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
- LinqDataSourceDeleteEventArgs.cs
- ProcessStartInfo.cs
- TextServicesDisplayAttribute.cs
- SmtpTransport.cs
- StringReader.cs
- CharacterBufferReference.cs
- MobileListItem.cs
- HTTPNotFoundHandler.cs
- RunClient.cs
- LassoHelper.cs
- HandlerBase.cs
- XmlImplementation.cs
- SwitchExpression.cs
- PhysicalAddress.cs
- CustomActivityDesigner.cs
- COM2EnumConverter.cs
- HtmlGenericControl.cs
- SpellCheck.cs
- CacheAxisQuery.cs
- FileSystemWatcher.cs
- LinqMaximalSubtreeNominator.cs
- CodeTypeReference.cs
- DataGridViewRowErrorTextNeededEventArgs.cs
- SHA384Cng.cs
- TypeElementCollection.cs
- DomainUpDown.cs
- GPRECT.cs
- ActivityCodeDomSerializer.cs
- CompositeDuplexBindingElement.cs
- PersonalizationAdministration.cs
- PhoneCallDesigner.cs
- DataMisalignedException.cs
- Button.cs
- X509Certificate.cs
- WebPartConnectionsDisconnectVerb.cs
- IntegerValidatorAttribute.cs
- TemplateLookupAction.cs
- CompoundFileStorageReference.cs
- SiteMapNodeCollection.cs
- ControlFilterExpression.cs
- TdsParser.cs
- X509CertificateClaimSet.cs
- FrameworkElementAutomationPeer.cs
- ObjectDataProvider.cs
- SafeNativeMethodsCLR.cs
- WhitespaceSignificantCollectionAttribute.cs
- UserPreferenceChangedEventArgs.cs
- RefreshPropertiesAttribute.cs
- DesignBindingPropertyDescriptor.cs
- columnmapfactory.cs
- PerfProviderCollection.cs
- OracleRowUpdatedEventArgs.cs
- IncrementalReadDecoders.cs
- LocalFileSettingsProvider.cs
- XmlEncoding.cs
- BuildProvider.cs
- XhtmlBasicValidationSummaryAdapter.cs
- BasePattern.cs
- EditorZoneAutoFormat.cs
- AliasGenerator.cs
- uribuilder.cs
- ResourceFallbackManager.cs
- SetIterators.cs
- AssemblyBuilder.cs
- ConfigurationPermission.cs
- X509Extension.cs
- NamespaceDecl.cs
- InvokeGenerator.cs
- LayoutTableCell.cs
- PackageDigitalSignatureManager.cs
- DESCryptoServiceProvider.cs
- EntryPointNotFoundException.cs
- UnauthorizedWebPart.cs
- TextTrailingWordEllipsis.cs
- WebPartsPersonalizationAuthorization.cs
- TypeEnumerableViewSchema.cs
- XmlSchemaAppInfo.cs
- __FastResourceComparer.cs
- DoubleStorage.cs
- DisableDpiAwarenessAttribute.cs
- UniqueEventHelper.cs
- Listbox.cs
- HostingEnvironmentSection.cs
- DynamicScriptObject.cs
- MemberMemberBinding.cs
- FileDialogPermission.cs
- TreeWalker.cs
- CodeAccessPermission.cs
- arc.cs
- XmlSchemaGroupRef.cs
- WizardStepCollectionEditor.cs
- IxmlLineInfo.cs
- InvokeMethodActivity.cs
- HealthMonitoringSectionHelper.cs
- DrawingContextDrawingContextWalker.cs
- SingleTagSectionHandler.cs
- XmlLanguage.cs
- WebPartTransformerAttribute.cs
- CharUnicodeInfo.cs
- WebException.cs