How to name std::thread on Mac OS X in C++11? - c++

Question

I want to name a thread, but unfortunately the pthread_setname_np() on Mac works only inside current thread.
Then I do the wrapper around std::thread with a following constructor:
template <class F, class ... Args>
Thread::Thread(const char* name, F&& f, Args&&... args) {
thread_ = std::thread([name, f, args...]() {
pthread_setname_np(name);
f(args...);
});
}
But it doesn't work with class methods:
error: called object type '<complex type>' is not a function or function pointer
f(args...);
^
In the code like this:
threads_.emplace_back("Name", &Aggregator<T>::DoPop, this, some_arg);
What is a proper way to wrap the std::thread and set the thread name, preserving the whole interface excepting the name argument in the constructor?

Answer 1

You can use std::mem_fn to call a member function. The first argument in args has to be the pointer to the member object.
Example:
#include <thread>
#include <functional>
template <class F, class ... Args>
std::thread thread_factory(const char* name, F&& f, Args&&... args) {
return std::thread([=]{
pthread_setname_np(name);
auto fun = std::mem_fn(f);
fun(args...);
});
}
struct test {
int t(int val) {
return val;
}
};
int main() {
test t;
auto b = thread_factory("name", &test::t, &t, 5);
b.join();
}

Answer 2

you have to bind your member function to a class instance. here's your function presented slightly differently with a (working) test:
#include <iostream>
#include <thread>
template <class F, class ... Args>
std::thread launch_named_thread(const char* name, F&& f, Args&&... args) {
return std::thread([name, f, args...]() {
pthread_setname_np(name);
f(args...);
});
}
struct myclass
{
void thread_loop(int i)
{
std::cout << i << std::endl;
}
};
auto main() -> int
{
myclass x;
auto t = launch_named_thread("hello", std::bind(&myclass::thread_loop, &x, 6));
// this could be:
// auto t = launch_named_thread("hello", std::bind(&myclass::thread_loop, &x, std::placeholders::_1), 6);
// the difference is subtle. i'll leave it to you to work out why
t.join();
return 0;
}