I'm a little confused about how to pass an object to the pthread_create function. I've found a lot of piecemeal information concerning casting to void*, passing arguments to pthread_create, etc., but nothing that ties it all together. I just want to make sure I've tied it all together and am not doing anything stupid. Let's say I have the following thread class:
Edit: fixed mis-matched static_cast
.
class ProducerThread {
pthread_t thread;
pthread_attr_t thread_attr;
ProducerThread(const ProducerThread& x);
ProducerThread& operator= (const ProducerThread& x);
virtual void *thread_routine(void *arg) {
ProtectedBuffer<int> *buffer = static_cast<ProtectedBuffer<int> *> arg;
int randomdata;
while(1) {
randomdata = RandomDataGen();
buffer->push_back(randomdata);
}
pthread_exit();
}
public:
ProtectedBuffer<int> buffer;
ProducerThread() {
int err_chk;
pthread_attr_init(&thread_attr);
pthread_attr_setdetachstate(&thread_attr,PTHREAD_CREATE_DETACHED);
err_chk = pthread_create(&thread, &thread_attr, thread_routine, static_cast<void *> arg);
if (err_chk != 0) {
throw ThreadException(err_chk);
}
}
~ProducerThread() {
pthread_cancel(&thread);
pthread_attr_destroy(&thread_attr);
}
}
To clarify, the data in the ProtectedBuffer
class can only be accessed with methods like ProtectedBuffer::push_back(int arg)
, which use mutexes to protect the actual data.
My main question is: am I using static_cast
correctly? And my secondary question is do I need that first line in virtual void *thread_routine(void *arg)
where I copy the passed void pointer to a pointer to ProtectedBuffer
?
Also, if I've done anything else that might cause problems, I'd appreciate hearing it.