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
- _ServiceNameStore.cs
- IsolatedStorageFilePermission.cs
- DPTypeDescriptorContext.cs
- X509Certificate.cs
- ValidationErrorEventArgs.cs
- ContainerParaClient.cs
- DigestComparer.cs
- EncoderBestFitFallback.cs
- InputElement.cs
- SqlBuffer.cs
- TextContainer.cs
- OdbcEnvironment.cs
- EntityKeyElement.cs
- EnumCodeDomSerializer.cs
- WebPartEditorOkVerb.cs
- XmlTextReaderImplHelpers.cs
- ClientEventManager.cs
- ToolStripPanelDesigner.cs
- XamlClipboardData.cs
- FrameworkTemplate.cs
- ResourceManagerWrapper.cs
- ConstantSlot.cs
- ForwardPositionQuery.cs
- LocationSectionRecord.cs
- XmlSerializableWriter.cs
- AlphabeticalEnumConverter.cs
- BCryptNative.cs
- PropertyToken.cs
- DependencyObjectType.cs
- Deflater.cs
- WebCategoryAttribute.cs
- ViewValidator.cs
- Variant.cs
- Ray3DHitTestResult.cs
- FlowLayout.cs
- CoreSwitches.cs
- QueryStack.cs
- TextBlock.cs
- messageonlyhwndwrapper.cs
- WizardForm.cs
- PhysicalAddress.cs
- HttpApplication.cs
- WSSecurityJan2004.cs
- COAUTHIDENTITY.cs
- ListBoxItem.cs
- SmiTypedGetterSetter.cs
- AnonymousIdentificationModule.cs
- XsltOutput.cs
- XPathAxisIterator.cs
- DockEditor.cs
- ListBindingConverter.cs
- SessionStateSection.cs
- SoapSchemaImporter.cs
- HttpRuntime.cs
- Mutex.cs
- BehaviorEditorPart.cs
- XmlDomTextWriter.cs
- DivideByZeroException.cs
- FontResourceCache.cs
- RegexWorker.cs
- ValidationRule.cs
- AppDomainManager.cs
- ItemDragEvent.cs
- GroupQuery.cs
- SchemaCollectionCompiler.cs
- DefaultTextStore.cs
- ImportContext.cs
- ObjectDataSourceSelectingEventArgs.cs
- CodeIdentifier.cs
- TransformerTypeCollection.cs
- ConfigXmlText.cs
- OptionalColumn.cs
- SystemIPGlobalStatistics.cs
- TargetInvocationException.cs
- DbConnectionPoolIdentity.cs
- FontUnit.cs
- AsymmetricSignatureDeformatter.cs
- SystemThemeKey.cs
- SortableBindingList.cs
- Listbox.cs
- BufferBuilder.cs
- FeatureSupport.cs
- _HelperAsyncResults.cs
- PathGeometry.cs
- UnauthorizedWebPart.cs
- TableRowCollection.cs
- Italic.cs
- LocalValueEnumerator.cs
- CmsInterop.cs
- SettingsPropertyIsReadOnlyException.cs
- FormViewPagerRow.cs
- QueryStatement.cs
- prefixendpointaddressmessagefilter.cs
- TemplateColumn.cs
- XhtmlConformanceSection.cs
- WebPartsPersonalizationAuthorization.cs
- XmlHelper.cs
- ExponentialEase.cs
- SpotLight.cs
- WindowsListBox.cs