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
- XmlAutoDetectWriter.cs
- RequestQueryProcessor.cs
- PointHitTestResult.cs
- HtmlInputPassword.cs
- Panel.cs
- _AutoWebProxyScriptHelper.cs
- ClientTarget.cs
- ValueQuery.cs
- PrintController.cs
- SqlColumnizer.cs
- Helper.cs
- SerializationTrace.cs
- DataServiceException.cs
- CustomWebEventKey.cs
- SessionSwitchEventArgs.cs
- ScriptModule.cs
- TriState.cs
- HttpProfileBase.cs
- XPathQilFactory.cs
- AssertUtility.cs
- MonthChangedEventArgs.cs
- _SpnDictionary.cs
- TextAction.cs
- TextEndOfLine.cs
- AsmxEndpointPickerExtension.cs
- TableRow.cs
- HandlerBase.cs
- SizeIndependentAnimationStorage.cs
- Cell.cs
- DigestTraceRecordHelper.cs
- XMLUtil.cs
- SafeThemeHandle.cs
- ObjectCacheSettings.cs
- InternalConfigRoot.cs
- RegionData.cs
- InputMethodStateTypeInfo.cs
- DrawingContextWalker.cs
- NameValuePair.cs
- DataGridViewAutoSizeModeEventArgs.cs
- TabControl.cs
- EncoderBestFitFallback.cs
- MultiTouchSystemGestureLogic.cs
- ObjectPersistData.cs
- RectangleHotSpot.cs
- DbReferenceCollection.cs
- LookupNode.cs
- ConnectionManagementElementCollection.cs
- SQLBinary.cs
- LinkedResourceCollection.cs
- CqlParser.cs
- FixedHyperLink.cs
- GeneralTransform3DGroup.cs
- LoadRetryHandler.cs
- ProcessModelInfo.cs
- TypeRefElement.cs
- Selector.cs
- TextComposition.cs
- FileEnumerator.cs
- XmlWellformedWriter.cs
- EqualityComparer.cs
- Visitors.cs
- TextServicesContext.cs
- CqlErrorHelper.cs
- VideoDrawing.cs
- ProxyGenerationError.cs
- NavigateEvent.cs
- HtmlWindow.cs
- MessageSecurityVersion.cs
- XmlWrappingReader.cs
- ObfuscateAssemblyAttribute.cs
- IfAction.cs
- ContainerUIElement3D.cs
- ListViewItem.cs
- RequestResponse.cs
- DependencyPropertyAttribute.cs
- ExpressionBuilderCollection.cs
- Model3D.cs
- ClientTarget.cs
- PageSettings.cs
- TreeNodeCollection.cs
- ComponentGlyph.cs
- TypeBuilder.cs
- BitmapData.cs
- ParameterEditorUserControl.cs
- MimeReflector.cs
- XPathAncestorQuery.cs
- Clipboard.cs
- ExtendedProtectionPolicy.cs
- Codec.cs
- SerializationObjectManager.cs
- WebPartVerbsEventArgs.cs
- QuadraticBezierSegment.cs
- COM2EnumConverter.cs
- RangeBase.cs
- ReceiveParametersContent.cs
- BindingSource.cs
- securitymgrsite.cs
- CqlQuery.cs
- OdbcErrorCollection.cs
- TargetPerspective.cs