Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableIntMinMaxAggregationOperator.cs / 1305376 / NullableIntMinMaxAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableIntMinMaxAggregationOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined min/max aggregation and its enumerator, for Nullable ints. /// internal sealed class NullableIntMinMaxAggregationOperator : InlinedAggregationOperator{ private readonly int m_sign; // The sign (-1 for min, 1 for max). //---------------------------------------------------------------------------------------- // Constructs a new instance of a min/max associative operator. // internal NullableIntMinMaxAggregationOperator(IEnumerable child, int sign) : base(child) { Contract.Assert(sign == -1 || sign == 1, "invalid sign"); m_sign = sign; } //--------------------------------------------------------------------------------------- // Executes the entire query tree, and aggregates the intermediate results into the // final result based on the binary operators and final reduction. // // Return Value: // The single result of aggregation. // protected override int? InternalAggregate(ref Exception singularExceptionToThrow) { // Because the final reduction is typically much cheaper than the intermediate // reductions over the individual partitions, and because each parallel partition // will do a lot of work to produce a single output element, we prefer to turn off // pipelining, and process the final reductions serially. using (IEnumerator enumerator = GetEnumerator(ParallelMergeOptions.FullyBuffered, true)) { // Just return null right away for empty results. if (!enumerator.MoveNext()) { return null; } int? best = enumerator.Current; // Based on the sign, do either a min or max reduction. if (m_sign == -1) { while (enumerator.MoveNext()) { int? current = enumerator.Current; if (best == null || current < best) { best = current; } } } else { while (enumerator.MoveNext()) { int? current = enumerator.Current; if (best == null || current > best) { best = current; } } } return best; } } //--------------------------------------------------------------------------------------- // Creates an enumerator that is used internally for the final aggregation step. // protected override QueryOperatorEnumerator CreateEnumerator ( int index, int count, QueryOperatorEnumerator source, object sharedData, CancellationToken cancellationToken) { return new NullableIntMinMaxAggregationOperatorEnumerator (source, index, m_sign, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableIntMinMaxAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator { private QueryOperatorEnumerator m_source; // The source data. private int m_sign; // The sign for comparisons (-1 means min, 1 means max). //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableIntMinMaxAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, int sign, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; m_sign = sign; } //--------------------------------------------------------------------------------------- // Tallies up the min/max of the underlying data source, walking the entire thing the first // time MoveNext is called on this object. // protected override bool MoveNextCore(ref int? currentElement) { // Based on the sign, do either a min or max reduction. QueryOperatorEnumerator source = m_source; TKey keyUnused = default(TKey); if (source.MoveNext(ref currentElement, ref keyUnused)) { int i = 0; // We just scroll through the enumerator and find the min or max. if (m_sign == -1) { int? elem = default(int?); while (source.MoveNext(ref elem, ref keyUnused)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (currentElement == null || elem < currentElement) { currentElement = elem; } } } else { int? elem = default(int?); while (source.MoveNext(ref elem, ref keyUnused)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (currentElement == null || elem > currentElement) { currentElement = elem; } } } // The sum has been calculated. Now just return. return true; } return false; } //---------------------------------------------------------------------------------------- // Dispose of resources associated with the underlying enumerator. // protected override void Dispose(bool disposing) { Contract.Assert(m_source != null); m_source.Dispose(); } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- ConvertersCollection.cs
- IntPtr.cs
- DrawingVisualDrawingContext.cs
- ComPlusContractBehavior.cs
- NeutralResourcesLanguageAttribute.cs
- FontStretches.cs
- NetTcpSection.cs
- MenuAutomationPeer.cs
- ConstructorNeedsTagAttribute.cs
- SqlDataSourceSelectingEventArgs.cs
- LineBreakRecord.cs
- CommandBindingCollection.cs
- IdentityModelStringsVersion1.cs
- Serializer.cs
- ApplicationFileParser.cs
- StackSpiller.Generated.cs
- XPathMultyIterator.cs
- RemoveStoryboard.cs
- TdsValueSetter.cs
- DeviceSpecificChoice.cs
- ParameterRetriever.cs
- SrgsToken.cs
- XPathScanner.cs
- ExpressionBuilder.cs
- SamlAssertion.cs
- GeometryCollection.cs
- ColorContextHelper.cs
- MarshalByRefObject.cs
- HtmlEncodedRawTextWriter.cs
- UpDownBase.cs
- Thickness.cs
- PointAnimationUsingPath.cs
- ObjectStateEntryDbUpdatableDataRecord.cs
- DelegatingTypeDescriptionProvider.cs
- EnvironmentPermission.cs
- ComplexBindingPropertiesAttribute.cs
- RowToParametersTransformer.cs
- DynamicDocumentPaginator.cs
- CommonXSendMessage.cs
- Quad.cs
- TextureBrush.cs
- XslAst.cs
- ObjectListTitleAttribute.cs
- Control.cs
- ListBoxAutomationPeer.cs
- OutOfProcStateClientManager.cs
- ManagementBaseObject.cs
- SmiSettersStream.cs
- LostFocusEventManager.cs
- XmlSchemaSubstitutionGroup.cs
- ReflectionHelper.cs
- CodeCompiler.cs
- CryptoApi.cs
- TextRangeSerialization.cs
- RunInstallerAttribute.cs
- UnionExpr.cs
- ProviderUtil.cs
- ProviderException.cs
- LateBoundChannelParameterCollection.cs
- TextureBrush.cs
- StringSorter.cs
- SubclassTypeValidator.cs
- DbCommandDefinition.cs
- HintTextConverter.cs
- CompilerCollection.cs
- TextElementEnumerator.cs
- DBDataPermission.cs
- HandlerBase.cs
- WindowsIdentity.cs
- safesecurityhelperavalon.cs
- LongSumAggregationOperator.cs
- InterleavedZipPartStream.cs
- ReadOnlyHierarchicalDataSource.cs
- OSFeature.cs
- X509CertificateValidator.cs
- XmlSchemaObjectCollection.cs
- LinqToSqlWrapper.cs
- SqlDataSource.cs
- TogglePattern.cs
- EventLogException.cs
- TextServicesCompartmentContext.cs
- Literal.cs
- Polyline.cs
- BoolExpr.cs
- XsltQilFactory.cs
- EdmFunction.cs
- wgx_sdk_version.cs
- SqlXmlStorage.cs
- WebPartConnectionsEventArgs.cs
- DefaultDialogButtons.cs
- MexHttpsBindingCollectionElement.cs
- CredentialCache.cs
- DetailsViewUpdateEventArgs.cs
- Crc32Helper.cs
- FrameworkElementFactory.cs
- AccessControlList.cs
- FirstQueryOperator.cs
- FileFormatException.cs
- HttpConfigurationSystem.cs
- XmlDocumentType.cs