Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableDoubleAverageAggregationOperator.cs / 1305376 / NullableDoubleAverageAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDoubleAverageAggregationOperator.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 doubles. /// internal sealed class NullableDoubleAverageAggregationOperator : InlinedAggregationOperator, double?> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal NullableDoubleAverageAggregationOperator(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 double? 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 NullableDoubleAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDoubleAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableDoubleAverageAggregationOperatorEnumerator(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. double sum = 0.0; long count = 0; QueryOperatorEnumerator source = m_source; double? current = default(double?); TKey keyUnused = default(TKey); int i = 0; while (source.MoveNext(ref current, ref keyUnused)) { if (current.HasValue) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); 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. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDoubleAverageAggregationOperator.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 doubles. /// internal sealed class NullableDoubleAverageAggregationOperator : InlinedAggregationOperator, double?> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal NullableDoubleAverageAggregationOperator(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 double? 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 NullableDoubleAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDoubleAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableDoubleAverageAggregationOperatorEnumerator(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. double sum = 0.0; long count = 0; QueryOperatorEnumerator source = m_source; double? current = default(double?); TKey keyUnused = default(TKey); int i = 0; while (source.MoveNext(ref current, ref keyUnused)) { if (current.HasValue) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); 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
- PermissionAttributes.cs
- GridViewRowEventArgs.cs
- LinqToSqlWrapper.cs
- AdornerPresentationContext.cs
- StylusDevice.cs
- Decoder.cs
- RSAPKCS1KeyExchangeDeformatter.cs
- WebSysDescriptionAttribute.cs
- PolyBezierSegment.cs
- Switch.cs
- COM2ICategorizePropertiesHandler.cs
- DbProviderServices.cs
- ThreadStateException.cs
- XpsResource.cs
- StreamSecurityUpgradeInitiator.cs
- CheckoutException.cs
- UriSection.cs
- ActivityMarkupSerializationProvider.cs
- ListViewTableRow.cs
- cookiecollection.cs
- ToolStripOverflow.cs
- __Error.cs
- DataServiceRequestOfT.cs
- HWStack.cs
- DateTimeFormatInfoScanner.cs
- TranslateTransform3D.cs
- HybridWebProxyFinder.cs
- ToolStripLocationCancelEventArgs.cs
- EtwTrace.cs
- EditBehavior.cs
- GPRECT.cs
- ParseChildrenAsPropertiesAttribute.cs
- BulletDecorator.cs
- FixedSOMContainer.cs
- ClientSettingsProvider.cs
- EventSourceCreationData.cs
- FormsAuthenticationUser.cs
- Triplet.cs
- URIFormatException.cs
- FamilyTypefaceCollection.cs
- OptimisticConcurrencyException.cs
- CompositeFontFamily.cs
- XXXOnTypeBuilderInstantiation.cs
- HtmlImage.cs
- GridViewHeaderRowPresenterAutomationPeer.cs
- FixedStringLookup.cs
- TdsParser.cs
- Visitor.cs
- WeakReferenceList.cs
- SimpleMailWebEventProvider.cs
- PtsPage.cs
- GeneralTransform3D.cs
- AutoResizedEvent.cs
- DataGridViewCellCancelEventArgs.cs
- WindowsEditBoxRange.cs
- XmlSortKey.cs
- MethodToken.cs
- NameHandler.cs
- ListManagerBindingsCollection.cs
- DataGridTableCollection.cs
- SqlVisitor.cs
- ExpressionEditorSheet.cs
- Serializer.cs
- LiteralControl.cs
- ExpressionBindings.cs
- ManagementObjectCollection.cs
- WindowsUpDown.cs
- HyperLinkStyle.cs
- GenerateHelper.cs
- SafeEventLogWriteHandle.cs
- DataGridViewAutoSizeColumnModeEventArgs.cs
- Cursor.cs
- XmlNodeList.cs
- _HTTPDateParse.cs
- OleCmdHelper.cs
- DataGridAddNewRow.cs
- CustomAttribute.cs
- WorkflowMarkupSerializationManager.cs
- CapabilitiesState.cs
- ControlsConfig.cs
- ResXResourceWriter.cs
- NodeFunctions.cs
- OpCodes.cs
- WebPartVerbCollection.cs
- GridViewSortEventArgs.cs
- BitmapFrame.cs
- FragmentQueryKB.cs
- WebCategoryAttribute.cs
- WindowsRichEdit.cs
- GeneralTransformGroup.cs
- CacheDependency.cs
- followingsibling.cs
- PersistenceTypeAttribute.cs
- BrowsableAttribute.cs
- RoleService.cs
- PackageStore.cs
- UrlPath.cs
- ImageConverter.cs
- ImpersonationContext.cs
- followingsibling.cs