Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / LongMinMaxAggregationOperator.cs / 1305376 / LongMinMaxAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // LongMinMaxAggregationOperator.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 longs. /// internal sealed class LongMinMaxAggregationOperator : 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 LongMinMaxAggregationOperator(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)) { // Throw an error for empty results. if (!enumerator.MoveNext()) { singularExceptionToThrow = new InvalidOperationException(SR.GetString(SR.NoElements)); return default(long); } 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 (current < best) { best = current; } } } else { while (enumerator.MoveNext()) { long current = enumerator.Current; if (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 LongMinMaxAggregationOperatorEnumerator (source, index, m_sign, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class LongMinMaxAggregationOperatorEnumerator : 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 LongMinMaxAggregationOperatorEnumerator(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 (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 (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
- TraceXPathNavigator.cs
- XPathChildIterator.cs
- WebRequestModuleElementCollection.cs
- IriParsingElement.cs
- ConstraintEnumerator.cs
- UserControlCodeDomTreeGenerator.cs
- SourceFileBuildProvider.cs
- OleDbPermission.cs
- UidManager.cs
- CodeTypeReferenceExpression.cs
- XamlReaderHelper.cs
- IndexingContentUnit.cs
- CombinedHttpChannel.cs
- EventPropertyMap.cs
- _ConnectionGroup.cs
- ClientSection.cs
- SoapTypeAttribute.cs
- SHA384Managed.cs
- TrackingStringDictionary.cs
- OptimalBreakSession.cs
- EndpointInstanceProvider.cs
- DbProviderConfigurationHandler.cs
- XamlSerializerUtil.cs
- SourceItem.cs
- RoutedEventArgs.cs
- ToolStripHighContrastRenderer.cs
- TrackingServices.cs
- LayoutInformation.cs
- CacheAxisQuery.cs
- CollectionEditVerbManager.cs
- SoundPlayerAction.cs
- IdentityReference.cs
- Package.cs
- Parameter.cs
- ServiceNameCollection.cs
- TranslateTransform.cs
- CancelEventArgs.cs
- NamespaceList.cs
- RoutedUICommand.cs
- PropertyDescriptorGridEntry.cs
- BmpBitmapDecoder.cs
- SafeEventHandle.cs
- DeferredTextReference.cs
- JoinTreeSlot.cs
- PropertyDescriptorCollection.cs
- IODescriptionAttribute.cs
- TypeConverter.cs
- DataGridItemEventArgs.cs
- DiscoveryMessageSequence11.cs
- SqlMethodAttribute.cs
- ButtonField.cs
- ToolStripMenuItem.cs
- TheQuery.cs
- Renderer.cs
- SspiHelper.cs
- LoadedOrUnloadedOperation.cs
- GlobalizationAssembly.cs
- nulltextcontainer.cs
- RemotingConfiguration.cs
- XPathNodeIterator.cs
- ThreadWorkerController.cs
- TextChangedEventArgs.cs
- AstTree.cs
- RectangleGeometry.cs
- EdmRelationshipRoleAttribute.cs
- TranslateTransform.cs
- GridViewUpdateEventArgs.cs
- X509CertificateCollection.cs
- VSDExceptions.cs
- SoapSchemaMember.cs
- baseaxisquery.cs
- UrlSyndicationContent.cs
- DesigntimeLicenseContextSerializer.cs
- DataServiceKeyAttribute.cs
- SoapCodeExporter.cs
- AssemblyCollection.cs
- SqlGenericUtil.cs
- IPHostEntry.cs
- CompositeDataBoundControl.cs
- ScriptMethodAttribute.cs
- PerfCounters.cs
- MultiViewDesigner.cs
- WindowsFormsSynchronizationContext.cs
- HelpPage.cs
- AlphaSortedEnumConverter.cs
- CommandID.cs
- Selection.cs
- ThemeDirectoryCompiler.cs
- SQLUtility.cs
- ArraySubsetEnumerator.cs
- WebProxyScriptElement.cs
- OperationContextScope.cs
- NotifyCollectionChangedEventArgs.cs
- ItemsPresenter.cs
- InboundActivityHelper.cs
- MimeTypeMapper.cs
- Line.cs
- FreezableDefaultValueFactory.cs
- ConsumerConnectionPoint.cs
- Ticks.cs