future.h

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/*
 * 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.
 */

#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;
    }

    template<typename T>
    class Future
    {
        friend class common::Promise<T>;

    public:
        typedef T ValueType;

        Future(const Future<ValueType>& src) :
            state(src.state)
        {
            // No-op.
        }

        Future& operator=(const Future<ValueType>& other)
        {
            state = other.state;

            return *this;
        }

        void Wait() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Wait();
        }

        bool WaitFor(int32_t msTimeout) const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->WaitFor(msTimeout);
        }

        const ValueType& GetValue() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->GetValue();
        }

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

            assert(state0 != 0);

            state0->Cancel();
        }

        bool IsReady()
        {
            common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->IsSet();
        }

    private:
        Future(common::concurrent::SharedPointer< common::SharedState<ValueType> > state0) :
            state(state0)
        {
            // No-op.
        }

        common::concurrent::SharedPointer< common::SharedState<ValueType> > state;
    };

    template<>
    class Future<void>
    {
        friend class common::Promise<void>;

    public:
        typedef void ValueType;

        Future(const Future<ValueType>& src) :
            state(src.state)
        {
            // No-op.
        }

        Future& operator=(const Future<ValueType>& other)
        {
            state = other.state;

            return *this;
        }

        void Wait() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->Wait();
        }

        bool WaitFor(int32_t msTimeout) const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->WaitFor(msTimeout);
        }

        void GetValue() const
        {
            const common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            state0->GetValue();
        }

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

            assert(state0 != 0);

            state0->Cancel();
        }

        bool IsReady()
        {
            common::SharedState<ValueType>* state0 = state.Get();

            assert(state0 != 0);

            return state0->IsSet();
        }

    private:
        Future(common::concurrent::SharedPointer< common::SharedState<ValueType> > state0) :
            state(state0)
        {
            // No-op.
        }

        common::concurrent::SharedPointer< common::SharedState<ValueType> > state;
    };
}

#endif //_IGNITE_FUTURE