Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableDoubleMinMaxAggregationOperator.cs / 1305376 / NullableDoubleMinMaxAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDoubleMinMaxAggregationOperator.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{Double}s. /// /// Notes: /// Note that normally double.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 NullableDoubleMinMaxAggregationOperator : 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 NullableDoubleMinMaxAggregationOperator(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 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)) { // Just return null right away for empty results. if (!enumerator.MoveNext()) { return null; } double? best = enumerator.Current; // Based on the sign, do either a min or max reduction. if (m_sign == -1) { while (enumerator.MoveNext()) { double? current = enumerator.Current; if (current == null) continue; if (best == null || current < best || double.IsNaN(current.GetValueOrDefault())) { best = current; } } } else { while (enumerator.MoveNext()) { double? current = enumerator.Current; if (current == null) continue; if (best == null || current > best || double.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 NullableDoubleMinMaxAggregationOperatorEnumerator (source, index, m_sign, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDoubleMinMaxAggregationOperatorEnumerator : 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 NullableDoubleMinMaxAggregationOperatorEnumerator(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 double? 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) { double? elem = default(double?); 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 || double.IsNaN(elem.GetValueOrDefault())) { currentElement = elem; } } } else { double? elem = default(double?); 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 || double.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
- HttpModuleAction.cs
- HuffmanTree.cs
- UpdatableGenericsFeature.cs
- ToolStripGripRenderEventArgs.cs
- ErrorItem.cs
- FixUpCollection.cs
- BindingNavigator.cs
- _SSPISessionCache.cs
- Function.cs
- BuiltInExpr.cs
- AnnotationComponentManager.cs
- _AuthenticationState.cs
- ServiceDebugBehavior.cs
- Context.cs
- DropSource.cs
- HtmlInputRadioButton.cs
- XmlSiteMapProvider.cs
- JavaScriptString.cs
- AutomationPropertyInfo.cs
- HuffmanTree.cs
- CodeStatement.cs
- DBBindings.cs
- Missing.cs
- OSEnvironmentHelper.cs
- StylusShape.cs
- EventLogException.cs
- DefaultValueMapping.cs
- ModuleBuilderData.cs
- DbBuffer.cs
- RangeValuePattern.cs
- TextBlock.cs
- FlowDocumentPage.cs
- XmlDataSourceView.cs
- ChannelPoolSettingsElement.cs
- BindingOperations.cs
- TemplateBamlRecordReader.cs
- DataGridRowClipboardEventArgs.cs
- PageAsyncTask.cs
- EventManager.cs
- EntityContainerEmitter.cs
- FixedSOMGroup.cs
- AvTrace.cs
- DataServiceProcessingPipeline.cs
- DesignerSelectionListAdapter.cs
- TemplateNodeContextMenu.cs
- InkCanvasSelectionAdorner.cs
- WpfPayload.cs
- HierarchicalDataSourceControl.cs
- _SslState.cs
- OAVariantLib.cs
- PingOptions.cs
- ProfileSection.cs
- PageParser.cs
- NameTable.cs
- TextTreeUndo.cs
- WrappedKeySecurityToken.cs
- WindowVisualStateTracker.cs
- SecurityKeyIdentifier.cs
- EnumConverter.cs
- DataSet.cs
- IriParsingElement.cs
- XmlSchemaSimpleContentExtension.cs
- EntityDataSourceDataSelectionPanel.cs
- Run.cs
- XmlNode.cs
- BaseDataBoundControl.cs
- EnumerationRangeValidationUtil.cs
- AsymmetricCryptoHandle.cs
- MultiTrigger.cs
- StateMachineSubscription.cs
- MetaData.cs
- AuthorizationRuleCollection.cs
- OutOfProcStateClientManager.cs
- ObjectDataSourceChooseMethodsPanel.cs
- DataGridCommandEventArgs.cs
- ContextMenu.cs
- BindingWorker.cs
- TypeDescriptionProvider.cs
- RSAOAEPKeyExchangeFormatter.cs
- IPGlobalProperties.cs
- FormViewInsertEventArgs.cs
- SimpleApplicationHost.cs
- PerformanceCounterCategory.cs
- BitmapEffect.cs
- ResolveDuplexCD1AsyncResult.cs
- AuthenticateEventArgs.cs
- TextFindEngine.cs
- PageWrapper.cs
- ErrorLog.cs
- ContentType.cs
- SymbolMethod.cs
- Line.cs
- DomNameTable.cs
- XmlRawWriter.cs
- UIElementPropertyUndoUnit.cs
- ConnectivityStatus.cs
- CodeAttributeArgument.cs
- _LazyAsyncResult.cs
- WebBrowserBase.cs
- DataGridViewColumnDividerDoubleClickEventArgs.cs