Use of class function in thread

[Tomaz Rotovnik]

:confused:How can I implement a class function, which can be run in separate thread Example class AudioIn { public: AudioIn(); virtual ~AudioIn(); void StartProc(); HANDLE Thread; DWORD m_ThreadID; HANDLE hEvent; }; AudioIn::AudioIn() { hEvent = CreateEvent(NULL,TRUE,FALSE,NULL); Thread = CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)AudioIn::StartProc,NULL,0,&m_ThreadID); } Is it possible? I'm creating console application in VC++. Sorry for stupid question. Tomaz

[valikac]

Yes. One your example, declare StartProc as a static public member function. Kuphryn

[Tomaz Rotovnik]

How can I get few parameters into static class function? Should I declare a structure Thread = CreateThread(NULL,0,AudioIn::StartProc,declared-structure,0,&m_ThreadID); or is there a simple way? Thank you Tomaz

[Joaquin M Lopez Munoz]

You have to declare a structure and pass a pointer to it. There are some common problems regarding who owns this structure. Consider the following:

void foo()
{
data d;
// fill d;
CreateThread(...,&d,...)
}

This seems OK and will probably work some times until it suddenly stops to do it. The reason is that, when the thread starts executing and access d, it is perfectly normal that foo has already exited, and d is no longer valid. So, you have to dynamically allocate the data:

void foo()
{
data* d=new data;
// fill d;
CreateThread(...,d,...)
}

Now the problem is who deletes d? The most reasonable choice is to let the thread delete the data:

MyThread(LPVOID arg)
{
data * d=(data *)arg;
...
delete d; // d no longer needed.
...
}

This is almost perfect: you should take into account the rare case when the thread does not launch (due to insufficient resources, for instance):

void foo()
{
data* d=new data;
// fill d;
if(!CreateThread(...,d,...)){
delete d; // no thread launched, clean up the mess ourselves
}
}

That's it, hope it helps. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

[jason99]

Hi Tomaz, the problem is that CreateThread() is a c function...and c doesn't know anything about classes or virtual tables... try this: //--------------------------------------------------- void YourClass::AnyFunction() { // declarations DWORD dwId; // create the thread CreateThread(NULL,0,(LPTHREAD_START_ROUTINE)StartAddress,(LPVOID)this,0,&dwId); } DWORD YourClass::StartAddress(LPVOID lpParam) { // call the thread function ((YourClass*)lpParam)->ThreadFunction(); } void YourClass::ThreadFunction() { ... } //--------------------------------------------------- in the header you should declare the thread start procedure as follows: static DWORD StartAddress(LPVOID lpParam); ..this should do it

[Tomaz Rotovnik]

:laugh:It is working. Thank you. Tomaz