/*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2017-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
-
#pragma once
+#include <algorithm>
+#include <cassert>
#include <chrono>
#include <thread>
-#include <folly/experimental/fibers/Baton.h>
#include <folly/Optional.h>
-#include <folly/futures/detail/Core.h>
+#include <folly/executors/InlineExecutor.h>
#include <folly/futures/Timekeeper.h>
+#include <folly/futures/detail/Core.h>
+#include <folly/synchronization/Baton.h>
+
+#ifndef FOLLY_FUTURE_USING_FIBER
+#if FOLLY_MOBILE || defined(__APPLE__)
+#define FOLLY_FUTURE_USING_FIBER 0
+#else
+#define FOLLY_FUTURE_USING_FIBER 1
+#include <folly/fibers/Baton.h>
+#endif
+#endif
namespace folly {
class Timekeeper;
+namespace futures {
+namespace detail {
+#if FOLLY_FUTURE_USING_FIBER
+typedef folly::fibers::Baton FutureBatonType;
+#else
+typedef folly::Baton<> FutureBatonType;
+#endif
+} // namespace detail
+} // namespace futures
+
+namespace detail {
+std::shared_ptr<Timekeeper> getTimekeeperSingleton();
+} // namespace detail
+
+namespace futures {
namespace detail {
- Timekeeper* getTimekeeperSingleton();
+// Guarantees that the stored functor is destructed before the stored promise
+// may be fulfilled. Assumes the stored functor to be noexcept-destructible.
+template <typename T, typename F>
+class CoreCallbackState {
+ public:
+ template <typename FF>
+ CoreCallbackState(Promise<T>&& promise, FF&& func) noexcept(
+ noexcept(F(std::declval<FF>())))
+ : func_(std::forward<FF>(func)), promise_(std::move(promise)) {
+ assert(before_barrier());
+ }
+
+ CoreCallbackState(CoreCallbackState&& that) noexcept(
+ noexcept(F(std::declval<F>()))) {
+ if (that.before_barrier()) {
+ new (&func_) F(std::move(that.func_));
+ promise_ = that.stealPromise();
+ }
+ }
+
+ CoreCallbackState& operator=(CoreCallbackState&&) = delete;
+
+ ~CoreCallbackState() {
+ if (before_barrier()) {
+ stealPromise();
+ }
+ }
+
+ template <typename... Args>
+ auto invoke(Args&&... args) noexcept(
+ noexcept(std::declval<F&&>()(std::declval<Args&&>()...))) {
+ assert(before_barrier());
+ return std::move(func_)(std::forward<Args>(args)...);
+ }
+
+ template <typename... Args>
+ auto tryInvoke(Args&&... args) noexcept {
+ return makeTryWith([&] { return invoke(std::forward<Args>(args)...); });
+ }
+
+ void setTry(Try<T>&& t) {
+ stealPromise().setTry(std::move(t));
+ }
+
+ void setException(exception_wrapper&& ew) {
+ stealPromise().setException(std::move(ew));
+ }
+
+ Promise<T> stealPromise() noexcept {
+ assert(before_barrier());
+ func_.~F();
+ return std::move(promise_);
+ }
+
+ private:
+ bool before_barrier() const noexcept {
+ return !promise_.isFulfilled();
+ }
+
+ union {
+ F func_;
+ };
+ Promise<T> promise_{Promise<T>::makeEmpty()};
+};
+
+template <typename T, typename F>
+inline auto makeCoreCallbackState(Promise<T>&& p, F&& f) noexcept(
+ noexcept(CoreCallbackState<T, _t<std::decay<F>>>(
+ std::declval<Promise<T>&&>(),
+ std::declval<F&&>()))) {
+ return CoreCallbackState<T, _t<std::decay<F>>>(
+ std::move(p), std::forward<F>(f));
}
template <class T>
-Future<T>::Future(Future<T>&& other) noexcept : core_(other.core_) {
+FutureBase<T>::FutureBase(SemiFuture<T>&& other) noexcept : core_(other.core_) {
other.core_ = nullptr;
}
template <class T>
-Future<T>& Future<T>::operator=(Future<T>&& other) noexcept {
- std::swap(core_, other.core_);
- return *this;
+FutureBase<T>::FutureBase(Future<T>&& other) noexcept : core_(other.core_) {
+ other.core_ = nullptr;
}
template <class T>
template <class T2, typename>
-Future<T>::Future(T2&& val) : core_(nullptr) {
- Promise<T> p;
- p.setValue(std::forward<T2>(val));
- *this = p.getFuture();
-}
+FutureBase<T>::FutureBase(T2&& val)
+ : core_(new futures::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();
+template <typename T2>
+FutureBase<T>::FutureBase(
+ typename std::enable_if<std::is_same<Unit, T2>::value>::type*)
+ : core_(new futures::detail::Core<T>(Try<T>(T()))) {}
+
+template <class T>
+template <
+ class... Args,
+ typename std::enable_if<std::is_constructible<T, Args&&...>::value, int>::
+ type>
+FutureBase<T>::FutureBase(in_place_t, Args&&... args)
+ : core_(
+ new futures::detail::Core<T>(in_place, std::forward<Args>(args)...)) {
}
+template <class T>
+template <class FutureType>
+void FutureBase<T>::assign(FutureType& other) noexcept {
+ std::swap(core_, other.core_);
+}
template <class T>
-Future<T>::~Future() {
+FutureBase<T>::~FutureBase() {
detach();
}
template <class T>
-void Future<T>::detach() {
+T& FutureBase<T>::value() & {
+ return result().value();
+}
+
+template <class T>
+T const& FutureBase<T>::value() const& {
+ return result().value();
+}
+
+template <class T>
+T&& FutureBase<T>::value() && {
+ return std::move(result().value());
+}
+
+template <class T>
+T const&& FutureBase<T>::value() const&& {
+ return std::move(result().value());
+}
+
+template <class T>
+Try<T>& FutureBase<T>::result() & {
+ throwIfInvalid();
+
+ return core_->getTry();
+}
+
+template <class T>
+Try<T> const& FutureBase<T>::result() const& {
+ throwIfInvalid();
+
+ return core_->getTry();
+}
+
+template <class T>
+Try<T>&& FutureBase<T>::result() && {
+ throwIfInvalid();
+
+ return std::move(core_->getTry());
+}
+
+template <class T>
+Try<T> const&& FutureBase<T>::result() const&& {
+ throwIfInvalid();
+
+ return std::move(core_->getTry());
+}
+
+template <class T>
+bool FutureBase<T>::isReady() const {
+ throwIfInvalid();
+ return core_->ready();
+}
+
+template <class T>
+bool FutureBase<T>::hasValue() {
+ return core_->getTry().hasValue();
+}
+
+template <class T>
+bool FutureBase<T>::hasException() {
+ return core_->getTry().hasException();
+}
+
+template <class T>
+void FutureBase<T>::detach() {
if (core_) {
core_->detachFuture();
core_ = nullptr;
}
template <class T>
-void Future<T>::throwIfInvalid() const {
- if (!core_)
- throw NoState();
+void FutureBase<T>::throwIfInvalid() const {
+ if (!core_) {
+ throwNoState();
+ }
}
template <class T>
-template <class F>
-void Future<T>::setCallback_(F&& func) {
- throwIfInvalid();
- core_->setCallback(std::move(func));
+Optional<Try<T>> FutureBase<T>::poll() {
+ Optional<Try<T>> o;
+ if (core_->ready()) {
+ o = std::move(core_->getTry());
+ }
+ return o;
}
-// unwrap
+template <class T>
+void FutureBase<T>::raise(exception_wrapper exception) {
+ core_->raise(std::move(exception));
+}
template <class T>
template <class F>
-typename std::enable_if<isFuture<F>::value,
- Future<typename isFuture<T>::Inner>>::type
-Future<T>::unwrap() {
- return then([](Future<typename isFuture<T>::Inner> internal_future) {
- return internal_future;
- });
+void FutureBase<T>::setCallback_(F&& func) {
+ throwIfInvalid();
+ core_->setCallback(std::forward<F>(func));
}
+template <class T>
+FutureBase<T>::FutureBase(futures::detail::EmptyConstruct) noexcept
+ : core_(nullptr) {}
+
// then
// Variant: returns a value
template <class T>
template <typename F, typename R, bool isTry, typename... Args>
typename std::enable_if<!R::ReturnsFuture::value, typename R::Return>::type
-Future<T>::thenImplementation(F func, detail::argResult<isTry, F, Args...>) {
+FutureBase<T>::thenImplementation(
+ F&& func,
+ futures::detail::argResult<isTry, F, Args...>) {
static_assert(sizeof...(Args) <= 1, "Then must take zero/one argument");
typedef typename R::ReturnsFuture::Inner B;
- throwIfInvalid();
+ this->throwIfInvalid();
- // 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));
+ Promise<B> p;
+ p.core_->setInterruptHandlerNoLock(this->core_->getInterruptHandler());
// grab the Future now before we lose our handle on the Promise
- auto f = p->getFuture();
- if (getExecutor()) {
- f.setExecutor(getExecutor());
- }
+ auto f = p.getFuture();
+ f.core_->setExecutorNoLock(this->getExecutor());
/* This is a bit tricky.
persist beyond the callback, if it gets moved), and so it is an
optimization to just make it shared from the get-go.
- We have to move in the Promise and func using the MoveWrapper
- hack. (func could be copied but it's a big drag on perf).
-
- Two subtle but important points about this design. detail::Core has no
- back pointers to Future or Promise, so if Future or Promise get moved
- (and they will be moved in performant code) we don't have to do
+ Two subtle but important points about this design. futures::detail::Core
+ has no back pointers to Future or Promise, so if Future or Promise get
+ moved (and they will be moved in performant code) we don't have to do
anything fancy. And because we store the continuation in the
- detail::Core, not in the Future, we can execute the continuation even
- after the Future has gone out of scope. This is an intentional design
+ futures::detail::Core, not in the Future, we can execute the continuation
+ even after the Future has gone out of scope. This is an intentional design
decision. It is likely we will want to be able to cancel a continuation
in some circumstances, but I think it should be explicit not implicit
in the destruction of the Future used to create it.
*/
- setCallback_(
- [p, funcm](Try<T>&& t) mutable {
- if (!isTry && t.hasException()) {
- p->setException(std::move(t.exception()));
- } else {
- p->setWith([&]() {
- return (*funcm)(t.template get<isTry, Args>()...);
- });
- }
- });
+ this->setCallback_(
+ [state = futures::detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T>&& t) mutable {
+ if (!isTry && t.hasException()) {
+ state.setException(std::move(t.exception()));
+ } else {
+ state.setTry(makeTryWith(
+ [&] { return state.invoke(t.template get<isTry, Args>()...); }));
+ }
+ });
return f;
}
template <class T>
template <typename F, typename R, bool isTry, typename... Args>
typename std::enable_if<R::ReturnsFuture::value, typename R::Return>::type
-Future<T>::thenImplementation(F func, detail::argResult<isTry, F, Args...>) {
+FutureBase<T>::thenImplementation(
+ F&& func,
+ futures::detail::argResult<isTry, F, Args...>) {
static_assert(sizeof...(Args) <= 1, "Then must take zero/one argument");
typedef typename R::ReturnsFuture::Inner B;
+ this->throwIfInvalid();
- throwIfInvalid();
-
- // wrap these so we can move them into the lambda
- folly::MoveWrapper<Promise<B>> p;
- folly::MoveWrapper<F> funcm(std::forward<F>(func));
+ Promise<B> p;
+ p.core_->setInterruptHandlerNoLock(this->core_->getInterruptHandler());
// grab the Future now before we lose our handle on the Promise
- auto f = p->getFuture();
- if (getExecutor()) {
- f.setExecutor(getExecutor());
- }
+ auto f = p.getFuture();
+ f.core_->setExecutorNoLock(this->getExecutor());
- setCallback_(
- [p, funcm](Try<T>&& t) mutable {
- if (!isTry && t.hasException()) {
- p->setException(std::move(t.exception()));
- } else {
- try {
- auto f2 = (*funcm)(t.template get<isTry, Args>()...);
- // that didn't throw, now we can steal p
- f2.setCallback_([p](Try<B>&& b) mutable {
- p->setTry(std::move(b));
- });
- } catch (const std::exception& e) {
- p->setException(exception_wrapper(std::current_exception(), e));
- } catch (...) {
- p->setException(exception_wrapper(std::current_exception()));
+ this->setCallback_(
+ [state = futures::detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T>&& t) mutable {
+ if (!isTry && t.hasException()) {
+ state.setException(std::move(t.exception()));
+ } else {
+ auto tf2 = state.tryInvoke(t.template get<isTry, Args>()...);
+ if (tf2.hasException()) {
+ state.setException(std::move(tf2.exception()));
+ } else {
+ tf2->setCallback_([p = state.stealPromise()](Try<B> && b) mutable {
+ p.setTry(std::move(b));
+ });
+ }
}
- }
- });
+ });
return f;
}
+} // namespace detail
+} // namespace futures
+
+template <class T>
+SemiFuture<typename std::decay<T>::type> makeSemiFuture(T&& t) {
+ return makeSemiFuture(Try<typename std::decay<T>::type>(std::forward<T>(t)));
+}
+
+// makeSemiFutureWith(SemiFuture<T>()) -> SemiFuture<T>
+template <class F>
+typename std::enable_if<
+ isSemiFuture<typename std::result_of<F()>::type>::value,
+ typename std::result_of<F()>::type>::type
+makeSemiFutureWith(F&& func) {
+ using InnerType =
+ typename isSemiFuture<typename std::result_of<F()>::type>::Inner;
+ try {
+ return std::forward<F>(func)();
+ } catch (std::exception& e) {
+ return makeSemiFuture<InnerType>(
+ exception_wrapper(std::current_exception(), e));
+ } catch (...) {
+ return makeSemiFuture<InnerType>(
+ exception_wrapper(std::current_exception()));
+ }
+}
+
+// makeSemiFutureWith(T()) -> SemiFuture<T>
+// makeSemiFutureWith(void()) -> SemiFuture<Unit>
+template <class F>
+typename std::enable_if<
+ !(isSemiFuture<typename std::result_of<F()>::type>::value),
+ SemiFuture<Unit::LiftT<typename std::result_of<F()>::type>>>::type
+makeSemiFutureWith(F&& func) {
+ using LiftedResult = Unit::LiftT<typename std::result_of<F()>::type>;
+ return makeSemiFuture<LiftedResult>(
+ makeTryWith([&func]() mutable { return std::forward<F>(func)(); }));
+}
+
+template <class T>
+SemiFuture<T> makeSemiFuture(std::exception_ptr const& e) {
+ return makeSemiFuture(Try<T>(e));
+}
+
+template <class T>
+SemiFuture<T> makeSemiFuture(exception_wrapper ew) {
+ return makeSemiFuture(Try<T>(std::move(ew)));
+}
+
+template <class T, class E>
+typename std::
+ enable_if<std::is_base_of<std::exception, E>::value, SemiFuture<T>>::type
+ makeSemiFuture(E const& e) {
+ return makeSemiFuture(Try<T>(make_exception_wrapper<E>(e)));
+}
+
+template <class T>
+SemiFuture<T> makeSemiFuture(Try<T>&& t) {
+ return SemiFuture<T>(new futures::detail::Core<T>(std::move(t)));
+}
+
+// This must be defined after the constructors to avoid a bug in MSVC
+// https://connect.microsoft.com/VisualStudio/feedback/details/3142777/out-of-line-constructor-definition-after-implicit-reference-causes-incorrect-c2244
+inline SemiFuture<Unit> makeSemiFuture() {
+ return makeSemiFuture(Unit{});
+}
+
+template <class T>
+SemiFuture<T> SemiFuture<T>::makeEmpty() {
+ return SemiFuture<T>(futures::detail::EmptyConstruct{});
+}
+
+template <class T>
+SemiFuture<T>::SemiFuture(SemiFuture<T>&& other) noexcept
+ : futures::detail::FutureBase<T>(std::move(other)) {}
+
+template <class T>
+SemiFuture<T>::SemiFuture(Future<T>&& other) noexcept
+ : futures::detail::FutureBase<T>(std::move(other)) {
+ // SemiFuture should not have an executor on construction
+ if (this->core_) {
+ this->setExecutor(nullptr);
+ }
+}
+
+template <class T>
+SemiFuture<T>& SemiFuture<T>::operator=(SemiFuture<T>&& other) noexcept {
+ this->assign(other);
+ return *this;
+}
+
+template <class T>
+SemiFuture<T>& SemiFuture<T>::operator=(Future<T>&& other) noexcept {
+ this->assign(other);
+ // SemiFuture should not have an executor on construction
+ if (this->core_) {
+ this->setExecutor(nullptr);
+ }
+ return *this;
+}
+
+template <class T>
+void SemiFuture<T>::boost_() {
+ // If a SemiFuture has an executor it should be deferred, so boost it
+ if (auto e = this->getExecutor()) {
+ // We know in a SemiFuture that if we have an executor it should be
+ // DeferredExecutor. Verify this in debug mode.
+ DCHECK(nullptr != dynamic_cast<DeferredExecutor*>(e));
+
+ auto ka = static_cast<DeferredExecutor*>(e)->getKeepAliveToken();
+ static_cast<DeferredExecutor*>(e)->boost();
+ }
+}
+
+template <class T>
+inline Future<T> SemiFuture<T>::via(Executor* executor, int8_t priority) && {
+ throwIfInvalid();
+ if (!executor) {
+ throwNoExecutor();
+ }
+
+ // If current executor is deferred, boost block to ensure that work
+ // progresses and is run on the new executor.
+ auto oldExecutor = this->getExecutor();
+ if (oldExecutor && executor && (executor != oldExecutor)) {
+ // We know in a SemiFuture that if we have an executor it should be
+ // DeferredExecutor. Verify this in debug mode.
+ DCHECK(nullptr != dynamic_cast<DeferredExecutor*>(this->getExecutor()));
+ if (static_cast<DeferredExecutor*>(oldExecutor)) {
+ executor->add([oldExecutorKA = oldExecutor->getKeepAliveToken()]() {
+ static_cast<DeferredExecutor*>(oldExecutorKA.get())->boost();
+ });
+ }
+ }
+
+ this->setExecutor(executor, priority);
+
+ auto newFuture = Future<T>(this->core_);
+ this->core_ = nullptr;
+ return newFuture;
+}
+
+template <class T>
+template <typename F>
+SemiFuture<typename futures::detail::callableResult<T, F>::Return::value_type>
+SemiFuture<T>::defer(F&& func) && {
+ // If we already have a deferred executor, use it, otherwise create one
+ auto defKeepAlive = this->getExecutor()
+ ? this->getExecutor()->getKeepAliveToken()
+ : DeferredExecutor::create();
+ auto e = defKeepAlive.get();
+ // We know in a SemiFuture that if we have an executor it should be
+ // DeferredExecutor (either it was that way before, or we just created it).
+ // Verify this in debug mode.
+ DCHECK(nullptr != dynamic_cast<DeferredExecutor*>(e));
+ // Convert to a folly::future with a deferred executor
+ // Will be low-cost if this is not a new executor as via optimises for that
+ // case
+ auto sf =
+ std::move(*this)
+ .via(e)
+ // Then add the work, with a wrapper function that captures the
+ // keepAlive so the executor is destroyed at the right time.
+ .then(
+ DeferredExecutor::wrap(std::move(defKeepAlive), std::move(func)))
+ // Finally, convert back o a folly::SemiFuture to hide the executor
+ .semi();
+ // Carry deferred executor through chain as constructor from Future will
+ // nullify it
+ sf.setExecutor(e);
+ return sf;
+}
+
+template <class T>
+Future<T> Future<T>::makeEmpty() {
+ return Future<T>(futures::detail::EmptyConstruct{});
+}
+
+template <class T>
+Future<T>::Future(Future<T>&& other) noexcept
+ : futures::detail::FutureBase<T>(std::move(other)) {}
+
+template <class T>
+Future<T>& Future<T>::operator=(Future<T>&& other) noexcept {
+ this->assign(other);
+ return *this;
+}
+
+template <class T>
+template <
+ class T2,
+ typename std::enable_if<
+ !std::is_same<T, typename std::decay<T2>::type>::value &&
+ std::is_constructible<T, T2&&>::value &&
+ std::is_convertible<T2&&, T>::value,
+ int>::type>
+Future<T>::Future(Future<T2>&& other)
+ : Future(std::move(other).then([](T2&& v) { return T(std::move(v)); })) {}
+
+template <class T>
+template <
+ class T2,
+ typename std::enable_if<
+ !std::is_same<T, typename std::decay<T2>::type>::value &&
+ std::is_constructible<T, T2&&>::value &&
+ !std::is_convertible<T2&&, T>::value,
+ int>::type>
+Future<T>::Future(Future<T2>&& other)
+ : Future(std::move(other).then([](T2&& v) { return T(std::move(v)); })) {}
+
+template <class T>
+template <
+ class T2,
+ typename std::enable_if<
+ !std::is_same<T, typename std::decay<T2>::type>::value &&
+ std::is_constructible<T, T2&&>::value,
+ int>::type>
+Future<T>& Future<T>::operator=(Future<T2>&& other) {
+ return operator=(
+ std::move(other).then([](T2&& v) { return T(std::move(v)); }));
+}
+
+// unwrap
+
+template <class T>
+template <class F>
+typename std::
+ enable_if<isFuture<F>::value, Future<typename isFuture<T>::Inner>>::type
+ Future<T>::unwrap() {
+ return then([](Future<typename isFuture<T>::Inner> internal_future) {
+ return internal_future;
+ });
+}
+
+template <class T>
+inline Future<T> Future<T>::via(Executor* executor, int8_t priority) && {
+ this->throwIfInvalid();
+
+ this->setExecutor(executor, priority);
+
+ auto newFuture = Future<T>(this->core_);
+ this->core_ = nullptr;
+ return newFuture;
+}
+
+template <class T>
+inline Future<T> Future<T>::via(Executor* executor, int8_t priority) & {
+ this->throwIfInvalid();
+ Promise<T> p;
+ auto f = p.getFuture();
+ auto func = [p = std::move(p)](Try<T>&& t) mutable {
+ p.setTry(std::move(t));
+ };
+ using R = futures::detail::callableResult<T, decltype(func)>;
+ this->template thenImplementation<decltype(func), R>(
+ std::move(func), typename R::Arg());
+ return std::move(f).via(executor, priority);
+}
template <typename T>
template <typename R, typename Caller, typename... Args>
Future<typename isFuture<R>::Inner>
Future<T>::then(R(Caller::*func)(Args...), Caller *instance) {
- typedef typename std::remove_cv<
- typename std::remove_reference<
- typename detail::ArgType<Args...>::FirstArg>::type>::type FirstArg;
+ typedef typename std::remove_cv<typename std::remove_reference<
+ typename futures::detail::ArgType<Args...>::FirstArg>::type>::type
+ FirstArg;
+
return then([instance, func](Try<T>&& t){
return (instance->*func)(t.template get<isTry<FirstArg>::value, Args>()...);
});
}
template <class T>
-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<Arg>(arg), std::forward<Args>(args)...).
- via(oldX);
-}
-
-template <class T>
-Future<void> Future<T>::then() {
- return then([] (Try<T>&& t) {});
+Future<Unit> Future<T>::then() {
+ return then([] () {});
}
// onError where the callback returns T
template <class T>
template <class F>
typename std::enable_if<
- !detail::callableWith<F, exception_wrapper>::value &&
- !detail::Extract<F>::ReturnsFuture::value,
- Future<T>>::type
+ !futures::detail::callableWith<F, exception_wrapper>::value &&
+ !futures::detail::callableWith<F, exception_wrapper&>::value &&
+ !futures::detail::Extract<F>::ReturnsFuture::value,
+ Future<T>>::type
Future<T>::onError(F&& func) {
- typedef typename detail::Extract<F>::FirstArg Exn;
+ typedef std::remove_reference_t<
+ typename futures::detail::Extract<F>::FirstArg>
+ Exn;
static_assert(
- std::is_same<typename detail::Extract<F>::RawReturn, T>::value,
+ std::is_same<typename futures::detail::Extract<F>::RawReturn, T>::value,
"Return type of onError callback must be T or Future<T>");
Promise<T> p;
+ p.core_->setInterruptHandlerNoLock(this->core_->getInterruptHandler());
auto f = p.getFuture();
- auto pm = folly::makeMoveWrapper(std::move(p));
- auto funcm = folly::makeMoveWrapper(std::move(func));
- setCallback_([pm, funcm](Try<T>&& t) mutable {
- if (!t.template withException<Exn>([&] (Exn& e) {
- pm->setWith([&]{
- return (*funcm)(e);
- });
- })) {
- pm->setTry(std::move(t));
- }
- });
+
+ this->setCallback_(
+ [state = futures::detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T>&& t) mutable {
+ if (auto e = t.template tryGetExceptionObject<Exn>()) {
+ state.setTry(makeTryWith([&] { return state.invoke(*e); }));
+ } else {
+ state.setTry(std::move(t));
+ }
+ });
return f;
}
template <class T>
template <class F>
typename std::enable_if<
- !detail::callableWith<F, exception_wrapper>::value &&
- detail::Extract<F>::ReturnsFuture::value,
- Future<T>>::type
+ !futures::detail::callableWith<F, exception_wrapper>::value &&
+ !futures::detail::callableWith<F, exception_wrapper&>::value &&
+ futures::detail::Extract<F>::ReturnsFuture::value,
+ Future<T>>::type
Future<T>::onError(F&& func) {
static_assert(
- std::is_same<typename detail::Extract<F>::Return, Future<T>>::value,
+ std::is_same<typename futures::detail::Extract<F>::Return, Future<T>>::
+ value,
"Return type of onError callback must be T or Future<T>");
- typedef typename detail::Extract<F>::FirstArg Exn;
+ typedef std::remove_reference_t<
+ typename futures::detail::Extract<F>::FirstArg>
+ Exn;
Promise<T> p;
auto f = p.getFuture();
- auto pm = folly::makeMoveWrapper(std::move(p));
- auto funcm = folly::makeMoveWrapper(std::move(func));
- setCallback_([pm, funcm](Try<T>&& t) mutable {
- if (!t.template withException<Exn>([&] (Exn& e) {
- try {
- auto f2 = (*funcm)(e);
- f2.setCallback_([pm](Try<T>&& t2) mutable {
- pm->setTry(std::move(t2));
+
+ this->setCallback_(
+ [state = futures::detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T>&& t) mutable {
+ if (auto e = t.template tryGetExceptionObject<Exn>()) {
+ auto tf2 = state.tryInvoke(*e);
+ if (tf2.hasException()) {
+ state.setException(std::move(tf2.exception()));
+ } else {
+ tf2->setCallback_([p = state.stealPromise()](Try<T> && t3) mutable {
+ p.setTry(std::move(t3));
});
- } catch (const std::exception& e2) {
- pm->setException(exception_wrapper(std::current_exception(), e2));
- } catch (...) {
- pm->setException(exception_wrapper(std::current_exception()));
}
- })) {
- pm->setTry(std::move(t));
- }
- });
+ } else {
+ state.setTry(std::move(t));
+ }
+ });
return f;
}
template <class T>
template <class F>
-Future<T> Future<T>::ensure(F func) {
- MoveWrapper<F> funcw(std::move(func));
- return this->then([funcw](Try<T>&& t) {
- (*funcw)();
+Future<T> Future<T>::ensure(F&& func) {
+ return this->then([funcw = std::forward<F>(func)](Try<T> && t) mutable {
+ std::move(funcw)();
return makeFuture(std::move(t));
});
}
template <class T>
template <class F>
Future<T> Future<T>::onTimeout(Duration dur, F&& func, Timekeeper* tk) {
- auto funcw = folly::makeMoveWrapper(std::forward<F>(func));
- return within(dur, tk)
- .onError([funcw](TimedOut const&) { return (*funcw)(); });
+ return within(dur, tk).onError([funcw = std::forward<F>(func)](
+ TimedOut const&) { return std::move(funcw)(); });
}
template <class T>
template <class F>
typename std::enable_if<
- detail::callableWith<F, exception_wrapper>::value &&
- detail::Extract<F>::ReturnsFuture::value,
- Future<T>>::type
+ futures::detail::callableWith<F, exception_wrapper>::value &&
+ futures::detail::Extract<F>::ReturnsFuture::value,
+ Future<T>>::type
Future<T>::onError(F&& func) {
static_assert(
- std::is_same<typename detail::Extract<F>::Return, Future<T>>::value,
+ std::is_same<typename futures::detail::Extract<F>::Return, Future<T>>::
+ value,
"Return type of onError callback must be T or Future<T>");
Promise<T> p;
auto f = p.getFuture();
- auto pm = folly::makeMoveWrapper(std::move(p));
- auto funcm = folly::makeMoveWrapper(std::move(func));
- setCallback_([pm, funcm](Try<T> t) mutable {
- if (t.hasException()) {
- try {
- auto f2 = (*funcm)(std::move(t.exception()));
- f2.setCallback_([pm](Try<T> t2) mutable {
- pm->setTry(std::move(t2));
- });
- } catch (const std::exception& e2) {
- pm->setException(exception_wrapper(std::current_exception(), e2));
- } catch (...) {
- pm->setException(exception_wrapper(std::current_exception()));
- }
- } else {
- pm->setTry(std::move(t));
- }
- });
+ this->setCallback_(
+ [state = futures::detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T> t) mutable {
+ if (t.hasException()) {
+ auto tf2 = state.tryInvoke(std::move(t.exception()));
+ if (tf2.hasException()) {
+ state.setException(std::move(tf2.exception()));
+ } else {
+ tf2->setCallback_([p = state.stealPromise()](Try<T> && t3) mutable {
+ p.setTry(std::move(t3));
+ });
+ }
+ } else {
+ state.setTry(std::move(t));
+ }
+ });
return f;
}
template <class T>
template <class F>
typename std::enable_if<
- detail::callableWith<F, exception_wrapper>::value &&
- !detail::Extract<F>::ReturnsFuture::value,
- Future<T>>::type
+ futures::detail::callableWith<F, exception_wrapper>::value &&
+ !futures::detail::Extract<F>::ReturnsFuture::value,
+ Future<T>>::type
Future<T>::onError(F&& func) {
static_assert(
- std::is_same<typename detail::Extract<F>::Return, Future<T>>::value,
+ std::is_same<typename futures::detail::Extract<F>::Return, Future<T>>::
+ value,
"Return type of onError callback must be T or Future<T>");
Promise<T> p;
auto f = p.getFuture();
- auto pm = folly::makeMoveWrapper(std::move(p));
- auto funcm = folly::makeMoveWrapper(std::move(func));
- setCallback_([pm, funcm](Try<T> t) mutable {
- if (t.hasException()) {
- pm->setWith([&]{
- return (*funcm)(std::move(t.exception()));
+ this->setCallback_(
+ [state = futures::detail::makeCoreCallbackState(
+ std::move(p), std::forward<F>(func))](Try<T>&& t) mutable {
+ if (t.hasException()) {
+ state.setTry(makeTryWith(
+ [&] { return state.invoke(std::move(t.exception())); }));
+ } else {
+ state.setTry(std::move(t));
+ }
});
- } else {
- pm->setTry(std::move(t));
- }
- });
return f;
}
-template <class T>
-typename std::add_lvalue_reference<T>::type Future<T>::value() {
- throwIfInvalid();
-
- return core_->getTry().value();
-}
-
-template <class T>
-typename std::add_lvalue_reference<const T>::type Future<T>::value() const {
- throwIfInvalid();
-
- return core_->getTry().value();
-}
-
-template <class T>
-Try<T>& Future<T>::getTry() {
- throwIfInvalid();
-
- return core_->getTry();
-}
-
-template <class T>
-Optional<Try<T>> Future<T>::poll() {
- Optional<Try<T>> o;
- if (core_->ready()) {
- o = std::move(core_->getTry());
- }
- return o;
-}
-
-template <class T>
-inline Future<T> Future<T>::via(Executor* executor, int8_t priority) && {
- throwIfInvalid();
-
- setExecutor(executor, priority);
-
- return std::move(*this);
-}
-
-template <class T>
-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, priority);
-}
-
-template <class T>
-bool Future<T>::isReady() const {
- throwIfInvalid();
- return core_->ready();
-}
-
-template <class T>
-void Future<T>::raise(exception_wrapper exception) {
- core_->raise(std::move(exception));
+template <class Func>
+auto via(Executor* x, Func&& func)
+ -> Future<typename isFuture<decltype(std::declval<Func>()())>::Inner> {
+ // TODO make this actually more performant. :-P #7260175
+ return via(x).then(std::forward<Func>(func));
}
// makeFuture
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();
+inline Future<Unit> makeFuture() {
+ return makeFuture(Unit{});
}
+// makeFutureWith(Future<T>()) -> Future<T>
template <class F>
-auto makeFutureWith(
- 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();
+typename std::enable_if<isFuture<typename std::result_of<F()>::type>::value,
+ typename std::result_of<F()>::type>::type
+makeFutureWith(F&& func) {
+ using InnerType =
+ typename isFuture<typename std::result_of<F()>::type>::Inner;
+ try {
+ return std::forward<F>(func)();
+ } catch (std::exception& e) {
+ return makeFuture<InnerType>(
+ exception_wrapper(std::current_exception(), e));
+ } catch (...) {
+ return makeFuture<InnerType>(exception_wrapper(std::current_exception()));
+ }
}
+// makeFutureWith(T()) -> Future<T>
+// makeFutureWith(void()) -> Future<Unit>
template <class F>
-auto makeFutureWith(F const& func) -> Future<decltype(func())> {
- F copy = func;
- return makeFutureWith(std::move(copy));
+typename std::enable_if<
+ !(isFuture<typename std::result_of<F()>::type>::value),
+ Future<Unit::LiftT<typename std::result_of<F()>::type>>>::type
+makeFutureWith(F&& func) {
+ using LiftedResult = Unit::LiftT<typename std::result_of<F()>::type>;
+ return makeFuture<LiftedResult>(
+ makeTryWith([&func]() mutable { return std::forward<F>(func)(); }));
}
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();
-}
-
-template <>
-inline Future<void> makeFuture(Try<void>&& t) {
- if (t.hasException()) {
- return makeFuture<void>(std::move(t.exception()));
- } else {
- return makeFuture();
- }
+ return Future<T>(new futures::detail::Core<T>(std::move(t)));
}
// via
-Future<void> via(Executor* executor, int8_t priority) {
+Future<Unit> via(Executor* executor, int8_t priority) {
return makeFuture().via(executor, priority);
}
// collectAll (variadic)
template <typename... Fs>
-typename detail::VariadicContext<
- typename std::decay<Fs>::type::value_type...>::type
+typename futures::detail::CollectAllVariadicContext<
+ typename std::decay<Fs>::type::value_type...>::type
collectAll(Fs&&... fs) {
- auto ctx = std::make_shared<detail::VariadicContext<
- typename std::decay<Fs>::type::value_type...>>();
- detail::collectAllVariadicHelper(ctx,
- std::forward<typename std::decay<Fs>::type>(fs)...);
+ auto ctx = std::make_shared<futures::detail::CollectAllVariadicContext<
+ typename std::decay<Fs>::type::value_type...>>();
+ futures::detail::collectVariadicHelper<
+ futures::detail::CollectAllVariadicContext>(ctx, std::forward<Fs>(fs)...);
return ctx->p.getFuture();
}
typename std::iterator_traits<InputIterator>::value_type::value_type T;
struct CollectAllContext {
- CollectAllContext(int n) : results(n) {}
+ CollectAllContext(size_t n) : results(n) {}
~CollectAllContext() {
p.setValue(std::move(results));
}
std::vector<Try<T>> results;
};
- auto ctx = std::make_shared<CollectAllContext>(std::distance(first, last));
+ auto ctx =
+ std::make_shared<CollectAllContext>(size_t(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();
}
+// collect (iterator)
+
+namespace futures {
namespace detail {
template <typename T>
struct CollectContext {
- struct Nothing { explicit Nothing(int n) {} };
+ struct Nothing {
+ explicit Nothing(int /* n */) {}
+ };
using Result = typename std::conditional<
std::is_void<T>::value,
Nothing,
std::vector<Optional<T>>>::type;
- explicit CollectContext(int n) : result(n) {}
+ explicit CollectContext(size_t n) : result(n) {}
~CollectContext() {
if (!threw.exchange(true)) {
// map Optional<T> -> T
}
Promise<Result> p;
InternalResult result;
- std::atomic<bool> threw;
+ std::atomic<bool> threw {false};
};
-// Specialize for void (implementations in Future.cpp)
-
-template <>
-CollectContext<void>::~CollectContext();
-
-template <>
-void CollectContext<void>::setPartialResult(size_t i, Try<void>& t);
-
-}
+} // namespace detail
+} // namespace futures
template <class InputIterator>
-Future<typename detail::CollectContext<
- typename std::iterator_traits<InputIterator>::value_type::value_type>::Result>
+Future<typename futures::detail::CollectContext<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;
- auto ctx = std::make_shared<detail::CollectContext<T>>(
- std::distance(first, last));
+ auto ctx = std::make_shared<futures::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)) {
return ctx->p.getFuture();
}
+// collect (variadic)
+
+template <typename... Fs>
+typename futures::detail::CollectVariadicContext<
+ typename std::decay<Fs>::type::value_type...>::type
+collect(Fs&&... fs) {
+ auto ctx = std::make_shared<futures::detail::CollectVariadicContext<
+ typename std::decay<Fs>::type::value_type...>>();
+ futures::detail::collectVariadicHelper<
+ futures::detail::CollectVariadicContext>(ctx, std::forward<Fs>(fs)...);
+ return ctx->p.getFuture();
+}
+
+// collectAny (iterator)
+
template <class InputIterator>
Future<
std::pair<size_t,
typename std::iterator_traits<InputIterator>::value_type::value_type T;
struct CollectAnyContext {
- CollectAnyContext(size_t n) : done(false) {};
+ CollectAnyContext() {}
Promise<std::pair<size_t, Try<T>>> p;
- std::atomic<bool> done;
+ std::atomic<bool> done {false};
};
- auto ctx = std::make_shared<CollectAnyContext>(std::distance(first, last));
+ auto ctx = std::make_shared<CollectAnyContext>();
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();
}
+// collectAnyWithoutException (iterator)
+
+template <class InputIterator>
+Future<std::pair<
+ size_t,
+ typename std::iterator_traits<InputIterator>::value_type::value_type>>
+collectAnyWithoutException(InputIterator first, InputIterator last) {
+ typedef
+ typename std::iterator_traits<InputIterator>::value_type::value_type T;
+
+ struct CollectAnyWithoutExceptionContext {
+ CollectAnyWithoutExceptionContext(){}
+ Promise<std::pair<size_t, T>> p;
+ std::atomic<bool> done{false};
+ std::atomic<size_t> nFulfilled{0};
+ size_t nTotal;
+ };
+
+ auto ctx = std::make_shared<CollectAnyWithoutExceptionContext>();
+ ctx->nTotal = size_t(std::distance(first, last));
+
+ mapSetCallback<T>(first, last, [ctx](size_t i, Try<T>&& t) {
+ if (!t.hasException() && !ctx->done.exchange(true)) {
+ ctx->p.setValue(std::make_pair(i, std::move(t.value())));
+ } else if (++ctx->nFulfilled == ctx->nTotal) {
+ ctx->p.setException(t.exception());
+ }
+ });
+ 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>>>>
auto c = ++ctx->completed;
if (c <= n) {
assert(ctx->v.size() < n);
- ctx->v.push_back(std::make_pair(i, std::move(t)));
+ ctx->v.emplace_back(i, std::move(t));
if (c == n) {
ctx->p.setTry(Try<V>(std::move(ctx->v)));
}
return ctx->p.getFuture();
}
+// reduce (iterator)
+
template <class It, class T, class F>
Future<T> reduce(It first, It last, T&& initial, F&& func) {
if (first == last) {
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;
+ futures::detail::callableWith<F, T&&, Try<ItT>&&>::value,
+ Try<ItT>,
+ ItT>::type Arg;
typedef isTry<Arg> IsTry;
- 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&&>());
- });
+ auto f = first->then(
+ [ minitial = std::move(initial), 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 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_;
+ // Use global inline executor singleton
+ auto executor = &InlineExecutor::instance();
+ return window(executor, std::move(input), std::move(func), n);
+}
- 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));
+template <class Collection, class F, class ItT, class Result>
+std::vector<Future<Result>>
+window(Executor* executor, Collection input, F func, size_t n) {
+ struct WindowContext {
+ WindowContext(Executor* executor_, Collection&& input_, F&& func_)
+ : executor(executor_),
+ input(std::move(input_)),
+ promises(input.size()),
+ func(std::move(func_)) {}
+ std::atomic<size_t> i{0};
+ Executor* executor;
+ Collection input;
+ std::vector<Promise<Result>> promises;
+ F func;
+
+ static inline void spawn(std::shared_ptr<WindowContext> ctx) {
+ size_t i = ctx->i++;
+ if (i < ctx->input.size()) {
+ auto fut = ctx->func(std::move(ctx->input[i]));
+ fut.setCallback_([ctx = std::move(ctx), i](Try<Result>&& t) mutable {
+ const auto executor_ = ctx->executor;
+ executor_->add([ctx = std::move(ctx), i, t = std::move(t)]() mutable {
+ 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));
+ executor, std::move(input), std::move(func));
+ // Start the first n Futures
for (size_t i = 0; i < max; ++i) {
- // Start the first n Futures
- WindowContext::spawn(ctx);
+ executor->add([ctx]() mutable { WindowContext::spawn(std::move(ctx)); });
}
std::vector<Future<Result>> futures;
- futures.reserve(ctx->promises_.size());
- for (auto& promise : ctx->promises_) {
+ 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);
+ return then([
+ minitial = std::forward<I>(initial),
+ mfunc = std::forward<F>(func)
+ ](T& vals) mutable {
+ auto ret = std::move(minitial);
for (auto& val : vals) {
- ret = (*mfunc)(std::move(ret), std::move(val));
+ ret = mfunc(std::move(ret), std::move(val));
}
return ret;
});
}
+// unorderedReduce (iterator)
+
template <class It, class T, class F, class ItT, class Arg>
Future<T> unorderedReduce(It first, It last, T initial, F func) {
if (first == last) {
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_;
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));
+ mapSetCallback<ItT>(
+ first,
+ last,
+ [ctx](size_t /* i */, Try<ItT>&& 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 = std::move(t) ](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 ctx->promise_.getFuture();
}
+// within
+
template <class T>
Future<T> Future<T>::within(Duration dur, Timekeeper* tk) {
return within(dur, TimedOut(), tk);
Future<T> Future<T>::within(Duration dur, E e, Timekeeper* tk) {
struct Context {
- Context(E ex) : exception(std::move(ex)), promise(), token(false) {}
+ Context(E ex) : exception(std::move(ex)), promise() {}
E exception;
+ Future<Unit> thisFuture;
Promise<T> promise;
- std::atomic<bool> token;
+ std::atomic<bool> token {false};
};
- auto ctx = std::make_shared<Context>(std::move(e));
- if (!tk) {
- tk = folly::detail::getTimekeeperSingleton();
+ if (this->isReady()) {
+ return std::move(*this);
}
- tk->after(dur)
- .then([ctx](Try<void> const& t) {
- if (ctx->token.exchange(true) == false) {
- if (t.hasException()) {
- ctx->promise.setException(std::move(t.exception()));
- } else {
- ctx->promise.setException(std::move(ctx->exception));
- }
- }
- });
+ std::shared_ptr<Timekeeper> tks;
+ if (LIKELY(!tk)) {
+ tks = folly::detail::getTimekeeperSingleton();
+ tk = tks.get();
+ }
+
+ if (UNLIKELY(!tk)) {
+ return makeFuture<T>(NoTimekeeper());
+ }
+
+ auto ctx = std::make_shared<Context>(std::move(e));
- this->then([ctx](Try<T>&& t) {
+ ctx->thisFuture = this->then([ctx](Try<T>&& t) mutable {
if (ctx->token.exchange(true) == false) {
ctx->promise.setTry(std::move(t));
}
});
- return ctx->promise.getFuture().via(getExecutor());
+ // Have time keeper use a weak ptr to hold ctx,
+ // so that ctx can be deallocated as soon as the future job finished.
+ tk->after(dur).then([weakCtx = to_weak_ptr(ctx)](Try<Unit> const& t) mutable {
+ auto lockedCtx = weakCtx.lock();
+ if (!lockedCtx) {
+ // ctx already released. "this" completed first, cancel "after"
+ return;
+ }
+ // "after" completed first, cancel "this"
+ lockedCtx->thisFuture.raise(TimedOut());
+ if (lockedCtx->token.exchange(true) == false) {
+ if (t.hasException()) {
+ lockedCtx->promise.setException(std::move(t.exception()));
+ } else {
+ lockedCtx->promise.setException(std::move(lockedCtx->exception));
+ }
+ }
+ });
+
+ return ctx->promise.getFuture().via(this->getExecutor());
}
+// delayed
+
template <class T>
Future<T> Future<T>::delayed(Duration dur, Timekeeper* tk) {
return collectAll(*this, futures::sleep(dur, tk))
- .then([](std::tuple<Try<T>, Try<void>> tup) {
- Try<T>& t = std::get<0>(tup);
- return makeFuture<T>(std::move(t));
- });
+ .then([](std::tuple<Try<T>, Try<Unit>> tup) {
+ Try<T>& t = std::get<0>(tup);
+ return makeFuture<T>(std::move(t));
+ });
}
+namespace futures {
namespace detail {
template <class T>
-void waitImpl(Future<T>& f) {
- // short-circuit if there's nothing to do
- if (f.isReady()) return;
+void doBoost(folly::Future<T>& /* usused */) {}
- folly::fibers::Baton baton;
- f = f.then([&](Try<T> t) {
- baton.post();
- return makeFuture(std::move(t));
- });
- baton.wait();
+template <class T>
+void doBoost(folly::SemiFuture<T>& f) {
+ f.boost_();
+}
- // There's a race here between the return here and the actual finishing of
- // the future. f is completed, but the setup may not have finished on done
- // after the baton has posted.
- while (!f.isReady()) {
- std::this_thread::yield();
+template <class FutureType, typename T = typename FutureType::value_type>
+void waitImpl(FutureType& f) {
+ // short-circuit if there's nothing to do
+ if (f.isReady()) {
+ return;
}
+
+ FutureBatonType baton;
+ f.setCallback_([&](const Try<T>& /* t */) { baton.post(); });
+ doBoost(f);
+ baton.wait();
+ assert(f.isReady());
}
-template <class T>
-void waitImpl(Future<T>& f, Duration dur) {
+template <class FutureType, typename T = typename FutureType::value_type>
+void waitImpl(FutureType& f, Duration dur) {
// short-circuit if there's nothing to do
- if (f.isReady()) return;
+ if (f.isReady()) {
+ return;
+ }
- auto baton = std::make_shared<folly::fibers::Baton>();
- f = f.then([baton](Try<T> t) {
+ Promise<T> promise;
+ auto ret = promise.getFuture();
+ auto baton = std::make_shared<FutureBatonType>();
+ f.setCallback_([baton, promise = std::move(promise)](Try<T>&& t) mutable {
+ promise.setTry(std::move(t));
baton->post();
- return makeFuture(std::move(t));
});
-
- // Let's preserve the invariant that if we did not timeout (timed_wait returns
- // true), then the returned Future is complete when it is returned to the
- // caller. We need to wait out the race for that Future to complete.
- if (baton->timed_wait(dur)) {
- while (!f.isReady()) {
- std::this_thread::yield();
- }
+ doBoost(f);
+ f = std::move(ret);
+ if (baton->try_wait_for(dur)) {
+ assert(f.isReady());
}
}
template <class T>
void waitViaImpl(Future<T>& f, DrivableExecutor* e) {
+ // Set callback so to ensure that the via executor has something on it
+ // so that once the preceding future triggers this callback, drive will
+ // always have a callback to satisfy it
+ if (f.isReady()) {
+ return;
+ }
+ f = f.via(e).then([](T&& t) { return std::move(t); });
+ while (!f.isReady()) {
+ e->drive();
+ }
+ assert(f.isReady());
+}
+
+template <class T>
+void waitViaImpl(SemiFuture<T>& f, DrivableExecutor* e) {
+ // Set callback so to ensure that the via executor has something on it
+ // so that once the preceding future triggers this callback, drive will
+ // always have a callback to satisfy it
+ if (f.isReady()) {
+ return;
+ }
+ f = std::move(f).via(e).then([](T&& t) { return std::move(t); });
while (!f.isReady()) {
e->drive();
}
+ assert(f.isReady());
+}
+
+} // namespace detail
+} // namespace futures
+
+template <class T>
+SemiFuture<T>& SemiFuture<T>::wait() & {
+ futures::detail::waitImpl(*this);
+ return *this;
+}
+
+template <class T>
+SemiFuture<T>&& SemiFuture<T>::wait() && {
+ futures::detail::waitImpl(*this);
+ return std::move(*this);
+}
+
+template <class T>
+SemiFuture<T>& SemiFuture<T>::wait(Duration dur) & {
+ futures::detail::waitImpl(*this, dur);
+ return *this;
+}
+
+template <class T>
+SemiFuture<T>&& SemiFuture<T>::wait(Duration dur) && {
+ futures::detail::waitImpl(*this, dur);
+ return std::move(*this);
+}
+
+template <class T>
+SemiFuture<T>& SemiFuture<T>::waitVia(DrivableExecutor* e) & {
+ futures::detail::waitViaImpl(*this, e);
+ return *this;
+}
+
+template <class T>
+SemiFuture<T>&& SemiFuture<T>::waitVia(DrivableExecutor* e) && {
+ futures::detail::waitViaImpl(*this, e);
+ return std::move(*this);
+}
+
+template <class T>
+T SemiFuture<T>::get() && {
+ return std::move(wait()).value();
+}
+
+template <class T>
+T SemiFuture<T>::get(Duration dur) && {
+ wait(dur);
+ if (this->isReady()) {
+ return std::move(this->value());
+ } else {
+ throwTimedOut();
+ }
+}
+
+template <class T>
+Try<T> SemiFuture<T>::getTry() && {
+ return std::move(wait()).result();
+}
+
+template <class T>
+Try<T> SemiFuture<T>::getTry(Duration dur) && {
+ wait(dur);
+ if (this->isReady()) {
+ return std::move(this->result());
+ } else {
+ throwTimedOut();
+ }
}
-} // detail
+template <class T>
+T SemiFuture<T>::getVia(DrivableExecutor* e) && {
+ return std::move(waitVia(e)).value();
+}
+
+template <class T>
+Try<T> SemiFuture<T>::getTryVia(DrivableExecutor* e) && {
+ return std::move(waitVia(e)).result();
+}
template <class T>
Future<T>& Future<T>::wait() & {
- detail::waitImpl(*this);
+ futures::detail::waitImpl(*this);
return *this;
}
template <class T>
Future<T>&& Future<T>::wait() && {
- detail::waitImpl(*this);
+ futures::detail::waitImpl(*this);
return std::move(*this);
}
template <class T>
Future<T>& Future<T>::wait(Duration dur) & {
- detail::waitImpl(*this, dur);
+ futures::detail::waitImpl(*this, dur);
return *this;
}
template <class T>
Future<T>&& Future<T>::wait(Duration dur) && {
- detail::waitImpl(*this, dur);
+ futures::detail::waitImpl(*this, dur);
return std::move(*this);
}
template <class T>
Future<T>& Future<T>::waitVia(DrivableExecutor* e) & {
- detail::waitViaImpl(*this, e);
+ futures::detail::waitViaImpl(*this, e);
return *this;
}
template <class T>
Future<T>&& Future<T>::waitVia(DrivableExecutor* e) && {
- detail::waitViaImpl(*this, e);
+ futures::detail::waitViaImpl(*this, e);
return std::move(*this);
}
return std::move(wait().value());
}
-template <>
-inline void Future<void>::get() {
- wait().value();
-}
-
template <class T>
T Future<T>::get(Duration dur) {
wait(dur);
- if (isReady()) {
- return std::move(value());
+ if (this->isReady()) {
+ return std::move(this->value());
} else {
- throw TimedOut();
+ throwTimedOut();
}
}
-template <>
-inline void Future<void>::get(Duration dur) {
- wait(dur);
- if (isReady()) {
- return;
- } else {
- throw TimedOut();
- }
+template <class T>
+Try<T>& Future<T>::getTry() {
+ return result();
}
template <class T>
return std::move(waitVia(e).value());
}
-template <>
-inline void Future<void>::getVia(DrivableExecutor* e) {
- waitVia(e).value();
+template <class T>
+Try<T>& Future<T>::getTryVia(DrivableExecutor* e) {
+ return waitVia(e).getTry();
}
+namespace futures {
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>
+struct TryEquals {
+ static bool equals(const Try<T>& t1, const Try<T>& t2) {
+ return t1.value() == t2.value();
+ }
+};
+} // namespace detail
+} // namespace futures
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 detail::TryEquals<T>::equals(std::get<0>(t), std::get<1>(t));
+ return futures::detail::TryEquals<T>::equals(
+ std::get<0>(t), std::get<1>(t));
} else {
return false;
}
template <class T>
template <class F>
-Future<T> Future<T>::filter(F predicate) {
- auto p = folly::makeMoveWrapper(std::move(predicate));
- return this->then([p](T val) {
+Future<T> Future<T>::filter(F&& predicate) {
+ return this->then([p = std::forward<F>(predicate)](T val) {
T const& valConstRef = val;
- if (!(*p)(valConstRef)) {
- throw PredicateDoesNotObtain();
+ if (!p(valConstRef)) {
+ throwPredicateDoesNotObtain();
}
return val;
});
}
-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 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 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 F>
+inline Future<Unit> when(bool p, F&& thunk) {
+ return p ? std::forward<F>(thunk)().unit() : makeFuture();
+}
+
+template <class P, class F>
+Future<Unit> whileDo(P&& predicate, F&& thunk) {
+ if (predicate()) {
+ auto future = thunk();
+ return future.then([
+ predicate = std::forward<P>(predicate),
+ thunk = std::forward<F>(thunk)
+ ]() mutable {
+ return whileDo(std::forward<P>(predicate), std::forward<F>(thunk));
+ });
+ }
+ return makeFuture();
}
-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));
+template <class F>
+Future<Unit> times(const int n, F&& thunk) {
+ return folly::whileDo(
+ [ n, count = std::make_unique<std::atomic<int>>(0) ]() mutable {
+ return count->fetch_add(1) < n;
+ },
+ std::forward<F>(thunk));
}
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;
- for (auto it = first; it != last; it++) {
- results.push_back(it->then(func));
- }
- return results;
+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;
+ for (auto it = first; it != last; it++) {
+ results.push_back(it->then(func));
}
+ return results;
}
+} // namespace futures
// Instantiate the most common Future types to save compile time
-extern template class Future<void>;
+extern template class Future<Unit>;
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
-// using it, however it is not difficult to add when needed. Refer to
-// Future<void> for guidance. std::future and boost::future code would also be
-// instructive.
projects / folly.git / blobdiff