Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / FloatAverageAggregationOperator.cs / 1305376 / FloatAverageAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // FloatAverageAggregationOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined average aggregation operator and its enumerator, for floats. /// internal sealed class FloatAverageAggregationOperator : InlinedAggregationOperator, float> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal FloatAverageAggregationOperator(IEnumerable child) : base(child) { } //--------------------------------------------------------------------------------------- // 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)) { // Throw an error for empty results. if (!enumerator.MoveNext()) { singularExceptionToThrow = new InvalidOperationException(SR.GetString(SR.NoElements)); return default(float); } Pair result = enumerator.Current; // Simply add together the sums and totals. while (enumerator.MoveNext()) { checked { result.First += enumerator.Current.First; result.Second += enumerator.Current.Second; } } // And divide the sum by the total to obtain the final result. return (float)(result.First / result.Second); } } //--------------------------------------------------------------------------------------- // Creates an enumerator that is used internally for the final aggregation step. // protected override QueryOperatorEnumerator , int> CreateEnumerator ( int index, int count, QueryOperatorEnumerator source, object sharedData, CancellationToken cancellationToken) { return new FloatAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class FloatAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal FloatAverageAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; } //--------------------------------------------------------------------------------------- // Tallies up the average of the underlying data source, walking the entire thing the first // time MoveNext is called on this object. // protected override bool MoveNextCore(ref Pair currentElement) { // The temporary result contains the running sum and count, respectively. double sum = 0.0; long count = 0; QueryOperatorEnumerator source = m_source; float current = default(float); TKey keyUnused = default(TKey); if (source.MoveNext(ref current, ref keyUnused)) { int i = 0; do { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); checked { sum += current; count++; } } while (source.MoveNext(ref current, ref keyUnused)); currentElement = new Pair (sum, count); 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
- BadImageFormatException.cs
- errorpatternmatcher.cs
- ResourceDictionaryCollection.cs
- DistinctQueryOperator.cs
- Pair.cs
- ObjectDesignerDataSourceView.cs
- SurrogateEncoder.cs
- RowCache.cs
- Component.cs
- XmlSchemaAppInfo.cs
- HttpListenerRequest.cs
- TextServicesLoader.cs
- ApplicationContext.cs
- ConstructorBuilder.cs
- odbcmetadatacolumnnames.cs
- EventLogPropertySelector.cs
- MarkedHighlightComponent.cs
- IBuiltInEvidence.cs
- Misc.cs
- PopupEventArgs.cs
- GridItemPattern.cs
- CultureTableRecord.cs
- HotCommands.cs
- XPathDocumentBuilder.cs
- KoreanCalendar.cs
- LogicalExpressionTypeConverter.cs
- SliderAutomationPeer.cs
- ArglessEventHandlerProxy.cs
- FtpRequestCacheValidator.cs
- CroppedBitmap.cs
- EditCommandColumn.cs
- CodeCatchClause.cs
- FormsAuthenticationUser.cs
- CheckBox.cs
- MissingSatelliteAssemblyException.cs
- Win32MouseDevice.cs
- Vertex.cs
- UnmanagedHandle.cs
- MachineKey.cs
- MediaTimeline.cs
- ThreadWorkerController.cs
- Storyboard.cs
- Underline.cs
- DocumentSchemaValidator.cs
- SchemaMerger.cs
- Base64Encoder.cs
- SequentialWorkflowRootDesigner.cs
- SafeMemoryMappedFileHandle.cs
- XmlIlGenerator.cs
- CommandValueSerializer.cs
- NameValueFileSectionHandler.cs
- FormatConvertedBitmap.cs
- MemoryStream.cs
- HttpModuleCollection.cs
- Composition.cs
- SafeHandles.cs
- Stopwatch.cs
- TableHeaderCell.cs
- Profiler.cs
- ComponentGlyph.cs
- ManifestResourceInfo.cs
- LookupBindingPropertiesAttribute.cs
- SqlUtils.cs
- PropertyDescriptor.cs
- ProfilePropertySettings.cs
- VBCodeProvider.cs
- FileDataSourceCache.cs
- GridViewHeaderRowPresenterAutomationPeer.cs
- LabelLiteral.cs
- MethodCallTranslator.cs
- DebugView.cs
- TrustManager.cs
- TextElementEnumerator.cs
- MobileComponentEditorPage.cs
- ParallelDesigner.cs
- DataGridTextColumn.cs
- DesignerPainter.cs
- ReturnType.cs
- ToolStripDropDownDesigner.cs
- TextEffectCollection.cs
- CatalogZone.cs
- UIHelper.cs
- JavaScriptObjectDeserializer.cs
- UiaCoreProviderApi.cs
- Table.cs
- WebProxyScriptElement.cs
- ScrollPattern.cs
- NetworkInformationException.cs
- ReflectPropertyDescriptor.cs
- TaskFormBase.cs
- PersistenceProvider.cs
- CfgParser.cs
- ManagementOptions.cs
- GridViewAutomationPeer.cs
- MessageQueuePermissionEntry.cs
- PropertyGridCommands.cs
- SymbolType.cs
- Localizer.cs
- SupportsEventValidationAttribute.cs
- SiteMap.cs