Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / DoubleAverageAggregationOperator.cs / 1305376 / DoubleAverageAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // DoubleAverageAggregationOperator.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 doubles. /// internal sealed class DoubleAverageAggregationOperator : InlinedAggregationOperator, double> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal DoubleAverageAggregationOperator(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 double 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(double); } 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 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 DoubleAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class DoubleAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal DoubleAverageAggregationOperatorEnumerator(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; double current = default(double); 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. // ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // DoubleAverageAggregationOperator.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 doubles. /// internal sealed class DoubleAverageAggregationOperator : InlinedAggregationOperator, double> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal DoubleAverageAggregationOperator(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 double 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(double); } 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 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 DoubleAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class DoubleAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal DoubleAverageAggregationOperatorEnumerator(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; double current = default(double); 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
- HandleTable.cs
- OrderedHashRepartitionStream.cs
- InvokeHandlers.cs
- GlyphsSerializer.cs
- LockingPersistenceProvider.cs
- ActiveDocumentEvent.cs
- DrawListViewItemEventArgs.cs
- ExeConfigurationFileMap.cs
- CancelEventArgs.cs
- DynamicDocumentPaginator.cs
- DetailsViewInsertedEventArgs.cs
- SqlDataSourceView.cs
- NavigationCommands.cs
- TimelineGroup.cs
- WebPartEditorOkVerb.cs
- ErrorInfoXmlDocument.cs
- MemberDescriptor.cs
- FileDialogCustomPlace.cs
- TextTreePropertyUndoUnit.cs
- BamlTreeNode.cs
- RequiredFieldValidator.cs
- CatalogZoneAutoFormat.cs
- X509Chain.cs
- DataGridViewElement.cs
- _IPv6Address.cs
- DefaultShape.cs
- ObjectDataSourceMethodEditor.cs
- Trace.cs
- BufferedReadStream.cs
- DateTimeFormatInfoScanner.cs
- TextDecorations.cs
- ComplexBindingPropertiesAttribute.cs
- streamingZipPartStream.cs
- WebPartDisplayModeCollection.cs
- DataIdProcessor.cs
- SaveFileDialog.cs
- ExplicitDiscriminatorMap.cs
- NullableLongSumAggregationOperator.cs
- GcSettings.cs
- DataControlLinkButton.cs
- WebRequestModuleElement.cs
- WindowExtensionMethods.cs
- JsonFormatWriterGenerator.cs
- StringTraceRecord.cs
- ItemType.cs
- RsaSecurityToken.cs
- login.cs
- SqlParameterizer.cs
- UpdateProgress.cs
- Localizer.cs
- XmlDataSourceNodeDescriptor.cs
- BindableTemplateBuilder.cs
- Queue.cs
- ControlPaint.cs
- ToolStripRenderer.cs
- MyContact.cs
- X509Certificate2Collection.cs
- TraceContext.cs
- ISCIIEncoding.cs
- ComponentEditorPage.cs
- AnnotationResourceChangedEventArgs.cs
- AnonymousIdentificationSection.cs
- PrivateUnsafeNativeCompoundFileMethods.cs
- ProxyBuilder.cs
- ControlCodeDomSerializer.cs
- COM2PropertyDescriptor.cs
- TrackingServices.cs
- SingleAnimation.cs
- DelegateHelpers.Generated.cs
- ComplusTypeValidator.cs
- ValidationSummary.cs
- ExpressionConverter.cs
- ToolStripDropDownDesigner.cs
- MultiTargetingUtil.cs
- TransformPattern.cs
- FullTextBreakpoint.cs
- AgileSafeNativeMemoryHandle.cs
- RegexStringValidator.cs
- Util.cs
- TimeoutValidationAttribute.cs
- SecurityContextSecurityTokenParameters.cs
- SqlDependencyListener.cs
- DivideByZeroException.cs
- MatrixUtil.cs
- _BaseOverlappedAsyncResult.cs
- IMembershipProvider.cs
- FixedSOMTableCell.cs
- PrivateUnsafeNativeCompoundFileMethods.cs
- TemplateBindingExtension.cs
- BaseCodePageEncoding.cs
- PriorityQueue.cs
- TextBlock.cs
- EventWaitHandleSecurity.cs
- OleDbEnumerator.cs
- Debug.cs
- Oid.cs
- InternalCache.cs
- OutArgument.cs
- BaseDataList.cs
- DataTableMappingCollection.cs