modules/platforms/cpp/common/include/ignite/future.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @file
 * Declares ignite::Future class template.
 */


#ifndef _IGNITE_FUTURE
#define _IGNITE_FUTURE

#include <ignite/common/shared_state.h>
#include <ignite/ignite_error.h>

namespace ignite
{
    namespace common
    {
        // Forward declaration
        template<typename T>
        class Promise;
    }

    /**
     * Future class template. Used to get result of the asynchroniously
     * started computation.
     *
     * @tparam T Future value type.
     */
    template<typename T>
    class Future
    {
        friend class common::Promise<T>;

    public:
        /** Template value type */
        typedef T ValueType;

        /**
         * Copy constructor.
         *
         * @param src Instance to copy.
         */
        Future(const Future<ValueType>& src) :
            state(src.state)
        {
            // No-op.
        }

        /**
         * Assignment operator.
         *
         * @param other Other instance.
         * @return *this.
         */
        Future& operator=(const Future<ValueType>& other)
        {
            state = other.state;

            return *this;
        }

        /**
         * Wait for value to be set.
         * Active thread will be blocked until value or error will be set.
         */
        void Wait() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Wait();
        }

        /**
         * Wait for value to be set for specified time.
         * Active thread will be blocked until value or error will be set or timeout will end.
         *
         * @param msTimeout Timeout in milliseconds.
         * @return True if the object has been triggered and false in case of timeout.
         */
        bool WaitFor(int32_t msTimeout) const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->WaitFor(msTimeout);
        }

        /**
         * Get the set value.
         * Active thread will be blocked until value or error will be set.
         *
         * @throw IgniteError if error has been set.
         * @return Value that has been set on success.
         */
        const ValueType& GetValue() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->GetValue();
        }

        /**
         * Cancel related operation.
         */
        void Cancel()
        {
            common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Cancel();
        }

        /**
         * Check if the future ready.
         */
        bool IsReady()
        {
            common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->IsSet();
        }

    private:
        /**
         * Constructor.
         *
         * @param state0 Shared state instance.
         */
        Future(common::concurrent::SharedPointer< common::SharedState<ValueType> > state0) :
            state(state0)
        {
            // No-op.
        }

        /** Shared state. */
        common::concurrent::SharedPointer< common::SharedState<ValueType> > state;
    };

    /**
     * Specialization for void type.
     */
    template<>
    class Future<void>
    {
        friend class common::Promise<void>;

    public:
        /** Template value type */
        typedef void ValueType;

        /**
         * Copy constructor.
         *
         * @param src Instance to copy.
         */
        Future(const Future<ValueType>& src) :
            state(src.state)
        {
            // No-op.
        }

        /**
         * Assignment operator.
         *
         * @param other Other instance.
         * @return *this.
         */
        Future& operator=(const Future<ValueType>& other)
        {
            state = other.state;

            return *this;
        }

        /**
         * Wait for value to be set.
         * Active thread will be blocked until value or error will be set.
         */
        void Wait() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Wait();
        }

        /**
         * Wait for value to be set for specified time.
         * Active thread will be blocked until value or error will be set or timeout will end.
         *
         * @param msTimeout Timeout in milliseconds.
         * @return True if the object has been triggered and false in case of timeout.
         */
        bool WaitFor(int32_t msTimeout) const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->WaitFor(msTimeout);
        }

        /**
         * Wait for operation complition or error.
         * Active thread will be blocked until value or error will be set.
         *
         * @throw IgniteError if error has been set.
         */
        void GetValue() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->GetValue();
        }

        /**
         * Cancel related operation.
         */
        void Cancel()
        {
            common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Cancel();
        }

        /**
         * Check if the future ready.
         */
        bool IsReady()
        {
            common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->IsSet();
        }

    private:
        /**
         * Constructor.
         *
         * @param state0 Shared state instance.
         */
        Future(common::concurrent::SharedPointer< common::SharedState<ValueType> > state0) :
            state(state0)
        {
            // No-op.
        }

        /** Shared state. */
        common::concurrent::SharedPointer< common::SharedState<ValueType> > state;
    };

    /**
     * Specialization for shared pointer.
     */
    template<typename T>
    class Future< common::concurrent::SharedPointer<T> >
    {
        friend class common::Promise< common::concurrent::SharedPointer<T> >;

    public:
        /** Template value type */
        typedef T ValueType;

        /** Template value type shared pointer */
        typedef common::concurrent::SharedPointer<ValueType> SP_ValueType;

        /**
         * Copy constructor.
         *
         * @param src Instance to copy.
         */
        Future(const Future<SP_ValueType>& src) :
            state(src.state)
        {
            // No-op.
        }

        /**
         * Assignment operator.
         *
         * @param other Other instance.
         * @return *this.
         */
        Future& operator=(const Future<SP_ValueType>& other)
        {
            if (this != &other)
                state = other.state;

            return *this;
        }

        /**
         * Wait for value to be set.
         * Active thread will be blocked until value or error will be set.
         */
        void Wait() const
        {
            const common::SharedState<SP_ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Wait();
        }

        /**
         * Wait for value to be set for specified time.
         * Active thread will be blocked until value or error will be set or timeout will end.
         *
         * @param msTimeout Timeout in milliseconds.
         * @return True if the object has been triggered and false in case of timeout.
         */
        bool WaitFor(int32_t msTimeout) const
        {
            const common::SharedState<SP_ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->WaitFor(msTimeout);
        }

        /**
         * Get the set value.
         * Active thread will be blocked until value or error will be set.
         *
         * @throw IgniteError if error has been set.
         * @return Value that has been set on success.
         */
        SP_ValueType GetValue() const
        {
            const common::SharedState<SP_ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->GetValue();
        }

        /**
         * Cancel related operation.
         */
        void Cancel()
        {
            common::SharedState<SP_ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Cancel();
        }

        /**
         * Check if the future ready.
         */
        bool IsReady()
        {
            common::SharedState<SP_ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->IsSet();
        }

    private:
        /**
         * Constructor.
         *
         * @param state0 Shared state instance.
         */
        Future(common::concurrent::SharedPointer< common::SharedState<SP_ValueType> > state0) :
            state(state0)
        {
            // No-op.
        }

        /** Shared state. */
        common::concurrent::SharedPointer< common::SharedState<SP_ValueType> > state;
    };
}

#endif //_IGNITE_FUTURE