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
- WorkflowRuntimeServiceElement.cs
- Geometry.cs
- CqlErrorHelper.cs
- TableTextElementCollectionInternal.cs
- ActivityWithResultWrapper.cs
- EncoderExceptionFallback.cs
- UriTemplateTableMatchCandidate.cs
- NamespaceDisplayAutomationPeer.cs
- TypedCompletedAsyncResult.cs
- CompositeDuplexElement.cs
- XAMLParseException.cs
- EmptyCollection.cs
- ControlBindingsConverter.cs
- BinaryExpression.cs
- _ServiceNameStore.cs
- Message.cs
- TableLayoutSettings.cs
- ClientOptions.cs
- SelectionEditor.cs
- LoadRetryStrategyFactory.cs
- CodeGroup.cs
- ResourceManagerWrapper.cs
- precedingquery.cs
- MaterialGroup.cs
- HtmlWindowCollection.cs
- ReflectionHelper.cs
- MachineKeyValidationConverter.cs
- EmptyEnumerator.cs
- InputProcessorProfiles.cs
- ListDataBindEventArgs.cs
- DataPagerFieldItem.cs
- DocumentPaginator.cs
- DecimalStorage.cs
- ParallelDesigner.xaml.cs
- FormViewPagerRow.cs
- StorageMappingFragment.cs
- SqlGatherConsumedAliases.cs
- BaseValidator.cs
- SqlComparer.cs
- TraceContextEventArgs.cs
- ASCIIEncoding.cs
- ReflectionUtil.cs
- HijriCalendar.cs
- WebAdminConfigurationHelper.cs
- httpserverutility.cs
- ToolStripActionList.cs
- SHA384Managed.cs
- QualifiedCellIdBoolean.cs
- infer.cs
- HttpContextBase.cs
- WebAdminConfigurationHelper.cs
- SqlInternalConnection.cs
- XmlUtf8RawTextWriter.cs
- WpfKnownType.cs
- XPathChildIterator.cs
- ColumnTypeConverter.cs
- InputLanguage.cs
- CodeDirectoryCompiler.cs
- EntityContainerRelationshipSetEnd.cs
- ToolStripRenderer.cs
- GroupItemAutomationPeer.cs
- TraceSection.cs
- XPathEmptyIterator.cs
- DataChangedEventManager.cs
- SecurityPermission.cs
- NameValueFileSectionHandler.cs
- DebugView.cs
- FrameDimension.cs
- LinqDataView.cs
- AppDomain.cs
- BlurBitmapEffect.cs
- ColumnReorderedEventArgs.cs
- InProcStateClientManager.cs
- DoubleMinMaxAggregationOperator.cs
- UrlMappingCollection.cs
- VirtualPath.cs
- _ConnectStream.cs
- UnsafeNativeMethodsCLR.cs
- FixedElement.cs
- ObjectContextServiceProvider.cs
- HtmlControl.cs
- SharedStatics.cs
- StringUtil.cs
- InheritanceAttribute.cs
- DrawItemEvent.cs
- TextAutomationPeer.cs
- URLString.cs
- MyContact.cs
- ByteStorage.cs
- EncryptedKeyIdentifierClause.cs
- GridViewUpdatedEventArgs.cs
- CallbackException.cs
- SqlConnectionFactory.cs
- RouteValueDictionary.cs
- FontClient.cs
- HtmlControl.cs
- _ConnectStream.cs
- WizardForm.cs
- FloaterParagraph.cs
- MessageTraceRecord.cs