1 | /* |
2 | * Copyright 2014-present Facebook, Inc. |
3 | * |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | * you may not use this file except in compliance with the License. |
6 | * You may obtain a copy of the License at |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
10 | * Unless required by applicable law or agreed to in writing, software |
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | * See the License for the specific language governing permissions and |
14 | * limitations under the License. |
15 | */ |
16 | #pragma once |
17 | |
18 | #include <algorithm> |
19 | #include <cassert> |
20 | #include <chrono> |
21 | #include <thread> |
22 | |
23 | #include <folly/Optional.h> |
24 | #include <folly/executors/InlineExecutor.h> |
25 | #include <folly/executors/QueuedImmediateExecutor.h> |
26 | #include <folly/futures/detail/Core.h> |
27 | #include <folly/synchronization/Baton.h> |
28 | |
29 | #ifndef FOLLY_FUTURE_USING_FIBER |
30 | #if FOLLY_MOBILE || defined(__APPLE__) |
31 | #define FOLLY_FUTURE_USING_FIBER 0 |
32 | #else |
33 | #define FOLLY_FUTURE_USING_FIBER 1 |
34 | #include <folly/fibers/Baton.h> |
35 | #endif |
36 | #endif |
37 | |
38 | namespace folly { |
39 | |
40 | class Timekeeper; |
41 | |
42 | namespace futures { |
43 | namespace detail { |
44 | #if FOLLY_FUTURE_USING_FIBER |
45 | typedef folly::fibers::Baton FutureBatonType; |
46 | #else |
47 | typedef folly::Baton<> FutureBatonType; |
48 | #endif |
49 | } // namespace detail |
50 | } // namespace futures |
51 | |
52 | namespace detail { |
53 | std::shared_ptr<Timekeeper> getTimekeeperSingleton(); |
54 | } // namespace detail |
55 | |
56 | namespace futures { |
57 | namespace detail { |
58 | // Guarantees that the stored functor is destructed before the stored promise |
59 | // may be fulfilled. Assumes the stored functor to be noexcept-destructible. |
60 | template <typename T, typename F> |
61 | class CoreCallbackState { |
62 | using DF = std::decay_t<F>; |
63 | |
64 | public: |
65 | CoreCallbackState(Promise<T>&& promise, F&& func) noexcept( |
66 | noexcept(DF(std::declval<F&&>()))) |
67 | : func_(std::forward<F>(func)), promise_(std::move(promise)) { |
68 | assert(before_barrier()); |
69 | } |
70 | |
71 | CoreCallbackState(CoreCallbackState&& that) noexcept( |
72 | noexcept(DF(std::declval<F&&>()))) { |
73 | if (that.before_barrier()) { |
74 | new (&func_) DF(std::forward<F>(that.func_)); |
75 | promise_ = that.stealPromise(); |
76 | } |
77 | } |
78 | |
79 | CoreCallbackState& operator=(CoreCallbackState&&) = delete; |
80 | |
81 | ~CoreCallbackState() { |
82 | if (before_barrier()) { |
83 | stealPromise(); |
84 | } |
85 | } |
86 | |
87 | template <typename... Args> |
88 | auto invoke(Args&&... args) noexcept( |
89 | noexcept(std::declval<F&&>()(std::declval<Args&&>()...))) { |
90 | assert(before_barrier()); |
91 | return std::forward<F>(func_)(std::forward<Args>(args)...); |
92 | } |
93 | |
94 | template <typename... Args> |
95 | auto tryInvoke(Args&&... args) noexcept { |
96 | return makeTryWith([&] { return invoke(std::forward<Args>(args)...); }); |
97 | } |
98 | |
99 | void setTry(Try<T>&& t) { |
100 | stealPromise().setTry(std::move(t)); |
101 | } |
102 | |
103 | void setException(exception_wrapper&& ew) { |
104 | stealPromise().setException(std::move(ew)); |
105 | } |
106 | |
107 | Promise<T> stealPromise() noexcept { |
108 | assert(before_barrier()); |
109 | func_.~DF(); |
110 | return std::move(promise_); |
111 | } |
112 | |
113 | private: |
114 | bool before_barrier() const noexcept { |
115 | return !promise_.isFulfilled(); |
116 | } |
117 | |
118 | union { |
119 | DF func_; |
120 | }; |
121 | Promise<T> promise_{Promise<T>::makeEmpty()}; |
122 | }; |
123 | |
124 | template <typename T, typename F> |
125 | auto makeCoreCallbackState(Promise<T>&& p, F&& f) noexcept( |
126 | noexcept(CoreCallbackState<T, F>( |
127 | std::declval<Promise<T>&&>(), |
128 | std::declval<F&&>()))) { |
129 | return CoreCallbackState<T, F>(std::move(p), std::forward<F>(f)); |
130 | } |
131 | |
132 | template <typename T, typename R, typename... Args> |
133 | auto makeCoreCallbackState(Promise<T>&& p, R (&f)(Args...)) noexcept { |
134 | return CoreCallbackState<T, R (*)(Args...)>(std::move(p), &f); |
135 | } |
136 | |
137 | template <class T> |
138 | FutureBase<T>::FutureBase(SemiFuture<T>&& other) noexcept : core_(other.core_) { |
139 | other.core_ = nullptr; |
140 | } |
141 | |
142 | template <class T> |
143 | FutureBase<T>::FutureBase(Future<T>&& other) noexcept : core_(other.core_) { |
144 | other.core_ = nullptr; |
145 | } |
146 | |
147 | template <class T> |
148 | template <class T2, typename> |
149 | FutureBase<T>::FutureBase(T2&& val) |
150 | : core_(Core::make(Try<T>(std::forward<T2>(val)))) {} |
151 | |
152 | template <class T> |
153 | template <typename T2> |
154 | FutureBase<T>::FutureBase( |
155 | typename std::enable_if<std::is_same<Unit, T2>::value>::type*) |
156 | : core_(Core::make(Try<T>(T()))) {} |
157 | |
158 | template <class T> |
159 | template < |
160 | class... Args, |
161 | typename std::enable_if<std::is_constructible<T, Args&&...>::value, int>:: |
162 | type> |
163 | FutureBase<T>::FutureBase(in_place_t, Args&&... args) |
164 | : core_(Core::make(in_place, std::forward<Args>(args)...)) {} |
165 | |
166 | template <class T> |
167 | void FutureBase<T>::assign(FutureBase<T>&& other) noexcept { |
168 | detach(); |
169 | core_ = exchange(other.core_, nullptr); |
170 | } |
171 | |
172 | template <class T> |
173 | FutureBase<T>::~FutureBase() { |
174 | detach(); |
175 | } |
176 | |
177 | template <class T> |
178 | T& FutureBase<T>::value() & { |
179 | return result().value(); |
180 | } |
181 | |
182 | template <class T> |
183 | T const& FutureBase<T>::value() const& { |
184 | return result().value(); |
185 | } |
186 | |
187 | template <class T> |
188 | T&& FutureBase<T>::value() && { |
189 | return std::move(result().value()); |
190 | } |
191 | |
192 | template <class T> |
193 | T const&& FutureBase<T>::value() const&& { |
194 | return std::move(result().value()); |
195 | } |
196 | |
197 | template <class T> |
198 | Try<T>& FutureBase<T>::result() & { |
199 | return getCoreTryChecked(); |
200 | } |
201 | |
202 | template <class T> |
203 | Try<T> const& FutureBase<T>::result() const& { |
204 | return getCoreTryChecked(); |
205 | } |
206 | |
207 | template <class T> |
208 | Try<T>&& FutureBase<T>::result() && { |
209 | return std::move(getCoreTryChecked()); |
210 | } |
211 | |
212 | template <class T> |
213 | Try<T> const&& FutureBase<T>::result() const&& { |
214 | return std::move(getCoreTryChecked()); |
215 | } |
216 | |
217 | template <class T> |
218 | bool FutureBase<T>::isReady() const { |
219 | return getCore().hasResult(); |
220 | } |
221 | |
222 | template <class T> |
223 | bool FutureBase<T>::hasValue() const { |
224 | return result().hasValue(); |
225 | } |
226 | |
227 | template <class T> |
228 | bool FutureBase<T>::hasException() const { |
229 | return result().hasException(); |
230 | } |
231 | |
232 | template <class T> |
233 | void FutureBase<T>::detach() { |
234 | if (core_) { |
235 | core_->detachFuture(); |
236 | core_ = nullptr; |
237 | } |
238 | } |
239 | |
240 | template <class T> |
241 | void FutureBase<T>::throwIfInvalid() const { |
242 | if (!core_) { |
243 | throw_exception<FutureInvalid>(); |
244 | } |
245 | } |
246 | |
247 | template <class T> |
248 | void FutureBase<T>::throwIfContinued() const { |
249 | if (!core_ || core_->hasCallback()) { |
250 | throw_exception<FutureAlreadyContinued>(); |
251 | } |
252 | } |
253 | |
254 | template <class T> |
255 | Optional<Try<T>> FutureBase<T>::poll() { |
256 | auto& core = getCore(); |
257 | return core.hasResult() ? Optional<Try<T>>(std::move(core.getTry())) |
258 | : Optional<Try<T>>(); |
259 | } |
260 | |
261 | template <class T> |
262 | void FutureBase<T>::raise(exception_wrapper exception) { |
263 | getCore().raise(std::move(exception)); |
264 | } |
265 | |
266 | template <class T> |
267 | template <class F> |
268 | void FutureBase<T>::setCallback_(F&& func) { |
269 | throwIfContinued(); |
270 | getCore().setCallback(std::forward<F>(func), RequestContext::saveContext()); |
271 | } |
272 | |
273 | template <class T> |
274 | FutureBase<T>::FutureBase(futures::detail::EmptyConstruct) noexcept |
275 | : core_(nullptr) {} |
276 | |
277 | // MSVC 2017 Update 7 released with a bug that causes issues expanding to an |
278 | // empty parameter pack when invoking a templated member function. It should |
279 | // be fixed for MSVC 2017 Update 8. |
280 | // TODO: Remove. |
281 | namespace detail_msvc_15_7_workaround { |
282 | template <typename R, std::size_t S> |
283 | using IfArgsSizeIs = std::enable_if_t<R::Arg::ArgsSize::value == S, int>; |
284 | template <typename R, typename State, typename T, IfArgsSizeIs<R, 0> = 0> |
285 | decltype(auto) invoke(R, State& state, Try<T>& /* t */) { |
286 | return state.invoke(); |
287 | } |
288 | template <typename R, typename State, typename T, IfArgsSizeIs<R, 1> = 0> |
289 | decltype(auto) invoke(R, State& state, Try<T>& t) { |
290 | using Arg0 = typename R::Arg::ArgList::FirstArg; |
291 | return state.invoke(t.template get<R::Arg::isTry(), Arg0>()); |
292 | } |
293 | template <typename R, typename State, typename T, IfArgsSizeIs<R, 0> = 0> |
294 | decltype(auto) tryInvoke(R, State& state, Try<T>& /* t */) { |
295 | return state.tryInvoke(); |
296 | } |
297 | template <typename R, typename State, typename T, IfArgsSizeIs<R, 1> = 0> |
298 | decltype(auto) tryInvoke(R, State& state, Try<T>& t) { |
299 | using Arg0 = typename R::Arg::ArgList::FirstArg; |
300 | return state.tryInvoke(t.template get<R::Arg::isTry(), Arg0>()); |
301 | } |
302 | } // namespace detail_msvc_15_7_workaround |
303 | |
304 | // then |
305 | |
306 | // Variant: returns a value |
307 | // e.g. f.then([](Try<T>&& t){ return t.value(); }); |
308 | template <class T> |
309 | template <typename F, typename R> |
310 | typename std::enable_if<!R::ReturnsFuture::value, typename R::Return>::type |
311 | FutureBase<T>::thenImplementation(F&& func, R) { |
312 | static_assert( |
313 | R::Arg::ArgsSize::value <= 1, "Then must take zero/one argument" ); |
314 | typedef typename R::ReturnsFuture::Inner B; |
315 | |
316 | Promise<B> p; |
317 | p.core_->setInterruptHandlerNoLock(this->getCore().getInterruptHandler()); |
318 | |
319 | // grab the Future now before we lose our handle on the Promise |
320 | auto sf = p.getSemiFuture(); |
321 | sf.setExecutor(this->getExecutor()); |
322 | auto f = Future<B>(sf.core_); |
323 | sf.core_ = nullptr; |
324 | |
325 | /* This is a bit tricky. |
326 | |
327 | We can't just close over *this in case this Future gets moved. So we |
328 | make a new dummy Future. We could figure out something more |
329 | sophisticated that avoids making a new Future object when it can, as an |
330 | optimization. But this is correct. |
331 | |
332 | core_ can't be moved, it is explicitly disallowed (as is copying). But |
333 | if there's ever a reason to allow it, this is one place that makes that |
334 | assumption and would need to be fixed. We use a standard shared pointer |
335 | for core_ (by copying it in), which means in essence obj holds a shared |
336 | pointer to itself. But this shouldn't leak because Promise will not |
337 | outlive the continuation, because Promise will setException() with a |
338 | broken Promise if it is destructed before completed. We could use a |
339 | weak pointer but it would have to be converted to a shared pointer when |
340 | func is executed (because the Future returned by func may possibly |
341 | persist beyond the callback, if it gets moved), and so it is an |
342 | optimization to just make it shared from the get-go. |
343 | |
344 | Two subtle but important points about this design. futures::detail::Core |
345 | has no back pointers to Future or Promise, so if Future or Promise get |
346 | moved (and they will be moved in performant code) we don't have to do |
347 | anything fancy. And because we store the continuation in the |
348 | futures::detail::Core, not in the Future, we can execute the continuation |
349 | even after the Future has gone out of scope. This is an intentional design |
350 | decision. It is likely we will want to be able to cancel a continuation |
351 | in some circumstances, but I think it should be explicit not implicit |
352 | in the destruction of the Future used to create it. |
353 | */ |
354 | this->setCallback_( |
355 | [state = futures::detail::makeCoreCallbackState( |
356 | std::move(p), std::forward<F>(func))](Try<T>&& t) mutable { |
357 | if (!R::Arg::isTry() && t.hasException()) { |
358 | state.setException(std::move(t.exception())); |
359 | } else { |
360 | state.setTry(makeTryWith([&] { |
361 | return detail_msvc_15_7_workaround::invoke(R{}, state, t); |
362 | })); |
363 | } |
364 | }); |
365 | return f; |
366 | } |
367 | |
368 | // Pass through a simple future as it needs no deferral adaptation |
369 | template <class T> |
370 | Future<T> chainExecutor(Executor*, Future<T>&& f) { |
371 | return std::move(f); |
372 | } |
373 | |
374 | // Correctly chain a SemiFuture for deferral |
375 | template <class T> |
376 | Future<T> chainExecutor(Executor* e, SemiFuture<T>&& f) { |
377 | if (!e) { |
378 | e = &InlineExecutor::instance(); |
379 | } |
380 | return std::move(f).via(e); |
381 | } |
382 | |
383 | // Variant: returns a Future |
384 | // e.g. f.then([](T&& t){ return makeFuture<T>(t); }); |
385 | template <class T> |
386 | template <typename F, typename R> |
387 | typename std::enable_if<R::ReturnsFuture::value, typename R::Return>::type |
388 | FutureBase<T>::thenImplementation(F&& func, R) { |
389 | static_assert( |
390 | R::Arg::ArgsSize::value <= 1, "Then must take zero/one argument" ); |
391 | typedef typename R::ReturnsFuture::Inner B; |
392 | |
393 | Promise<B> p; |
394 | p.core_->setInterruptHandlerNoLock(this->getCore().getInterruptHandler()); |
395 | |
396 | // grab the Future now before we lose our handle on the Promise |
397 | auto sf = p.getSemiFuture(); |
398 | auto* e = this->getExecutor(); |
399 | sf.setExecutor(e); |
400 | auto f = Future<B>(sf.core_); |
401 | sf.core_ = nullptr; |
402 | |
403 | this->setCallback_( |
404 | [state = futures::detail::makeCoreCallbackState( |
405 | std::move(p), std::forward<F>(func))](Try<T>&& t) mutable { |
406 | if (!R::Arg::isTry() && t.hasException()) { |
407 | state.setException(std::move(t.exception())); |
408 | } else { |
409 | // Ensure that if function returned a SemiFuture we correctly chain |
410 | // potential deferral. |
411 | auto tf2 = detail_msvc_15_7_workaround::tryInvoke(R{}, state, t); |
412 | if (tf2.hasException()) { |
413 | state.setException(std::move(tf2.exception())); |
414 | } else { |
415 | auto statePromise = state.stealPromise(); |
416 | auto tf3 = chainExecutor( |
417 | statePromise.core_->getExecutor(), *std::move(tf2)); |
418 | std::exchange(statePromise.core_, nullptr) |
419 | ->setProxy(std::exchange(tf3.core_, nullptr)); |
420 | } |
421 | } |
422 | }); |
423 | |
424 | return f; |
425 | } |
426 | |
427 | template <class T> |
428 | template <typename E> |
429 | SemiFuture<T> |
430 | FutureBase<T>::withinImplementation(Duration dur, E e, Timekeeper* tk) && { |
431 | struct Context { |
432 | explicit Context(E ex) : exception(std::move(ex)) {} |
433 | E exception; |
434 | Future<Unit> thisFuture; |
435 | Promise<T> promise; |
436 | std::atomic<bool> token{false}; |
437 | }; |
438 | |
439 | std::shared_ptr<Timekeeper> tks; |
440 | if (LIKELY(!tk)) { |
441 | tks = folly::detail::getTimekeeperSingleton(); |
442 | tk = tks.get(); |
443 | } |
444 | |
445 | if (UNLIKELY(!tk)) { |
446 | return makeSemiFuture<T>(FutureNoTimekeeper()); |
447 | } |
448 | |
449 | auto ctx = std::make_shared<Context>(std::move(e)); |
450 | |
451 | auto f = [ctx](Try<T>&& t) { |
452 | if (!ctx->token.exchange(true, std::memory_order_relaxed)) { |
453 | ctx->promise.setTry(std::move(t)); |
454 | } |
455 | }; |
456 | using R = futures::detail::callableResult<T, decltype(f)>; |
457 | ctx->thisFuture = this->thenImplementation(std::move(f), R{}); |
458 | |
459 | // Properly propagate interrupt values through futures chained after within() |
460 | ctx->promise.setInterruptHandler( |
461 | [weakCtx = to_weak_ptr(ctx)](const exception_wrapper& ex) { |
462 | if (auto lockedCtx = weakCtx.lock()) { |
463 | lockedCtx->thisFuture.raise(ex); |
464 | } |
465 | }); |
466 | |
467 | // Have time keeper use a weak ptr to hold ctx, |
468 | // so that ctx can be deallocated as soon as the future job finished. |
469 | tk->after(dur).thenTry([weakCtx = to_weak_ptr(ctx)](Try<Unit>&& t) mutable { |
470 | auto lockedCtx = weakCtx.lock(); |
471 | if (!lockedCtx) { |
472 | // ctx already released. "this" completed first, cancel "after" |
473 | return; |
474 | } |
475 | // "after" completed first, cancel "this" |
476 | lockedCtx->thisFuture.raise(FutureTimeout()); |
477 | if (!lockedCtx->token.exchange(true, std::memory_order_relaxed)) { |
478 | if (t.hasException()) { |
479 | lockedCtx->promise.setException(std::move(t.exception())); |
480 | } else { |
481 | lockedCtx->promise.setException(std::move(lockedCtx->exception)); |
482 | } |
483 | } |
484 | }); |
485 | |
486 | return ctx->promise.getSemiFuture(); |
487 | } |
488 | |
489 | /** |
490 | * Defer work until executor is actively boosted. |
491 | * |
492 | * NOTE: that this executor is a private implementation detail belonging to the |
493 | * Folly Futures library and not intended to be used elsewhere. It is designed |
494 | * specifically for the use case of deferring work on a SemiFuture. It is NOT |
495 | * thread safe. Please do not use for any other purpose without great care. |
496 | */ |
497 | class DeferredExecutor final : public Executor { |
498 | public: |
499 | void add(Func func) override { |
500 | auto state = state_.load(std::memory_order_acquire); |
501 | if (state == State::DETACHED) { |
502 | return; |
503 | } |
504 | if (state == State::HAS_EXECUTOR) { |
505 | executor_->add(std::move(func)); |
506 | return; |
507 | } |
508 | DCHECK(state == State::EMPTY); |
509 | func_ = std::move(func); |
510 | if (state_.compare_exchange_strong( |
511 | state, |
512 | State::HAS_FUNCTION, |
513 | std::memory_order_release, |
514 | std::memory_order_acquire)) { |
515 | return; |
516 | } |
517 | DCHECK(state == State::DETACHED || state == State::HAS_EXECUTOR); |
518 | if (state == State::DETACHED) { |
519 | std::exchange(func_, nullptr); |
520 | return; |
521 | } |
522 | executor_->add(std::exchange(func_, nullptr)); |
523 | } |
524 | |
525 | Executor* getExecutor() const { |
526 | assert(executor_.get()); |
527 | return executor_.get(); |
528 | } |
529 | |
530 | void setExecutor(folly::Executor::KeepAlive<> executor) { |
531 | if (nestedExecutors_) { |
532 | auto nestedExecutors = std::exchange(nestedExecutors_, nullptr); |
533 | for (auto& nestedExecutor : *nestedExecutors) { |
534 | nestedExecutor->setExecutor(executor.copy()); |
535 | } |
536 | } |
537 | executor_ = std::move(executor); |
538 | auto state = state_.load(std::memory_order_acquire); |
539 | if (state == State::EMPTY && |
540 | state_.compare_exchange_strong( |
541 | state, |
542 | State::HAS_EXECUTOR, |
543 | std::memory_order_release, |
544 | std::memory_order_acquire)) { |
545 | return; |
546 | } |
547 | |
548 | DCHECK(state == State::HAS_FUNCTION); |
549 | state_.store(State::HAS_EXECUTOR, std::memory_order_release); |
550 | executor_->add(std::exchange(func_, nullptr)); |
551 | } |
552 | |
553 | void detach() { |
554 | if (nestedExecutors_) { |
555 | auto nestedExecutors = std::exchange(nestedExecutors_, nullptr); |
556 | for (auto& nestedExecutor : *nestedExecutors) { |
557 | nestedExecutor->detach(); |
558 | } |
559 | } |
560 | auto state = state_.load(std::memory_order_acquire); |
561 | if (state == State::EMPTY && |
562 | state_.compare_exchange_strong( |
563 | state, |
564 | State::DETACHED, |
565 | std::memory_order_release, |
566 | std::memory_order_acquire)) { |
567 | return; |
568 | } |
569 | |
570 | DCHECK(state == State::HAS_FUNCTION); |
571 | state_.store(State::DETACHED, std::memory_order_release); |
572 | std::exchange(func_, nullptr); |
573 | } |
574 | |
575 | void setNestedExecutors( |
576 | std::vector<folly::Executor::KeepAlive<DeferredExecutor>> executors) { |
577 | DCHECK(!nestedExecutors_); |
578 | nestedExecutors_ = std::make_unique< |
579 | std::vector<folly::Executor::KeepAlive<DeferredExecutor>>>( |
580 | std::move(executors)); |
581 | } |
582 | |
583 | static KeepAlive<DeferredExecutor> create() { |
584 | return makeKeepAlive<DeferredExecutor>(new DeferredExecutor()); |
585 | } |
586 | |
587 | private: |
588 | DeferredExecutor() {} |
589 | |
590 | bool keepAliveAcquire() override { |
591 | auto keepAliveCount = |
592 | keepAliveCount_.fetch_add(1, std::memory_order_relaxed); |
593 | DCHECK(keepAliveCount > 0); |
594 | return true; |
595 | } |
596 | |
597 | void keepAliveRelease() override { |
598 | auto keepAliveCount = |
599 | keepAliveCount_.fetch_sub(1, std::memory_order_acq_rel); |
600 | DCHECK(keepAliveCount > 0); |
601 | if (keepAliveCount == 1) { |
602 | delete this; |
603 | } |
604 | } |
605 | |
606 | enum class State { EMPTY, HAS_FUNCTION, HAS_EXECUTOR, DETACHED }; |
607 | std::atomic<State> state_{State::EMPTY}; |
608 | Func func_; |
609 | folly::Executor::KeepAlive<> executor_; |
610 | std::unique_ptr<std::vector<folly::Executor::KeepAlive<DeferredExecutor>>> |
611 | nestedExecutors_; |
612 | std::atomic<ssize_t> keepAliveCount_{1}; |
613 | }; |
614 | |
615 | class WaitExecutor final : public folly::Executor { |
616 | public: |
617 | void add(Func func) override { |
618 | auto wQueue = queue_.wlock(); |
619 | if (wQueue->detached) { |
620 | return; |
621 | } |
622 | bool empty = wQueue->funcs.empty(); |
623 | wQueue->funcs.push_back(std::move(func)); |
624 | if (empty) { |
625 | baton_.post(); |
626 | } |
627 | } |
628 | |
629 | void drive() { |
630 | baton_.wait(); |
631 | baton_.reset(); |
632 | auto funcs = std::move(queue_.wlock()->funcs); |
633 | for (auto& func : funcs) { |
634 | std::exchange(func, nullptr)(); |
635 | } |
636 | } |
637 | |
638 | using Clock = std::chrono::steady_clock; |
639 | |
640 | bool driveUntil(Clock::time_point deadline) { |
641 | if (!baton_.try_wait_until(deadline)) { |
642 | return false; |
643 | } |
644 | baton_.reset(); |
645 | auto funcs = std::move(queue_.wlock()->funcs); |
646 | for (auto& func : funcs) { |
647 | std::exchange(func, nullptr)(); |
648 | } |
649 | return true; |
650 | } |
651 | |
652 | void detach() { |
653 | // Make sure we don't hold the lock while destroying funcs. |
654 | [&] { |
655 | auto wQueue = queue_.wlock(); |
656 | wQueue->detached = true; |
657 | return std::move(wQueue->funcs); |
658 | }(); |
659 | } |
660 | |
661 | static KeepAlive<WaitExecutor> create() { |
662 | return makeKeepAlive<WaitExecutor>(new WaitExecutor()); |
663 | } |
664 | |
665 | private: |
666 | WaitExecutor() {} |
667 | |
668 | bool keepAliveAcquire() override { |
669 | auto keepAliveCount = |
670 | keepAliveCount_.fetch_add(1, std::memory_order_relaxed); |
671 | DCHECK(keepAliveCount > 0); |
672 | return true; |
673 | } |
674 | |
675 | void keepAliveRelease() override { |
676 | auto keepAliveCount = |
677 | keepAliveCount_.fetch_sub(1, std::memory_order_acq_rel); |
678 | DCHECK(keepAliveCount > 0); |
679 | if (keepAliveCount == 1) { |
680 | delete this; |
681 | } |
682 | } |
683 | |
684 | struct Queue { |
685 | std::vector<Func> funcs; |
686 | bool detached{false}; |
687 | }; |
688 | |
689 | folly::Synchronized<Queue> queue_; |
690 | FutureBatonType baton_; |
691 | |
692 | std::atomic<ssize_t> keepAliveCount_{1}; |
693 | }; |
694 | |
695 | // Vector-like structure to play with window, |
696 | // which otherwise expects a vector of size `times`, |
697 | // which would be expensive with large `times` sizes. |
698 | struct WindowFakeVector { |
699 | using iterator = std::vector<size_t>::iterator; |
700 | |
701 | WindowFakeVector(size_t size) : size_(size) {} |
702 | |
703 | size_t operator[](const size_t index) const { |
704 | return index; |
705 | } |
706 | size_t size() const { |
707 | return size_; |
708 | } |
709 | |
710 | private: |
711 | size_t size_; |
712 | }; |
713 | } // namespace detail |
714 | } // namespace futures |
715 | |
716 | template <class T> |
717 | SemiFuture<typename std::decay<T>::type> makeSemiFuture(T&& t) { |
718 | return makeSemiFuture(Try<typename std::decay<T>::type>(std::forward<T>(t))); |
719 | } |
720 | |
721 | // makeSemiFutureWith(SemiFuture<T>()) -> SemiFuture<T> |
722 | template <class F> |
723 | typename std::enable_if< |
724 | isFutureOrSemiFuture<invoke_result_t<F>>::value, |
725 | SemiFuture<typename invoke_result_t<F>::value_type>>::type |
726 | makeSemiFutureWith(F&& func) { |
727 | using InnerType = typename isFutureOrSemiFuture<invoke_result_t<F>>::Inner; |
728 | try { |
729 | return std::forward<F>(func)(); |
730 | } catch (std::exception& e) { |
731 | return makeSemiFuture<InnerType>( |
732 | exception_wrapper(std::current_exception(), e)); |
733 | } catch (...) { |
734 | return makeSemiFuture<InnerType>( |
735 | exception_wrapper(std::current_exception())); |
736 | } |
737 | } |
738 | |
739 | // makeSemiFutureWith(T()) -> SemiFuture<T> |
740 | // makeSemiFutureWith(void()) -> SemiFuture<Unit> |
741 | template <class F> |
742 | typename std::enable_if< |
743 | !(isFutureOrSemiFuture<invoke_result_t<F>>::value), |
744 | SemiFuture<lift_unit_t<invoke_result_t<F>>>>::type |
745 | makeSemiFutureWith(F&& func) { |
746 | using LiftedResult = lift_unit_t<invoke_result_t<F>>; |
747 | return makeSemiFuture<LiftedResult>( |
748 | makeTryWith([&func]() mutable { return std::forward<F>(func)(); })); |
749 | } |
750 | |
751 | template <class T> |
752 | SemiFuture<T> makeSemiFuture(std::exception_ptr const& e) { |
753 | return makeSemiFuture(Try<T>(e)); |
754 | } |
755 | |
756 | template <class T> |
757 | SemiFuture<T> makeSemiFuture(exception_wrapper ew) { |
758 | return makeSemiFuture(Try<T>(std::move(ew))); |
759 | } |
760 | |
761 | template <class T, class E> |
762 | typename std:: |
763 | enable_if<std::is_base_of<std::exception, E>::value, SemiFuture<T>>::type |
764 | makeSemiFuture(E const& e) { |
765 | return makeSemiFuture(Try<T>(make_exception_wrapper<E>(e))); |
766 | } |
767 | |
768 | template <class T> |
769 | SemiFuture<T> makeSemiFuture(Try<T> t) { |
770 | return SemiFuture<T>(SemiFuture<T>::Core::make(std::move(t))); |
771 | } |
772 | |
773 | // This must be defined after the constructors to avoid a bug in MSVC |
774 | // https://connect.microsoft.com/VisualStudio/feedback/details/3142777/out-of-line-constructor-definition-after-implicit-reference-causes-incorrect-c2244 |
775 | inline SemiFuture<Unit> makeSemiFuture() { |
776 | return makeSemiFuture(Unit{}); |
777 | } |
778 | |
779 | template <class T> |
780 | SemiFuture<T> SemiFuture<T>::makeEmpty() { |
781 | return SemiFuture<T>(futures::detail::EmptyConstruct{}); |
782 | } |
783 | |
784 | template <class T> |
785 | typename SemiFuture<T>::DeferredExecutor* SemiFuture<T>::getDeferredExecutor() |
786 | const { |
787 | if (auto executor = this->getExecutor()) { |
788 | assert(dynamic_cast<DeferredExecutor*>(executor) != nullptr); |
789 | return static_cast<DeferredExecutor*>(executor); |
790 | } |
791 | return nullptr; |
792 | } |
793 | |
794 | template <class T> |
795 | folly::Executor::KeepAlive<typename SemiFuture<T>::DeferredExecutor> |
796 | SemiFuture<T>::stealDeferredExecutor() const { |
797 | if (auto executor = this->getExecutor()) { |
798 | assert(dynamic_cast<DeferredExecutor*>(executor) != nullptr); |
799 | auto executorKeepAlive = |
800 | folly::getKeepAliveToken(static_cast<DeferredExecutor*>(executor)); |
801 | this->core_->setExecutor(nullptr); |
802 | return executorKeepAlive; |
803 | } |
804 | return {}; |
805 | } |
806 | |
807 | template <class T> |
808 | void SemiFuture<T>::releaseDeferredExecutor(Core* core) { |
809 | if (!core) { |
810 | return; |
811 | } |
812 | if (auto executor = core->getExecutor()) { |
813 | assert(dynamic_cast<DeferredExecutor*>(executor) != nullptr); |
814 | static_cast<DeferredExecutor*>(executor)->detach(); |
815 | core->setExecutor(nullptr); |
816 | } |
817 | } |
818 | |
819 | template <class T> |
820 | SemiFuture<T>::~SemiFuture() { |
821 | releaseDeferredExecutor(this->core_); |
822 | } |
823 | |
824 | template <class T> |
825 | SemiFuture<T>::SemiFuture(SemiFuture<T>&& other) noexcept |
826 | : futures::detail::FutureBase<T>(std::move(other)) {} |
827 | |
828 | template <class T> |
829 | SemiFuture<T>::SemiFuture(Future<T>&& other) noexcept |
830 | : futures::detail::FutureBase<T>(std::move(other)) { |
831 | // SemiFuture should not have an executor on construction |
832 | if (this->core_) { |
833 | this->setExecutor(nullptr); |
834 | } |
835 | } |
836 | |
837 | template <class T> |
838 | SemiFuture<T>& SemiFuture<T>::operator=(SemiFuture<T>&& other) noexcept { |
839 | releaseDeferredExecutor(this->core_); |
840 | this->assign(std::move(other)); |
841 | return *this; |
842 | } |
843 | |
844 | template <class T> |
845 | SemiFuture<T>& SemiFuture<T>::operator=(Future<T>&& other) noexcept { |
846 | releaseDeferredExecutor(this->core_); |
847 | this->assign(std::move(other)); |
848 | // SemiFuture should not have an executor on construction |
849 | if (this->core_) { |
850 | this->setExecutor(nullptr); |
851 | } |
852 | return *this; |
853 | } |
854 | |
855 | template <class T> |
856 | Future<T> SemiFuture<T>::via( |
857 | Executor::KeepAlive<> executor, |
858 | int8_t priority) && { |
859 | if (!executor) { |
860 | throw_exception<FutureNoExecutor>(); |
861 | } |
862 | |
863 | if (auto deferredExecutor = getDeferredExecutor()) { |
864 | deferredExecutor->setExecutor(executor.copy()); |
865 | } |
866 | |
867 | auto newFuture = Future<T>(this->core_); |
868 | this->core_ = nullptr; |
869 | newFuture.setExecutor(std::move(executor), priority); |
870 | |
871 | return newFuture; |
872 | } |
873 | |
874 | template <class T> |
875 | Future<T> SemiFuture<T>::via(Executor* executor, int8_t priority) && { |
876 | return std::move(*this).via(getKeepAliveToken(executor), priority); |
877 | } |
878 | |
879 | template <class T> |
880 | Future<T> SemiFuture<T>::toUnsafeFuture() && { |
881 | return std::move(*this).via(&InlineExecutor::instance()); |
882 | } |
883 | |
884 | template <class T> |
885 | template <typename F> |
886 | SemiFuture<typename futures::detail::tryCallableResult<T, F>::value_type> |
887 | SemiFuture<T>::defer(F&& func) && { |
888 | DeferredExecutor* deferredExecutor = getDeferredExecutor(); |
889 | if (!deferredExecutor) { |
890 | auto newDeferredExecutor = DeferredExecutor::create(); |
891 | deferredExecutor = newDeferredExecutor.get(); |
892 | this->setExecutor(std::move(newDeferredExecutor)); |
893 | } |
894 | |
895 | auto sf = Future<T>(this->core_).thenTry(std::forward<F>(func)).semi(); |
896 | this->core_ = nullptr; |
897 | // Carry deferred executor through chain as constructor from Future will |
898 | // nullify it |
899 | sf.setExecutor(deferredExecutor); |
900 | return sf; |
901 | } |
902 | |
903 | template <class T> |
904 | template <typename F> |
905 | SemiFuture< |
906 | typename futures::detail::tryExecutorCallableResult<T, F>::value_type> |
907 | SemiFuture<T>::defer(F&& func) && { |
908 | DeferredExecutor* deferredExecutor = getDeferredExecutor(); |
909 | if (!deferredExecutor) { |
910 | auto newDeferredExecutor = DeferredExecutor::create(); |
911 | deferredExecutor = newDeferredExecutor.get(); |
912 | this->setExecutor(std::move(newDeferredExecutor)); |
913 | } |
914 | return std::move(*this).defer( |
915 | [deferredExecutor, f = std::forward<F>(func)](Try<T>&& t) mutable { |
916 | return f(deferredExecutor->getExecutor(), std::move(t)); |
917 | }); |
918 | } |
919 | |
920 | template <class T> |
921 | template <typename F> |
922 | SemiFuture<typename futures::detail::valueCallableResult<T, F>::value_type> |
923 | SemiFuture<T>::deferValue(F&& func) && { |
924 | return std::move(*this).defer([f = std::forward<F>(func)]( |
925 | folly::Try<T>&& t) mutable { |
926 | return std::forward<F>(f)( |
927 | t.template get< |
928 | false, |
929 | typename futures::detail::valueCallableResult<T, F>::FirstArg>()); |
930 | }); |
931 | } |
932 | |
933 | template <class T> |
934 | template <class ExceptionType, class F> |
935 | SemiFuture<T> SemiFuture<T>::deferError(F&& func) && { |
936 | return std::move(*this).defer( |
937 | [func = std::forward<F>(func)](Try<T>&& t) mutable { |
938 | if (auto e = t.template tryGetExceptionObject<ExceptionType>()) { |
939 | return makeSemiFutureWith( |
940 | [&]() mutable { return std::forward<F>(func)(*e); }); |
941 | } else { |
942 | return makeSemiFuture<T>(std::move(t)); |
943 | } |
944 | }); |
945 | } |
946 | |
947 | template <class T> |
948 | template <class F> |
949 | SemiFuture<T> SemiFuture<T>::deferError(F&& func) && { |
950 | return std::move(*this).defer( |
951 | [func = std::forward<F>(func)](Try<T> t) mutable { |
952 | if (t.hasException()) { |
953 | return makeSemiFutureWith([&]() mutable { |
954 | return std::forward<F>(func)(std::move(t.exception())); |
955 | }); |
956 | } else { |
957 | return makeSemiFuture<T>(std::move(t)); |
958 | } |
959 | }); |
960 | } |
961 | |
962 | template <typename T> |
963 | SemiFuture<T> SemiFuture<T>::delayed(Duration dur, Timekeeper* tk) && { |
964 | return collectAllSemiFuture(*this, futures::sleep(dur, tk)) |
965 | .toUnsafeFuture() |
966 | .thenValue([](std::tuple<Try<T>, Try<Unit>> tup) { |
967 | Try<T>& t = std::get<0>(tup); |
968 | return makeFuture<T>(std::move(t)); |
969 | }); |
970 | } |
971 | |
972 | template <class T> |
973 | Future<T> Future<T>::makeEmpty() { |
974 | return Future<T>(futures::detail::EmptyConstruct{}); |
975 | } |
976 | |
977 | template <class T> |
978 | Future<T>::Future(Future<T>&& other) noexcept |
979 | : futures::detail::FutureBase<T>(std::move(other)) {} |
980 | |
981 | template <class T> |
982 | Future<T>& Future<T>::operator=(Future<T>&& other) noexcept { |
983 | this->assign(std::move(other)); |
984 | return *this; |
985 | } |
986 | |
987 | template <class T> |
988 | template < |
989 | class T2, |
990 | typename std::enable_if< |
991 | !std::is_same<T, typename std::decay<T2>::type>::value && |
992 | std::is_constructible<T, T2&&>::value && |
993 | std::is_convertible<T2&&, T>::value, |
994 | int>::type> |
995 | Future<T>::Future(Future<T2>&& other) |
996 | : Future( |
997 | std::move(other).thenValue([](T2&& v) { return T(std::move(v)); })) {} |
998 | |
999 | template <class T> |
1000 | template < |
1001 | class T2, |
1002 | typename std::enable_if< |
1003 | !std::is_same<T, typename std::decay<T2>::type>::value && |
1004 | std::is_constructible<T, T2&&>::value && |
1005 | !std::is_convertible<T2&&, T>::value, |
1006 | int>::type> |
1007 | Future<T>::Future(Future<T2>&& other) |
1008 | : Future( |
1009 | std::move(other).thenValue([](T2&& v) { return T(std::move(v)); })) {} |
1010 | |
1011 | template <class T> |
1012 | template < |
1013 | class T2, |
1014 | typename std::enable_if< |
1015 | !std::is_same<T, typename std::decay<T2>::type>::value && |
1016 | std::is_constructible<T, T2&&>::value, |
1017 | int>::type> |
1018 | Future<T>& Future<T>::operator=(Future<T2>&& other) { |
1019 | return operator=( |
1020 | std::move(other).thenValue([](T2&& v) { return T(std::move(v)); })); |
1021 | } |
1022 | |
1023 | // unwrap |
1024 | |
1025 | template <class T> |
1026 | template <class F> |
1027 | typename std:: |
1028 | enable_if<isFuture<F>::value, Future<typename isFuture<T>::Inner>>::type |
1029 | Future<T>::unwrap() && { |
1030 | return std::move(*this).thenValue( |
1031 | [](Future<typename isFuture<T>::Inner> internal_future) { |
1032 | return internal_future; |
1033 | }); |
1034 | } |
1035 | |
1036 | template <class T> |
1037 | Future<T> Future<T>::via(Executor::KeepAlive<> executor, int8_t priority) && { |
1038 | this->setExecutor(std::move(executor), priority); |
1039 | |
1040 | auto newFuture = Future<T>(this->core_); |
1041 | this->core_ = nullptr; |
1042 | return newFuture; |
1043 | } |
1044 | |
1045 | template <class T> |
1046 | Future<T> Future<T>::via(Executor* executor, int8_t priority) && { |
1047 | return std::move(*this).via(getKeepAliveToken(executor), priority); |
1048 | } |
1049 | |
1050 | template <class T> |
1051 | Future<T> Future<T>::via(Executor::KeepAlive<> executor, int8_t priority) & { |
1052 | this->throwIfInvalid(); |
1053 | Promise<T> p; |
1054 | auto sf = p.getSemiFuture(); |
1055 | auto func = [p = std::move(p)](Try<T>&& t) mutable { |
1056 | p.setTry(std::move(t)); |
1057 | }; |
1058 | using R = futures::detail::callableResult<T, decltype(func)>; |
1059 | this->thenImplementation(std::move(func), R{}); |
1060 | // Construct future from semifuture manually because this may not have |
1061 | // an executor set due to legacy code. This means we can bypass the executor |
1062 | // check in SemiFuture::via |
1063 | auto f = Future<T>(sf.core_); |
1064 | sf.core_ = nullptr; |
1065 | return std::move(f).via(std::move(executor), priority); |
1066 | } |
1067 | |
1068 | template <class T> |
1069 | Future<T> Future<T>::via(Executor* executor, int8_t priority) & { |
1070 | return via(getKeepAliveToken(executor), priority); |
1071 | } |
1072 | |
1073 | template <typename T> |
1074 | template <typename R, typename Caller, typename... Args> |
1075 | Future<typename isFuture<R>::Inner> Future<T>::then( |
1076 | R (Caller::*func)(Args...), |
1077 | Caller* instance) && { |
1078 | typedef typename std::remove_cv<typename std::remove_reference< |
1079 | typename futures::detail::ArgType<Args...>::FirstArg>::type>::type |
1080 | FirstArg; |
1081 | |
1082 | return std::move(*this).thenTry([instance, func](Try<T>&& t) { |
1083 | return (instance->*func)(t.template get<isTry<FirstArg>::value, Args>()...); |
1084 | }); |
1085 | } |
1086 | |
1087 | template <class T> |
1088 | template <typename F> |
1089 | Future<typename futures::detail::tryCallableResult<T, F>::value_type> |
1090 | Future<T>::thenTry(F&& func) && { |
1091 | auto lambdaFunc = [f = std::forward<F>(func)](folly::Try<T>&& t) mutable { |
1092 | return std::forward<F>(f)(std::move(t)); |
1093 | }; |
1094 | using R = futures::detail::tryCallableResult<T, decltype(lambdaFunc)>; |
1095 | return this->thenImplementation(std::move(lambdaFunc), R{}); |
1096 | } |
1097 | |
1098 | template <class T> |
1099 | template <typename F> |
1100 | Future<typename futures::detail::valueCallableResult<T, F>::value_type> |
1101 | Future<T>::thenValue(F&& func) && { |
1102 | auto lambdaFunc = [f = std::forward<F>(func)](folly::Try<T>&& t) mutable { |
1103 | return std::forward<F>(f)( |
1104 | t.template get< |
1105 | false, |
1106 | typename futures::detail::valueCallableResult<T, F>::FirstArg>()); |
1107 | }; |
1108 | using R = futures::detail::tryCallableResult<T, decltype(lambdaFunc)>; |
1109 | return this->thenImplementation(std::move(lambdaFunc), R{}); |
1110 | } |
1111 | |
1112 | template <class T> |
1113 | template <class ExceptionType, class F> |
1114 | Future<T> Future<T>::thenError(F&& func) && { |
1115 | // Forward to onError but ensure that returned future carries the executor |
1116 | // Allow for applying to future with null executor while this is still |
1117 | // possible. |
1118 | auto* ePtr = this->getExecutor(); |
1119 | auto e = folly::getKeepAliveToken(ePtr ? *ePtr : InlineExecutor::instance()); |
1120 | |
1121 | FOLLY_PUSH_WARNING |
1122 | FOLLY_GNU_DISABLE_WARNING("-Wdeprecated-declarations" ) |
1123 | return std::move(*this) |
1124 | .onError([func = std::forward<F>(func)](ExceptionType& ex) mutable { |
1125 | return std::forward<F>(func)(ex); |
1126 | }) |
1127 | .via(std::move(e)); |
1128 | FOLLY_POP_WARNING |
1129 | } |
1130 | |
1131 | template <class T> |
1132 | template <class F> |
1133 | Future<T> Future<T>::thenError(F&& func) && { |
1134 | // Forward to onError but ensure that returned future carries the executor |
1135 | // Allow for applying to future with null executor while this is still |
1136 | // possible. |
1137 | auto* ePtr = this->getExecutor(); |
1138 | auto e = folly::getKeepAliveToken(ePtr ? *ePtr : InlineExecutor::instance()); |
1139 | |
1140 | FOLLY_PUSH_WARNING |
1141 | FOLLY_GNU_DISABLE_WARNING("-Wdeprecated-declarations" ) |
1142 | return std::move(*this) |
1143 | .onError([func = std::forward<F>(func)]( |
1144 | folly::exception_wrapper&& ex) mutable { |
1145 | return std::forward<F>(func)(std::move(ex)); |
1146 | }) |
1147 | .via(std::move(e)); |
1148 | FOLLY_POP_WARNING |
1149 | } |
1150 | |
1151 | template <class T> |
1152 | Future<Unit> Future<T>::then() && { |
1153 | return std::move(*this).thenValue([](T&&) {}); |
1154 | } |
1155 | |
1156 | // onError where the callback returns T |
1157 | template <class T> |
1158 | template <class F> |
1159 | typename std::enable_if< |
1160 | !is_invocable<F, exception_wrapper>::value && |
1161 | !futures::detail::Extract<F>::ReturnsFuture::value, |
1162 | Future<T>>::type |
1163 | Future<T>::onError(F&& func) && { |
1164 | typedef std::remove_reference_t< |
1165 | typename futures::detail::Extract<F>::FirstArg> |
1166 | Exn; |
1167 | static_assert( |
1168 | std::is_same<typename futures::detail::Extract<F>::RawReturn, T>::value, |
1169 | "Return type of onError callback must be T or Future<T>" ); |
1170 | |
1171 | Promise<T> p; |
1172 | p.core_->setInterruptHandlerNoLock(this->getCore().getInterruptHandler()); |
1173 | auto sf = p.getSemiFuture(); |
1174 | |
1175 | this->setCallback_( |
1176 | [state = futures::detail::makeCoreCallbackState( |
1177 | std::move(p), std::forward<F>(func))](Try<T>&& t) mutable { |
1178 | if (auto e = t.template tryGetExceptionObject<Exn>()) { |
1179 | state.setTry(makeTryWith([&] { return state.invoke(*e); })); |
1180 | } else { |
1181 | state.setTry(std::move(t)); |
1182 | } |
1183 | }); |
1184 | |
1185 | // Allow for applying to future with null executor while this is still |
1186 | // possible. |
1187 | // TODO(T26801487): Should have an executor |
1188 | return std::move(sf).via(&InlineExecutor::instance()); |
1189 | } |
1190 | |
1191 | // onError where the callback returns Future<T> |
1192 | template <class T> |
1193 | template <class F> |
1194 | typename std::enable_if< |
1195 | !is_invocable<F, exception_wrapper>::value && |
1196 | futures::detail::Extract<F>::ReturnsFuture::value, |
1197 | Future<T>>::type |
1198 | Future<T>::onError(F&& func) && { |
1199 | static_assert( |
1200 | std::is_same<typename futures::detail::Extract<F>::Return, Future<T>>:: |
1201 | value, |
1202 | "Return type of onError callback must be T or Future<T>" ); |
1203 | typedef std::remove_reference_t< |
1204 | typename futures::detail::Extract<F>::FirstArg> |
1205 | Exn; |
1206 | |
1207 | Promise<T> p; |
1208 | auto sf = p.getSemiFuture(); |
1209 | |
1210 | this->setCallback_( |
1211 | [state = futures::detail::makeCoreCallbackState( |
1212 | std::move(p), std::forward<F>(func))](Try<T>&& t) mutable { |
1213 | if (auto e = t.template tryGetExceptionObject<Exn>()) { |
1214 | auto tf2 = state.tryInvoke(*e); |
1215 | if (tf2.hasException()) { |
1216 | state.setException(std::move(tf2.exception())); |
1217 | } else { |
1218 | tf2->setCallback_([p = state.stealPromise()](Try<T>&& t3) mutable { |
1219 | p.setTry(std::move(t3)); |
1220 | }); |
1221 | } |
1222 | } else { |
1223 | state.setTry(std::move(t)); |
1224 | } |
1225 | }); |
1226 | |
1227 | // Allow for applying to future with null executor while this is still |
1228 | // possible. |
1229 | // TODO(T26801487): Should have an executor |
1230 | return std::move(sf).via(&InlineExecutor::instance()); |
1231 | } |
1232 | |
1233 | template <class T> |
1234 | template <class F> |
1235 | Future<T> Future<T>::ensure(F&& func) && { |
1236 | return std::move(*this).thenTry( |
1237 | [funcw = std::forward<F>(func)](Try<T>&& t) mutable { |
1238 | std::forward<F>(funcw)(); |
1239 | return makeFuture(std::move(t)); |
1240 | }); |
1241 | } |
1242 | |
1243 | template <class T> |
1244 | template <class F> |
1245 | Future<T> Future<T>::onTimeout(Duration dur, F&& func, Timekeeper* tk) && { |
1246 | return std::move(*this).within(dur, tk).template thenError<FutureTimeout>( |
1247 | [funcw = std::forward<F>(func)](auto const&) mutable { |
1248 | return std::forward<F>(funcw)(); |
1249 | }); |
1250 | } |
1251 | |
1252 | template <class T> |
1253 | template <class F> |
1254 | typename std::enable_if< |
1255 | is_invocable<F, exception_wrapper>::value && |
1256 | futures::detail::Extract<F>::ReturnsFuture::value, |
1257 | Future<T>>::type |
1258 | Future<T>::onError(F&& func) && { |
1259 | static_assert( |
1260 | std::is_same<typename futures::detail::Extract<F>::Return, Future<T>>:: |
1261 | value, |
1262 | "Return type of onError callback must be T or Future<T>" ); |
1263 | |
1264 | Promise<T> p; |
1265 | auto sf = p.getSemiFuture(); |
1266 | this->setCallback_( |
1267 | [state = futures::detail::makeCoreCallbackState( |
1268 | std::move(p), std::forward<F>(func))](Try<T> t) mutable { |
1269 | if (t.hasException()) { |
1270 | auto tf2 = state.tryInvoke(std::move(t.exception())); |
1271 | if (tf2.hasException()) { |
1272 | state.setException(std::move(tf2.exception())); |
1273 | } else { |
1274 | tf2->setCallback_([p = state.stealPromise()](Try<T>&& t3) mutable { |
1275 | p.setTry(std::move(t3)); |
1276 | }); |
1277 | } |
1278 | } else { |
1279 | state.setTry(std::move(t)); |
1280 | } |
1281 | }); |
1282 | |
1283 | // Allow for applying to future with null executor while this is still |
1284 | // possible. |
1285 | // TODO(T26801487): Should have an executor |
1286 | return std::move(sf).via(&InlineExecutor::instance()); |
1287 | } |
1288 | |
1289 | // onError(exception_wrapper) that returns T |
1290 | template <class T> |
1291 | template <class F> |
1292 | typename std::enable_if< |
1293 | is_invocable<F, exception_wrapper>::value && |
1294 | !futures::detail::Extract<F>::ReturnsFuture::value, |
1295 | Future<T>>::type |
1296 | Future<T>::onError(F&& func) && { |
1297 | static_assert( |
1298 | std::is_same<typename futures::detail::Extract<F>::Return, Future<T>>:: |
1299 | value, |
1300 | "Return type of onError callback must be T or Future<T>" ); |
1301 | |
1302 | Promise<T> p; |
1303 | auto sf = p.getSemiFuture(); |
1304 | this->setCallback_( |
1305 | [state = futures::detail::makeCoreCallbackState( |
1306 | std::move(p), std::forward<F>(func))](Try<T>&& t) mutable { |
1307 | if (t.hasException()) { |
1308 | state.setTry(makeTryWith( |
1309 | [&] { return state.invoke(std::move(t.exception())); })); |
1310 | } else { |
1311 | state.setTry(std::move(t)); |
1312 | } |
1313 | }); |
1314 | |
1315 | // Allow for applying to future with null executor while this is still |
1316 | // possible. |
1317 | // TODO(T26801487): Should have an executor |
1318 | return std::move(sf).via(&InlineExecutor::instance()); |
1319 | } |
1320 | |
1321 | template <class Func> |
1322 | auto via(Executor* x, Func&& func) -> Future< |
1323 | typename isFutureOrSemiFuture<decltype(std::declval<Func>()())>::Inner> { |
1324 | // TODO make this actually more performant. :-P #7260175 |
1325 | return via(x).thenValue([f = std::forward<Func>(func)](auto&&) mutable { |
1326 | return std::forward<Func>(f)(); |
1327 | }); |
1328 | } |
1329 | |
1330 | template <class Func> |
1331 | auto via(Executor::KeepAlive<> x, Func&& func) -> Future< |
1332 | typename isFutureOrSemiFuture<decltype(std::declval<Func>()())>::Inner> { |
1333 | return via(std::move(x)) |
1334 | .thenValue([f = std::forward<Func>(func)](auto&&) mutable { |
1335 | return std::forward<Func>(f)(); |
1336 | }); |
1337 | } |
1338 | |
1339 | // makeFuture |
1340 | |
1341 | template <class T> |
1342 | Future<typename std::decay<T>::type> makeFuture(T&& t) { |
1343 | return makeFuture(Try<typename std::decay<T>::type>(std::forward<T>(t))); |
1344 | } |
1345 | |
1346 | inline Future<Unit> makeFuture() { |
1347 | return makeFuture(Unit{}); |
1348 | } |
1349 | |
1350 | // makeFutureWith(Future<T>()) -> Future<T> |
1351 | template <class F> |
1352 | typename std:: |
1353 | enable_if<isFuture<invoke_result_t<F>>::value, invoke_result_t<F>>::type |
1354 | makeFutureWith(F&& func) { |
1355 | using InnerType = typename isFuture<invoke_result_t<F>>::Inner; |
1356 | try { |
1357 | return std::forward<F>(func)(); |
1358 | } catch (std::exception& e) { |
1359 | return makeFuture<InnerType>( |
1360 | exception_wrapper(std::current_exception(), e)); |
1361 | } catch (...) { |
1362 | return makeFuture<InnerType>(exception_wrapper(std::current_exception())); |
1363 | } |
1364 | } |
1365 | |
1366 | // makeFutureWith(T()) -> Future<T> |
1367 | // makeFutureWith(void()) -> Future<Unit> |
1368 | template <class F> |
1369 | typename std::enable_if< |
1370 | !(isFuture<invoke_result_t<F>>::value), |
1371 | Future<lift_unit_t<invoke_result_t<F>>>>::type |
1372 | makeFutureWith(F&& func) { |
1373 | using LiftedResult = lift_unit_t<invoke_result_t<F>>; |
1374 | return makeFuture<LiftedResult>( |
1375 | makeTryWith([&func]() mutable { return std::forward<F>(func)(); })); |
1376 | } |
1377 | |
1378 | template <class T> |
1379 | Future<T> makeFuture(std::exception_ptr const& e) { |
1380 | return makeFuture(Try<T>(e)); |
1381 | } |
1382 | |
1383 | template <class T> |
1384 | Future<T> makeFuture(exception_wrapper ew) { |
1385 | return makeFuture(Try<T>(std::move(ew))); |
1386 | } |
1387 | |
1388 | template <class T, class E> |
1389 | typename std::enable_if<std::is_base_of<std::exception, E>::value, Future<T>>:: |
1390 | type |
1391 | makeFuture(E const& e) { |
1392 | return makeFuture(Try<T>(make_exception_wrapper<E>(e))); |
1393 | } |
1394 | |
1395 | template <class T> |
1396 | Future<T> makeFuture(Try<T> t) { |
1397 | return Future<T>(Future<T>::Core::make(std::move(t))); |
1398 | } |
1399 | |
1400 | // via |
1401 | Future<Unit> via(Executor* executor, int8_t priority) { |
1402 | return makeFuture().via(executor, priority); |
1403 | } |
1404 | |
1405 | Future<Unit> via(Executor::KeepAlive<> executor, int8_t priority) { |
1406 | return makeFuture().via(std::move(executor), priority); |
1407 | } |
1408 | |
1409 | namespace futures { |
1410 | namespace detail { |
1411 | |
1412 | template <typename V, typename... Fs, std::size_t... Is> |
1413 | FOLLY_ALWAYS_INLINE FOLLY_ATTR_VISIBILITY_HIDDEN void |
1414 | foreach_(index_sequence<Is...>, V&& v, Fs&&... fs) { |
1415 | using _ = int[]; |
1416 | void(_{0, (void(v(index_constant<Is>{}, static_cast<Fs&&>(fs))), 0)...}); |
1417 | } |
1418 | template <typename V, typename... Fs> |
1419 | FOLLY_ALWAYS_INLINE FOLLY_ATTR_VISIBILITY_HIDDEN void foreach( |
1420 | V&& v, |
1421 | Fs&&... fs) { |
1422 | using _ = index_sequence_for<Fs...>; |
1423 | foreach_(_{}, static_cast<V&&>(v), static_cast<Fs&&>(fs)...); |
1424 | } |
1425 | |
1426 | template <typename T> |
1427 | DeferredExecutor* getDeferredExecutor(SemiFuture<T>& future) { |
1428 | return future.getDeferredExecutor(); |
1429 | } |
1430 | |
1431 | template <typename T> |
1432 | folly::Executor::KeepAlive<DeferredExecutor> stealDeferredExecutor( |
1433 | SemiFuture<T>& future) { |
1434 | return future.stealDeferredExecutor(); |
1435 | } |
1436 | |
1437 | template <typename T> |
1438 | folly::Executor::KeepAlive<DeferredExecutor> stealDeferredExecutor(Future<T>&) { |
1439 | return {}; |
1440 | } |
1441 | |
1442 | template <typename... Ts> |
1443 | void stealDeferredExecutorsVariadic( |
1444 | std::vector<folly::Executor::KeepAlive<DeferredExecutor>>& executors, |
1445 | Ts&... ts) { |
1446 | auto foreach = [&](auto& future) { |
1447 | if (auto executor = stealDeferredExecutor(future)) { |
1448 | executors.push_back(std::move(executor)); |
1449 | } |
1450 | return folly::unit; |
1451 | }; |
1452 | [](...) {}(foreach(ts)...); |
1453 | } |
1454 | |
1455 | template <class InputIterator> |
1456 | void stealDeferredExecutors( |
1457 | std::vector<folly::Executor::KeepAlive<DeferredExecutor>>& executors, |
1458 | InputIterator first, |
1459 | InputIterator last) { |
1460 | for (auto it = first; it != last; ++it) { |
1461 | if (auto executor = stealDeferredExecutor(*it)) { |
1462 | executors.push_back(std::move(executor)); |
1463 | } |
1464 | } |
1465 | } |
1466 | } // namespace detail |
1467 | } // namespace futures |
1468 | |
1469 | // collectAll (variadic) |
1470 | |
1471 | template <typename... Fs> |
1472 | SemiFuture<std::tuple<Try<typename remove_cvref_t<Fs>::value_type>...>> |
1473 | collectAllSemiFuture(Fs&&... fs) { |
1474 | using Result = std::tuple<Try<typename remove_cvref_t<Fs>::value_type>...>; |
1475 | struct Context { |
1476 | ~Context() { |
1477 | p.setValue(std::move(results)); |
1478 | } |
1479 | Promise<Result> p; |
1480 | Result results; |
1481 | }; |
1482 | |
1483 | std::vector<folly::Executor::KeepAlive<futures::detail::DeferredExecutor>> |
1484 | executors; |
1485 | futures::detail::stealDeferredExecutorsVariadic(executors, fs...); |
1486 | |
1487 | auto ctx = std::make_shared<Context>(); |
1488 | futures::detail::foreach( |
1489 | [&](auto i, auto&& f) { |
1490 | f.setCallback_([i, ctx](auto&& t) { |
1491 | std::get<i.value>(ctx->results) = std::move(t); |
1492 | }); |
1493 | }, |
1494 | static_cast<Fs&&>(fs)...); |
1495 | |
1496 | auto future = ctx->p.getSemiFuture(); |
1497 | if (!executors.empty()) { |
1498 | auto work = [](Try<typename decltype(future)::value_type>&& t) { |
1499 | return std::move(t).value(); |
1500 | }; |
1501 | future = std::move(future).defer(work); |
1502 | auto deferredExecutor = futures::detail::getDeferredExecutor(future); |
1503 | deferredExecutor->setNestedExecutors(std::move(executors)); |
1504 | } |
1505 | return future; |
1506 | } |
1507 | |
1508 | template <typename... Fs> |
1509 | Future<std::tuple<Try<typename remove_cvref_t<Fs>::value_type>...>> collectAll( |
1510 | Fs&&... fs) { |
1511 | return collectAllSemiFuture(std::forward<Fs>(fs)...).toUnsafeFuture(); |
1512 | } |
1513 | |
1514 | // collectAll (iterator) |
1515 | |
1516 | template <class InputIterator> |
1517 | SemiFuture<std::vector< |
1518 | Try<typename std::iterator_traits<InputIterator>::value_type::value_type>>> |
1519 | collectAllSemiFuture(InputIterator first, InputIterator last) { |
1520 | using F = typename std::iterator_traits<InputIterator>::value_type; |
1521 | using T = typename F::value_type; |
1522 | |
1523 | struct Context { |
1524 | explicit Context(size_t n) : results(n) {} |
1525 | ~Context() { |
1526 | p.setValue(std::move(results)); |
1527 | } |
1528 | Promise<std::vector<Try<T>>> p; |
1529 | std::vector<Try<T>> results; |
1530 | }; |
1531 | |
1532 | std::vector<folly::Executor::KeepAlive<futures::detail::DeferredExecutor>> |
1533 | executors; |
1534 | futures::detail::stealDeferredExecutors(executors, first, last); |
1535 | |
1536 | auto ctx = std::make_shared<Context>(size_t(std::distance(first, last))); |
1537 | |
1538 | for (size_t i = 0; first != last; ++first, ++i) { |
1539 | first->setCallback_( |
1540 | [i, ctx](Try<T>&& t) { ctx->results[i] = std::move(t); }); |
1541 | } |
1542 | |
1543 | auto future = ctx->p.getSemiFuture(); |
1544 | if (!executors.empty()) { |
1545 | future = std::move(future).defer( |
1546 | [](Try<typename decltype(future)::value_type>&& t) { |
1547 | return std::move(t).value(); |
1548 | }); |
1549 | auto deferredExecutor = futures::detail::getDeferredExecutor(future); |
1550 | deferredExecutor->setNestedExecutors(std::move(executors)); |
1551 | } |
1552 | return future; |
1553 | } |
1554 | |
1555 | template <class InputIterator> |
1556 | Future<std::vector< |
1557 | Try<typename std::iterator_traits<InputIterator>::value_type::value_type>>> |
1558 | collectAll(InputIterator first, InputIterator last) { |
1559 | return collectAllSemiFuture(first, last).toUnsafeFuture(); |
1560 | } |
1561 | |
1562 | // collect (iterator) |
1563 | |
1564 | // TODO(T26439406): Make return SemiFuture |
1565 | template <class InputIterator> |
1566 | Future<std::vector< |
1567 | typename std::iterator_traits<InputIterator>::value_type::value_type>> |
1568 | collect(InputIterator first, InputIterator last) { |
1569 | using F = typename std::iterator_traits<InputIterator>::value_type; |
1570 | using T = typename F::value_type; |
1571 | |
1572 | struct Context { |
1573 | explicit Context(size_t n) : result(n) { |
1574 | finalResult.reserve(n); |
1575 | } |
1576 | ~Context() { |
1577 | if (!threw.load(std::memory_order_relaxed)) { |
1578 | // map Optional<T> -> T |
1579 | std::transform( |
1580 | result.begin(), |
1581 | result.end(), |
1582 | std::back_inserter(finalResult), |
1583 | [](Optional<T>& o) { return std::move(o.value()); }); |
1584 | p.setValue(std::move(finalResult)); |
1585 | } |
1586 | } |
1587 | Promise<std::vector<T>> p; |
1588 | std::vector<Optional<T>> result; |
1589 | std::vector<T> finalResult; |
1590 | std::atomic<bool> threw{false}; |
1591 | }; |
1592 | |
1593 | auto ctx = std::make_shared<Context>(std::distance(first, last)); |
1594 | for (size_t i = 0; first != last; ++first, ++i) { |
1595 | first->setCallback_([i, ctx](Try<T>&& t) { |
1596 | if (t.hasException()) { |
1597 | if (!ctx->threw.exchange(true, std::memory_order_relaxed)) { |
1598 | ctx->p.setException(std::move(t.exception())); |
1599 | } |
1600 | } else if (!ctx->threw.load(std::memory_order_relaxed)) { |
1601 | ctx->result[i] = std::move(t.value()); |
1602 | } |
1603 | }); |
1604 | } |
1605 | return ctx->p.getSemiFuture().via(&InlineExecutor::instance()); |
1606 | } |
1607 | |
1608 | // collect (variadic) |
1609 | |
1610 | // TODO(T26439406): Make return SemiFuture |
1611 | template <typename... Fs> |
1612 | Future<std::tuple<typename remove_cvref_t<Fs>::value_type...>> collect( |
1613 | Fs&&... fs) { |
1614 | using Result = std::tuple<typename remove_cvref_t<Fs>::value_type...>; |
1615 | struct Context { |
1616 | ~Context() { |
1617 | if (!threw.load(std::memory_order_relaxed)) { |
1618 | p.setValue(unwrapTryTuple(std::move(results))); |
1619 | } |
1620 | } |
1621 | Promise<Result> p; |
1622 | std::tuple<Try<typename remove_cvref_t<Fs>::value_type>...> results; |
1623 | std::atomic<bool> threw{false}; |
1624 | }; |
1625 | |
1626 | auto ctx = std::make_shared<Context>(); |
1627 | futures::detail::foreach( |
1628 | [&](auto i, auto&& f) { |
1629 | f.setCallback_([i, ctx](auto&& t) { |
1630 | if (t.hasException()) { |
1631 | if (!ctx->threw.exchange(true, std::memory_order_relaxed)) { |
1632 | ctx->p.setException(std::move(t.exception())); |
1633 | } |
1634 | } else if (!ctx->threw.load(std::memory_order_relaxed)) { |
1635 | std::get<i.value>(ctx->results) = std::move(t); |
1636 | } |
1637 | }); |
1638 | }, |
1639 | static_cast<Fs&&>(fs)...); |
1640 | return ctx->p.getSemiFuture().via(&InlineExecutor::instance()); |
1641 | } |
1642 | |
1643 | // collectAny (iterator) |
1644 | |
1645 | // TODO(T26439406): Make return SemiFuture |
1646 | template <class InputIterator> |
1647 | Future<std::pair< |
1648 | size_t, |
1649 | Try<typename std::iterator_traits<InputIterator>::value_type::value_type>>> |
1650 | collectAny(InputIterator first, InputIterator last) { |
1651 | using F = typename std::iterator_traits<InputIterator>::value_type; |
1652 | using T = typename F::value_type; |
1653 | |
1654 | struct Context { |
1655 | Promise<std::pair<size_t, Try<T>>> p; |
1656 | std::atomic<bool> done{false}; |
1657 | }; |
1658 | |
1659 | auto ctx = std::make_shared<Context>(); |
1660 | for (size_t i = 0; first != last; ++first, ++i) { |
1661 | first->setCallback_([i, ctx](Try<T>&& t) { |
1662 | if (!ctx->done.exchange(true, std::memory_order_relaxed)) { |
1663 | ctx->p.setValue(std::make_pair(i, std::move(t))); |
1664 | } |
1665 | }); |
1666 | } |
1667 | return ctx->p.getSemiFuture().via(&InlineExecutor::instance()); |
1668 | } |
1669 | |
1670 | // collectAnyWithoutException (iterator) |
1671 | |
1672 | template <class InputIterator> |
1673 | SemiFuture<std::pair< |
1674 | size_t, |
1675 | typename std::iterator_traits<InputIterator>::value_type::value_type>> |
1676 | collectAnyWithoutException(InputIterator first, InputIterator last) { |
1677 | using F = typename std::iterator_traits<InputIterator>::value_type; |
1678 | using T = typename F::value_type; |
1679 | |
1680 | struct Context { |
1681 | Context(size_t n) : nTotal(n) {} |
1682 | Promise<std::pair<size_t, T>> p; |
1683 | std::atomic<bool> done{false}; |
1684 | std::atomic<size_t> nFulfilled{0}; |
1685 | size_t nTotal; |
1686 | }; |
1687 | |
1688 | std::vector<folly::Executor::KeepAlive<futures::detail::DeferredExecutor>> |
1689 | executors; |
1690 | futures::detail::stealDeferredExecutors(executors, first, last); |
1691 | |
1692 | auto ctx = std::make_shared<Context>(size_t(std::distance(first, last))); |
1693 | for (size_t i = 0; first != last; ++first, ++i) { |
1694 | first->setCallback_([i, ctx](Try<T>&& t) { |
1695 | if (!t.hasException() && |
1696 | !ctx->done.exchange(true, std::memory_order_relaxed)) { |
1697 | ctx->p.setValue(std::make_pair(i, std::move(t.value()))); |
1698 | } else if ( |
1699 | ctx->nFulfilled.fetch_add(1, std::memory_order_relaxed) + 1 == |
1700 | ctx->nTotal) { |
1701 | ctx->p.setException(t.exception()); |
1702 | } |
1703 | }); |
1704 | } |
1705 | |
1706 | auto future = ctx->p.getSemiFuture(); |
1707 | if (!executors.empty()) { |
1708 | future = std::move(future).defer( |
1709 | [](Try<typename decltype(future)::value_type>&& t) { |
1710 | return std::move(t).value(); |
1711 | }); |
1712 | auto deferredExecutor = futures::detail::getDeferredExecutor(future); |
1713 | deferredExecutor->setNestedExecutors(std::move(executors)); |
1714 | } |
1715 | return future; |
1716 | } |
1717 | |
1718 | // collectN (iterator) |
1719 | |
1720 | template <class InputIterator> |
1721 | SemiFuture<std::vector<std::pair< |
1722 | size_t, |
1723 | Try<typename std::iterator_traits<InputIterator>::value_type::value_type>>>> |
1724 | collectN(InputIterator first, InputIterator last, size_t n) { |
1725 | using F = typename std::iterator_traits<InputIterator>::value_type; |
1726 | using T = typename F::value_type; |
1727 | using Result = std::vector<std::pair<size_t, Try<T>>>; |
1728 | |
1729 | struct Context { |
1730 | explicit Context(size_t numFutures, size_t min_) |
1731 | : v(numFutures), min(min_) {} |
1732 | |
1733 | std::vector<Optional<Try<T>>> v; |
1734 | size_t min; |
1735 | std::atomic<size_t> completed = {0}; // # input futures completed |
1736 | std::atomic<size_t> stored = {0}; // # output values stored |
1737 | Promise<Result> p; |
1738 | }; |
1739 | |
1740 | assert(n > 0); |
1741 | assert(std::distance(first, last) >= 0); |
1742 | |
1743 | if (size_t(std::distance(first, last)) < n) { |
1744 | return SemiFuture<Result>( |
1745 | exception_wrapper(std::runtime_error("Not enough futures" ))); |
1746 | } |
1747 | |
1748 | // for each completed Future, increase count and add to vector, until we |
1749 | // have n completed futures at which point we fulfil our Promise with the |
1750 | // vector |
1751 | auto ctx = std::make_shared<Context>(size_t(std::distance(first, last)), n); |
1752 | for (size_t i = 0; first != last; ++first, ++i) { |
1753 | first->setCallback_([i, ctx](Try<T>&& t) { |
1754 | // relaxed because this guards control but does not guard data |
1755 | auto const c = 1 + ctx->completed.fetch_add(1, std::memory_order_relaxed); |
1756 | if (c > ctx->min) { |
1757 | return; |
1758 | } |
1759 | ctx->v[i] = std::move(t); |
1760 | |
1761 | // release because the stored values in all threads must be visible below |
1762 | // acquire because no stored value is permitted to be fetched early |
1763 | auto const s = 1 + ctx->stored.fetch_add(1, std::memory_order_acq_rel); |
1764 | if (s < ctx->min) { |
1765 | return; |
1766 | } |
1767 | Result result; |
1768 | result.reserve(ctx->completed.load()); |
1769 | for (size_t j = 0; j < ctx->v.size(); ++j) { |
1770 | auto& entry = ctx->v[j]; |
1771 | if (entry.hasValue()) { |
1772 | result.emplace_back(j, std::move(entry).value()); |
1773 | } |
1774 | } |
1775 | ctx->p.setTry(Try<Result>(std::move(result))); |
1776 | }); |
1777 | } |
1778 | |
1779 | return ctx->p.getSemiFuture(); |
1780 | } |
1781 | |
1782 | // reduce (iterator) |
1783 | |
1784 | template <class It, class T, class F> |
1785 | Future<T> reduce(It first, It last, T&& initial, F&& func) { |
1786 | if (first == last) { |
1787 | return makeFuture(std::forward<T>(initial)); |
1788 | } |
1789 | |
1790 | typedef typename std::iterator_traits<It>::value_type::value_type ItT; |
1791 | typedef typename std:: |
1792 | conditional<is_invocable<F, T&&, Try<ItT>&&>::value, Try<ItT>, ItT>::type |
1793 | Arg; |
1794 | typedef isTry<Arg> IsTry; |
1795 | |
1796 | auto sfunc = std::make_shared<std::decay_t<F>>(std::forward<F>(func)); |
1797 | |
1798 | auto f = std::move(*first).thenTry( |
1799 | [initial = std::forward<T>(initial), sfunc](Try<ItT>&& head) mutable { |
1800 | return (*sfunc)( |
1801 | std::move(initial), head.template get<IsTry::value, Arg&&>()); |
1802 | }); |
1803 | |
1804 | for (++first; first != last; ++first) { |
1805 | f = collectAllSemiFuture(f, *first).toUnsafeFuture().thenValue( |
1806 | [sfunc](std::tuple<Try<T>, Try<ItT>>&& t) { |
1807 | return (*sfunc)( |
1808 | std::move(std::get<0>(t).value()), |
1809 | // Either return a ItT&& or a Try<ItT>&& depending |
1810 | // on the type of the argument of func. |
1811 | std::get<1>(t).template get<IsTry::value, Arg&&>()); |
1812 | }); |
1813 | } |
1814 | |
1815 | return f; |
1816 | } |
1817 | |
1818 | // window (collection) |
1819 | |
1820 | template <class Collection, class F, class ItT, class Result> |
1821 | std::vector<Future<Result>> window(Collection input, F func, size_t n) { |
1822 | // Use global QueuedImmediateExecutor singleton to avoid stack overflow. |
1823 | auto executor = &QueuedImmediateExecutor::instance(); |
1824 | return window(executor, std::move(input), std::move(func), n); |
1825 | } |
1826 | |
1827 | template <class F> |
1828 | auto window(size_t times, F func, size_t n) |
1829 | -> std::vector<invoke_result_t<F, size_t>> { |
1830 | return window(futures::detail::WindowFakeVector(times), std::move(func), n); |
1831 | } |
1832 | |
1833 | template <class Collection, class F, class ItT, class Result> |
1834 | std::vector<Future<Result>> |
1835 | window(Executor* executor, Collection input, F func, size_t n) { |
1836 | return window( |
1837 | getKeepAliveToken(executor), std::move(input), std::move(func), n); |
1838 | } |
1839 | |
1840 | template <class Collection, class F, class ItT, class Result> |
1841 | std::vector<Future<Result>> |
1842 | window(Executor::KeepAlive<> executor, Collection input, F func, size_t n) { |
1843 | struct WindowContext { |
1844 | WindowContext( |
1845 | Executor::KeepAlive<> executor_, |
1846 | Collection&& input_, |
1847 | F&& func_) |
1848 | : executor(std::move(executor_)), |
1849 | input(std::move(input_)), |
1850 | promises(input.size()), |
1851 | func(std::move(func_)) {} |
1852 | std::atomic<size_t> i{0}; |
1853 | Executor::KeepAlive<> executor; |
1854 | Collection input; |
1855 | std::vector<Promise<Result>> promises; |
1856 | F func; |
1857 | |
1858 | static void spawn(std::shared_ptr<WindowContext> ctx) { |
1859 | size_t i = ctx->i.fetch_add(1, std::memory_order_relaxed); |
1860 | if (i < ctx->input.size()) { |
1861 | auto fut = makeSemiFutureWith( |
1862 | [&] { return ctx->func(std::move(ctx->input[i])); }) |
1863 | .via(ctx->executor.get()); |
1864 | |
1865 | fut.setCallback_([ctx = std::move(ctx), i](Try<Result>&& t) mutable { |
1866 | ctx->promises[i].setTry(std::move(t)); |
1867 | // Chain another future onto this one |
1868 | spawn(std::move(ctx)); |
1869 | }); |
1870 | } |
1871 | } |
1872 | }; |
1873 | |
1874 | auto max = std::min(n, input.size()); |
1875 | |
1876 | auto ctx = std::make_shared<WindowContext>( |
1877 | executor.copy(), std::move(input), std::move(func)); |
1878 | |
1879 | // Start the first n Futures |
1880 | for (size_t i = 0; i < max; ++i) { |
1881 | executor->add([ctx]() mutable { WindowContext::spawn(std::move(ctx)); }); |
1882 | } |
1883 | |
1884 | std::vector<Future<Result>> futures; |
1885 | futures.reserve(ctx->promises.size()); |
1886 | for (auto& promise : ctx->promises) { |
1887 | futures.emplace_back(promise.getSemiFuture().via(executor.copy())); |
1888 | } |
1889 | |
1890 | return futures; |
1891 | } |
1892 | |
1893 | // reduce |
1894 | |
1895 | template <class T> |
1896 | template <class I, class F> |
1897 | Future<I> Future<T>::reduce(I&& initial, F&& func) && { |
1898 | return std::move(*this).thenValue( |
1899 | [minitial = std::forward<I>(initial), |
1900 | mfunc = std::forward<F>(func)](T&& vals) mutable { |
1901 | auto ret = std::move(minitial); |
1902 | for (auto& val : vals) { |
1903 | ret = mfunc(std::move(ret), std::move(val)); |
1904 | } |
1905 | return ret; |
1906 | }); |
1907 | } |
1908 | |
1909 | // unorderedReduce (iterator) |
1910 | |
1911 | // TODO(T26439406): Make return SemiFuture |
1912 | template <class It, class T, class F> |
1913 | Future<T> unorderedReduce(It first, It last, T initial, F func) { |
1914 | using ItF = typename std::iterator_traits<It>::value_type; |
1915 | using ItT = typename ItF::value_type; |
1916 | using Arg = MaybeTryArg<F, T, ItT>; |
1917 | |
1918 | if (first == last) { |
1919 | return makeFuture(std::move(initial)); |
1920 | } |
1921 | |
1922 | typedef isTry<Arg> IsTry; |
1923 | |
1924 | struct Context { |
1925 | Context(T&& memo, F&& fn, size_t n) |
1926 | : lock_(), |
1927 | memo_(makeFuture<T>(std::move(memo))), |
1928 | func_(std::move(fn)), |
1929 | numThens_(0), |
1930 | numFutures_(n), |
1931 | promise_() {} |
1932 | |
1933 | folly::MicroSpinLock lock_; // protects memo_ and numThens_ |
1934 | Future<T> memo_; |
1935 | F func_; |
1936 | size_t numThens_; // how many Futures completed and called .then() |
1937 | size_t numFutures_; // how many Futures in total |
1938 | Promise<T> promise_; |
1939 | }; |
1940 | |
1941 | struct Fulfill { |
1942 | void operator()(Promise<T>&& p, T&& v) const { |
1943 | p.setValue(std::move(v)); |
1944 | } |
1945 | void operator()(Promise<T>&& p, Future<T>&& f) const { |
1946 | f.setCallback_( |
1947 | [p = std::move(p)](Try<T>&& t) mutable { p.setTry(std::move(t)); }); |
1948 | } |
1949 | }; |
1950 | |
1951 | auto ctx = std::make_shared<Context>( |
1952 | std::move(initial), std::move(func), std::distance(first, last)); |
1953 | for (size_t i = 0; first != last; ++first, ++i) { |
1954 | first->setCallback_([i, ctx](Try<ItT>&& t) { |
1955 | (void)i; |
1956 | // Futures can be completed in any order, simultaneously. |
1957 | // To make this non-blocking, we create a new Future chain in |
1958 | // the order of completion to reduce the values. |
1959 | // The spinlock just protects chaining a new Future, not actually |
1960 | // executing the reduce, which should be really fast. |
1961 | Promise<T> p; |
1962 | auto f = p.getFuture(); |
1963 | { |
1964 | folly::MSLGuard lock(ctx->lock_); |
1965 | f = exchange(ctx->memo_, std::move(f)); |
1966 | if (++ctx->numThens_ == ctx->numFutures_) { |
1967 | // After reducing the value of the last Future, fulfill the Promise |
1968 | ctx->memo_.setCallback_( |
1969 | [ctx](Try<T>&& t2) { ctx->promise_.setValue(std::move(t2)); }); |
1970 | } |
1971 | } |
1972 | f.setCallback_( |
1973 | [ctx, mp = std::move(p), mt = std::move(t)](Try<T>&& v) mutable { |
1974 | if (v.hasValue()) { |
1975 | try { |
1976 | Fulfill{}( |
1977 | std::move(mp), |
1978 | ctx->func_( |
1979 | std::move(v.value()), |
1980 | mt.template get<IsTry::value, Arg&&>())); |
1981 | } catch (std::exception& e) { |
1982 | mp.setException(exception_wrapper(std::current_exception(), e)); |
1983 | } catch (...) { |
1984 | mp.setException(exception_wrapper(std::current_exception())); |
1985 | } |
1986 | } else { |
1987 | mp.setTry(std::move(v)); |
1988 | } |
1989 | }); |
1990 | }); |
1991 | } |
1992 | return ctx->promise_.getSemiFuture().via(&InlineExecutor::instance()); |
1993 | } |
1994 | |
1995 | // within |
1996 | |
1997 | template <class T> |
1998 | Future<T> Future<T>::within(Duration dur, Timekeeper* tk) && { |
1999 | return std::move(*this).within(dur, FutureTimeout(), tk); |
2000 | } |
2001 | |
2002 | template <class T> |
2003 | template <class E> |
2004 | Future<T> Future<T>::within(Duration dur, E e, Timekeeper* tk) && { |
2005 | if (this->isReady()) { |
2006 | return std::move(*this); |
2007 | } |
2008 | |
2009 | auto* exe = this->getExecutor(); |
2010 | return std::move(*this) |
2011 | .withinImplementation(dur, e, tk) |
2012 | .via(exe ? exe : &InlineExecutor::instance()); |
2013 | } |
2014 | |
2015 | // delayed |
2016 | |
2017 | template <class T> |
2018 | Future<T> Future<T>::delayed(Duration dur, Timekeeper* tk) && { |
2019 | auto e = this->getExecutor(); |
2020 | return collectAllSemiFuture(*this, futures::sleep(dur, tk)) |
2021 | .via(e ? e : &InlineExecutor::instance()) |
2022 | .thenValue([](std::tuple<Try<T>, Try<Unit>>&& tup) { |
2023 | return makeFuture<T>(std::get<0>(std::move(tup))); |
2024 | }); |
2025 | } |
2026 | |
2027 | template <class T> |
2028 | Future<T> Future<T>::delayedUnsafe(Duration dur, Timekeeper* tk) { |
2029 | return std::move(*this).semi().delayed(dur, tk).toUnsafeFuture(); |
2030 | } |
2031 | |
2032 | namespace futures { |
2033 | namespace detail { |
2034 | |
2035 | template <class FutureType, typename T = typename FutureType::value_type> |
2036 | void waitImpl(FutureType& f) { |
2037 | if (std::is_base_of<Future<T>, FutureType>::value) { |
2038 | f = std::move(f).via(&InlineExecutor::instance()); |
2039 | } |
2040 | // short-circuit if there's nothing to do |
2041 | if (f.isReady()) { |
2042 | return; |
2043 | } |
2044 | |
2045 | Promise<T> promise; |
2046 | auto ret = promise.getSemiFuture(); |
2047 | auto baton = std::make_shared<FutureBatonType>(); |
2048 | f.setCallback_([baton, promise = std::move(promise)](Try<T>&& t) mutable { |
2049 | promise.setTry(std::move(t)); |
2050 | baton->post(); |
2051 | }); |
2052 | convertFuture(std::move(ret), f); |
2053 | baton->wait(); |
2054 | assert(f.isReady()); |
2055 | } |
2056 | |
2057 | template <class T> |
2058 | void convertFuture(SemiFuture<T>&& sf, Future<T>& f) { |
2059 | // Carry executor from f, inserting an inline executor if it did not have one |
2060 | auto* exe = f.getExecutor(); |
2061 | f = std::move(sf).via(exe ? exe : &InlineExecutor::instance()); |
2062 | } |
2063 | |
2064 | template <class T> |
2065 | void convertFuture(SemiFuture<T>&& sf, SemiFuture<T>& f) { |
2066 | f = std::move(sf); |
2067 | } |
2068 | |
2069 | template <class FutureType, typename T = typename FutureType::value_type> |
2070 | void waitImpl(FutureType& f, Duration dur) { |
2071 | if (std::is_base_of<Future<T>, FutureType>::value) { |
2072 | f = std::move(f).via(&InlineExecutor::instance()); |
2073 | } |
2074 | // short-circuit if there's nothing to do |
2075 | if (f.isReady()) { |
2076 | return; |
2077 | } |
2078 | |
2079 | Promise<T> promise; |
2080 | auto ret = promise.getSemiFuture(); |
2081 | auto baton = std::make_shared<FutureBatonType>(); |
2082 | f.setCallback_([baton, promise = std::move(promise)](Try<T>&& t) mutable { |
2083 | promise.setTry(std::move(t)); |
2084 | baton->post(); |
2085 | }); |
2086 | convertFuture(std::move(ret), f); |
2087 | if (baton->try_wait_for(dur)) { |
2088 | assert(f.isReady()); |
2089 | } |
2090 | } |
2091 | |
2092 | template <class T> |
2093 | void waitViaImpl(Future<T>& f, DrivableExecutor* e) { |
2094 | // Set callback so to ensure that the via executor has something on it |
2095 | // so that once the preceding future triggers this callback, drive will |
2096 | // always have a callback to satisfy it |
2097 | if (f.isReady()) { |
2098 | return; |
2099 | } |
2100 | f = std::move(f).via(e).thenValue([](T&& t) { return std::move(t); }); |
2101 | while (!f.isReady()) { |
2102 | e->drive(); |
2103 | } |
2104 | assert(f.isReady()); |
2105 | f = std::move(f).via(&InlineExecutor::instance()); |
2106 | } |
2107 | |
2108 | template <class T, typename Rep, typename Period> |
2109 | void waitViaImpl( |
2110 | Future<T>& f, |
2111 | TimedDrivableExecutor* e, |
2112 | const std::chrono::duration<Rep, Period>& timeout) { |
2113 | // Set callback so to ensure that the via executor has something on it |
2114 | // so that once the preceding future triggers this callback, drive will |
2115 | // always have a callback to satisfy it |
2116 | if (f.isReady()) { |
2117 | return; |
2118 | } |
2119 | // Chain operations, ensuring that the executor is kept alive for the duration |
2120 | f = std::move(f).via(e).thenValue( |
2121 | [keepAlive = getKeepAliveToken(e)](T&& t) { return std::move(t); }); |
2122 | auto now = std::chrono::steady_clock::now(); |
2123 | auto deadline = now + timeout; |
2124 | while (!f.isReady() && (now < deadline)) { |
2125 | e->try_drive_until(deadline); |
2126 | now = std::chrono::steady_clock::now(); |
2127 | } |
2128 | assert(f.isReady() || (now >= deadline)); |
2129 | if (f.isReady()) { |
2130 | f = std::move(f).via(&InlineExecutor::instance()); |
2131 | } |
2132 | } |
2133 | |
2134 | } // namespace detail |
2135 | } // namespace futures |
2136 | |
2137 | template <class T> |
2138 | SemiFuture<T>& SemiFuture<T>::wait() & { |
2139 | if (auto deferredExecutor = getDeferredExecutor()) { |
2140 | // Make sure that the last callback in the future chain will be run on the |
2141 | // WaitExecutor. |
2142 | Promise<T> promise; |
2143 | auto ret = promise.getSemiFuture(); |
2144 | setCallback_( |
2145 | [p = std::move(promise)](auto&& r) mutable { p.setTry(std::move(r)); }); |
2146 | auto waitExecutor = futures::detail::WaitExecutor::create(); |
2147 | deferredExecutor->setExecutor(waitExecutor.copy()); |
2148 | while (!ret.isReady()) { |
2149 | waitExecutor->drive(); |
2150 | } |
2151 | waitExecutor->detach(); |
2152 | this->detach(); |
2153 | *this = std::move(ret); |
2154 | } else { |
2155 | futures::detail::waitImpl(*this); |
2156 | } |
2157 | return *this; |
2158 | } |
2159 | |
2160 | template <class T> |
2161 | SemiFuture<T>&& SemiFuture<T>::wait() && { |
2162 | return std::move(wait()); |
2163 | } |
2164 | |
2165 | template <class T> |
2166 | SemiFuture<T>& SemiFuture<T>::wait(Duration dur) & { |
2167 | if (auto deferredExecutor = getDeferredExecutor()) { |
2168 | // Make sure that the last callback in the future chain will be run on the |
2169 | // WaitExecutor. |
2170 | Promise<T> promise; |
2171 | auto ret = promise.getSemiFuture(); |
2172 | setCallback_( |
2173 | [p = std::move(promise)](auto&& r) mutable { p.setTry(std::move(r)); }); |
2174 | auto waitExecutor = futures::detail::WaitExecutor::create(); |
2175 | auto deadline = futures::detail::WaitExecutor::Clock::now() + dur; |
2176 | deferredExecutor->setExecutor(waitExecutor.copy()); |
2177 | while (!ret.isReady()) { |
2178 | if (!waitExecutor->driveUntil(deadline)) { |
2179 | break; |
2180 | } |
2181 | } |
2182 | waitExecutor->detach(); |
2183 | this->detach(); |
2184 | *this = std::move(ret); |
2185 | } else { |
2186 | futures::detail::waitImpl(*this, dur); |
2187 | } |
2188 | return *this; |
2189 | } |
2190 | |
2191 | template <class T> |
2192 | bool SemiFuture<T>::wait(Duration dur) && { |
2193 | auto future = std::move(*this); |
2194 | future.wait(dur); |
2195 | return future.isReady(); |
2196 | } |
2197 | |
2198 | template <class T> |
2199 | T SemiFuture<T>::get() && { |
2200 | return std::move(*this).getTry().value(); |
2201 | } |
2202 | |
2203 | template <class T> |
2204 | T SemiFuture<T>::get(Duration dur) && { |
2205 | return std::move(*this).getTry(dur).value(); |
2206 | } |
2207 | |
2208 | template <class T> |
2209 | Try<T> SemiFuture<T>::getTry() && { |
2210 | wait(); |
2211 | auto future = folly::Future<T>(this->core_); |
2212 | this->core_ = nullptr; |
2213 | return std::move(std::move(future).getTry()); |
2214 | } |
2215 | |
2216 | template <class T> |
2217 | Try<T> SemiFuture<T>::getTry(Duration dur) && { |
2218 | wait(dur); |
2219 | auto future = folly::Future<T>(this->core_); |
2220 | this->core_ = nullptr; |
2221 | |
2222 | if (!future.isReady()) { |
2223 | throw_exception<FutureTimeout>(); |
2224 | } |
2225 | return std::move(std::move(future).getTry()); |
2226 | } |
2227 | |
2228 | template <class T> |
2229 | Future<T>& Future<T>::wait() & { |
2230 | futures::detail::waitImpl(*this); |
2231 | return *this; |
2232 | } |
2233 | |
2234 | template <class T> |
2235 | Future<T>&& Future<T>::wait() && { |
2236 | futures::detail::waitImpl(*this); |
2237 | return std::move(*this); |
2238 | } |
2239 | |
2240 | template <class T> |
2241 | Future<T>& Future<T>::wait(Duration dur) & { |
2242 | futures::detail::waitImpl(*this, dur); |
2243 | return *this; |
2244 | } |
2245 | |
2246 | template <class T> |
2247 | Future<T>&& Future<T>::wait(Duration dur) && { |
2248 | futures::detail::waitImpl(*this, dur); |
2249 | return std::move(*this); |
2250 | } |
2251 | |
2252 | template <class T> |
2253 | Future<T>& Future<T>::waitVia(DrivableExecutor* e) & { |
2254 | futures::detail::waitViaImpl(*this, e); |
2255 | return *this; |
2256 | } |
2257 | |
2258 | template <class T> |
2259 | Future<T>&& Future<T>::waitVia(DrivableExecutor* e) && { |
2260 | futures::detail::waitViaImpl(*this, e); |
2261 | return std::move(*this); |
2262 | } |
2263 | |
2264 | template <class T> |
2265 | Future<T>& Future<T>::waitVia(TimedDrivableExecutor* e, Duration dur) & { |
2266 | futures::detail::waitViaImpl(*this, e, dur); |
2267 | return *this; |
2268 | } |
2269 | |
2270 | template <class T> |
2271 | Future<T>&& Future<T>::waitVia(TimedDrivableExecutor* e, Duration dur) && { |
2272 | futures::detail::waitViaImpl(*this, e, dur); |
2273 | return std::move(*this); |
2274 | } |
2275 | |
2276 | template <class T> |
2277 | T Future<T>::get() && { |
2278 | wait(); |
2279 | return copy(std::move(*this)).value(); |
2280 | } |
2281 | |
2282 | template <class T> |
2283 | T Future<T>::get(Duration dur) && { |
2284 | wait(dur); |
2285 | auto future = copy(std::move(*this)); |
2286 | if (!future.isReady()) { |
2287 | throw_exception<FutureTimeout>(); |
2288 | } |
2289 | return std::move(future).value(); |
2290 | } |
2291 | |
2292 | template <class T> |
2293 | Try<T>& Future<T>::getTry() { |
2294 | return result(); |
2295 | } |
2296 | |
2297 | template <class T> |
2298 | T Future<T>::getVia(DrivableExecutor* e) { |
2299 | return std::move(waitVia(e).value()); |
2300 | } |
2301 | |
2302 | template <class T> |
2303 | T Future<T>::getVia(TimedDrivableExecutor* e, Duration dur) { |
2304 | waitVia(e, dur); |
2305 | if (!this->isReady()) { |
2306 | throw_exception<FutureTimeout>(); |
2307 | } |
2308 | return std::move(value()); |
2309 | } |
2310 | |
2311 | template <class T> |
2312 | Try<T>& Future<T>::getTryVia(DrivableExecutor* e) { |
2313 | return waitVia(e).getTry(); |
2314 | } |
2315 | |
2316 | template <class T> |
2317 | Try<T>& Future<T>::getTryVia(TimedDrivableExecutor* e, Duration dur) { |
2318 | waitVia(e, dur); |
2319 | if (!this->isReady()) { |
2320 | throw_exception<FutureTimeout>(); |
2321 | } |
2322 | return result(); |
2323 | } |
2324 | |
2325 | namespace futures { |
2326 | namespace detail { |
2327 | template <class T> |
2328 | struct TryEquals { |
2329 | static bool equals(const Try<T>& t1, const Try<T>& t2) { |
2330 | return t1.value() == t2.value(); |
2331 | } |
2332 | }; |
2333 | } // namespace detail |
2334 | } // namespace futures |
2335 | |
2336 | template <class T> |
2337 | Future<bool> Future<T>::willEqual(Future<T>& f) { |
2338 | return collectAllSemiFuture(*this, f).toUnsafeFuture().thenValue( |
2339 | [](const std::tuple<Try<T>, Try<T>>& t) { |
2340 | if (std::get<0>(t).hasValue() && std::get<1>(t).hasValue()) { |
2341 | return futures::detail::TryEquals<T>::equals( |
2342 | std::get<0>(t), std::get<1>(t)); |
2343 | } else { |
2344 | return false; |
2345 | } |
2346 | }); |
2347 | } |
2348 | |
2349 | template <class T> |
2350 | template <class F> |
2351 | Future<T> Future<T>::filter(F&& predicate) && { |
2352 | return std::move(*this).thenValue([p = std::forward<F>(predicate)](T val) { |
2353 | T const& valConstRef = val; |
2354 | if (!p(valConstRef)) { |
2355 | throw_exception<FuturePredicateDoesNotObtain>(); |
2356 | } |
2357 | return val; |
2358 | }); |
2359 | } |
2360 | |
2361 | template <class F> |
2362 | Future<Unit> when(bool p, F&& thunk) { |
2363 | return p ? std::forward<F>(thunk)().unit() : makeFuture(); |
2364 | } |
2365 | |
2366 | template <class P, class F> |
2367 | Future<Unit> whileDo(P&& predicate, F&& thunk) { |
2368 | if (predicate()) { |
2369 | auto future = thunk(); |
2370 | return std::move(future).thenValue( |
2371 | [predicate = std::forward<P>(predicate), |
2372 | thunk = std::forward<F>(thunk)](auto&&) mutable { |
2373 | return whileDo(std::forward<P>(predicate), std::forward<F>(thunk)); |
2374 | }); |
2375 | } |
2376 | return makeFuture(); |
2377 | } |
2378 | |
2379 | template <class F> |
2380 | Future<Unit> times(const int n, F&& thunk) { |
2381 | return folly::whileDo( |
2382 | [n, count = std::make_unique<std::atomic<int>>(0)]() mutable { |
2383 | return count->fetch_add(1, std::memory_order_relaxed) < n; |
2384 | }, |
2385 | std::forward<F>(thunk)); |
2386 | } |
2387 | |
2388 | namespace futures { |
2389 | template <class It, class F, class ItT, class Tag, class Result> |
2390 | std::vector<Future<Result>> mapValue(It first, It last, F func) { |
2391 | std::vector<Future<Result>> results; |
2392 | results.reserve(std::distance(first, last)); |
2393 | for (auto it = first; it != last; it++) { |
2394 | results.push_back(std::move(*it).thenValue(func)); |
2395 | } |
2396 | return results; |
2397 | } |
2398 | |
2399 | template <class It, class F, class ItT, class Tag, class Result> |
2400 | std::vector<Future<Result>> mapTry(It first, It last, F func, int) { |
2401 | std::vector<Future<Result>> results; |
2402 | results.reserve(std::distance(first, last)); |
2403 | for (auto it = first; it != last; it++) { |
2404 | results.push_back(std::move(*it).thenTry(func)); |
2405 | } |
2406 | return results; |
2407 | } |
2408 | |
2409 | template <class It, class F, class ItT, class Tag, class Result> |
2410 | std::vector<Future<Result>> |
2411 | mapValue(Executor& exec, It first, It last, F func) { |
2412 | std::vector<Future<Result>> results; |
2413 | results.reserve(std::distance(first, last)); |
2414 | for (auto it = first; it != last; it++) { |
2415 | results.push_back(std::move(*it).via(&exec).thenValue(func)); |
2416 | } |
2417 | return results; |
2418 | } |
2419 | |
2420 | template <class It, class F, class ItT, class Tag, class Result> |
2421 | std::vector<Future<Result>> |
2422 | mapTry(Executor& exec, It first, It last, F func, int) { |
2423 | std::vector<Future<Result>> results; |
2424 | results.reserve(std::distance(first, last)); |
2425 | for (auto it = first; it != last; it++) { |
2426 | results.push_back(std::move(*it).via(&exec).thenTry(func)); |
2427 | } |
2428 | return results; |
2429 | } |
2430 | |
2431 | } // namespace futures |
2432 | |
2433 | template <class Clock> |
2434 | Future<Unit> Timekeeper::at(std::chrono::time_point<Clock> when) { |
2435 | auto now = Clock::now(); |
2436 | |
2437 | if (when <= now) { |
2438 | return makeFuture(); |
2439 | } |
2440 | |
2441 | return after(std::chrono::duration_cast<Duration>(when - now)); |
2442 | } |
2443 | |
2444 | // Instantiate the most common Future types to save compile time |
2445 | extern template class Future<Unit>; |
2446 | extern template class Future<bool>; |
2447 | extern template class Future<int>; |
2448 | extern template class Future<int64_t>; |
2449 | extern template class Future<std::string>; |
2450 | extern template class Future<double>; |
2451 | } // namespace folly |
2452 | |