Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableDecimalAverageAggregationOperator.cs / 1305376 / NullableDecimalAverageAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDecimalAverageAggregationOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined average aggregation operator and its enumerator, for Nullable decimals. /// internal sealed class NullableDecimalAverageAggregationOperator : InlinedAggregationOperator, decimal?> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal NullableDecimalAverageAggregationOperator(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 decimal? 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)) { // If the sequence was empty, return null right away. if (!enumerator.MoveNext()) { return null; } Pair result = enumerator.Current; // Simply add together the sums and totals. while (enumerator.MoveNext()) { checked { result.First += enumerator.Current.First; result.Second += enumerator.Current.Second; } } // And divide the sum by the total to obtain the final result. return result.First / result.Second; } } //--------------------------------------------------------------------------------------- // Creates an enumerator that is used internally for the final aggregation step. // protected override QueryOperatorEnumerator , int> CreateEnumerator ( int index, int count, QueryOperatorEnumerator source, object sharedData, CancellationToken cancellationToken) { return new NullableDecimalAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDecimalAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableDecimalAverageAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; } //--------------------------------------------------------------------------------------- // Tallies up the average of the underlying data source, walking the entire thing the first // time MoveNext is called on this object. // protected override bool MoveNextCore(ref Pair currentElement) { // The temporary result contains the running sum and count, respectively. decimal sum = 0.0m; long count = 0; QueryOperatorEnumerator source = m_source; decimal? current = default(decimal?); TKey currentKey = default(TKey); int i = 0; while (source.MoveNext(ref current, ref currentKey)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (current.HasValue) { sum += current.GetValueOrDefault(); count++; } } currentElement = new Pair (sum, count); return count > 0; } //---------------------------------------------------------------------------------------- // 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. // ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDecimalAverageAggregationOperator.cs // // [....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined average aggregation operator and its enumerator, for Nullable decimals. /// internal sealed class NullableDecimalAverageAggregationOperator : InlinedAggregationOperator, decimal?> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal NullableDecimalAverageAggregationOperator(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 decimal? 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)) { // If the sequence was empty, return null right away. if (!enumerator.MoveNext()) { return null; } Pair result = enumerator.Current; // Simply add together the sums and totals. while (enumerator.MoveNext()) { checked { result.First += enumerator.Current.First; result.Second += enumerator.Current.Second; } } // And divide the sum by the total to obtain the final result. return result.First / result.Second; } } //--------------------------------------------------------------------------------------- // Creates an enumerator that is used internally for the final aggregation step. // protected override QueryOperatorEnumerator , int> CreateEnumerator ( int index, int count, QueryOperatorEnumerator source, object sharedData, CancellationToken cancellationToken) { return new NullableDecimalAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDecimalAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableDecimalAverageAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; } //--------------------------------------------------------------------------------------- // Tallies up the average of the underlying data source, walking the entire thing the first // time MoveNext is called on this object. // protected override bool MoveNextCore(ref Pair currentElement) { // The temporary result contains the running sum and count, respectively. decimal sum = 0.0m; long count = 0; QueryOperatorEnumerator source = m_source; decimal? current = default(decimal?); TKey currentKey = default(TKey); int i = 0; while (source.MoveNext(ref current, ref currentKey)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (current.HasValue) { sum += current.GetValueOrDefault(); count++; } } currentElement = new Pair (sum, count); return count > 0; } //---------------------------------------------------------------------------------------- // 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
- Atom10ItemFormatter.cs
- SpecialFolderEnumConverter.cs
- GroupDescription.cs
- BamlRecordReader.cs
- WebPartMinimizeVerb.cs
- HttpCapabilitiesEvaluator.cs
- OSFeature.cs
- AlgoModule.cs
- RegisteredHiddenField.cs
- newitemfactory.cs
- XmlSerializerSection.cs
- FileSystemEventArgs.cs
- SiblingIterators.cs
- SqlTrackingService.cs
- StylusPointProperties.cs
- TimeSpanConverter.cs
- FixedDocumentPaginator.cs
- MatrixAnimationUsingKeyFrames.cs
- RectangleConverter.cs
- TextTreeTextElementNode.cs
- DynamicEntity.cs
- SessionParameter.cs
- util.cs
- TreeIterator.cs
- WindowsListViewGroupSubsetLink.cs
- SettingsPropertyWrongTypeException.cs
- CodeExpressionStatement.cs
- PropertyPushdownHelper.cs
- LicFileLicenseProvider.cs
- AxisAngleRotation3D.cs
- odbcmetadatacollectionnames.cs
- SymbolEqualComparer.cs
- XmlImplementation.cs
- CharEnumerator.cs
- XmlSchemaSubstitutionGroup.cs
- ScriptComponentDescriptor.cs
- DataGridViewRow.cs
- Color.cs
- ContentElementCollection.cs
- IndexedSelectQueryOperator.cs
- SQLSingle.cs
- wgx_commands.cs
- NavigationPropertySingletonExpression.cs
- NonClientArea.cs
- TextRunTypographyProperties.cs
- ApplicationServicesHostFactory.cs
- FileSystemWatcher.cs
- Hash.cs
- ScrollItemPatternIdentifiers.cs
- ComponentDispatcherThread.cs
- GenerateTemporaryAssemblyTask.cs
- Roles.cs
- XmlAutoDetectWriter.cs
- TemplateColumn.cs
- Highlights.cs
- UniqueEventHelper.cs
- ConfigurationManagerInternalFactory.cs
- UmAlQuraCalendar.cs
- ManipulationVelocities.cs
- DialogResultConverter.cs
- ChangePassword.cs
- FixedPage.cs
- ExtenderControl.cs
- DataFormats.cs
- HeaderElement.cs
- Compiler.cs
- EventKeyword.cs
- DynamicDataResources.Designer.cs
- CapabilitiesAssignment.cs
- EndpointInstanceProvider.cs
- XPathSelectionIterator.cs
- RSACryptoServiceProvider.cs
- StylusPointPropertyUnit.cs
- TextEditorParagraphs.cs
- CollectionTypeElement.cs
- OleDbInfoMessageEvent.cs
- PropertyPathWorker.cs
- XamlReader.cs
- BamlStream.cs
- HMACSHA512.cs
- PointAnimationBase.cs
- AutomationElementIdentifiers.cs
- WmpBitmapEncoder.cs
- Missing.cs
- MachineKeySection.cs
- ConfigurationManagerInternalFactory.cs
- StylusDevice.cs
- DebugHandleTracker.cs
- DotAtomReader.cs
- XPathDocument.cs
- ColorKeyFrameCollection.cs
- OleDbException.cs
- QilStrConcatenator.cs
- PKCS1MaskGenerationMethod.cs
- DataListItemCollection.cs
- CompiledQuery.cs
- Model3DCollection.cs
- ElementHost.cs
- RadialGradientBrush.cs
- AspCompat.cs