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
- OwnerDrawPropertyBag.cs
- ClientSettingsSection.cs
- DSASignatureDeformatter.cs
- BuilderPropertyEntry.cs
- XmlReflectionImporter.cs
- ClientRuntimeConfig.cs
- ChannelEndpointElementCollection.cs
- FormParameter.cs
- LayoutManager.cs
- DataControlButton.cs
- EntityCommand.cs
- CodeSnippetStatement.cs
- PeerResolverBindingElement.cs
- TogglePatternIdentifiers.cs
- CompiledRegexRunnerFactory.cs
- ADMembershipUser.cs
- StaticResourceExtension.cs
- PreservationFileReader.cs
- TextDpi.cs
- QueueTransferProtocol.cs
- DataGridViewComboBoxCell.cs
- ReferentialConstraint.cs
- ScrollContentPresenter.cs
- ToolStripControlHost.cs
- EmptyReadOnlyDictionaryInternal.cs
- PlainXmlWriter.cs
- MemberProjectionIndex.cs
- BoundColumn.cs
- ThreadStaticAttribute.cs
- DefaultAsyncDataDispatcher.cs
- ExpressionDumper.cs
- dbdatarecord.cs
- TreeNodeCollection.cs
- FileRecordSequenceCompletedAsyncResult.cs
- MetafileHeaderWmf.cs
- OleDbConnection.cs
- ScrollItemPattern.cs
- X509PeerCertificateElement.cs
- SqlDataSourceCommandEventArgs.cs
- ThreadExceptionEvent.cs
- EmbeddedMailObjectsCollection.cs
- MatrixCamera.cs
- StringStorage.cs
- WeakReferenceList.cs
- SqlDataSourceStatusEventArgs.cs
- RenderData.cs
- BaseTemplateBuildProvider.cs
- KeyboardEventArgs.cs
- GridItemPatternIdentifiers.cs
- LambdaCompiler.Binary.cs
- DiagnosticTraceSchemas.cs
- COM2PropertyBuilderUITypeEditor.cs
- ReadWriteControlDesigner.cs
- DataBoundControlAdapter.cs
- ASCIIEncoding.cs
- ReadOnlyKeyedCollection.cs
- TextCompositionManager.cs
- SqlMethodAttribute.cs
- ParamArrayAttribute.cs
- PageThemeCodeDomTreeGenerator.cs
- SqlStatistics.cs
- SerializationAttributes.cs
- WsrmFault.cs
- XdrBuilder.cs
- FixedSchema.cs
- AuthenticatingEventArgs.cs
- VSWCFServiceContractGenerator.cs
- HttpListenerRequest.cs
- HotCommands.cs
- TdsValueSetter.cs
- ElementHostPropertyMap.cs
- GradientStop.cs
- DesignerProperties.cs
- XPathDescendantIterator.cs
- DbProviderConfigurationHandler.cs
- FlowPosition.cs
- Missing.cs
- BuilderPropertyEntry.cs
- HtmlInputPassword.cs
- C14NUtil.cs
- VSWCFServiceContractGenerator.cs
- TextSelectionHighlightLayer.cs
- InvalidPrinterException.cs
- EventLogTraceListener.cs
- HttpResponseHeader.cs
- TraceHandlerErrorFormatter.cs
- SmtpAuthenticationManager.cs
- XLinq.cs
- FontStyle.cs
- SpnEndpointIdentity.cs
- DictionaryBase.cs
- DataGridViewElement.cs
- PassportIdentity.cs
- TreeViewItemAutomationPeer.cs
- TraceContextRecord.cs
- ArraySortHelper.cs
- PublishLicense.cs
- TextRange.cs
- SiteOfOriginContainer.cs
- SmiSettersStream.cs