Using a c++ class member function as a c callback function, thread safe version

Question

The original question, got a great answer as to how to do the non thread safe version.

Here is the code, which I\'ve tried to slightly modify to get to work:

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Answer 1

If each thread just need one instance of specific object, you can use a global variable for object pointer with __thread storage class, __thread makes global variables unique to that thread.

Using monotonic class with static member for callback is another solution, like previous solution, you can use __thread for separating monothonic class instances for each thread.

Also be aware, __thread isn't standard thing

Edit

Here is an example

class.h

class someClass{
     private:
         someMethod(){ ... }
}

class.cpp

__thread void * objectPointer;

void initialize(){
    someClass * classPtr = new someClass();
    objectPointer = (void *) classPtr;
}

void * callbackFunction(void * args){
    someClass * obj = objectPointer;
    obj->someMethod();
}