Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableLongMinMaxAggregationOperator.cs / 1305376 / NullableLongMinMaxAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableLongMinMaxAggregationOperator.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{Int64}s. /// internal sealed class NullableLongMinMaxAggregationOperator : 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 NullableLongMinMaxAggregationOperator(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 long? 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; } long? best = enumerator.Current; // Based on the sign, do either a min or max reduction. if (m_sign == -1) { while (enumerator.MoveNext()) { long? current = enumerator.Current; if (best == null || current < best) { best = current; } } } else { while (enumerator.MoveNext()) { long? current = enumerator.Current; if (best == null || current > best) { 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 NullableLongMinMaxAggregationOperatorEnumerator (source, index, m_sign, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableLongMinMaxAggregationOperatorEnumerator : 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 NullableLongMinMaxAggregationOperatorEnumerator(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 long? 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) { long? elem = default(long?); while (source.MoveNext(ref elem, ref keyUnused)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (currentElement == null || elem < currentElement) { currentElement = elem; } } } else { long? elem = default(long?); while (source.MoveNext(ref elem, ref keyUnused)) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (currentElement == null || elem > currentElement) { 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
- StringValidatorAttribute.cs
- TreeViewDataItemAutomationPeer.cs
- SqlStatistics.cs
- DoubleCollectionConverter.cs
- EqualityComparer.cs
- IPAddressCollection.cs
- OdbcTransaction.cs
- TextWriterEngine.cs
- CollectionContainer.cs
- TypeDescriptionProviderAttribute.cs
- CodeTypeParameter.cs
- InvariantComparer.cs
- GeneralTransformCollection.cs
- ProxyAttribute.cs
- EntityDataSourceStatementEditorForm.cs
- ParameterExpression.cs
- SoapFault.cs
- AttachedPropertyBrowsableForChildrenAttribute.cs
- ImpersonationContext.cs
- PagedDataSource.cs
- ClientSettingsStore.cs
- PersonalizationStateInfoCollection.cs
- DesignerActionPanel.cs
- ExtensibleClassFactory.cs
- DbProviderSpecificTypePropertyAttribute.cs
- ColorAnimationBase.cs
- GZipStream.cs
- TextRangeEditLists.cs
- TriggerActionCollection.cs
- SignedPkcs7.cs
- DirtyTextRange.cs
- InitializerFacet.cs
- UInt32Converter.cs
- PositiveTimeSpanValidator.cs
- CompiledQuery.cs
- WebPartVerbCollection.cs
- Page.cs
- Matrix3D.cs
- RoleBoolean.cs
- DescendentsWalker.cs
- InputLanguageProfileNotifySink.cs
- ExceptionHandlers.cs
- MessageQueueConverter.cs
- CultureInfoConverter.cs
- HtmlWindow.cs
- HtmlButton.cs
- SqlLiftIndependentRowExpressions.cs
- CheckBoxList.cs
- TraceXPathNavigator.cs
- EntityDataSourceColumn.cs
- SchemaSetCompiler.cs
- FlowDocumentFormatter.cs
- SqlProviderManifest.cs
- RubberbandSelector.cs
- MediaContext.cs
- RulePatternOps.cs
- ContentType.cs
- SecurityContextTokenValidationException.cs
- ThreadNeutralSemaphore.cs
- CatchDesigner.xaml.cs
- ExpressionBuilderContext.cs
- EllipseGeometry.cs
- SweepDirectionValidation.cs
- RegexCompiler.cs
- AdRotator.cs
- ScrollEventArgs.cs
- ContentElement.cs
- FeatureAttribute.cs
- DataColumnPropertyDescriptor.cs
- Transform.cs
- OciEnlistContext.cs
- ListViewInsertedEventArgs.cs
- DispatcherExceptionEventArgs.cs
- Inline.cs
- DataGridViewRowEventArgs.cs
- RootBrowserWindowProxy.cs
- PagesChangedEventArgs.cs
- EntityContainer.cs
- SemanticKeyElement.cs
- XmlQueryTypeFactory.cs
- UpdateRecord.cs
- AssemblyFilter.cs
- storagemappingitemcollection.viewdictionary.cs
- DataGridPageChangedEventArgs.cs
- RestHandlerFactory.cs
- GZipStream.cs
- Image.cs
- WebHttpSecurityModeHelper.cs
- ZipQueryOperator.cs
- InstanceDescriptor.cs
- Interlocked.cs
- CustomErrorsSectionWrapper.cs
- OracleColumn.cs
- ConnectionManagementSection.cs
- XsdBuildProvider.cs
- FormView.cs
- MsmqActivation.cs
- ReadOnlyHierarchicalDataSourceView.cs
- XsdBuildProvider.cs
- WsdlHelpGeneratorElement.cs