blob: eb673754a593b0af8d8908f37f4f979b372e72bd [file] [log] [blame]
* Copyright 2015 Facebook, Inc.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#pragma once
#include <folly/Portability.h>
#include <folly/futures/Try.h>
#include <functional>
namespace folly {
// forward declaration
template <class T> class Future;
template <class T>
class Promise {
// not copyable
Promise(Promise const&) = delete;
Promise& operator=(Promise const&) = delete;
// movable
Promise(Promise<T>&&) noexcept;
Promise& operator=(Promise<T>&&) noexcept;
/** Return a Future tied to the shared core state. This can be called only
once, thereafter Future already retrieved exception will be raised. */
Future<T> getFuture();
/** Fulfill the Promise with an exception_wrapper */
void setException(exception_wrapper ew);
/** Fulfill the Promise with an exception_ptr, e.g.
try {
} catch (...) {
FOLLY_DEPRECATED("use setException(exception_wrapper)")
void setException(std::exception_ptr const&);
/** Fulfill the Promise with an exception type E, which can be passed to
std::make_exception_ptr(). Useful for originating exceptions. If you
caught an exception the exception_wrapper form is more appropriate.
template <class E>
typename std::enable_if<std::is_base_of<std::exception, E>::value>::type
setException(E const&);
/// Set an interrupt handler to handle interrupts. See the documentation for
/// Future::raise(). Your handler can do whatever it wants, but if you
/// bother to set one then you probably will want to fulfill the promise with
/// an exception (or special value) indicating how the interrupt was
/// handled.
void setInterruptHandler(std::function<void(exception_wrapper const&)>);
/// Sugar to fulfill this Promise<Unit>
template <class B = T>
typename std::enable_if<std::is_same<Unit, B>::value, void>::type
setValue() {
/** Set the value (use perfect forwarding for both move and copy) */
template <class M>
void setValue(M&& value);
void setTry(Try<T>&& t);
/** Fulfill this Promise with the result of a function that takes no
arguments and returns something implicitly convertible to T.
Captures exceptions. e.g.
p.setWith([] { do something that may throw; return a T; });
template <class F>
void setWith(F&& func);
bool isFulfilled();
typedef typename Future<T>::corePtr corePtr;
template <class> friend class Future;
// Whether the Future has been retrieved (a one-time operation).
bool retrieved_;
// shared core state object
corePtr core_;
void throwIfFulfilled();
void throwIfRetrieved();
void detach();
#include <folly/futures/Future.h>
#include <folly/futures/Promise-inl.h>