Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Unary / ConcatQueryOperator.cs / 1305376 / ConcatQueryOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // ConcatQueryOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// Concatenates one data source with another. Order preservation is used to ensure /// the output is actually a concatenation -- i.e. one after the other. The only /// special synchronization required is to find the largest index N in the first data /// source so that the indices of elements in the second data source can be offset /// by adding N+1. This makes it appear to the order preservation infrastructure as /// though all elements in the second came after all elements in the first, which is /// precisely what we want. /// ///internal sealed class ConcatQueryOperator : BinaryQueryOperator { private readonly bool m_prematureMergeLeft = false; // Whether to prematurely merge the left data source private readonly bool m_prematureMergeRight = false; // Whether to prematurely merge the right data source //---------------------------------------------------------------------------------------- // Initializes a new concatenation operator. // // Arguments: // child - the child whose data we will reverse // internal ConcatQueryOperator(ParallelQuery firstChild, ParallelQuery secondChild) : base(firstChild, secondChild) { Contract.Assert(firstChild != null, "first child data source cannot be null"); Contract.Assert(secondChild != null, "second child data source cannot be null"); m_outputOrdered = LeftChild.OutputOrdered || RightChild.OutputOrdered; m_prematureMergeLeft = LeftChild.OrdinalIndexState.IsWorseThan(OrdinalIndexState.Increasing); m_prematureMergeRight = RightChild.OrdinalIndexState.IsWorseThan(OrdinalIndexState.Increasing); if ((LeftChild.OrdinalIndexState == OrdinalIndexState.Indexible) && (RightChild.OrdinalIndexState == OrdinalIndexState.Indexible)) { SetOrdinalIndex(OrdinalIndexState.Indexible); } else { SetOrdinalIndex(OrdinalIndexState.Shuffled); } } //--------------------------------------------------------------------------------------- // Just opens the current operator, including opening the child and wrapping it with // partitions as needed. // internal override QueryResults Open(QuerySettings settings, bool preferStriping) { // We just open the children operators. QueryResults leftChildResults = LeftChild.Open(settings, preferStriping); QueryResults rightChildResults = RightChild.Open(settings, preferStriping); return ConcatQueryOperatorResults.NewResults(leftChildResults, rightChildResults, this, settings, preferStriping); } public override void WrapPartitionedStream ( PartitionedStream leftStream, PartitionedStream rightStream, IPartitionedStreamRecipient outputRecipient, bool preferStriping, QuerySettings settings) { OrdinalIndexState leftChildIndexState = leftStream.OrdinalIndexState; int partitionCount = leftStream.PartitionCount; PartitionedStream leftStreamInc; PartitionedStream rightStreamInc; // Prematurely merge the left results, if necessary if (m_prematureMergeLeft) { ListQueryResults leftStreamResults = ExecuteAndCollectResults(leftStream, partitionCount, LeftChild.OutputOrdered, preferStriping, settings); leftStreamInc = leftStreamResults.GetPartitionedStream(); } else { Contract.Assert(!ExchangeUtilities.IsWorseThan(leftStream.OrdinalIndexState, OrdinalIndexState.Increasing)); leftStreamInc = (PartitionedStream )(object)leftStream; } // Prematurely merge the right results, if necessary if (m_prematureMergeRight) { ListQueryResults rightStreamResults = ExecuteAndCollectResults(rightStream, partitionCount, LeftChild.OutputOrdered, preferStriping, settings); rightStreamInc = rightStreamResults.GetPartitionedStream(); } else { Contract.Assert(!ExchangeUtilities.IsWorseThan(rightStream.OrdinalIndexState, OrdinalIndexState.Increasing)); rightStreamInc = (PartitionedStream )(object)rightStream; } // Generate the shared data. IComparer > comparer = ConcatKey .MakeComparer( leftStreamInc.KeyComparer, rightStreamInc.KeyComparer); var outputStream = new PartitionedStream >(partitionCount, comparer, OrdinalIndexState); for (int i = 0; i < partitionCount; i++) { outputStream[i] = new ConcatQueryOperatorEnumerator (leftStreamInc[i], rightStreamInc[i]); } outputRecipient.Receive(outputStream); } //--------------------------------------------------------------------------------------- // Returns an enumerable that represents the query executing sequentially. // internal override IEnumerable AsSequentialQuery(CancellationToken token) { return LeftChild.AsSequentialQuery(token).Concat(RightChild.AsSequentialQuery(token)); } //--------------------------------------------------------------------------------------- // Whether this operator performs a premature merge. // internal override bool LimitsParallelism { get { return m_prematureMergeLeft || m_prematureMergeLeft; } } //---------------------------------------------------------------------------------------- // The enumerator type responsible for concatenating two data sources. // class ConcatQueryOperatorEnumerator : QueryOperatorEnumerator > { private QueryOperatorEnumerator m_firstSource; // The first data source to enumerate. private QueryOperatorEnumerator m_secondSource; // The second data source to enumerate. private bool m_begunSecond; // Whether this partition has begun enumerating the second source yet. //--------------------------------------------------------------------------------------- // Instantiates a new select enumerator. // internal ConcatQueryOperatorEnumerator( QueryOperatorEnumerator firstSource, QueryOperatorEnumerator secondSource) { Contract.Assert(firstSource != null); Contract.Assert(secondSource != null); m_firstSource = firstSource; m_secondSource = secondSource; } //---------------------------------------------------------------------------------------- // MoveNext advances to the next element in the output. While the first data source has // elements, this consists of just advancing through it. After this, all partitions must // synchronize at a barrier and publish the maximum index N. Finally, all partitions can // move on to the second data source, adding N+1 to indices in order to get the correct // index offset. // internal override bool MoveNext(ref TSource currentElement, ref ConcatKey currentKey) { Contract.Assert(m_firstSource != null); Contract.Assert(m_secondSource != null); // If we are still enumerating the first source, fetch the next item. if (!m_begunSecond) { // If elements remain, just return true and continue enumerating the left. TLeftKey leftKey = default(TLeftKey); if (m_firstSource.MoveNext(ref currentElement, ref leftKey)) { currentKey = ConcatKey .MakeLeft(leftKey); return true; } m_begunSecond = true; } // Now either move on to, or continue, enumerating the right data source. TRightKey rightKey = default(TRightKey); if (m_secondSource.MoveNext(ref currentElement, ref rightKey)) { currentKey = ConcatKey .MakeRight(rightKey); return true; } return false; } protected override void Dispose(bool disposing) { m_firstSource.Dispose(); m_secondSource.Dispose(); } } //------------------------------------------------------------------------------------ // Query results for a Concat operator. The results are indexible if the child // results were indexible. // class ConcatQueryOperatorResults : BinaryQueryOperatorResults { ConcatQueryOperator m_concatOp; // Operator that generated the results int m_leftChildCount; // The number of elements in the left child result set int m_rightChildCount; // The number of elements in the right child result set public static QueryResults NewResults( QueryResults leftChildQueryResults, QueryResults rightChildQueryResults, ConcatQueryOperator op, QuerySettings settings, bool preferStriping) { if (leftChildQueryResults.IsIndexible && rightChildQueryResults.IsIndexible) { return new ConcatQueryOperatorResults( leftChildQueryResults, rightChildQueryResults, op, settings, preferStriping); } else { return new BinaryQueryOperatorResults( leftChildQueryResults, rightChildQueryResults, op, settings, preferStriping); } } private ConcatQueryOperatorResults( QueryResults leftChildQueryResults, QueryResults rightChildQueryResults, ConcatQueryOperator concatOp, QuerySettings settings, bool preferStriping) : base(leftChildQueryResults, rightChildQueryResults, concatOp, settings, preferStriping) { m_concatOp = concatOp; Contract.Assert(leftChildQueryResults.IsIndexible && rightChildQueryResults.IsIndexible); m_leftChildCount = leftChildQueryResults.ElementsCount; m_rightChildCount = rightChildQueryResults.ElementsCount; } internal override bool IsIndexible { get { return true; } } internal override int ElementsCount { get { Contract.Assert(m_leftChildCount >= 0 && m_rightChildCount >= 0); return m_leftChildCount + m_rightChildCount; } } internal override TSource GetElement(int index) { if (index < m_leftChildCount) { return m_leftChildQueryResults.GetElement(index); } else { return m_rightChildQueryResults.GetElement(index - m_leftChildCount); } } } } //--------------------------------------------------------------------------------------- // ConcatKey represents an ordering key for the Concat operator. It knows whether the // element it is associated with is from the left source or the right source, and also // the elements ordering key. // internal struct ConcatKey { private readonly TLeftKey m_leftKey; private readonly TRightKey m_rightKey; private readonly bool m_isLeft; private ConcatKey(TLeftKey leftKey, TRightKey rightKey, bool isLeft) { m_leftKey = leftKey; m_rightKey = rightKey; m_isLeft = isLeft; } internal static ConcatKey MakeLeft(TLeftKey leftKey) { return new ConcatKey (leftKey, default(TRightKey), true); } internal static ConcatKey MakeRight(TRightKey rightKey) { return new ConcatKey (default(TLeftKey), rightKey, false); } internal static IComparer > MakeComparer( IComparer leftComparer, IComparer rightComparer) { return new ConcatKeyComparer(leftComparer, rightComparer); } //---------------------------------------------------------------------------------------- // ConcatKeyComparer compares ConcatKeys, so that elements from the left source come // before elements from the right source, and elements within each source are ordered // according to the corresponding order key. // private class ConcatKeyComparer : IComparer > { private IComparer m_leftComparer; private IComparer m_rightComparer; internal ConcatKeyComparer(IComparer leftComparer, IComparer rightComparer) { m_leftComparer = leftComparer; m_rightComparer = rightComparer; } public int Compare(ConcatKey x, ConcatKey y) { // If one element is from the left source and the other not, the element from the left source // comes earlier. if (x.m_isLeft != y.m_isLeft) { return x.m_isLeft ? -1 : 1; } // Elements are from the same source (left or right). Compare the corresponding keys. if (x.m_isLeft) { return m_leftComparer.Compare(x.m_leftKey, y.m_leftKey); } return m_rightComparer.Compare(x.m_rightKey, y.m_rightKey); } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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