}
template <class T>
-template <class T2,
- typename std::enable_if<!isFuture<T2>::value, void*>::type>
-Future<T>::Future(T2&& val) : core_(nullptr) {
- Promise<T> p;
- p.setValue(std::forward<T2>(val));
- *this = p.getFuture();
-}
+template <class T2, typename>
+Future<T>::Future(T2&& val)
+ : core_(new detail::Core<T>(Try<T>(std::forward<T2>(val)))) {}
template <class T>
template <class T2,
typename std::enable_if<
folly::is_void_or_unit<T2>::value,
int>::type>
-Future<T>::Future() : core_(nullptr) {
- Promise<T> p;
- p.setValue();
- *this = p.getFuture();
-}
+Future<T>::Future()
+ : core_(new detail::Core<T>(Try<T>())) {}
template <class T>
// wrap these so we can move them into the lambda
folly::MoveWrapper<Promise<B>> p;
+ p->setInterruptHandler(core_->getInterruptHandler());
folly::MoveWrapper<F> funcm(std::forward<F>(func));
// grab the Future now before we lose our handle on the Promise
});
}
-// TODO(6838553)
-#ifndef __clang__
template <class T>
-template <class... Args>
-auto Future<T>::then(Executor* x, Args&&... args)
- -> decltype(this->then(std::forward<Args>(args)...))
+template <class Executor, class Arg, class... Args>
+auto Future<T>::then(Executor* x, Arg&& arg, Args&&... args)
+ -> decltype(this->then(std::forward<Arg>(arg),
+ std::forward<Args>(args)...))
{
auto oldX = getExecutor();
setExecutor(x);
- return this->then(std::forward<Args>(args)...).via(oldX);
+ return this->then(std::forward<Arg>(arg), std::forward<Args>(args)...).
+ via(oldX);
}
-#endif
template <class T>
Future<void> Future<T>::then() {
}
template <class T>
-template <typename Executor>
-inline Future<T> Future<T>::via(Executor* executor) && {
+inline Future<T> Future<T>::via(Executor* executor, int8_t priority) && {
throwIfInvalid();
- setExecutor(executor);
+ setExecutor(executor, priority);
return std::move(*this);
}
template <class T>
-template <typename Executor>
-inline Future<T> Future<T>::via(Executor* executor) & {
+inline Future<T> Future<T>::via(Executor* executor, int8_t priority) & {
throwIfInvalid();
MoveWrapper<Promise<T>> p;
auto f = p->getFuture();
then([p](Try<T>&& t) mutable { p->setTry(std::move(t)); });
- return std::move(f).via(executor);
+ return std::move(f).via(executor, priority);
+}
+
+
+template <class Func>
+auto via(Executor* x, Func func)
+ -> Future<typename isFuture<decltype(func())>::Inner>
+// this would work, if not for Future<void> :-/
+// -> decltype(via(x).then(func))
+{
+ // TODO make this actually more performant. :-P #7260175
+ return via(x).then(func);
}
template <class T>
template <class T>
Future<typename std::decay<T>::type> makeFuture(T&& t) {
- Promise<typename std::decay<T>::type> p;
- p.setValue(std::forward<T>(t));
- return p.getFuture();
+ return makeFuture(Try<typename std::decay<T>::type>(std::forward<T>(t)));
}
inline // for multiple translation units
Future<void> makeFuture() {
- Promise<void> p;
- p.setValue();
- return p.getFuture();
+ return makeFuture(Try<void>());
}
template <class F>
F&& func,
typename std::enable_if<!std::is_reference<F>::value, bool>::type sdf)
-> Future<decltype(func())> {
- Promise<decltype(func())> p;
- p.setWith(
- [&func]() {
- return (func)();
- });
- return p.getFuture();
+ return makeFuture(makeTryWith([&func]() {
+ return (func)();
+ }));
}
template <class F>
auto makeFutureWith(F const& func) -> Future<decltype(func())> {
F copy = func;
- return makeFutureWith(std::move(copy));
+ return makeFuture(makeTryWith(std::move(copy)));
}
template <class T>
Future<T> makeFuture(std::exception_ptr const& e) {
- Promise<T> p;
- p.setException(e);
- return p.getFuture();
+ return makeFuture(Try<T>(e));
}
template <class T>
Future<T> makeFuture(exception_wrapper ew) {
- Promise<T> p;
- p.setException(std::move(ew));
- return p.getFuture();
+ return makeFuture(Try<T>(std::move(ew)));
}
template <class T, class E>
typename std::enable_if<std::is_base_of<std::exception, E>::value,
Future<T>>::type
makeFuture(E const& e) {
- Promise<T> p;
- p.setException(make_exception_wrapper<E>(e));
- return p.getFuture();
+ return makeFuture(Try<T>(make_exception_wrapper<E>(e)));
}
template <class T>
Future<T> makeFuture(Try<T>&& t) {
- Promise<typename std::decay<T>::type> p;
- p.setTry(std::move(t));
- return p.getFuture();
+ return Future<T>(new detail::Core<T>(std::move(t)));
}
-template <>
-inline Future<void> makeFuture(Try<void>&& t) {
- if (t.hasException()) {
- return makeFuture<void>(std::move(t.exception()));
- } else {
- return makeFuture();
- }
+// via
+Future<void> via(Executor* executor, int8_t priority) {
+ return makeFuture().via(executor, priority);
}
-// via
-template <typename Executor>
-Future<void> via(Executor* executor) {
- return makeFuture().via(executor);
+// mapSetCallback calls func(i, Try<T>) when every future completes
+
+template <class T, class InputIterator, class F>
+void mapSetCallback(InputIterator first, InputIterator last, F func) {
+ for (size_t i = 0; first != last; ++first, ++i) {
+ first->setCallback_([func, i](Try<T>&& t) {
+ func(i, std::move(t));
+ });
+ }
}
-// when (variadic)
+// collectAll (variadic)
template <typename... Fs>
-typename detail::VariadicContext<
+typename detail::CollectAllVariadicContext<
typename std::decay<Fs>::type::value_type...>::type
collectAll(Fs&&... fs) {
- auto ctx =
- new detail::VariadicContext<typename std::decay<Fs>::type::value_type...>();
- ctx->total = sizeof...(fs);
- auto f_saved = ctx->p.getFuture();
- detail::collectAllVariadicHelper(ctx,
- std::forward<typename std::decay<Fs>::type>(fs)...);
- return f_saved;
+ auto ctx = std::make_shared<detail::CollectAllVariadicContext<
+ typename std::decay<Fs>::type::value_type...>>();
+ detail::collectVariadicHelper<detail::CollectAllVariadicContext>(
+ ctx, std::forward<typename std::decay<Fs>::type>(fs)...);
+ return ctx->p.getFuture();
}
-// when (iterator)
+// collectAll (iterator)
template <class InputIterator>
Future<
typedef
typename std::iterator_traits<InputIterator>::value_type::value_type T;
- if (first >= last) {
- return makeFuture(std::vector<Try<T>>());
- }
- size_t n = std::distance(first, last);
-
- auto ctx = new detail::WhenAllContext<T>();
-
- ctx->results.resize(n);
-
- auto f_saved = ctx->p.getFuture();
-
- for (size_t i = 0; first != last; ++first, ++i) {
- assert(i < n);
- auto& f = *first;
- f.setCallback_([ctx, i, n](Try<T> t) {
- ctx->results[i] = std::move(t);
- if (++ctx->count == n) {
- ctx->p.setValue(std::move(ctx->results));
- delete ctx;
- }
- });
- }
+ struct CollectAllContext {
+ CollectAllContext(int n) : results(n) {}
+ ~CollectAllContext() {
+ p.setValue(std::move(results));
+ }
+ Promise<std::vector<Try<T>>> p;
+ std::vector<Try<T>> results;
+ };
- return f_saved;
+ auto ctx = std::make_shared<CollectAllContext>(std::distance(first, last));
+ mapSetCallback<T>(first, last, [ctx](size_t i, Try<T>&& t) {
+ ctx->results[i] = std::move(t);
+ });
+ return ctx->p.getFuture();
}
-namespace detail {
-
-template <class, class, typename = void> struct CollectContextHelper;
+// collect (iterator)
-template <class T, class VecT>
-struct CollectContextHelper<T, VecT,
- typename std::enable_if<std::is_same<T, VecT>::value>::type> {
- static inline std::vector<T>&& getResults(std::vector<VecT>& results) {
- return std::move(results);
- }
-};
-
-template <class T, class VecT>
-struct CollectContextHelper<T, VecT,
- typename std::enable_if<!std::is_same<T, VecT>::value>::type> {
- static inline std::vector<T> getResults(std::vector<VecT>& results) {
- std::vector<T> finalResults;
- finalResults.reserve(results.size());
- for (auto& opt : results) {
- finalResults.push_back(std::move(opt.value()));
- }
- return finalResults;
- }
-};
+namespace detail {
template <typename T>
struct CollectContext {
-
- typedef typename std::conditional<
- std::is_default_constructible<T>::value,
- T,
- Optional<T>
- >::type VecT;
-
- explicit CollectContext(int n) : count(0), threw(false) {
- results.resize(n);
- }
-
- Promise<std::vector<T>> p;
- std::vector<VecT> results;
- std::atomic<size_t> count;
- std::atomic_bool threw;
-
- typedef std::vector<T> result_type;
-
- static inline Future<std::vector<T>> makeEmptyFuture() {
- return makeFuture(std::vector<T>());
- }
-
- inline void setValue() {
- p.setValue(CollectContextHelper<T, VecT>::getResults(results));
+ struct Nothing { explicit Nothing(int n) {} };
+
+ using Result = typename std::conditional<
+ std::is_void<T>::value,
+ void,
+ std::vector<T>>::type;
+
+ using InternalResult = typename std::conditional<
+ std::is_void<T>::value,
+ Nothing,
+ std::vector<Optional<T>>>::type;
+
+ explicit CollectContext(int n) : result(n) {}
+ ~CollectContext() {
+ if (!threw.exchange(true)) {
+ // map Optional<T> -> T
+ std::vector<T> finalResult;
+ finalResult.reserve(result.size());
+ std::transform(result.begin(), result.end(),
+ std::back_inserter(finalResult),
+ [](Optional<T>& o) { return std::move(o.value()); });
+ p.setValue(std::move(finalResult));
+ }
}
-
- inline void addResult(int i, Try<T>& t) {
- results[i] = std::move(t.value());
+ inline void setPartialResult(size_t i, Try<T>& t) {
+ result[i] = std::move(t.value());
}
+ Promise<Result> p;
+ InternalResult result;
+ std::atomic<bool> threw;
};
-template <>
-struct CollectContext<void> {
-
- explicit CollectContext(int n) : count(0), threw(false) {}
-
- Promise<void> p;
- std::atomic<size_t> count;
- std::atomic_bool threw;
-
- typedef void result_type;
-
- static inline Future<void> makeEmptyFuture() {
- return makeFuture();
- }
+// Specialize for void (implementations in Future.cpp)
- inline void setValue() {
- p.setValue();
- }
+template <>
+CollectContext<void>::~CollectContext();
- inline void addResult(int i, Try<void>& t) {
- // do nothing
- }
-};
+template <>
+void CollectContext<void>::setPartialResult(size_t i, Try<void>& t);
-} // detail
+}
template <class InputIterator>
Future<typename detail::CollectContext<
- typename std::iterator_traits<InputIterator>::value_type::value_type
->::result_type>
+ typename std::iterator_traits<InputIterator>::value_type::value_type>::Result>
collect(InputIterator first, InputIterator last) {
typedef
typename std::iterator_traits<InputIterator>::value_type::value_type T;
- if (first >= last) {
- return detail::CollectContext<T>::makeEmptyFuture();
- }
-
- size_t n = std::distance(first, last);
- auto ctx = new detail::CollectContext<T>(n);
- auto f_saved = ctx->p.getFuture();
-
- for (size_t i = 0; first != last; ++first, ++i) {
- assert(i < n);
- auto& f = *first;
- f.setCallback_([ctx, i, n](Try<T> t) {
- auto c = ++ctx->count;
-
- if (t.hasException()) {
- if (!ctx->threw.exchange(true)) {
- ctx->p.setException(std::move(t.exception()));
- }
- } else if (!ctx->threw) {
- ctx->addResult(i, t);
- if (c == n) {
- ctx->setValue();
- }
+ auto ctx = std::make_shared<detail::CollectContext<T>>(
+ std::distance(first, last));
+ mapSetCallback<T>(first, last, [ctx](size_t i, Try<T>&& t) {
+ if (t.hasException()) {
+ if (!ctx->threw.exchange(true)) {
+ ctx->p.setException(std::move(t.exception()));
}
+ } else if (!ctx->threw) {
+ ctx->setPartialResult(i, t);
+ }
+ });
+ return ctx->p.getFuture();
+}
- if (c == n) {
- delete ctx;
- }
- });
- }
+// collect (variadic)
- return f_saved;
+template <typename... Fs>
+typename detail::CollectVariadicContext<
+ typename std::decay<Fs>::type::value_type...>::type
+collect(Fs&&... fs) {
+ auto ctx = std::make_shared<detail::CollectVariadicContext<
+ typename std::decay<Fs>::type::value_type...>>();
+ detail::collectVariadicHelper<detail::CollectVariadicContext>(
+ ctx, std::forward<typename std::decay<Fs>::type>(fs)...);
+ return ctx->p.getFuture();
}
+// collectAny (iterator)
+
template <class InputIterator>
Future<
std::pair<size_t,
Try<
typename
- std::iterator_traits<InputIterator>::value_type::value_type> > >
+ std::iterator_traits<InputIterator>::value_type::value_type>>>
collectAny(InputIterator first, InputIterator last) {
typedef
typename std::iterator_traits<InputIterator>::value_type::value_type T;
- auto ctx = new detail::WhenAnyContext<T>(std::distance(first, last));
- auto f_saved = ctx->p.getFuture();
-
- for (size_t i = 0; first != last; first++, i++) {
- auto& f = *first;
- f.setCallback_([i, ctx](Try<T>&& t) {
- if (!ctx->done.exchange(true)) {
- ctx->p.setValue(std::make_pair(i, std::move(t)));
- }
- ctx->decref();
- });
- }
+ struct CollectAnyContext {
+ CollectAnyContext(size_t n) : done(false) {};
+ Promise<std::pair<size_t, Try<T>>> p;
+ std::atomic<bool> done;
+ };
- return f_saved;
+ auto ctx = std::make_shared<CollectAnyContext>(std::distance(first, last));
+ mapSetCallback<T>(first, last, [ctx](size_t i, Try<T>&& t) {
+ if (!ctx->done.exchange(true)) {
+ ctx->p.setValue(std::make_pair(i, std::move(t)));
+ }
+ });
+ return ctx->p.getFuture();
}
+// collectN (iterator)
+
template <class InputIterator>
Future<std::vector<std::pair<size_t, Try<typename
std::iterator_traits<InputIterator>::value_type::value_type>>>>
std::iterator_traits<InputIterator>::value_type::value_type T;
typedef std::vector<std::pair<size_t, Try<T>>> V;
- struct ctx_t {
+ struct CollectNContext {
V v;
- size_t completed;
+ std::atomic<size_t> completed = {0};
Promise<V> p;
};
- auto ctx = std::make_shared<ctx_t>();
- ctx->completed = 0;
-
- // for each completed Future, increase count and add to vector, until we
- // have n completed futures at which point we fulfill our Promise with the
- // vector
- auto it = first;
- size_t i = 0;
- while (it != last) {
- it->then([ctx, n, i](Try<T>&& t) {
- auto& v = ctx->v;
+ auto ctx = std::make_shared<CollectNContext>();
+
+ if (size_t(std::distance(first, last)) < n) {
+ ctx->p.setException(std::runtime_error("Not enough futures"));
+ } else {
+ // for each completed Future, increase count and add to vector, until we
+ // have n completed futures at which point we fulfil our Promise with the
+ // vector
+ mapSetCallback<T>(first, last, [ctx, n](size_t i, Try<T>&& t) {
auto c = ++ctx->completed;
if (c <= n) {
assert(ctx->v.size() < n);
- v.push_back(std::make_pair(i, std::move(t)));
+ ctx->v.push_back(std::make_pair(i, std::move(t)));
if (c == n) {
- ctx->p.setTry(Try<V>(std::move(v)));
+ ctx->p.setTry(Try<V>(std::move(ctx->v)));
}
}
});
-
- it++;
- i++;
- }
-
- if (i < n) {
- ctx->p.setException(std::runtime_error("Not enough futures"));
}
return ctx->p.getFuture();
}
-template <class It, class T, class F, class ItT, class Arg>
-typename std::enable_if<!isFutureResult<F, T, Arg>::value, Future<T>>::type
-reduce(It first, It last, T initial, F func) {
+// reduce (iterator)
+
+template <class It, class T, class F>
+Future<T> reduce(It first, It last, T&& initial, F&& func) {
if (first == last) {
return makeFuture(std::move(initial));
}
+ typedef typename std::iterator_traits<It>::value_type::value_type ItT;
+ typedef typename std::conditional<
+ detail::callableWith<F, T&&, Try<ItT>&&>::value, Try<ItT>, ItT>::type Arg;
typedef isTry<Arg> IsTry;
- return collectAll(first, last)
- .then([initial, func](std::vector<Try<ItT>>& vals) mutable {
- for (auto& val : vals) {
- initial = func(std::move(initial),
- // Either return a ItT&& or a Try<ItT>&& depending
- // on the type of the argument of func.
- val.template get<IsTry::value, Arg&&>());
- }
- return initial;
+ folly::MoveWrapper<T> minitial(std::move(initial));
+ auto sfunc = std::make_shared<F>(std::move(func));
+
+ auto f = first->then([minitial, sfunc](Try<ItT>& head) mutable {
+ return (*sfunc)(std::move(*minitial),
+ head.template get<IsTry::value, Arg&&>());
+ });
+
+ for (++first; first != last; ++first) {
+ f = collectAll(f, *first).then([sfunc](std::tuple<Try<T>, Try<ItT>>& t) {
+ return (*sfunc)(std::move(std::get<0>(t).value()),
+ // Either return a ItT&& or a Try<ItT>&& depending
+ // on the type of the argument of func.
+ std::get<1>(t).template get<IsTry::value, Arg&&>());
});
+ }
+
+ return f;
+}
+
+// window (collection)
+
+template <class Collection, class F, class ItT, class Result>
+std::vector<Future<Result>>
+window(Collection input, F func, size_t n) {
+ struct WindowContext {
+ WindowContext(Collection&& i, F&& fn)
+ : i_(0), input_(std::move(i)), promises_(input_.size()),
+ func_(std::move(fn))
+ {}
+ std::atomic<size_t> i_;
+ Collection input_;
+ std::vector<Promise<Result>> promises_;
+ F func_;
+
+ static inline void spawn(const std::shared_ptr<WindowContext>& ctx) {
+ size_t i = ctx->i_++;
+ if (i < ctx->input_.size()) {
+ // Using setCallback_ directly since we don't need the Future
+ ctx->func_(std::move(ctx->input_[i])).setCallback_(
+ // ctx is captured by value
+ [ctx, i](Try<Result>&& t) {
+ ctx->promises_[i].setTry(std::move(t));
+ // Chain another future onto this one
+ spawn(std::move(ctx));
+ });
+ }
+ }
+ };
+
+ auto max = std::min(n, input.size());
+
+ auto ctx = std::make_shared<WindowContext>(
+ std::move(input), std::move(func));
+
+ for (size_t i = 0; i < max; ++i) {
+ // Start the first n Futures
+ WindowContext::spawn(ctx);
+ }
+
+ std::vector<Future<Result>> futures;
+ futures.reserve(ctx->promises_.size());
+ for (auto& promise : ctx->promises_) {
+ futures.emplace_back(promise.getFuture());
+ }
+
+ return futures;
+}
+
+// reduce
+
+template <class T>
+template <class I, class F>
+Future<I> Future<T>::reduce(I&& initial, F&& func) {
+ folly::MoveWrapper<I> minitial(std::move(initial));
+ folly::MoveWrapper<F> mfunc(std::move(func));
+ return then([minitial, mfunc](T& vals) mutable {
+ auto ret = std::move(*minitial);
+ for (auto& val : vals) {
+ ret = (*mfunc)(std::move(ret), std::move(val));
+ }
+ return ret;
+ });
}
+// unorderedReduce (iterator)
+
template <class It, class T, class F, class ItT, class Arg>
-typename std::enable_if<isFutureResult<F, T, Arg>::value, Future<T>>::type
-reduce(It first, It last, T initial, F func) {
+Future<T> unorderedReduce(It first, It last, T initial, F func) {
if (first == last) {
return makeFuture(std::move(initial));
}
typedef isTry<Arg> IsTry;
- auto f = first->then([initial, func](Try<ItT>& head) mutable {
- return func(std::move(initial),
- head.template get<IsTry::value, Arg&&>());
- });
+ struct UnorderedReduceContext {
+ UnorderedReduceContext(T&& memo, F&& fn, size_t n)
+ : lock_(), memo_(makeFuture<T>(std::move(memo))),
+ func_(std::move(fn)), numThens_(0), numFutures_(n), promise_()
+ {};
+ folly::MicroSpinLock lock_; // protects memo_ and numThens_
+ Future<T> memo_;
+ F func_;
+ size_t numThens_; // how many Futures completed and called .then()
+ size_t numFutures_; // how many Futures in total
+ Promise<T> promise_;
+ };
- for (++first; first != last; ++first) {
- f = collectAll(f, *first).then([func](std::tuple<Try<T>, Try<ItT>>& t) {
- return func(std::move(std::get<0>(t).value()),
- // Either return a ItT&& or a Try<ItT>&& depending
- // on the type of the argument of func.
- std::get<1>(t).template get<IsTry::value, Arg&&>());
+ auto ctx = std::make_shared<UnorderedReduceContext>(
+ std::move(initial), std::move(func), std::distance(first, last));
+
+ mapSetCallback<ItT>(first, last, [ctx](size_t i, Try<ItT>&& t) {
+ folly::MoveWrapper<Try<ItT>> mt(std::move(t));
+ // Futures can be completed in any order, simultaneously.
+ // To make this non-blocking, we create a new Future chain in
+ // the order of completion to reduce the values.
+ // The spinlock just protects chaining a new Future, not actually
+ // executing the reduce, which should be really fast.
+ folly::MSLGuard lock(ctx->lock_);
+ ctx->memo_ = ctx->memo_.then([ctx, mt](T&& v) mutable {
+ // Either return a ItT&& or a Try<ItT>&& depending
+ // on the type of the argument of func.
+ return ctx->func_(std::move(v), mt->template get<IsTry::value, Arg&&>());
});
- }
+ if (++ctx->numThens_ == ctx->numFutures_) {
+ // After reducing the value of the last Future, fulfill the Promise
+ ctx->memo_.setCallback_([ctx](Try<T>&& t2) {
+ ctx->promise_.setValue(std::move(t2));
+ });
+ }
+ });
- return f;
+ return ctx->promise_.getFuture();
}
+// within
+
template <class T>
Future<T> Future<T>::within(Duration dur, Timekeeper* tk) {
return within(dur, TimedOut(), tk);
}
});
- return ctx->promise.getFuture();
+ return ctx->promise.getFuture().via(getExecutor());
}
+// delayed
+
template <class T>
Future<T> Future<T>::delayed(Duration dur, Timekeeper* tk) {
return collectAll(*this, futures::sleep(dur, tk))
waitVia(e).value();
}
+namespace detail {
+ template <class T>
+ struct TryEquals {
+ static bool equals(const Try<T>& t1, const Try<T>& t2) {
+ return t1.value() == t2.value();
+ }
+ };
+
+ template <>
+ struct TryEquals<void> {
+ static bool equals(const Try<void>& t1, const Try<void>& t2) {
+ return true;
+ }
+ };
+}
+
template <class T>
Future<bool> Future<T>::willEqual(Future<T>& f) {
return collectAll(*this, f).then([](const std::tuple<Try<T>, Try<T>>& t) {
if (std::get<0>(t).hasValue() && std::get<1>(t).hasValue()) {
- return std::get<0>(t).value() == std::get<1>(t).value();
+ return detail::TryEquals<T>::equals(std::get<0>(t), std::get<1>(t));
} else {
return false;
}
});
}
-namespace futures {
- namespace {
- template <class Z>
- Future<Z> chainHelper(Future<Z> f) {
- return f;
- }
+template <class T>
+template <class Callback>
+auto Future<T>::thenMulti(Callback&& fn)
+ -> decltype(this->then(std::forward<Callback>(fn))) {
+ // thenMulti with one callback is just a then
+ return then(std::forward<Callback>(fn));
+}
- template <class Z, class F, class Fn, class... Callbacks>
- Future<Z> chainHelper(F f, Fn fn, Callbacks... fns) {
- return chainHelper<Z>(f.then(fn), fns...);
- }
- }
+template <class T>
+template <class Callback, class... Callbacks>
+auto Future<T>::thenMulti(Callback&& fn, Callbacks&&... fns)
+ -> decltype(this->then(std::forward<Callback>(fn)).
+ thenMulti(std::forward<Callbacks>(fns)...)) {
+ // thenMulti with two callbacks is just then(a).thenMulti(b, ...)
+ return then(std::forward<Callback>(fn)).
+ thenMulti(std::forward<Callbacks>(fns)...);
+}
- template <class A, class Z, class... Callbacks>
- std::function<Future<Z>(Try<A>)>
- chain(Callbacks... fns) {
- MoveWrapper<Promise<A>> pw;
- MoveWrapper<Future<Z>> fw(chainHelper<Z>(pw->getFuture(), fns...));
- return [=](Try<A> t) mutable {
- pw->setTry(std::move(t));
- return std::move(*fw);
- };
- }
+template <class T>
+template <class Callback, class... Callbacks>
+auto Future<T>::thenMultiWithExecutor(Executor* x, Callback&& fn,
+ Callbacks&&... fns)
+ -> decltype(this->then(std::forward<Callback>(fn)).
+ thenMulti(std::forward<Callbacks>(fns)...)) {
+ // thenMultiExecutor with two callbacks is
+ // via(x).then(a).thenMulti(b, ...).via(oldX)
+ auto oldX = getExecutor();
+ setExecutor(x);
+ return then(std::forward<Callback>(fn)).
+ thenMulti(std::forward<Callbacks>(fns)...).via(oldX);
+}
+template <class T>
+template <class Callback>
+auto Future<T>::thenMultiWithExecutor(Executor* x, Callback&& fn)
+ -> decltype(this->then(std::forward<Callback>(fn))) {
+ // thenMulti with one callback is just a then with an executor
+ return then(x, std::forward<Callback>(fn));
+}
+
+namespace futures {
template <class It, class F, class ItT, class Result>
std::vector<Future<Result>> map(It first, It last, F func) {
std::vector<Future<Result>> results;
}
}
+// Instantiate the most common Future types to save compile time
+extern template class Future<void>;
+extern template class Future<bool>;
+extern template class Future<int>;
+extern template class Future<int64_t>;
+extern template class Future<std::string>;
+extern template class Future<double>;
+
} // namespace folly
// I haven't included a Future<T&> specialization because I don't forsee us
projects / folly.git / blobdiff