lang/cs/Org.Apache.REEF.Network/Group/Operators/Impl/PipelinedReduceFunction.cs

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// to you under the Apache License, Version 2.0 (the
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// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
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using System.Collections.Generic;
using Org.Apache.REEF.Network.Group.Pipelining;
using Org.Apache.REEF.Utilities.Attributes;

namespace Org.Apache.REEF.Network.Group.Operators.Impl
{
    /// <summary>
    /// The class used to aggregate pipelined messages sent by ReduceSenders.
    /// </summary>
    /// <typeparam name="T">The message type.</typeparam>
    [Private]
    public sealed class PipelinedReduceFunction<T> : IReduceFunction<PipelineMessage<T>>
    {
        /// <summary>
        /// The base reduce function class that operates on actual message type T.
        /// </summary>
        /// <typeparam name="T">The message type.</typeparam>
        private readonly IReduceFunction<T> _baseReduceFunc;
        public PipelinedReduceFunction(IReduceFunction<T> baseReduceFunc)
        {
            _baseReduceFunc = baseReduceFunc;
        }
        
        /// <summary>
        /// Reduce the IEnumerable of pipeline messages into one pipeline message.
        /// </summary>
        /// <param name="elements">The pipeline messages to reduce</param>
        /// <returns>The reduced pipeline message</returns>
        public PipelineMessage<T> Reduce(IEnumerable<PipelineMessage<T>> elements)
        {
            var messageList = new List<T>();
            var isLast = false;

            foreach (var message in elements)
            {
                messageList.Add(message.Data);
                isLast = message.IsLast;
            }

            return new PipelineMessage<T>(_baseReduceFunc.Reduce(messageList), isLast);
        }
    }
}