#include <boost/optional.hpp>
#include <xbt/base.h>
+#include <xbt/functional.hpp>
#include <functional>
#include <future>
// Those are implementation details:
enum class FutureStatus;
template<class T> class FutureState;
-class FutureContinuation;
-template<class T, class F> class FutureContinuationImpl;
enum class FutureStatus {
not_ready,
done,
};
-/** A continuation attached to a future to be executed when it is ready */
-XBT_PUBLIC_CLASS FutureContinuation {
-public:
- FutureContinuation() {}
-
- // No copy:
- FutureContinuation(FutureContinuation&) = delete;
- FutureContinuation& operator=(FutureContinuation&) = delete;
-
- virtual ~FutureContinuation() {}
- virtual void operator()() = 0;
-};
-
-/** Default implementation of `FutureContinuation`
- *
- * @param T value type of the future
- * @param F type of the wrapped code/callback/continuation
- */
-template<class T, class F>
-class FutureContinuationImpl : public FutureContinuation {
-public:
- FutureContinuationImpl(std::shared_ptr<FutureState<T>> ptr, F callback)
- : ptr_(std::move(ptr)), callback_(std::move(callback)) {}
- ~FutureContinuationImpl() override {}
- void operator()() override
- {
- try {
- callback_(Future<T>(ptr_));
- }
- // Those exceptions are lost.
- // If we want to implement callback chaining, we'll have to catch them and
- // foward them to the next future.
- catch (...) {
- // We could log this.
- }
- }
-private:
- std::shared_ptr<FutureState<T>> ptr_;
- F callback_;
-};
-
/** Bases stuff for all @ref simgrid::kernel::FutureState<T> */
class FutureStateBase {
public:
this->set_ready();
}
- void set_continuation(std::unique_ptr<FutureContinuation> continuation)
+ void set_continuation(simgrid::xbt::Task<void()> continuation)
{
xbt_assert(!continuation_);
switch (status_) {
case FutureStatus::ready:
// The future is ready, execute the continuation directly.
// We might execute it from the event loop instead:
- (*continuation)();
+ continuation();
break;
case FutureStatus::not_ready:
// The future is not ready so we mast keep the continuation for
// We need to do this becase the current implementation of the
// continuation has a shared_ptr to the FutureState.
auto continuation = std::move(continuation_);
- (*continuation)();
+ continuation();
}
}
private:
FutureStatus status_ = FutureStatus::not_ready;
std::exception_ptr exception_;
- std::unique_ptr<FutureContinuation> continuation_;
+ simgrid::xbt::Task<void()> continuation_;
};
/** Shared state for future and promises
{
if (state_ == nullptr)
throw std::future_error(std::future_errc::no_state);
- std::unique_ptr<FutureContinuation> ptr =
- std::unique_ptr<FutureContinuation>(
- new FutureContinuationImpl<T,F>(state_, std::move(continuation)));
- state_->set_continuation(std::move(ptr));
- state_ = nullptr;
+ // Give shared-ownership to the continuation:
+ auto state = std::move(state_);
+ state->set_continuation(simgrid::xbt::makeTask(
+ std::move(continuation), state));
}
/** Get the value from the future
#include <functional>
#include <future>
#include <utility>
+#include <tuple>
#include <xbt/sysdep.h>
#include <xbt/utility.hpp>
>());
}
+template<class T> class Task;
+
+/** Type-erased run-once task
+ *
+ * * Like std::function but callable only once.
+ * However, it works with move-only types.
+ *
+ * * Like std::packaged_task<> but without the shared state.
+ */
+template<class R, class... Args>
+class Task<R(Args...)> {
+private:
+ // Type-erasure for the code:
+ class Base {
+ public:
+ virtual ~Base() {}
+ virtual R operator()(Args...) = 0;
+ };
+ template<class F>
+ class Impl : public Base {
+ public:
+ Impl(F&& code) : code_(std::move(code)) {}
+ Impl(F const& code) : code_(code) {}
+ ~Impl() override {}
+ R operator()(Args... args)
+ {
+ return code_(std::forward<Args>(args)...);
+ }
+ private:
+ F code_;
+ };
+ std::unique_ptr<Base> code_;
+public:
+ Task() {}
+ Task(std::nullptr_t) {}
+
+ template<class F>
+ Task(F&& code) :
+ code_(new Impl<F>(std::forward<F>(code))) {}
+
+ operator bool() const { return code_ != nullptr; }
+ bool operator!() const { return code_ == nullptr; }
+
+ template<class... OtherArgs>
+ R operator()(OtherArgs&&... args)
+ {
+ std::unique_ptr<Base> code = std::move(code_);
+ return (*code)(std::forward<OtherArgs>(args)...);
+ }
+};
+
+template<class F, class... Args>
+auto makeTask(F code, Args... args)
+-> Task< decltype(code(std::move(args)...))() >
+{
+ typedef decltype(code(std::move(args)...)) result_type;
+
+ class Impl {
+ private:
+ F code_;
+ std::tuple<Args...> args_;
+ public:
+ Impl(F code, std::tuple<Args...> args) :
+ code_(std::move(code)),
+ args_(std::move(args)) {}
+ result_type operator()()
+ {
+ return simgrid::xbt::apply(std::move(code_), std::move(args_));
+ }
+ };
+
+ return Impl(std::move(code), std::make_tuple(std::move(args)...));
+}
+
}
}