msgthred.h

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//----------------------------------------------------------------------------
// ObjectWindows
// Copyright (c) 1995, 1996 by Borland International, All Rights Reserved
//
// Author Yura Bidus
/// \file
/// Definition of message queue oriented thread class support. Degenerates to a
/// simple message queue owner under non-threaded environments
//----------------------------------------------------------------------------
 
#if !defined(OWL_MSGTHRED_H)
#define OWL_MSGTHRED_H
 
#include <owl/private/defs.h>
#if defined(BI_HAS_PRAGMA_ONCE)
# pragma once
#endif
 
#if defined(BI_MULTI_THREAD)
# include <owl/thread.h>
#endif
 
#include <owl/wsysinc.h>
#include <owl/system.h>
 
 
namespace owl {
 
#include <owl/preclass.h>
 
class _OWLCLASS TMsgThread;
 
//
/// \class TMsgThread
// ~~~~~ ~~~~~~~~~~
/// TMsgThread implements basic behavior for threads that own message queues,
/// including mutex locking for the queue. This class provides message queue
/// oriented thread class support. TMsgThread degenerates to a simple message queue
/// owner under non-threaded environments.
#if defined(BI_MULTI_THREAD_RTL)
class _OWLCLASS TMsgThread :  public TThread
{
#else
class _OWLCLASS TMsgThread
{
  public:
    enum TCurrent {Current};
#endif
 
  public:
    TMsgThread(TCurrent);
 
    // Message queue functions
    //
    virtual int      MessageLoop();
    virtual bool     IdleAction(long idleCount);
    virtual bool     ProcessMsg(MSG& msg);
 
    bool             PumpWaitingMessages();
    void             FlushQueue();
 
    /// Is this queue thread running its message loop?
    //
    bool             IsRunning() const;
 
    // Message queue thread synchronization mechanism. Real multi-threading
    // requires compiler & RTL support (-MT)
    //
#if defined(BI_MULTI_THREAD_RTL)
# if defined(BI_USE_CRITICAL_SECTION)
    // Using a critical section is much faster, but prevents
    // cross-process locking and potentially breaks existing code.
    typedef TCriticalSection TMsgMutex;
# else
    typedef TMutex TMsgMutex;
# endif
    void    EnableMultiThreading(bool enable);
    TMsgMutex* GetMutex();
 
    class _OWLCLASS TQueueLock {
      public:
        TQueueLock(TMsgThread& app);
       ~TQueueLock();
        void Release(bool relinquish = false);
      private:
#if defined(BI_COMP_BORLAND)
        TMsgThread::TMsgMutex::TLock *Lock;
#else
        TMsgMutex::TLock *Lock;
#endif
    };
#endif
 
  protected:
#if defined(BI_MULTI_THREAD_RTL)  // No real threads without RTL support
    TMsgThread();
#endif
 
    // Override this for created threads, app thread is Run() from OwlMain
    //
    virtual int      Run();
 
    virtual void     InitInstance();
    virtual int      TermInstance(int status);
 
    bool          BreakMessageLoop;     ///< Message loop is broken via WM_QUIT
    int           MessageLoopResult;    ///< Return value from message loop
 
    // !CQ still need this with thread state?
    bool          LoopRunning;          ///< Track if the loop is running
 
#if defined(BI_MULTI_THREAD_RTL)
    // !CQ Just use a TMutex directly???
    class _OWLCLASS TAppMutex {
      public:
        TAppMutex();
       ~TAppMutex();
        TMsgMutex* GetMutex();
      private:
        TMsgMutex *Mutex;
    };
 
    TAppMutex     Mutex;                ///< Mutex to prevent multiple threads
                                        ///< from processing messages at the
                                        ///< same time.
  private:
    bool          UseMutex;
#endif
};
 
#include <owl/posclass.h>
 
//----------------------------------------------------------------------------
// Inline implementations
 
//
/// Returns true if this queue thread is running its message loop.
//
inline bool TMsgThread::IsRunning() const
{
  return LoopRunning;
}
 
#if defined(BI_MULTI_THREAD_RTL)
 
//
/// Enables or disables the use of the mutex to synchronize access to the message
/// queue. TMsgThread will only lock its message queue mutex when enabled. Real
/// multi-threading requires compiler and RTL support.
//
inline void TMsgThread::EnableMultiThreading(bool enable)
{
  UseMutex = enable;
}
 
//
/// Gets this message thread's mutex. Returns 0 if mutexes are not supported, or are
/// not enabled for this thread.
//
inline TMsgThread::TMsgMutex* TMsgThread::GetMutex()
{
  return UseMutex ? Mutex.GetMutex() : nullptr;
}
 
//
/// The mutex is always constructed/destructed if the system supports threads
//
inline TMsgThread::TAppMutex::TAppMutex()
:
  Mutex(nullptr)
{
    Mutex = new TMsgThread::TMsgMutex;
}
 
//
inline TMsgThread::TAppMutex::~TAppMutex()
{
    delete Mutex;
}
 
//
/// Get the apps mutex. Return 0 if mutexs are not supported, or are not enabled
/// for this app.
//
inline TMsgThread::TMsgMutex* TMsgThread::TAppMutex::GetMutex()
{
  return Mutex;
}
 
//
/// Only lock if the mutex is available. Do nothing otherwise.
//
inline TMsgThread::TQueueLock::TQueueLock(TMsgThread& app)
  : Lock(nullptr)
{
  TMsgMutex* appMutex = app.GetMutex();
  if (appMutex)
    Lock = new TMsgMutex::TLock(*appMutex);
}
 
//
/// Destruct the real lock if it was constructed (locked)
//
inline TMsgThread::TQueueLock::~TQueueLock()
{
  delete Lock;
}
 
//
/// Release the real lock if it was locked
//
inline void TMsgThread::TQueueLock::Release(bool relinquish)
{
  if (Lock) {
    CHECK(relinquish == true); InUse(relinquish);
    delete Lock;
    Lock = nullptr;
  }
}
 
#endif  // BI_MULTI_THREAD_RTL
 
} // OWL namespace
 
 
 
#endif  // OWL_MSGTHRED_H