X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/e709643ef0c5b61c6c878016c418bffa2b1b20cd..HEAD:/include/simgrid/kernel/future.hpp

diff --git a/include/simgrid/kernel/future.hpp b/include/simgrid/kernel/future.hpp
deleted file mode 100644
index 906d702937..0000000000
--- a/include/simgrid/kernel/future.hpp
+++ /dev/null
@@ -1,546 +0,0 @@
-/* Copyright (c) 2016-2020. The SimGrid Team.
- * All rights reserved.                                                     */
-
-/* This program is free software; you can redistribute it and/or modify it
- * under the terms of the license (GNU LGPL) which comes with this package. */
-
-#ifndef SIMGRID_KERNEL_FUTURE_HPP
-#define SIMGRID_KERNEL_FUTURE_HPP
-
-#include <functional>
-#include <future>
-#include <memory>
-#include <utility>
-#include <type_traits>
-
-#include <boost/optional.hpp>
-
-#include <xbt/base.h>
-#include <xbt/functional.hpp>
-#include <xbt/future.hpp>
-
-namespace simgrid {
-namespace kernel {
-
-// There are the public classes:
-template<class T> class Future;
-template<class T> class Promise;
-
-// Those are implementation details:
-enum class FutureStatus;
-template<class T> class FutureState;
-
-enum class FutureStatus {
-  not_ready,
-  ready,
-  done,
-};
-
-template<class T>
-struct is_future : std::false_type {};
-template<class T>
-struct is_future<Future<T>> : std::true_type {};
-
-/** Bases stuff for all @ref simgrid::kernel::FutureState<T> */
-class FutureStateBase {
-public:
-  // No copy/move:
-  FutureStateBase(FutureStateBase const&) = delete;
-  FutureStateBase& operator=(FutureStateBase const&) = delete;
-
-  XBT_PUBLIC void schedule(simgrid::xbt::Task<void()>&& job) const;
-
-  void set_exception(std::exception_ptr exception)
-  {
-    xbt_assert(exception_ == nullptr);
-    if (status_ != FutureStatus::not_ready)
-      throw std::future_error(std::future_errc::promise_already_satisfied);
-    exception_ = std::move(exception);
-    this->set_ready();
-  }
-
-  void set_continuation(simgrid::xbt::Task<void()>&& continuation)
-  {
-    xbt_assert(not continuation_);
-    switch (status_) {
-    case FutureStatus::done:
-      // This is not supposed to happen if continuation is set
-      // via the Promise:
-      xbt_die("Set continuation on finished future");
-      break;
-    case FutureStatus::ready:
-      // The future is ready, execute the continuation directly.
-      // We might execute it from the event loop instead:
-      schedule(std::move(continuation));
-      break;
-    case FutureStatus::not_ready:
-      // The future is not ready so we must keep the continuation for
-      // executing it later:
-      continuation_ = std::move(continuation);
-      break;
-    default:
-      DIE_IMPOSSIBLE;
-    }
-  }
-
-  FutureStatus get_status() const
-  {
-    return status_;
-  }
-
-  bool is_ready() const
-  {
-    return status_ == FutureStatus::ready;
-  }
-
-protected:
-  FutureStateBase() = default;
-  ~FutureStateBase() = default;
-
-  /** Set the future as ready and trigger the continuation */
-  void set_ready()
-  {
-    status_ = FutureStatus::ready;
-    if (continuation_) {
-      // We unregister the continuation before executing it.
-      // We need to do this because the current implementation of the
-      // continuation has a shared_ptr to the FutureState.
-      auto continuation = std::move(continuation_);
-      this->schedule(std::move(continuation));
-    }
-  }
-
-  /** Set the future as done and raise an exception if any
-   *
-   *  This does half the job of `.get()`.
-   **/
-  void resolve()
-  {
-    if (status_ != FutureStatus::ready)
-      xbt_die("Deadlock: this future is not ready");
-    status_ = FutureStatus::done;
-    if (exception_) {
-      std::exception_ptr exception = std::move(exception_);
-      exception_ = nullptr;
-      std::rethrow_exception(std::move(exception));
-    }
-  }
-
-private:
-  FutureStatus status_ = FutureStatus::not_ready;
-  std::exception_ptr exception_;
-  simgrid::xbt::Task<void()> continuation_;
-};
-
-/** Shared state for future and promises
- *
- *  You are not expected to use them directly but to create them
- *  implicitly through a @ref simgrid::kernel::Promise.
- *  Alternatively kernel operations could inherit or contain FutureState
- *  if they are managed with std::shared_ptr.
- **/
-template<class T>
-class FutureState : public FutureStateBase {
-public:
-  void set_value(T value)
-  {
-    if (this->get_status() != FutureStatus::not_ready)
-      throw std::future_error(std::future_errc::promise_already_satisfied);
-    value_ = std::move(value);
-    this->set_ready();
-  }
-
-  T get()
-  {
-    this->resolve();
-    xbt_assert(this->value_);
-    auto result = std::move(this->value_.get());
-    this->value_ = boost::optional<T>();
-    return result;
-  }
-
-private:
-  boost::optional<T> value_;
-};
-
-template<class T>
-class FutureState<T&> : public FutureStateBase {
-public:
-  void set_value(T& value)
-  {
-    if (this->get_status() != FutureStatus::not_ready)
-      throw std::future_error(std::future_errc::promise_already_satisfied);
-    value_ = &value;
-    this->set_ready();
-  }
-
-  T& get()
-  {
-    this->resolve();
-    xbt_assert(this->value_);
-    T* result = value_;
-    value_ = nullptr;
-    return *result;
-  }
-
-private:
-  T* value_ = nullptr;
-};
-
-template<>
-class FutureState<void> : public FutureStateBase {
-public:
-  void set_value()
-  {
-    if (this->get_status() != FutureStatus::not_ready)
-      throw std::future_error(std::future_errc::promise_already_satisfied);
-    this->set_ready();
-  }
-
-  void get()
-  {
-    this->resolve();
-  }
-};
-
-template <class T> void bind_promise(Promise<T>&& promise, Future<T> future)
-{
-  class PromiseBinder {
-  public:
-    explicit PromiseBinder(Promise<T>&& promise) : promise_(std::move(promise)) {}
-    void operator()(Future<T> future) { simgrid::xbt::set_promise(promise_, future); }
-
-  private:
-    Promise<T> promise_;
-  };
-  future.then_(PromiseBinder(std::move(promise)));
-}
-
-template <class T> Future<T> unwrap_future(Future<Future<T>> future);
-
-/** Result of some (probably) asynchronous operation in the SimGrid kernel
- *
- * @ref simgrid::simix::Future and @ref simgrid::simix::Future provide an
- * abstraction for asynchronous stuff happening in the SimGrid kernel. They
- * are based on C++1z futures.
- *
- * The future represents a value which will be available at some point when this
- * asynchronous operation is finished. Alternatively, if this operations fails,
- * the result of the operation might be an exception.
- *
- *  As the operation is possibly no terminated yet, we cannot get the result
- *  yet. Moreover, as we cannot block in the SimGrid kernel we cannot wait for
- *  it. However, we can attach some code/callback/continuation which will be
- *  executed when the operation terminates.
- *
- *  Example of the API (`simgrid::kernel::createProcess` does not exist):
- *  <pre>
- *  // Create a new process using the Worker code, this process returns
- *  // a std::string:
- *  simgrid::kernel::Future<std::string> future =
- *     simgrid::kernel::createProcess("worker42", host, Worker(42));
- *  // At this point, we just created the process so the result is not available.
- *  // However, we can attach some work do be done with this result:
- *  future.then([](simgrid::kernel::Future<std::string> result) {
- *    // This code is called when the operation is completed so the result is
- *    // available:
- *    try {
- *      // Try to get value, this might throw an exception if the operation
- *      // failed (such as an exception thrown by the worker process):
- *      std::string value = result.get();
- *      XBT_INFO("Value: %s", value.c_str());
- *    }
- *    catch(std::exception& e) {
- *      // This is an exception from the asynchronous operation:
- *      XBT_INFO("Error: %e", e.what());
- *    }
- *  );
- *  </pre>
- *
- *  This is based on C++1z std::future but with some differences:
- *
- *  * there is no thread synchronization (atomic, mutex, condition variable,
- *    etc.) because everything happens in the SimGrid event loop;
- *
- *  * it is purely asynchronous, you are expected to use `.then()`;
- *
- *  * inside the `.then()`, `.get()` can be used;
- *
- *  * `.get()` can only be used when `.is_ready()` (as everything happens in
- *     a single-thread, the future would be guaranteed to deadlock if `.get()`
- *     is called when the future is not ready);
- *
- *  * there is no future chaining support for now (`.then().then()`);
- *
- *  * there is no sharing (`shared_future`) for now.
- */
-template<class T>
-class Future {
-public:
-  Future() = default;
-  explicit Future(std::shared_ptr<FutureState<T>> state) : state_(std::move(state)) {}
-  ~Future() = default;
-
-  // Move type:
-  Future(Future&) = delete;
-  Future& operator=(const Future&) = delete;
-  Future(Future&&) noexcept        = default;
-  Future& operator=(Future&&) noexcept = default;
-
-  /** Whether the future is valid:.
-   *
-   *  A future which as been used (`.then` of `.get`) becomes invalid.
-   *
-   *  We can use `.then` on a valid future.
-   */
-  bool valid() const
-  {
-    return state_ != nullptr;
-  }
-
-  /** Whether the future is ready
-   *
-   *  A future is ready when it has an associated value or exception.
-   *
-   *  We can use `.get()` on ready futures.
-   **/
-  bool is_ready() const
-  {
-    return state_ != nullptr && state_->is_ready();
-  }
-
-  /** Attach a continuation to this future
-   *
-   *  This is like .then() but avoid the creation of a new future.
-   */
-  template<class F>
-  void then_(F continuation)
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    // Give shared-ownership to the continuation:
-    auto state = std::move(state_);
-    state->set_continuation(simgrid::xbt::make_task(std::move(continuation), state));
-  }
-
-  /** Attach a continuation to this future
-   *
-   *  This version never does future unwrapping.
-   */
-  template <class F> auto then_no_unwrap(F continuation) -> Future<decltype(continuation(std::move(*this)))>
-  {
-    typedef decltype(continuation(std::move(*this))) R;
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    auto state = std::move(state_);
-    // Create a new future...
-    Promise<R> promise;
-    Future<R> future = promise.get_future();
-    // ...and when the current future is ready...
-    state->set_continuation(simgrid::xbt::make_task(
-        [](Promise<R> promise, std::shared_ptr<FutureState<T>> state, F continuation) {
-          // ...set the new future value by running the continuation.
-          Future<T> future(std::move(state));
-          simgrid::xbt::fulfill_promise(promise, [&continuation, &future] { return continuation(std::move(future)); });
-        },
-        std::move(promise), state, std::move(continuation)));
-    return future;
-  }
-
-  /** Attach a continuation to this future
-   *
-   *  The future must be valid in order to make this call.
-   *  The continuation is executed when the future becomes ready.
-   *  The future becomes invalid after this call.
-   *
-   * @param continuation This function is called with a ready future
-   *                     the future is ready
-   * @exception std::future_error no state is associated with the future
-   */
-  template <class F>
-  auto then(F continuation) -> typename std::enable_if<not is_future<decltype(continuation(std::move(*this)))>::value,
-                                                       Future<decltype(continuation(std::move(*this)))>>::type
-  {
-    return this->then_no_unwrap(std::move(continuation));
-  }
-
-  /** Attach a continuation to this future (future chaining) */
-  template<class F>
-  auto then(F continuation)
-  -> typename std::enable_if<
-       is_future<decltype(continuation(std::move(*this)))>::value,
-       decltype(continuation(std::move(*this)))
-     >::type
-  {
-    return unwrap_future(this->then_no_unwrap(std::move(continuation)));
-  }
-
-  /** Get the value from the future
-   *
-   *  The future must be valid and ready in order to make this call.
-   *  std::future blocks when the future is not ready but we are
-   *  completely single-threaded so blocking would be a deadlock.
-   *  After the call, the future becomes invalid.
-   *
-   *  @return                      value of the future
-   *  @exception any               Exception from the future
-   *  @exception std::future_error no state is associated with the future
-   */
-  T get()
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    std::shared_ptr<FutureState<T>> state = std::move(state_);
-    return state->get();
-  }
-
-private:
-  std::shared_ptr<FutureState<T>> state_;
-};
-
-template <class T> Future<T> unwrap_future(Future<Future<T>> future)
-{
-  Promise<T> promise;
-  Future<T> result = promise.get_future();
-  bind_promise(std::move(promise), std::move(future));
-  return result;
-}
-
-/** Producer side of a @ref simgrid::kernel::Future
- *
- *  A @ref Promise is connected to some `Future` and can be used to
- *  set its result.
- *
- *  Similar to std::promise
- *
- *  <code>
- *  // Create a promise and a future:
- *  auto promise = std::make_shared<simgrid::kernel::Promise<T>>();
- *  auto future = promise->get_future();
- *
- *  simgrid::simix::Timer::set(date, [promise] {
- *    try {
- *      int value = compute_the_value();
- *      if (value < 0)
- *        throw std::logic_error("Bad value");
- *      // Whenever the operation is completed, we set the value
- *      // for the future:
- *      promise.set_value(value);
- *    }
- *    catch (...) {
- *      // If an error occurred, we can set an exception which
- *      // will be thrown by future.get():
- *      promise.set_exception(std::current_exception());
- *    }
- *  });
- *
- *  // Return the future to the caller:
- *  return future;
- *  </code>
- **/
-template<class T>
-class Promise {
-public:
-  Promise() = default;
-  explicit Promise(std::shared_ptr<FutureState<T>> state) : state_(std::move(state)) {}
-
-  // Move type
-  Promise(Promise const&) = delete;
-  Promise& operator=(Promise const&) = delete;
-  Promise(Promise&& that) noexcept : state_(std::move(that.state_)) { std::swap(future_get_, that.future_get_); }
-
-  Promise& operator=(Promise&& that) noexcept
-  {
-    this->state_ = std::move(that.state_);
-    this->future_get_ = that.future_get_;
-    that.future_get_ = false;
-    return *this;
-  }
-  Future<T> get_future()
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    if (future_get_)
-      throw std::future_error(std::future_errc::future_already_retrieved);
-    future_get_ = true;
-    return Future<T>(state_);
-  }
-  void set_value(T value)
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    state_->set_value(std::move(value));
-  }
-  void set_exception(std::exception_ptr exception)
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    state_->set_exception(std::move(exception));
-  }
-  ~Promise()
-  {
-    if (state_ && state_->get_status() == FutureStatus::not_ready)
-      state_->set_exception(std::make_exception_ptr(
-        std::future_error(std::future_errc::broken_promise)));
-  }
-
-private:
-  std::shared_ptr<FutureState<T>> state_{new FutureState<T>()};
-  bool future_get_ = false;
-};
-
-template<>
-class Promise<void> {
-public:
-  Promise() = default;
-  explicit Promise(std::shared_ptr<FutureState<void>> state) : state_(std::move(state)) {}
-  ~Promise()
-  {
-    if (state_ && state_->get_status() == FutureStatus::not_ready)
-      state_->set_exception(std::make_exception_ptr(
-        std::future_error(std::future_errc::broken_promise)));
-  }
-
-  // Move type
-  Promise(Promise const&) = delete;
-  Promise& operator=(Promise const&) = delete;
-  Promise(Promise&& that) noexcept : state_(std::move(that.state_)) { std::swap(future_get_, that.future_get_); }
-  Promise& operator=(Promise&& that) noexcept
-  {
-    this->state_ = std::move(that.state_);
-    this->future_get_ = that.future_get_;
-    that.future_get_ = false;
-    return *this;
-  }
-
-  Future<void> get_future()
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    if (future_get_)
-      throw std::future_error(std::future_errc::future_already_retrieved);
-    future_get_ = true;
-    return Future<void>(state_);
-  }
-  void set_value() const
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    state_->set_value();
-  }
-  void set_exception(std::exception_ptr exception) const
-  {
-    if (state_ == nullptr)
-      throw std::future_error(std::future_errc::no_state);
-    state_->set_exception(std::move(exception));
-  }
-
-private:
-  std::shared_ptr<FutureState<void>> state_{new FutureState<void>()};
-  bool future_get_ = false;
-};
-
-}
-}
-
-#endif