Changeset 6e97265 in mainline for uspace/lib/cpp/include/__bits/thread/future.hpp

Timestamp:

2019-06-30T14:37:40Z (5 years ago)

Author:

Jaroslav Jindrak <dzejrou@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

3a29607

Parents:

d86c00f0

Message:

cpp: refactor future to avoid code duplication, fix wait_for and wait_until, synchronization and compilation

File:

• uspace/lib/cpp/include/__bits/thread/future.hpp (modified) (3 diffs)

uspace/lib/cpp/include/__bits/thread/future.hpp

@@ -30 +30 @@
 #define LIBCPP_BITS_THREAD_FUTURE
 
+#include <__bits/thread/future_common.hpp>
+#include <__bits/thread/shared_state.hpp>
+#include <__bits/utility/forward_move.hpp>
 #include <cassert>
-#include <memory>
-#include <system_error>
-#include <thread>
-#include <tuple>
-#include <type_traits>
-#include <utility>
 
 namespace std
 {
     /**
-     * 30.6, futures:
-     */
-
-    enum class future_errc
-    { // The 5001 start is to not collide with system_error's codes.
-        broken_promise = 5001,
-        future_already_retrieved,
-        promise_already_satisfied,
-        no_state
-    };
-
-    enum class future_status
-    {
-        ready,
-        timeout,
-        deferred
-    };
-
-    /**
-     * 30.6.2, error handling:
-     */
-
-    template<>
-    struct is_error_code_enum<future_errc>: true_type
-    { /* DUMMY BODY */ };
-
-    error_code make_error_code(future_errc) noexcept;
-    error_condition make_error_condition(future_errc) noexcept;
-
-    const error_category& future_category() noexcept;
-
-    /**
-     * 30.6.3, class future_error:
-     */
-
-    class future_error: public logic_error
-    {
-        public:
-            future_error(error_code ec);
-
-            const error_code& code() const noexcept;
-            const char* what() const noexcept;
-
-        private:
-            error_code code_;
-    };
-
-    /**
      * 30.6.6, class template future:
      */
 
+    namespace aux
+    {
+        template<class R>
+        class future_base
+        {
+            public:
+                future_base() noexcept
+                    : state_{nullptr}
+                { /* DUMMY BODY */ }
+
+                future_base(const future_base&) = delete;
+
+                future_base(future_base&& rhs) noexcept
+                    : state_{std::move(rhs.state_)}
+                {
+                    rhs.state_ = nullptr;
+                }
+
+                future_base(aux::shared_state<R>* state)
+                    : state_{state}
+                {
+                    /**
+                     * Note: This is a custom non-standard constructor that allows
+                     *       us to create a future directly from a shared state. This
+                     *       should never be a problem as aux::shared_state is a private
+                     *       type and future has no constructor templates.
+                     */
+                }
+
+                virtual ~future_base()
+                {
+                    release_state_();
+                }
+
+                future_base& operator=(const future_base&) = delete;
+
+                future_base& operator=(future_base&& rhs) noexcept
+                {
+                    release_state_();
+                    state_ = std::move(rhs.state_);
+                    rhs.state_ = nullptr;
+                }
+
+                bool valid() const noexcept
+                {
+                    return state_ != nullptr;
+                }
+
+                void wait() const noexcept
+                {
+                    assert(state_);
+
+                    state_->wait();
+                }
+
+                template<class Rep, class Period>
+                future_status
+                wait_for(const chrono::duration<Rep, Period>& rel_time) const
+                {
+                    assert(state_);
+
+                    return state_->wait_for(rel_time);
+                }
+
+                template<class Clock, class Duration>
+                future_status
+                wait_until(
+                    const chrono::time_point<Clock, Duration>& abs_time
+                ) const
+                {
+                    assert(state_);
+
+                    return state_->wait_until(abs_time);
+                }
+
+            protected:
+                void release_state_()
+                {
+                    if (!state_)
+                        return;
+
+                    /**
+                     * Note: This is the 'release' move described in
+                     *       30.6.4 (5).
+                     * Last reference to state -> destroy state.
+                     * Decrement refcount of state otherwise.
+                     * Will not block, unless all following hold:
+                     *  1) State was created by call to std::async.
+                     *  2) State is not yet ready.
+                     *  3) This was the last reference to the shared state.
+                     */
+                    if (state_->decrement())
+                    {
+                        /**
+                         * The destroy call handles the special case
+                         * when 1) - 3) hold.
+                         */
+                        state_->destroy();
+                        delete state_;
+                        state_ = nullptr;
+                    }
+                }
+
+                aux::shared_state<R>* state_;
+        };
+    }
+
     template<class R>
     class shared_future;
 
     template<class R>
-    class future
+    class future: public aux::future_base<R>
     {
         public:
             future() noexcept
-                : state_{nullptr}
+                : aux::future_base<R>{}
             { /* DUMMY BODY */ }
 
@@ -106 +162 @@
 
             future(future&& rhs) noexcept
-                : state_{std::move(rhs.state_)}
-            {
-                rhs.state_ = nullptr;
-            }
+                : aux::future_base<R>{std::move(rhs.state_)}
+            { /* DUMMY BODY */ }
 
             future(aux::shared_state<R>* state)
-                : state_{state}
-            {
-                /**
-                 * Note: This is a custom non-standard constructor that allows
-                 *       us to create a future directly from a shared state. This
-                 *       should never be a problem as aux::shared_state is a private
-                 *       type and future has no constructor templates.
-                 */
-            }
-
-            ~future()
-            {
-                release_state_();
-            }
-
-            future& operator=(const future) = delete;
+                : aux::future_base<R>{state}
+            { /* DUMMY BODY */ }
+
+            future& operator=(const future&) = delete;
 
             future& operator=(future&& rhs) noexcept
             {
-                release_state_();
-                state_ = std::move(rhs.state_);
-                rhs.state_ = nullptr;
+                return aux::future_base<R>::operator=(std::move(rhs));
             }
 
@@ -143 +183 @@
             R get()
             {
-                assert(state_);
-
-                wait();
-
-                if (state_->has_exception())
-                    state_->throw_stored_exception();
-                auto res = std::move(state_->get());
-
-                release_state_();
+                assert(this->state_);
+
+                this->wait();
+
+                if (this->state_->has_exception())
+                    this->state_->throw_stored_exception();
+                auto res = std::move(this->state_->get());
+
+                this->release_state_();
 
                 return res;
             }
-
-            bool valid() const noexcept
-            {
-                return state_ != nullptr;
-            }
-
-            void wait() const noexcept
-            {
-                assert(state_);
-
-                state_->wait();
-            }
-
-            template<class Rep, class Period>
-            future_status wait_for(const chrono::duration<Rep, Period>& rel_time) const
-            {
-                assert(state_);
-
-                return state_->wait_for(rel_time);
-            }
-
-            template<class Clock, class Duration>
-            future_status wait_until(const chrono::time_point<Clock, Duration>& abs_time) const
-            {
-                assert(state_);
-
-                return state_->wait_until(abs_time);
-            }
-
-        private:
-            void release_state_()
-            {
-                if (!state_)
-                    return;
-
-                /**
-                 * Note: This is the 'release' move described in
-                 *       30.6.4 (5).
-                 * Last reference to state -> destroy state.
-                 * Decrement refcount of state otherwise.
-                 * Will not block, unless all following hold:
-                 *  1) State was created by call to std::async.
-                 *  2) State is not yet ready.
-                 *  3) This was the last reference to the shared state.
-                 */
-                if (state_->decrement())
-                {
-                    /**
-                     * The destroy call handles the special case
-                     * when 1) - 3) hold.
-                     */
-                    state_->destroy();
-                    delete state_;
-                    state_ = nullptr;
-                }
-            }
-
-            aux::shared_state<R>* state_;
     };