RUNNING, // The thread is already running
wxTHREAD_NOT_RUNNING, // The thread isn't running
wxTHREAD_KILLED, // Thread we waited for had to be killed
wxTHREAD_MISC_ERROR // Some other error
};
enum wxThreadKind
{
wxTHREAD_DETACHED,
wxTHREAD_JOINABLE
};
// defines the interval of priority
enum
{
WXTHREAD_MIN_PRIORITY = 0u,
WXTHREAD_DEFAULT_PRIORITY = 50u,
WXTHREAD_MAX_PRIORITY = 100u
};
// ----------------------------------------------------------------------------
// 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
// name comes from its usefulness in coordinating mutually-exclusive access to
// a shared resource. Only one thread at a time can own a mutex object.
// ----------------------------------------------------------------------------
// 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();
~wxMutex();
// Lock the mutex.
wxMutexError Lock();
// Try to lock the mutex: if it can't, returns immediately with an error.
wxMutexError TryLock();
// Unlock the mutex.
wxMutexError Unlock();
// Returns true if the mutex is locked.
bool IsLocked() const { return (m_locked > 0); }
protected:
friend class wxCondition;
// no assignment operator nor copy ctor
wxMutex(const wxMutex&);
wxMutex& operator=(const wxMutex&);
int m_locked;
wxMutexInternal *m_internal;
};
// a helper class which locks the mutex in the ctor and unlocks it in the dtor:
// this ensures that mutex is always unlocked, even if the function returns or
// throws an exception before it reaches the end
class WXDLLEXPORT wxMutexLocker
{
public:
// lock the mutex in the ctor
wxMutexLocker(wxMutex& mutex) : m_mutex(mutex)
{ m_isOk = m_mutex.Lock() == wxMUTEX_NO_ERROR; }
// returns TRUE if mutex was successfully locked in ctor
bool IsOk() const
{ return m_isOk; }
// unlock the mutex in dtor
~wxMutexLocker()
{ if ( IsOk() ) m_mutex.Unlock(); }
private:
// no assignment operator nor copy ctor
wxMutexLocker(const wxMutexLocker&);
wxMutexLocker& operator=(const wxMutexLocker&);
bool m_isOk;
wxMutex& m_mutex;
};
// ----------------------------------------------------------------------------
// Critical section: this is the same as mutex but is only visible to the
// threads of the same process. For the platforms which don't have native
// support for critical sections, they're implemented entirely in terms of
// mutexes.
//
// NB: wxCriticalSection object does not allocate any memory in its ctor
// 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
#define wxCRITSECT_IS_MUTEX 1
#else // MSW || Mac || OS2
#define WXCRITICAL_INLINE
#define wxCRITSECT_IS_MUTEX 0
#endif // MSW/!MSW
// you should consider wxCriticalSectionLocker whenever possible instead of
// directly working with wxCriticalSection class - it is safer
class WXDLLEXPORT wxCriticalSection
{
public:
// ctor & dtor
WXCRITICAL_INLINE wxCriticalSection();
WXCRITICAL_INLINE ~wxCriticalSection();
// enter the section (the same as locking a mutex)
WXCRITICAL_INLINE void Enter();
// leave the critical section (same as unlocking a mutex)
WXCRITICAL_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;
#else
// nothing for OS/2
#endif // !Unix/Unix
};
// keep your preprocessor name space clean
#undef WXCRITICAL_INLINE
// wxCriticalSectionLocker is the same to critical sections as wxMutexLocker is
// to th mutexes
class WXDLLEXPORT wxCriticalSectionLocker
{
public:
inline wxCriticalSectionLocker(wxCriticalSection& critsect);
inline ~wxCriticalSectionLocker();
private:
// no assignment operator nor copy ctor
wxCriticalSectionLocker(const wxCriticalSectionLocker&);
wxCriticalSectionLocker& operator=(const wxCriticalSectionLocker&);
wxCriticalSection& m_critsect;
};
// ----------------------------------------------------------------------------
// Condition variable: allows to block the thread execution until something
// happens (== condition is signaled)
// ----------------------------------------------------------------------------
class wxConditionInternal;
class WXDLLEXPORT wxCondition
{
public:
// constructor & destructor
wxCondition();
~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);
// signal the condition
// wakes up one (and only one) of the waiting threads
void Signal();
// wakes up all threads waiting onthis condition
void Broadcast();
private:
wxConditionInternal *m_internal;
};
// ----------------------------------------------------------------------------
// Thread class
// ----------------------------------------------------------------------------
// there are two different kinds of threads: joinable and detached (default)
// ones. Only joinable threads can return a return code and only detached
// threads auto-delete themselves - the user should delete the joinable
// threads manually.
// NB: in the function descriptions the words "this thread" mean the thread
// created by the wxThread object while "main thread" is the thread created
// during the process initialization (a.k.a. the GUI thread)
class wxThreadInternal;
class WXDLLEXPORT wxThread
{
public:
// the return type for the thread function
typedef void *ExitCode;
// static functions
// Returns the wxThread object for the calling thread. NULL is returned
// if the caller is the main thread (but it's recommended to use
// IsMain() and only call This() for threads other than the main one
// because NULL is also returned on error). If the thread wasn't
// created with wxThread class, the returned value is undefined.
static wxThread *This();
// Returns true if current thread is the main thread.
static bool IsMain();
// Release the rest of our time slice leting the other threads run
static void Yield();
// Sleep during the specified period of time in milliseconds
//
// 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();
// 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);
// functions that change the thread state: all these can only be called
// 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();
// starts execution of the thread - from the moment Run() is called
// the execution of wxThread::Entry() may start at any moment, caller
// shouldn't suppose that it starts after (or before) Run() returns.
wxThreadError Run();
// stops the thread if it's running and deletes the wxThread object if
// this is a detached thread freeing its memory - otherwise (for
// joinable threads) you still need to delete wxThread object
// yourself.
//
// this function only works if the thread calls TestDestroy()
// periodically - the thread will only be deleted the next time it
// does it!
//
// will fill the rc pointer with the thread exit code if it's !NULL
wxThreadError Delete(ExitCode *rc = (ExitCode *)NULL);
// waits for a joinable thread to finish and returns its exit code
//
// Returns (ExitCode)-1 on error (for example, if the thread is not
// joinable)
ExitCode Wait();
// kills the thread without giving it any chance to clean up - should
// not be used in normal circumstances, use Delete() instead. It is a
// dangerous function that should only be used in the most extreme
// cases!
//
// The wxThread object is deleted by Kill() if the thread is
// detachable, but you still have to delete it manually for joinable
// threads.
wxThreadError Kill();
// pause a running thread: as Delete(), this only works if the thread
// calls TestDestroy() regularly
wxThreadError Pause();
// resume a paused thread
wxThreadError Resume();
// priority
// Sets the priority to "prio": see WXTHREAD_XXX_PRIORITY constants
//
// NB: the priority can only be set before the thread is created
void SetPriority(unsigned int prio);
// Get the current priority.
unsigned int GetPriority() const;
// thread status inquiries
// Returns true if the thread is alive: i.e. running or suspended
bool IsAlive() const;
// Returns true if the thread is running (not paused, not killed).
bool IsRunning() const;
// Returns true if the thread is suspended
bool IsPaused() const;
// is the thread of detached kind?
bool IsDetached() const { return m_isDetached; }
// Get the thread ID - a platform dependent number which uniquely
// identifies a thread inside a process
unsigned long GetId() const;
// called when the thread exits - in the context of this thread
//
// NB: this function will not be called if the thread is Kill()ed
virtual void OnExit() { }
// dtor is public, but the detached threads should never be deleted - use
// Delete() instead (or leave the thread terminate by itself)
virtual ~wxThread();
protected:
// Returns TRUE if the thread was asked to terminate: this function should
// be called by the thread from time to time, otherwise the main thread
// will be left forever in Delete()!
bool TestDestroy();
// exits from the current thread - can be called only from this thread
void Exit(ExitCode exitcode = 0);
// entry point for the thread - called by Run() and executes in the context
// of this thread.
virtual void *Entry() = 0;
private:
// no copy ctor/assignment operator
wxThread(const wxThread&);
wxThread& operator=(const wxThread&);
friend class wxThreadInternal;
// the (platform-dependent) thread class implementation
wxThreadInternal *m_internal;
// protects access to any methods of wxThreadInternal object
wxCriticalSection m_critsect;
// true if the thread is detached, false if it is joinable
bool m_isDetached;
};
// ----------------------------------------------------------------------------
// Automatic initialization
// ----------------------------------------------------------------------------
// GUI mutex handling.
void WXDLLEXPORT wxMutexGuiEnter();
void WXDLLEXPORT wxMutexGuiLeave();
// macros for entering/leaving critical sections which may be used without
// 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() { }
// macros for entering/leaving critical sections which may be used without
// 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
// automatically unlock GUI mutex in dtor
class WXDLLEXPORT wxMutexGuiLocker
{
public:
wxMutexGuiLocker() { wxMutexGuiEnter(); }
~wxMutexGuiLocker() { wxMutexGuiLeave(); }
};
// -----------------------------------------------------------------------------
// implementation only until the end of file
// -----------------------------------------------------------------------------
#if wxUSE_THREADS
#if defined(__WXMSW__)
// 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();
// 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(__WXMAC__)
extern void WXDLLEXPORT wxMutexGuiLeaveOrEnter();
// 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__