Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableFloatMinMaxAggregationOperator.cs / 1305376 / NullableFloatMinMaxAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableFloatMinMaxAggregationOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined min/max aggregation and its enumerator, for Nullable floats. /// /// Notes: /// Note that normally float.NaN < anything is false, as is anything < NaN. This would /// lead to some strangeness in Min and Max, e.g. Min({ NaN, 5.0 } == NaN, yet /// Min({ 5.0, NaN }) == 5.0! We impose a total ordering so that NaN is smaller than /// everything, including -infinity, which is consistent with Comparer_T. /// internal sealed class NullableFloatMinMaxAggregationOperator : InlinedAggregationOperator{ private readonly int m_sign; // The sign (-1 for min, 1 for max). //---------------------------------------------------------------------------------------- // Constructs a new instance of a min/max associative operator. // internal NullableFloatMinMaxAggregationOperator(IEnumerable child, int sign) : base(child) { Contract.Assert(sign == -1 || sign == 1, "invalid sign"); m_sign = sign; } //--------------------------------------------------------------------------------------- // 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 float? 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)) { // Just return null right away for empty results. if (!enumerator.MoveNext()) { return null; } float? best = enumerator.Current; // Based on the sign, do either a min or max reduction. if (m_sign == -1) { while (enumerator.MoveNext()) { float? current = enumerator.Current; if (current == null) continue; if (best == null || current < best || float.IsNaN(current.GetValueOrDefault())) { best = current; } } } else { while (enumerator.MoveNext()) { float? current = enumerator.Current; if (current == null) continue; if (best == null || current > best || float.IsNaN(best.GetValueOrDefault())) { best = current; } } } return best; } } //--------------------------------------------------------------------------------------- // 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 NullableFloatMinMaxAggregationOperatorEnumerator (source, index, m_sign, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableFloatMinMaxAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator { private QueryOperatorEnumerator m_source; // The source data. private int m_sign; // The sign for comparisons (-1 means min, 1 means max). //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableFloatMinMaxAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, int sign, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; m_sign = sign; } //--------------------------------------------------------------------------------------- // Tallies up the min/max of the underlying data source, walking the entire thing the first // time MoveNext is called on this object. // protected override bool MoveNextCore(ref float? currentElement) { // Based on the sign, do either a min or max reduction. QueryOperatorEnumerator source = m_source; TKey keyUnused = default(TKey); if (source.MoveNext(ref currentElement, ref keyUnused)) { int i = 0; // We just scroll through the enumerator and find the min or max. if (m_sign == -1) { float? elem = default(float?); while (source.MoveNext(ref elem, ref keyUnused)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (elem == null) continue; if (currentElement == null || elem < currentElement || float.IsNaN(elem.GetValueOrDefault())) { currentElement = elem; } } } else { float? elem = default(float?); while (source.MoveNext(ref elem, ref keyUnused)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (elem == null) continue; if (currentElement == null || elem > currentElement || float.IsNaN(currentElement.GetValueOrDefault())) { currentElement = elem; } } } // The sum has been calculated. Now just return. 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
- DocumentViewerBaseAutomationPeer.cs
- InputProcessorProfilesLoader.cs
- Material.cs
- XmlAttributes.cs
- PropertyMapper.cs
- TemplateBuilder.cs
- UITypeEditor.cs
- SQLBytes.cs
- AncillaryOps.cs
- Attachment.cs
- LineSegment.cs
- TextBoxAutomationPeer.cs
- DataMemberListEditor.cs
- Native.cs
- WindowsTooltip.cs
- CellConstant.cs
- ClientBuildManager.cs
- MediaCommands.cs
- XmlSerializerNamespaces.cs
- PathNode.cs
- PersonalizableAttribute.cs
- BitmapEffectDrawingContextWalker.cs
- MultiplexingDispatchMessageFormatter.cs
- EventItfInfo.cs
- EasingKeyFrames.cs
- ClientData.cs
- TimeIntervalCollection.cs
- ProfessionalColorTable.cs
- GridViewDeletedEventArgs.cs
- EmptyStringExpandableObjectConverter.cs
- EtwTrace.cs
- HandledMouseEvent.cs
- ComplexLine.cs
- ClientTarget.cs
- MatchingStyle.cs
- BinaryParser.cs
- KnownAssemblyEntry.cs
- UpDownEvent.cs
- MappingItemCollection.cs
- HttpCapabilitiesSectionHandler.cs
- TrustManagerPromptUI.cs
- ConfigXmlComment.cs
- SecurityTokenSerializer.cs
- ObjectDataSourceChooseTypePanel.cs
- XD.cs
- InfoCardX509Validator.cs
- DetailsViewRowCollection.cs
- Encoder.cs
- ToolStripPanelSelectionGlyph.cs
- DBCSCodePageEncoding.cs
- NumericUpDownAccelerationCollection.cs
- ToolboxDataAttribute.cs
- PagerStyle.cs
- X509ChainPolicy.cs
- DataSourceControlBuilder.cs
- Latin1Encoding.cs
- NameNode.cs
- GcSettings.cs
- Pen.cs
- CodeNamespaceImport.cs
- PrimaryKeyTypeConverter.cs
- PersistenceMetadataNamespace.cs
- FileUtil.cs
- HScrollProperties.cs
- DispatcherExceptionEventArgs.cs
- TypeToken.cs
- WebDisplayNameAttribute.cs
- MonthCalendar.cs
- TrackBarRenderer.cs
- UriSection.cs
- WebServiceReceive.cs
- HtmlTextArea.cs
- UnsafeNativeMethods.cs
- TraceSource.cs
- MenuItemBinding.cs
- AnimationException.cs
- AncestorChangedEventArgs.cs
- BehaviorDragDropEventArgs.cs
- CssTextWriter.cs
- StickyNote.cs
- WindowsContainer.cs
- XmlNamespaceDeclarationsAttribute.cs
- ItemCheckedEvent.cs
- ColorPalette.cs
- WebPartManagerDesigner.cs
- EngineSiteSapi.cs
- ImageListStreamer.cs
- CallbackValidatorAttribute.cs
- SkewTransform.cs
- SchemaCollectionPreprocessor.cs
- OwnerDrawPropertyBag.cs
- SQLUtility.cs
- FontSourceCollection.cs
- HttpListenerElement.cs
- AsyncResult.cs
- DefaultAssemblyResolver.cs
- AssemblyCollection.cs
- UpdateExpressionVisitor.cs
- XmlSchemaSimpleContentRestriction.cs
- ViewGenerator.cs