Code:
/ 4.0 / 4.0 / untmp / 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.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- FixedNode.cs
- WindowsListViewItem.cs
- QilUnary.cs
- Parameter.cs
- TableHeaderCell.cs
- SchemeSettingElementCollection.cs
- VersionedStream.cs
- JsonUriDataContract.cs
- safex509handles.cs
- Utils.cs
- VerificationAttribute.cs
- RewritingSimplifier.cs
- UnsafeNetInfoNativeMethods.cs
- SamlConditions.cs
- SignatureDescription.cs
- XMLUtil.cs
- XmlDataLoader.cs
- XNameConverter.cs
- XmlBinaryWriter.cs
- DocumentPageTextView.cs
- XmlNodeChangedEventArgs.cs
- PriorityBindingExpression.cs
- OutOfProcStateClientManager.cs
- MetaModel.cs
- _LoggingObject.cs
- EventPrivateKey.cs
- WebZone.cs
- PtsContext.cs
- CheckedListBox.cs
- SqlDataSourceFilteringEventArgs.cs
- Avt.cs
- AttachedPropertyBrowsableForTypeAttribute.cs
- CodeGotoStatement.cs
- ListViewGroupCollectionEditor.cs
- ScaleTransform3D.cs
- _NestedMultipleAsyncResult.cs
- SqlConnectionFactory.cs
- EntityViewGenerator.cs
- SystemKeyConverter.cs
- ConnectionStringsSection.cs
- AudioLevelUpdatedEventArgs.cs
- FunctionQuery.cs
- InputMethodStateChangeEventArgs.cs
- StringPropertyBuilder.cs
- PrincipalPermission.cs
- DesignerWidgets.cs
- BinHexDecoder.cs
- ApplicationFileParser.cs
- RepeatBehaviorConverter.cs
- IMembershipProvider.cs
- RectangleConverter.cs
- TargetControlTypeAttribute.cs
- DependencyPropertyHelper.cs
- PopupEventArgs.cs
- DecimalAnimationBase.cs
- ZoneMembershipCondition.cs
- RemoteHelper.cs
- ThicknessConverter.cs
- ObjectStateFormatter.cs
- RawStylusInputCustomDataList.cs
- UInt64Converter.cs
- SqlProviderUtilities.cs
- ListenerAdaptersInstallComponent.cs
- _emptywebproxy.cs
- DataBinder.cs
- XmlSerializationGeneratedCode.cs
- EventArgs.cs
- InvalidCommandTreeException.cs
- SqlConnectionManager.cs
- WsatServiceCertificate.cs
- ExpressionPrefixAttribute.cs
- ScrollItemPattern.cs
- MaterialGroup.cs
- DatagridviewDisplayedBandsData.cs
- unsafenativemethodstextservices.cs
- RichTextBoxAutomationPeer.cs
- X509UI.cs
- Point3DCollectionValueSerializer.cs
- RequestCacheEntry.cs
- XpsS0ValidatingLoader.cs
- CodeExporter.cs
- InputDevice.cs
- PropertyEntry.cs
- AnimationStorage.cs
- BitConverter.cs
- ObjectDataSourceEventArgs.cs
- Process.cs
- Point.cs
- InternalConfigHost.cs
- TCPClient.cs
- FixedSOMLineRanges.cs
- Command.cs
- DES.cs
- NetMsmqBinding.cs
- ExpressionVisitor.cs
- SecurityTokenAuthenticator.cs
- MetadataSerializer.cs
- DaylightTime.cs
- SqlDataReaderSmi.cs
- Error.cs