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
- IconHelper.cs
- SignedPkcs7.cs
- ConfigurationCollectionAttribute.cs
- WebBrowserPermission.cs
- DataBoundControlActionList.cs
- Timer.cs
- BindingExpressionBase.cs
- XPathDocumentBuilder.cs
- SHA256Managed.cs
- UserControlDocumentDesigner.cs
- Common.cs
- ColorAnimationBase.cs
- DriveNotFoundException.cs
- DbDataRecord.cs
- NameValueConfigurationElement.cs
- ToolBarPanel.cs
- RSAProtectedConfigurationProvider.cs
- ResourceCategoryAttribute.cs
- ProfilePropertyNameValidator.cs
- TableRowsCollectionEditor.cs
- CommonXSendMessage.cs
- NameValuePermission.cs
- ProcessHostServerConfig.cs
- _FixedSizeReader.cs
- GridView.cs
- HostVisual.cs
- DispatcherExceptionFilterEventArgs.cs
- input.cs
- Utils.cs
- selecteditemcollection.cs
- ImageMapEventArgs.cs
- RegionInfo.cs
- NumberFormatter.cs
- MultipleViewPatternIdentifiers.cs
- HashMembershipCondition.cs
- AccessViolationException.cs
- DataRow.cs
- ReadOnlyAttribute.cs
- HttpServerUtilityBase.cs
- ReferencedAssembly.cs
- ArithmeticException.cs
- SqlUnionizer.cs
- WorkflowPageSetupDialog.cs
- _NtlmClient.cs
- RadioButtonFlatAdapter.cs
- DSACryptoServiceProvider.cs
- XmlDataSourceNodeDescriptor.cs
- Ops.cs
- TreeViewHitTestInfo.cs
- PackWebRequestFactory.cs
- UnsafeNativeMethodsPenimc.cs
- MenuItemStyleCollectionEditor.cs
- QilPatternFactory.cs
- NullableConverter.cs
- PrinterUnitConvert.cs
- ActivityDelegate.cs
- CounterSetInstance.cs
- MarkerProperties.cs
- DiscriminatorMap.cs
- ACL.cs
- Int64Converter.cs
- DrawingState.cs
- EventHandlerList.cs
- BitmapPalettes.cs
- RegexGroup.cs
- KnownBoxes.cs
- PageStatePersister.cs
- ImageListStreamer.cs
- ZoneButton.cs
- Size.cs
- ProfileWorkflowElement.cs
- PopupRoot.cs
- CopyAction.cs
- rsa.cs
- WS2007FederationHttpBinding.cs
- ConfigXmlComment.cs
- ColorTransform.cs
- DateTimeFormat.cs
- FontWeights.cs
- ObjectDataSourceStatusEventArgs.cs
- TypeLoadException.cs
- DependencyPropertyKey.cs
- StringAnimationUsingKeyFrames.cs
- FormViewPagerRow.cs
- MachineKeyValidationConverter.cs
- PersistenceTask.cs
- DataTableReader.cs
- SlipBehavior.cs
- OutputCacheProfileCollection.cs
- TypedAsyncResult.cs
- SingleSelectRootGridEntry.cs
- SafeArchiveContext.cs
- Attributes.cs
- ScriptControl.cs
- ObjectItemCollectionAssemblyCacheEntry.cs
- SignalGate.cs
- DataObjectAttribute.cs
- WebPartExportVerb.cs
- InvalidCommandTreeException.cs
- SQLUtility.cs