Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Binary / ZipQueryOperator.cs / 1305376 / ZipQueryOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // ZipQueryOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// A Zip operator combines two input data sources into a single output stream, /// using a pairwise element matching algorithm. For example, the result of zipping /// two vectors a = {0, 1, 2, 3} and b = {9, 8, 7, 6} is the vector of pairs, /// c = {(0,9), (1,8), (2,7), (3,6)}. Because the expectation is that each element /// is matched with the element in the other data source at the same ordinal /// position, the zip operator requires order preservation. /// ////// /// internal sealed class ZipQueryOperator : QueryOperator { private readonly Func m_resultSelector; // To select result elements. private readonly QueryOperator m_leftChild; private readonly QueryOperator m_rightChild; 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 zip operator. // // Arguments: // leftChild - the left data source from which to pull data. // rightChild - the right data source from which to pull data. // internal ZipQueryOperator( ParallelQuery leftChildSource, IEnumerable rightChildSource, Func resultSelector) :this( QueryOperator .AsQueryOperator(leftChildSource), QueryOperator .AsQueryOperator(rightChildSource), resultSelector) { } private ZipQueryOperator( QueryOperator left, QueryOperator right, Func resultSelector) : base(left.SpecifiedQuerySettings.Merge(right.SpecifiedQuerySettings)) { Contract.Assert(resultSelector != null, "operator cannot be null"); m_leftChild = left; m_rightChild = right; m_resultSelector = resultSelector; m_outputOrdered = m_leftChild.OutputOrdered || m_rightChild.OutputOrdered; m_prematureMergeLeft = m_leftChild.OrdinalIndexState != OrdinalIndexState.Indexible; m_prematureMergeRight = m_rightChild.OrdinalIndexState != OrdinalIndexState.Indexible; } //--------------------------------------------------------------------------------------- // Just opens the current operator, including opening the children and wrapping them with // partitions as needed. // internal override QueryResults Open(QuerySettings settings, bool preferStriping) { // We just open our child operators, left and then right. QueryResults leftChildResults = m_leftChild.Open(settings, preferStriping); QueryResults rightChildResults = m_rightChild.Open(settings, preferStriping); int partitionCount = settings.DegreeOfParallelism.Value; if (m_prematureMergeLeft) { PartitionedStreamMerger merger = new PartitionedStreamMerger ( false, ParallelMergeOptions.FullyBuffered, settings.TaskScheduler, m_leftChild.OutputOrdered, settings.CancellationState, settings.QueryId); leftChildResults.GivePartitionedStream(merger); leftChildResults = new ListQueryResults ( merger.MergeExecutor.GetResultsAsArray(), partitionCount, preferStriping); } if (m_prematureMergeRight) { PartitionedStreamMerger merger = new PartitionedStreamMerger ( false, ParallelMergeOptions.FullyBuffered, settings.TaskScheduler, m_rightChild.OutputOrdered, settings.CancellationState, settings.QueryId); rightChildResults.GivePartitionedStream(merger); rightChildResults = new ListQueryResults ( merger.MergeExecutor.GetResultsAsArray(), partitionCount, preferStriping); } return new ZipQueryOperatorResults(leftChildResults, rightChildResults, m_resultSelector, partitionCount, preferStriping); } //--------------------------------------------------------------------------------------- // Returns an enumerable that represents the query executing sequentially. // internal override IEnumerable AsSequentialQuery(CancellationToken token) { using(IEnumerator leftEnumerator = m_leftChild.AsSequentialQuery(token).GetEnumerator()) using(IEnumerator rightEnumerator = m_rightChild.AsSequentialQuery(token).GetEnumerator()) { while(leftEnumerator.MoveNext() && rightEnumerator.MoveNext()) { yield return m_resultSelector(leftEnumerator.Current, rightEnumerator.Current); } } } //--------------------------------------------------------------------------------------- // The state of the order index of the results returned by this operator. // internal override OrdinalIndexState OrdinalIndexState { get { return OrdinalIndexState.Indexible; } } //---------------------------------------------------------------------------------------- // Whether this operator performs a premature merge. // internal override bool LimitsParallelism { get { return m_prematureMergeLeft || m_prematureMergeRight; } } //--------------------------------------------------------------------------------------- // A special QueryResults class for the Zip operator. It requires that both of the child // QueryResults are indexible. // internal class ZipQueryOperatorResults : QueryResults { private readonly QueryResults m_leftChildResults; private readonly QueryResults m_rightChildResults; private readonly Func m_resultSelector; // To select result elements. private readonly int m_count; private readonly int m_partitionCount; private readonly bool m_preferStriping; internal ZipQueryOperatorResults( QueryResults leftChildResults, QueryResults rightChildResults, Func resultSelector, int partitionCount, bool preferStriping) { m_leftChildResults = leftChildResults; m_rightChildResults = rightChildResults; m_resultSelector = resultSelector; m_partitionCount = partitionCount; m_preferStriping = preferStriping; Contract.Assert(m_leftChildResults.IsIndexible); Contract.Assert(m_rightChildResults.IsIndexible); m_count = Math.Min(m_leftChildResults.Count, m_rightChildResults.Count); } internal override int ElementsCount { get { return m_count; } } internal override bool IsIndexible { get { return true; } } internal override TOutput GetElement(int index) { return m_resultSelector(m_leftChildResults.GetElement(index), m_rightChildResults.GetElement(index)); } internal override void GivePartitionedStream(IPartitionedStreamRecipient recipient) { PartitionedStream partitionedStream = ExchangeUtilities.PartitionDataSource(this, m_partitionCount, m_preferStriping); recipient.Receive(partitionedStream); } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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