void stop() override {
CAF_LOG_TRACE("");
// shutdown workers
class shutdown_helper : public resumable, public ref_counted {
public:
resumable::resume_result resume(execution_unit* ptr, size_t) override {
CAF_LOG_DEBUG("shutdown_helper::resume => shutdown worker");
CAF_ASSERT(ptr != nullptr);
std::unique_lock<std::mutex> guard(mtx);
last_worker = ptr;
cv.notify_all();
return resumable::shutdown_execution_unit;
}
void intrusive_ptr_add_ref_impl() override {
intrusive_ptr_add_ref(this);
}
void intrusive_ptr_release_impl() override {
intrusive_ptr_release(this);
}
shutdown_helper() : last_worker(nullptr) {
// nop
}
std::mutex mtx;
std::condition_variable cv;
execution_unit* last_worker;
};
// use a set to keep track of remaining workers
shutdown_helper sh;
std::set<worker_type*> alive_workers;
auto num = num_workers();
for (size_t i = 0; i < num; ++i) {
alive_workers.insert(worker_by_id(i));
sh.ref(); // make sure reference count is high enough
}
CAF_LOG_DEBUG("enqueue shutdown_helper into each worker");
while (!alive_workers.empty()) {
(*alive_workers.begin())->external_enqueue(&sh);
// since jobs can be stolen, we cannot assume that we have
// actually shut down the worker we've enqueued sh to
{ // lifetime scope of guard
std::unique_lock<std::mutex> guard(sh.mtx);
sh.cv.wait(guard, [&] { return sh.last_worker != nullptr; });
}
alive_workers.erase(static_cast<worker_type*>(sh.last_worker));
sh.last_worker = nullptr;
}
// shutdown utility actors
stop_actors();
// wait until all workers are done
for (auto& w : workers_) {
w->get_thread().join();
}
// run cleanup code for each resumable
auto f = &abstract_coordinator::cleanup_and_release;
for (auto& w : workers_)
policy_.foreach_resumable(w.get(), f);
policy_.foreach_central_resumable(this, f);
}
resumable* try_steal(Worker* self) {
auto p = self->parent();
if (p->num_workers() < 2) {
// you can't steal from yourself, can you?
return nullptr;
}
// roll the dice to pick a victim other than ourselves
auto victim = d(self).uniform(d(self).rengine);
if (victim == self->id())
victim = p->num_workers() - 1;
// steal oldest element from the victim's queue
return d(p->worker_by_id(victim)).queue.take_tail();
}