如何创建结构并通过pthread_create（）传递到新线程

Question

I have a callback function I am writing where I need to:

1 create a struct
2 create a new thread and pass this struct to the thread for it's exclusive use
3 return a pointer to this struct ... from the callback function ... to the main program.

This will allow communications through shared memory between the original program and the new threads.

I assume I have to use malloc since the scope of a struct created in the callback function is only in the function.

I can't make it static because I will create multiple threads each with their own personal struct.

I need to understand the process since I am a newbie.

Would it work this way?

1 malloc a chunk of memory "sizeof" the struct.
2 pass the pointer to this chunk to the new thread and return it to the main program.
3 once in the new thread make a new struct using this memory?

I have searched for a week now and can't see how this should be done.

BTW: I cannot modify the main program which is single threaded by design. I can only make this callback function to spawn one of many new threads and communicate thru this shared memory which I would like to be a struct.

Thanks.

struct myStruct
{
    int elem1;
    int elem2;
    int elem3;
};



int* callBack(some parameters)
{
    *p = malloc(sizeof(myStruct));

    result = pthead_create( ??, ??, void *(*newThread), *p);

    return p;
}


void newThread()
{
    // pull off *p from stack?

    // somehow use the declared struct to access the malloc mem

    p->elem1 = p->elem2 + p->elem3;
}

Answer 1

Threads created through pthread_create() take in a void* as their argument, so the prototype of your thread routine should be as follows:

void newThread(void* data)

This void* then corresponds to the pointer passed as the final argument to pthread_create . You can then cast this pointer to the appropriate data type (but make sure you get the right one!). An example is as follows:

void newThread(void* data)
{
    struct myStruct* p = data;
    p->elem1 = p->elem2 + p->elem3;
}