DoubleAverageAggregationOperator.cs

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using System.Collections.Generic;
using System.Threading;
 
namespace System.Linq.Parallel;
 
internal sealed class DoubleAverageAggregationOperator : InlinedAggregationOperator<double, Pair<double, long>, double>
{
    private sealed class DoubleAverageAggregationOperatorEnumerator<TKey> : InlinedAggregationOperatorEnumerator<Pair<double, long>>
    {
        private readonly QueryOperatorEnumerator<double, TKey> _source;
 
        internal DoubleAverageAggregationOperatorEnumerator(QueryOperatorEnumerator<double, TKey> source, int partitionIndex, CancellationToken cancellationToken)
            : base(partitionIndex, cancellationToken)
        {
            _source = source;
        }
 
        protected override bool MoveNextCore(ref Pair<double, long> currentElement)
        {
            double num = 0.0;
            long num2 = 0L;
            QueryOperatorEnumerator<double, TKey> source = _source;
            double currentElement2 = 0.0;
            TKey currentKey = default(TKey);
            if (source.MoveNext(ref currentElement2, ref currentKey))
            {
                int num3 = 0;
                do
                {
                    if ((num3++ & 0x3F) == 0)
                    {
                        _cancellationToken.ThrowIfCancellationRequested();
                    }
                    num += currentElement2;
                    num2 = checked(num2 + 1);
                }
                while (source.MoveNext(ref currentElement2, ref currentKey));
                currentElement = new Pair<double, long>(num, num2);
                return true;
            }
            return false;
        }
 
        protected override void Dispose(bool disposing)
        {
            _source.Dispose();
        }
    }
 
    internal DoubleAverageAggregationOperator(IEnumerable<double> child)
        : base(child)
    {
    }
 
    protected override double InternalAggregate(ref Exception singularExceptionToThrow)
    {
        checked
        {
            using IEnumerator<Pair<double, long>> enumerator = GetEnumerator(ParallelMergeOptions.FullyBuffered, suppressOrderPreservation: true);
            if (!enumerator.MoveNext())
            {
                singularExceptionToThrow = new InvalidOperationException(System.SR.NoElements);
                return 0.0;
            }
            Pair<double, long> current = enumerator.Current;
            while (enumerator.MoveNext())
            {
                current.First += enumerator.Current.First;
                current.Second += enumerator.Current.Second;
            }
            return current.First / (double)current.Second;
        }
    }
 
    protected override QueryOperatorEnumerator<Pair<double, long>, int> CreateEnumerator<TKey>(int index, int count, QueryOperatorEnumerator<double, TKey> source, object sharedData, CancellationToken cancellationToken)
    {
        return new DoubleAverageAggregationOperatorEnumerator<TKey>(source, index, cancellationToken);
    }
}