Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / CountAggregationOperator.cs / 1305376 / CountAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // CountAggregationOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined count aggregation and its enumerator. /// ///internal sealed class CountAggregationOperator : InlinedAggregationOperator { //---------------------------------------------------------------------------------------- // Constructs a new instance of the operator. // internal CountAggregationOperator(IEnumerable child) : base(child) { } //--------------------------------------------------------------------------------------- // 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)) { // We just reduce the elements in each output partition. int count = 0; while (enumerator.MoveNext()) { checked { count += enumerator.Current; } } return count; } } //--------------------------------------------------------------------------------------- // 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 CountAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class CountAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator { private readonly QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal CountAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; } //--------------------------------------------------------------------------------------- // Counts the elements in the underlying data source, walking the entire thing the first // time MoveNext is called on this object. // protected override bool MoveNextCore(ref int currentElement) { TSource elementUnused = default(TSource); TKey keyUnused = default(TKey); QueryOperatorEnumerator source = m_source; if (source.MoveNext(ref elementUnused, ref keyUnused)) { // We just scroll through the enumerator and keep a running count. int count = 0; int i = 0; do { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); checked { count++; } } while (source.MoveNext(ref elementUnused, ref keyUnused)); currentElement = count; 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
- QuaternionValueSerializer.cs
- FillBehavior.cs
- XomlSerializationHelpers.cs
- ExpandSegmentCollection.cs
- Constraint.cs
- StatusBarDesigner.cs
- EventProviderTraceListener.cs
- SQLDateTime.cs
- FactoryId.cs
- WindowProviderWrapper.cs
- QueryExtender.cs
- HeaderUtility.cs
- EventLogConfiguration.cs
- ZipIOCentralDirectoryFileHeader.cs
- Utils.cs
- UnsafeNativeMethodsTablet.cs
- PropertyBuilder.cs
- BuilderInfo.cs
- FileSystemEventArgs.cs
- GenerateTemporaryTargetAssembly.cs
- DropSource.cs
- MessageHeader.cs
- TimeSpanSecondsConverter.cs
- PaginationProgressEventArgs.cs
- VoiceInfo.cs
- BitmapFrameDecode.cs
- SimpleHandlerBuildProvider.cs
- OrderedDictionary.cs
- ToolboxItemFilterAttribute.cs
- AsyncResult.cs
- OutArgument.cs
- MetadataPropertyCollection.cs
- RenderContext.cs
- ParseChildrenAsPropertiesAttribute.cs
- DriveInfo.cs
- WebServiceErrorEvent.cs
- AxisAngleRotation3D.cs
- KeyInfo.cs
- AbstractExpressions.cs
- PseudoWebRequest.cs
- FixedSOMElement.cs
- ContainerParagraph.cs
- ComAwareEventInfo.cs
- DbParameterCollection.cs
- EntityDataSourceColumn.cs
- GPStream.cs
- TextPenaltyModule.cs
- CapacityStreamGeometryContext.cs
- EraserBehavior.cs
- DateTimeFormat.cs
- DebugView.cs
- TriggerAction.cs
- WebHttpDispatchOperationSelector.cs
- FrameworkReadOnlyPropertyMetadata.cs
- InputBinder.cs
- FontCacheLogic.cs
- X509CertificateCollection.cs
- OdbcErrorCollection.cs
- ClientSettingsProvider.cs
- DirectoryGroupQuery.cs
- MarkupCompiler.cs
- TabRenderer.cs
- CodeGen.cs
- TagNameToTypeMapper.cs
- InternalConfigHost.cs
- ActivityExecutionContextCollection.cs
- DrawingGroupDrawingContext.cs
- StackOverflowException.cs
- PointCollectionValueSerializer.cs
- ThreadExceptionDialog.cs
- HttpWriter.cs
- JobCollate.cs
- AssemblyAssociatedContentFileAttribute.cs
- RegexGroup.cs
- BamlResourceContent.cs
- ObjectDataSourceDisposingEventArgs.cs
- CatalogZoneBase.cs
- WebPartTransformerCollection.cs
- PenCursorManager.cs
- EntityDataSourceStatementEditor.cs
- XamlFigureLengthSerializer.cs
- SQLUtility.cs
- SqlXml.cs
- WsrmFault.cs
- ParseNumbers.cs
- EDesignUtil.cs
- ListViewSelectEventArgs.cs
- CustomErrorCollection.cs
- ImmutableObjectAttribute.cs
- XamlFxTrace.cs
- LinkTarget.cs
- SynchronousChannel.cs
- ScrollItemPattern.cs
- PersonalizableTypeEntry.cs
- DetailsViewPageEventArgs.cs
- ProcessHostMapPath.cs
- WebBrowserNavigatedEventHandler.cs
- NullRuntimeConfig.cs
- PropertyExpression.cs
- isolationinterop.cs