tdlight/tdactor/td/actor/PromiseFuture.h

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//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2023
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include "td/actor/actor.h"
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#include "td/utils/Closure.h"
#include "td/utils/common.h"
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#include "td/utils/invoke.h"
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#include "td/utils/Promise.h"
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#include "td/utils/ScopeGuard.h"
#include "td/utils/Status.h"
#include <tuple>
#include <utility>
namespace td {
namespace detail {
class EventPromise final : public PromiseInterface<Unit> {
public:
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void set_value(Unit &&) final {
ok_.try_emit();
fail_.clear();
}
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void set_error(Status &&) final {
do_set_error();
}
EventPromise(const EventPromise &other) = delete;
EventPromise &operator=(const EventPromise &other) = delete;
EventPromise(EventPromise &&other) = delete;
EventPromise &operator=(EventPromise &&other) = delete;
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~EventPromise() final {
do_set_error();
}
EventPromise() = default;
explicit EventPromise(EventFull ok) : ok_(std::move(ok)), use_ok_as_fail_(true) {
}
EventPromise(EventFull ok, EventFull fail) : ok_(std::move(ok)), fail_(std::move(fail)), use_ok_as_fail_(false) {
}
private:
EventFull ok_;
EventFull fail_;
bool use_ok_as_fail_ = false;
void do_set_error() {
if (use_ok_as_fail_) {
ok_.try_emit();
} else {
ok_.clear();
fail_.try_emit();
}
}
};
class SendClosure {
public:
template <class... ArgsT>
void operator()(ArgsT &&...args) const {
send_closure(std::forward<ArgsT>(args)...);
}
};
} // namespace detail
inline Promise<Unit> create_event_promise(EventFull &&ok) {
return Promise<Unit>(td::make_unique<detail::EventPromise>(std::move(ok)));
}
inline Promise<Unit> create_event_promise(EventFull ok, EventFull fail) {
return Promise<Unit>(td::make_unique<detail::EventPromise>(std::move(ok), std::move(fail)));
}
template <class T>
class FutureActor;
template <class T>
class PromiseActor;
template <class T>
class ActorTraits<FutureActor<T>> {
public:
static constexpr bool need_context = false;
static constexpr bool need_start_up = false;
};
template <class T>
class PromiseActor final : public PromiseInterface<T> {
friend class FutureActor<T>;
enum State { Waiting, Hangup };
public:
PromiseActor() = default;
PromiseActor(const PromiseActor &other) = delete;
PromiseActor &operator=(const PromiseActor &other) = delete;
PromiseActor(PromiseActor &&) = default;
PromiseActor &operator=(PromiseActor &&) = default;
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~PromiseActor() final {
close();
}
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void set_value(T &&value) final;
void set_error(Status &&error) final;
void close() {
future_id_.reset();
}
// NB: if true is returned no further events will be sent
bool is_hangup() {
if (state_ == State::Hangup) {
return true;
}
if (!future_id_.is_alive()) {
state_ = State::Hangup;
future_id_.release();
event_.clear();
return true;
}
return false;
}
template <class S>
friend void init_promise_future(PromiseActor<S> *promise, FutureActor<S> *future);
bool empty_promise() {
return future_id_.empty();
}
bool empty() {
return future_id_.empty();
}
private:
ActorOwn<FutureActor<T>> future_id_;
EventFull event_;
State state_ = State::Hangup;
void init() {
state_ = State::Waiting;
event_.clear();
}
};
template <class T>
class FutureActor final : public Actor {
friend class PromiseActor<T>;
public:
enum State { Waiting, Ready };
static constexpr int HANGUP_ERROR_CODE = 426487;
FutureActor() = default;
FutureActor(const FutureActor &other) = delete;
FutureActor &operator=(const FutureActor &other) = delete;
FutureActor(FutureActor &&other) = default;
FutureActor &operator=(FutureActor &&other) = default;
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~FutureActor() final = default;
bool is_ok() const {
return is_ready() && result_.is_ok();
}
bool is_error() const {
CHECK(is_ready());
return is_ready() && result_.is_error();
}
T move_as_ok() {
return move_as_result().move_as_ok();
}
Status move_as_error() TD_WARN_UNUSED_RESULT {
return move_as_result().move_as_error();
}
Result<T> move_as_result() TD_WARN_UNUSED_RESULT {
CHECK(is_ready());
SCOPE_EXIT {
do_stop();
};
return std::move(result_);
}
bool is_ready() const {
return !empty() && state_ == State::Ready;
}
void close() {
event_.clear();
result_.clear();
do_stop();
}
void set_event(EventFull &&event) {
CHECK(!empty());
event_ = std::move(event);
if (state_ != State::Waiting) {
event_.try_emit_later();
}
}
State get_state() const {
return state_;
}
template <class S>
friend void init_promise_future(PromiseActor<S> *promise, FutureActor<S> *future);
private:
EventFull event_;
Result<T> result_ = Status::Error(500, "Empty FutureActor");
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State state_ = State::Waiting;
void set_value(T &&value) {
set_result(std::move(value));
}
void set_error(Status &&error) {
set_result(std::move(error));
}
void set_result(Result<T> &&result) {
CHECK(state_ == State::Waiting);
result_ = std::move(result);
state_ = State::Ready;
event_.try_emit_later();
}
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void hangup() final {
set_error(Status::Error<HANGUP_ERROR_CODE>());
}
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void start_up() final {
// empty
}
void init() {
CHECK(empty());
state_ = State::Waiting;
event_.clear();
}
};
template <class T>
void PromiseActor<T>::set_value(T &&value) {
if (state_ == State::Waiting && !future_id_.empty()) {
send_closure(std::move(future_id_), &FutureActor<T>::set_value, std::move(value));
}
}
template <class T>
void PromiseActor<T>::set_error(Status &&error) {
if (state_ == State::Waiting && !future_id_.empty()) {
send_closure(std::move(future_id_), &FutureActor<T>::set_error, std::move(error));
}
}
template <class S>
void init_promise_future(PromiseActor<S> *promise, FutureActor<S> *future) {
promise->init();
future->init();
promise->future_id_ = register_actor("FutureActor", future);
CHECK(future->get_info() != nullptr);
}
template <class T>
class PromiseFuture {
public:
PromiseFuture() {
init_promise_future(&promise_, &future_);
}
PromiseActor<T> &promise() {
return promise_;
}
FutureActor<T> &future() {
return future_;
}
PromiseActor<T> &&move_promise() {
return std::move(promise_);
}
FutureActor<T> &&move_future() {
return std::move(future_);
}
private:
PromiseActor<T> promise_;
FutureActor<T> future_;
};
template <ActorSendType send_type, class T, class ActorAT, class ActorBT, class ResultT, class... DestArgsT,
class... ArgsT>
FutureActor<T> send_promise(ActorId<ActorAT> actor_id, ResultT (ActorBT::*func)(PromiseActor<T> &&, DestArgsT...),
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ArgsT &&...args) {
PromiseFuture<T> pf;
Scheduler::instance()->send_closure<send_type>(
std::move(actor_id), create_immediate_closure(func, pf.move_promise(), std::forward<ArgsT>(args)...));
return pf.move_future();
}
template <class... ArgsT>
auto promise_send_closure(ArgsT &&...args) {
return [t = std::make_tuple(std::forward<ArgsT>(args)...)](auto &&res) mutable {
call_tuple(detail::SendClosure(), std::tuple_cat(std::move(t), std::make_tuple(std::forward<decltype(res)>(res))));
};
}
template <class T>
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Promise<T> create_promise_from_promise_actor(PromiseActor<T> &&from) {
return Promise<T>(td::make_unique<PromiseActor<T>>(std::move(from)));
}
} // namespace td