Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableDoubleAverageAggregationOperator.cs / 1305376 / NullableDoubleAverageAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDoubleAverageAggregationOperator.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 Nullable doubles. /// internal sealed class NullableDoubleAverageAggregationOperator : InlinedAggregationOperator, double?> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal NullableDoubleAverageAggregationOperator(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)) { // If the sequence was empty, return null right away. if (!enumerator.MoveNext()) { return null; } 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 NullableDoubleAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDoubleAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableDoubleAverageAggregationOperatorEnumerator(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); int i = 0; while (source.MoveNext(ref current, ref keyUnused)) { if (current.HasValue) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); sum += current.GetValueOrDefault(); count++; } } currentElement = new Pair (sum, count); return count > 0; } //---------------------------------------------------------------------------------------- // 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. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableDoubleAverageAggregationOperator.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 Nullable doubles. /// internal sealed class NullableDoubleAverageAggregationOperator : InlinedAggregationOperator, double?> { //---------------------------------------------------------------------------------------- // Constructs a new instance of an average associative operator. // internal NullableDoubleAverageAggregationOperator(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)) { // If the sequence was empty, return null right away. if (!enumerator.MoveNext()) { return null; } 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 NullableDoubleAverageAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableDoubleAverageAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator > { private QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableDoubleAverageAggregationOperatorEnumerator(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); int i = 0; while (source.MoveNext(ref current, ref keyUnused)) { if (current.HasValue) { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); sum += current.GetValueOrDefault(); count++; } } currentElement = new Pair (sum, count); return count > 0; } //---------------------------------------------------------------------------------------- // 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
- TextTreePropertyUndoUnit.cs
- CustomError.cs
- DrawListViewColumnHeaderEventArgs.cs
- CompositeDuplexElement.cs
- XmlSchemaRedefine.cs
- TcpConnectionPoolSettings.cs
- ResourceDisplayNameAttribute.cs
- NetworkInformationException.cs
- ToolStripSplitStackLayout.cs
- Utils.cs
- XmlTypeAttribute.cs
- VectorCollection.cs
- MemberHolder.cs
- CellLabel.cs
- IgnoreFileBuildProvider.cs
- SmiGettersStream.cs
- CodeTypeParameterCollection.cs
- DesignerWithHeader.cs
- VisualTreeHelper.cs
- CheckBoxBaseAdapter.cs
- InstanceLockLostException.cs
- ClientTarget.cs
- NumberFormatInfo.cs
- FontFamilyConverter.cs
- ScriptIgnoreAttribute.cs
- ReflectionPermission.cs
- Tokenizer.cs
- HttpListenerPrefixCollection.cs
- RepeaterItemCollection.cs
- ScrollChangedEventArgs.cs
- Journal.cs
- Transform3DGroup.cs
- DataRowView.cs
- StorageComplexTypeMapping.cs
- DocumentEventArgs.cs
- TextBoxLine.cs
- EntityDataSourceReferenceGroup.cs
- BitmapCodecInfoInternal.cs
- DataGridViewCellStyleConverter.cs
- LogicalTreeHelper.cs
- WebPartTransformer.cs
- ViewStateException.cs
- SynchronizedInputHelper.cs
- ArraySet.cs
- CertificateReferenceElement.cs
- BamlTreeNode.cs
- XPathNodeInfoAtom.cs
- BamlLocalizer.cs
- UserControl.cs
- CodeArrayIndexerExpression.cs
- MultiView.cs
- MouseButtonEventArgs.cs
- ListItemParagraph.cs
- DataMemberAttribute.cs
- AsyncSerializedWorker.cs
- CaseStatement.cs
- ChannelTerminatedException.cs
- FactoryGenerator.cs
- Section.cs
- TableHeaderCell.cs
- DynamicQueryStringParameter.cs
- EncodingInfo.cs
- Debug.cs
- PersonalizableAttribute.cs
- BooleanStorage.cs
- OdbcRowUpdatingEvent.cs
- TextEmbeddedObject.cs
- XamlDesignerSerializationManager.cs
- HttpResponseInternalWrapper.cs
- MultiTrigger.cs
- VersionedStream.cs
- WriteStateInfoBase.cs
- DataGridViewCellStyleBuilderDialog.cs
- TrackingMemoryStreamFactory.cs
- SqlTypesSchemaImporter.cs
- AnimationException.cs
- RSAPKCS1KeyExchangeDeformatter.cs
- LoadWorkflowByInstanceKeyCommand.cs
- TreeNodeCollection.cs
- WindowsListView.cs
- DocumentXPathNavigator.cs
- SearchExpression.cs
- WebResponse.cs
- FixedSOMSemanticBox.cs
- ConvertersCollection.cs
- BaseParser.cs
- MatrixTransform3D.cs
- OverlappedAsyncResult.cs
- AppendHelper.cs
- DataControlReferenceCollection.cs
- TextMetrics.cs
- IndexedGlyphRun.cs
- EpmSyndicationContentDeSerializer.cs
- WindowsFormsHost.cs
- ExpressionPrinter.cs
- QuotedPrintableStream.cs
- Substitution.cs
- SqlConnection.cs
- FixedSchema.cs
- LeaseManager.cs