I am thinking about using classes to encapsulate threads for my
application.
My requirements are the following:
The thread implementation sould not know what has to be implemented in
the
thread frunction nor it has to define an abstract method to force
implementation
in that. (Then the implementation could not be instantiated)
Also the implementation should not derive from the thread class or
their interface.
(No direct dependencies by linking against the threading library)
That given, I would be able to late bind the real thread
implementation by runtime loading
the instance from any DLL / so module.
Typical samples of a thread class using a static member fuction. But I
prefer to
use a member callback for that. This way I could separate a specific
thread
implementation from the thread base class and also use dynamic loading
of this
class.
In the sample here I have leaved the static member function to be
called at first level.
The trick here I also use on other member callback issues in my
application is a typedef
and store both, the instance to the implementation and the pointer to
the given member
function.
Is there any issue, that let invalidate my concept ?
Thanks for your time !
Lothar
class lb_I_ThreadImplementation;
typedef (lb_I_ThreadImplementation::*lbThreadFunction)();
// My base for all classes (like Mocrosoft COM)
class lb_I_Unknown;
class lb_I_Thread : public lb_I_Unknown {
public:
// The thread implementation instance
lb_I_ThreadImplementation* getThreadImpl() = 0;
// The callback
lbThreadFunction getThreadMemberCallback() = 0;
lbErrCodes setThreadCallback(lb_I_ThreadImplementation* impl,
lbThreadFunction Tfn) = 0;
virtual lbErrCodes create() = 0;
virtual lbErrCodes run() = 0;
virtual lbErrCodes stop() = 0;
virtual lbErrCodes pause() = 0;
virtual lbErrCodes resume() = 0;
};
class lbThreadInternal; // For various operating systems
class lbThread : public lb_I_Thread {
public:
lbThread();
virtual ~lbThread();
lb_I_ThreadImplementation* getThreadImpl();
lbThreadFunction getThreadMemberCallback();
lbErrCodes setThreadCallback(lb_I_ThreadImplementation* impl,
lbThreadFunction Tfn);
lbErrCodes create();
lbErrCodes run();
lbErrCodes stop();
lbErrCodes pause();
lbErrCodes resume();
private:
lbThreadInternal* thread_internal;
lb_I_ThreadImplementation* threadimpl;
lbThreadFunction _tFn;
};
// Platform based implementation
class lbThreadInternal {
public:
lbThreadInternal()
{
lb_hThread = 0;
}
// create a new (suspended) thread (for the given thread object)
lbErrCodes Create(lbThread *thread);
lbErrCodes run();
lbErrCodes stop();
lbErrCodes pause();
lbErrCodes resume();
// thread function
static DWORD WinThreadStart(lbThread *thread);
private:
HANDLE lb_hThread; // handle of the thread
DWORD lb_ThreadId; // thread id
};
DWORD lbThreadInternal::WinThreadStart(lbThread *thread)
{
// store the thread object in the TLS
if ( !::TlsSetValue(s_tlsThisThread, thread) )
{
// Write some useful logmessage
return (DWORD)-1;
}
if (thread == NULL) {
// Write some useful logmessage
return (DWORD)-1;
}
DWORD ret = (thread->getThreadImpl()->*((lbThreadFunction) (thread-
>getThreadMemberCallback()))) ();delete thread;
return ret;
}
