+/** A blocking (`wait()`-based) future for SIMIX processes */
+// TODO, .wait_for
+// TODO, .wait_until
+// TODO, SharedFuture
+// TODO, simgrid::simix::when_all - wait for all future to be ready (this one is simple!)
+// TODO, simgrid::simix::when_any - wait for any future to be ready
+template <class T>
+class Future {
+public:
+ Future() { /* Nothing to do*/}
+ explicit Future(simgrid::kernel::Future<T> future) : future_(std::move(future)) {}
+ Future(Future&&) noexcept = default;
+ Future& operator=(Future&&) noexcept = default;
+
+ bool valid() const { return future_.valid(); }
+ T get()
+ {
+ if (not valid())
+ throw std::future_error(std::future_errc::no_state);
+ smx_actor_t self = SIMIX_process_self();
+ simgrid::xbt::Result<T> result;
+ simcall_run_blocking(
+ [this, &result, self] {
+ try {
+ // When the kernel future is ready...
+ this->future_.then_([&result, self](std::shared_ptr<simgrid::kernel::FutureState<T>> value) {
+ // ... wake up the process with the result of the kernel future.
+ simgrid::xbt::set_promise(result, simgrid::kernel::Future<T>(std::move(value)));
+ simgrid::simix::unblock(self);
+ });
+ } catch (...) {
+ result.set_exception(std::current_exception());
+ simgrid::simix::unblock(self);
+ }
+ },
+ nullptr);
+ return result.get();
+ }
+ bool is_ready() const
+ {
+ if (not valid())
+ throw std::future_error(std::future_errc::no_state);
+ return future_.is_ready();
+ }
+ void wait()
+ {
+ // The future is ready! We don't have to wait:
+ if (this->is_ready())
+ return;
+ // The future is not ready. We have to delegate to the SimGrid kernel:
+ std::exception_ptr exception;
+ smx_actor_t self = SIMIX_process_self();
+ simcall_run_blocking(
+ [this, &exception, self] {
+ try {
+ // When the kernel future is ready...
+ this->future_.then_([this, self](std::shared_ptr<simgrid::kernel::FutureState<T>> value) {
+ // ...store it the simix kernel and wake up.
+ this->future_ = simgrid::kernel::Future<T>(std::move(value));
+ simgrid::simix::unblock(self);
+ });
+ } catch (...) {
+ exception = std::current_exception();
+ simgrid::simix::unblock(self);
+ }
+ },
+ nullptr);
+ }
+
+private:
+ // We wrap an event-based kernel future:
+ simgrid::kernel::Future<T> future_;
+};
+
+/** Start some asynchronous work
+ *
+ * @param code SimGrid kernel code which returns a simgrid::kernel::Future
+ * @return Actor future
+ */
+template <class F> auto kernel_async(F code) -> Future<decltype(code().get())>
+{
+ typedef decltype(code().get()) T;
+
+ // Execute the code in the kernel and get the kernel future:
+ simgrid::kernel::Future<T> future = simgrid::kernel::actor::simcall(std::move(code));
+
+ // Wrap the kernel future in a actor future:
+ return simgrid::simix::Future<T>(std::move(future));
+}