Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Inlined / NullableLongSumAggregationOperator.cs / 1305376 / NullableLongSumAggregationOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // NullableLongSumAggregationOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// An inlined sum aggregation and its enumerator, for Nullable longs. /// internal sealed class NullableLongSumAggregationOperator : InlinedAggregationOperator{ //---------------------------------------------------------------------------------------- // Constructs a new instance of a sum associative operator. // internal NullableLongSumAggregationOperator(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 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)) { // We just reduce the elements in each output partition. long sum = 0L; while (enumerator.MoveNext()) { checked { sum += enumerator.Current.GetValueOrDefault(); } } return sum; } } //--------------------------------------------------------------------------------------- // 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 NullableLongSumAggregationOperatorEnumerator (source, index, cancellationToken); } //--------------------------------------------------------------------------------------- // This enumerator type encapsulates the intermediary aggregation over the underlying // (possibly partitioned) data source. // private class NullableLongSumAggregationOperatorEnumerator : InlinedAggregationOperatorEnumerator { private readonly QueryOperatorEnumerator m_source; // The source data. //---------------------------------------------------------------------------------------- // Instantiates a new aggregation operator. // internal NullableLongSumAggregationOperatorEnumerator(QueryOperatorEnumerator source, int partitionIndex, CancellationToken cancellationToken) : base(partitionIndex, cancellationToken) { Contract.Assert(source != null); m_source = source; } //--------------------------------------------------------------------------------------- // Tallies up the sum 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) { long? element = default(long?); TKey keyUnused = default(TKey); QueryOperatorEnumerator source = m_source; if (source.MoveNext(ref element, ref keyUnused)) { // We just scroll through the enumerator and accumulate the sum. long tempSum = 0L; int i = 0; do { if ((i++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); checked { tempSum += element.GetValueOrDefault(); } } while (source.MoveNext(ref element, ref keyUnused)); // The sum has been calculated. Now just return. currentElement = new long?(tempSum); 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
- TreeNodeClickEventArgs.cs
- ClientRoleProvider.cs
- Point4DValueSerializer.cs
- InputReferenceExpression.cs
- DecoderBestFitFallback.cs
- KeyValuePair.cs
- SqlBinder.cs
- TextCompositionEventArgs.cs
- SortedSet.cs
- LineSegment.cs
- Highlights.cs
- SmiGettersStream.cs
- UnionCodeGroup.cs
- WSHttpSecurity.cs
- ThreadStaticAttribute.cs
- GrammarBuilder.cs
- ASCIIEncoding.cs
- XmlBinaryWriterSession.cs
- WebServiceClientProxyGenerator.cs
- SmtpSpecifiedPickupDirectoryElement.cs
- ButtonBase.cs
- TextSimpleMarkerProperties.cs
- GlobalDataBindingHandler.cs
- DocumentSequence.cs
- SuppressIldasmAttribute.cs
- MethodExpr.cs
- PropertySet.cs
- SchemaCompiler.cs
- DeviceContext2.cs
- ToolStripSplitButton.cs
- MetabaseServerConfig.cs
- GetWinFXPath.cs
- ContentWrapperAttribute.cs
- Literal.cs
- WrappedIUnknown.cs
- WhitespaceRule.cs
- HoistedLocals.cs
- SmiXetterAccessMap.cs
- FamilyTypeface.cs
- WebPartConnectionsCancelEventArgs.cs
- DateTimeConverter2.cs
- TransactionScopeDesigner.cs
- SqlGatherConsumedAliases.cs
- Misc.cs
- TdsParserStateObject.cs
- ToggleProviderWrapper.cs
- OdbcConnectionString.cs
- PreviewKeyDownEventArgs.cs
- Line.cs
- MethodImplAttribute.cs
- RelationshipSet.cs
- TimeSpan.cs
- DataServiceConfiguration.cs
- ForceCopyBuildProvider.cs
- FontFamily.cs
- SelectedCellsChangedEventArgs.cs
- WmlSelectionListAdapter.cs
- DtdParser.cs
- ZipIOLocalFileBlock.cs
- MemoryMappedView.cs
- DataGridViewAutoSizeColumnsModeEventArgs.cs
- RoleManagerSection.cs
- ReverseInheritProperty.cs
- BinaryUtilClasses.cs
- RectConverter.cs
- VisualStyleTypesAndProperties.cs
- ProviderIncompatibleException.cs
- TextServicesProperty.cs
- UnhandledExceptionEventArgs.cs
- FixUp.cs
- IdnElement.cs
- LocalizableResourceBuilder.cs
- DriveInfo.cs
- ListViewDeletedEventArgs.cs
- UpdatePanelControlTrigger.cs
- XmlSchemaSequence.cs
- FileClassifier.cs
- NumberEdit.cs
- HttpFileCollectionWrapper.cs
- HttpCookieCollection.cs
- ToolBarPanel.cs
- ThreadExceptionEvent.cs
- WebPartsSection.cs
- AttachedAnnotationChangedEventArgs.cs
- FlowchartDesignerCommands.cs
- RowUpdatingEventArgs.cs
- JournalNavigationScope.cs
- ScaleTransform3D.cs
- GeometryDrawing.cs
- ElementProxy.cs
- BookmarkEventArgs.cs
- ResourceDescriptionAttribute.cs
- Header.cs
- EnumMember.cs
- ReflectionPermission.cs
- BmpBitmapDecoder.cs
- IsolatedStorageFilePermission.cs
- NativeMethods.cs
- PenThread.cs
- UITypeEditors.cs