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
- columnmapkeybuilder.cs
- ToolStripItemClickedEventArgs.cs
- recordstate.cs
- ExtenderControl.cs
- DLinqTableProvider.cs
- HttpStreamXmlDictionaryReader.cs
- PerformanceCounterScope.cs
- Journal.cs
- PartialCachingControl.cs
- initElementDictionary.cs
- SamlAudienceRestrictionCondition.cs
- TemplateEditingFrame.cs
- MobileContainerDesigner.cs
- XmlAtomicValue.cs
- UpWmlMobileTextWriter.cs
- ProtectedConfigurationProviderCollection.cs
- BaseWebProxyFinder.cs
- MultiSelectRootGridEntry.cs
- DocumentEventArgs.cs
- TranslateTransform3D.cs
- InstanceLockedException.cs
- WebPartCloseVerb.cs
- securitycriticaldataClass.cs
- EditingCoordinator.cs
- ChangeProcessor.cs
- CursorConverter.cs
- DataBoundControlAdapter.cs
- QueryUtil.cs
- MdiWindowListItemConverter.cs
- TextTreeNode.cs
- Attributes.cs
- TableItemProviderWrapper.cs
- SearchExpression.cs
- SQLInt16Storage.cs
- MetadataCacheItem.cs
- ResXResourceWriter.cs
- WebPartTracker.cs
- RangeEnumerable.cs
- Calendar.cs
- ProgressBarAutomationPeer.cs
- SqlDependencyUtils.cs
- SubstitutionList.cs
- DataGridRelationshipRow.cs
- LocalizedNameDescriptionPair.cs
- DataGridViewCellLinkedList.cs
- PageClientProxyGenerator.cs
- XmlWriterSettings.cs
- Validator.cs
- RegexGroup.cs
- UIElementHelper.cs
- PropertyChangingEventArgs.cs
- XmlText.cs
- RankException.cs
- HwndSourceParameters.cs
- NumberAction.cs
- Item.cs
- httpstaticobjectscollection.cs
- X509ScopedServiceCertificateElementCollection.cs
- EncodingTable.cs
- EmitterCache.cs
- PathNode.cs
- WebPartConnectionsConfigureVerb.cs
- HatchBrush.cs
- AppDomainCompilerProxy.cs
- BoundField.cs
- EntryPointNotFoundException.cs
- AutomationProperty.cs
- QueryModel.cs
- GiveFeedbackEvent.cs
- RIPEMD160.cs
- DataList.cs
- RemotingException.cs
- DirectionalLight.cs
- FormParameter.cs
- RecordConverter.cs
- AlphaSortedEnumConverter.cs
- TableAdapterManagerMethodGenerator.cs
- ClassImporter.cs
- UniqueEventHelper.cs
- DataGridCell.cs
- InheritanceContextChangedEventManager.cs
- UnknownWrapper.cs
- VScrollProperties.cs
- ConnectionString.cs
- DefaultParameterValueAttribute.cs
- TransformCollection.cs
- DataControlField.cs
- Helper.cs
- StylusButton.cs
- ErrorWrapper.cs
- SqlCacheDependencySection.cs
- TreeViewHitTestInfo.cs
- EntityCommand.cs
- Animatable.cs
- codemethodreferenceexpression.cs
- ExpressionPrinter.cs
- ChangeBlockUndoRecord.cs
- MouseActionConverter.cs
- TabPage.cs
- ViewPort3D.cs