HashJoinQueryOperatorEnumerator.cs

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using System.Diagnostics.CodeAnalysis;
using System.Threading;
 
namespace System.Linq.Parallel;
 
internal sealed class HashJoinQueryOperatorEnumerator<TLeftInput, TLeftKey, TRightInput, TRightKey, THashKey, TOutput, TOutputKey> : QueryOperatorEnumerator<TOutput, TOutputKey>
{
    private sealed class Mutables
    {
        internal TLeftInput _currentLeft;
 
        internal TLeftKey _currentLeftKey;
 
        internal HashJoinHashLookup<THashKey, TRightInput, TRightKey> _rightHashLookup;
 
        internal ListChunk<Pair<TRightInput, TRightKey>> _currentRightMatches;
 
        internal int _currentRightMatchesIndex;
 
        internal int _outputLoopCount;
    }
 
    private readonly QueryOperatorEnumerator<Pair<TLeftInput, THashKey>, TLeftKey> _leftSource;
 
    private readonly HashLookupBuilder<TRightInput, TRightKey, THashKey> _rightLookupBuilder;
 
    private readonly Func<TLeftInput, TRightInput, TOutput> _resultSelector;
 
    private readonly HashJoinOutputKeyBuilder<TLeftKey, TRightKey, TOutputKey> _outputKeyBuilder;
 
    private readonly CancellationToken _cancellationToken;
 
    private Mutables _mutables;
 
    internal HashJoinQueryOperatorEnumerator(QueryOperatorEnumerator<Pair<TLeftInput, THashKey>, TLeftKey> leftSource, HashLookupBuilder<TRightInput, TRightKey, THashKey> rightLookupBuilder, Func<TLeftInput, TRightInput, TOutput> resultSelector, HashJoinOutputKeyBuilder<TLeftKey, TRightKey, TOutputKey> outputKeyBuilder, CancellationToken cancellationToken)
    {
        _leftSource = leftSource;
        _rightLookupBuilder = rightLookupBuilder;
        _resultSelector = resultSelector;
        _outputKeyBuilder = outputKeyBuilder;
        _cancellationToken = cancellationToken;
    }
 
    internal override bool MoveNext([MaybeNullWhen(false)][AllowNull] ref TOutput currentElement, [AllowNull] ref TOutputKey currentKey)
    {
        Mutables mutables = _mutables;
        if (mutables == null)
        {
            mutables = (_mutables = new Mutables());
            mutables._rightHashLookup = _rightLookupBuilder.BuildHashLookup(_cancellationToken);
        }
        ListChunk<Pair<TRightInput, TRightKey>> currentRightMatches = mutables._currentRightMatches;
        if (currentRightMatches != null && mutables._currentRightMatchesIndex == currentRightMatches.Count)
        {
            mutables._currentRightMatches = currentRightMatches.Next;
            mutables._currentRightMatchesIndex = 0;
        }
        if (mutables._currentRightMatches == null)
        {
            Pair<TLeftInput, THashKey> currentElement2 = default(Pair<TLeftInput, THashKey>);
            TLeftKey currentKey2 = default(TLeftKey);
            while (_leftSource.MoveNext(ref currentElement2, ref currentKey2))
            {
                if ((mutables._outputLoopCount++ & 0x3F) == 0)
                {
                    _cancellationToken.ThrowIfCancellationRequested();
                }
                HashLookupValueList<TRightInput, TRightKey> value = default(HashLookupValueList<TRightInput, TRightKey>);
                TLeftInput first = currentElement2.First;
                THashKey second = currentElement2.Second;
                if (second != null && mutables._rightHashLookup.TryGetValue(second, ref value))
                {
                    mutables._currentRightMatches = value.Tail;
                    mutables._currentRightMatchesIndex = 0;
                    currentElement = _resultSelector(first, value.Head.First);
                    currentKey = _outputKeyBuilder.Combine(currentKey2, value.Head.Second);
                    if (value.Tail != null)
                    {
                        mutables._currentLeft = first;
                        mutables._currentLeftKey = currentKey2;
                    }
                    return true;
                }
            }
            return false;
        }
        Pair<TRightInput, TRightKey> pair = mutables._currentRightMatches._chunk[mutables._currentRightMatchesIndex];
        currentElement = _resultSelector(mutables._currentLeft, pair.First);
        currentKey = _outputKeyBuilder.Combine(mutables._currentLeftKey, pair.Second);
        mutables._currentRightMatchesIndex++;
        return true;
    }
 
    protected override void Dispose(bool disposing)
    {
        _leftSource.Dispose();
        _rightLookupBuilder.Dispose();
    }
}