Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Linq / Parallel / QueryOperators / Unary / WhereQueryOperator.cs / 1305376 / WhereQueryOperator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ // // WhereQueryOperator.cs // //[....] // // =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- using System.Collections.Generic; using System.Diagnostics.Contracts; using System.Threading; namespace System.Linq.Parallel { ////// The operator type for Where statements. This operator filters out elements that /// don't match a filter function (supplied at instantiation time). /// ///internal sealed class WhereQueryOperator : UnaryQueryOperator { // Predicate function. Used to filter out non-matching elements during execution. private Func m_predicate; //---------------------------------------------------------------------------------------- // Initializes a new where operator. // // Arguments: // child - the child operator or data source from which to pull data // predicate - a delegate representing the predicate function // // Assumptions: // predicate must be non null. // internal WhereQueryOperator(IEnumerable child, Func predicate) : base(child) { Contract.Assert(child != null, "child data source cannot be null"); Contract.Assert(predicate != null, "need a filter function"); SetOrdinalIndexState( ExchangeUtilities.Worse(Child.OrdinalIndexState, OrdinalIndexState.Increasing)); m_predicate = predicate; } internal override void WrapPartitionedStream ( PartitionedStream inputStream, IPartitionedStreamRecipient recipient, bool preferStriping, QuerySettings settings) { PartitionedStream outputStream = new PartitionedStream ( inputStream.PartitionCount, inputStream.KeyComparer, OrdinalIndexState); for (int i = 0; i < inputStream.PartitionCount; i++) { outputStream[i] = new WhereQueryOperatorEnumerator (inputStream[i], m_predicate, settings.CancellationState.MergedCancellationToken); } recipient.Receive(outputStream); } //--------------------------------------------------------------------------------------- // Just opens the current operator, including opening the child and wrapping it with // partitions as needed. // internal override QueryResults Open(QuerySettings settings, bool preferStriping) { // We just open the child operator. QueryResults childQueryResults = Child.Open(settings, preferStriping); // And then return the query results return new UnaryQueryOperatorResults(childQueryResults, this, settings, preferStriping); } //--------------------------------------------------------------------------------------- // Returns an enumerable that represents the query executing sequentially. // internal override IEnumerable AsSequentialQuery(CancellationToken token) { IEnumerable wrappedChild = CancellableEnumerable.Wrap(Child.AsSequentialQuery(token), token); return wrappedChild.Where(m_predicate); } //--------------------------------------------------------------------------------------- // Whether this operator performs a premature merge. // internal override bool LimitsParallelism { get { return false; } } //------------------------------------------------------------------------------------ // An enumerator that implements the filtering logic. // private class WhereQueryOperatorEnumerator : QueryOperatorEnumerator { private readonly QueryOperatorEnumerator m_source; // The data source to enumerate. private readonly Func m_predicate; // The predicate used for filtering. private CancellationToken m_cancellationToken; private Shared m_outputLoopCount; //----------------------------------------------------------------------------------- // Instantiates a new enumerator. // internal WhereQueryOperatorEnumerator(QueryOperatorEnumerator source, Func predicate, CancellationToken cancellationToken) { Contract.Assert(source != null); Contract.Assert(predicate != null); m_source = source; m_predicate = predicate; m_cancellationToken = cancellationToken; } //------------------------------------------------------------------------------------ // Moves to the next matching element in the underlying data stream. // internal override bool MoveNext(ref TInputOutput currentElement, ref TKey currentKey) { Contract.Assert(m_predicate != null, "expected a compiled operator"); // Iterate through the input until we reach the end of the sequence or find // an element matching the predicate. if (m_outputLoopCount == null) m_outputLoopCount = new Shared (0); while (m_source.MoveNext(ref currentElement, ref currentKey)) { if ((m_outputLoopCount.Value++ & CancellationState.POLL_INTERVAL) == 0) CancellationState.ThrowIfCanceled(m_cancellationToken); if (m_predicate(currentElement)) { return true; } } return false; } 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
- StylusPoint.cs
- TransportDefaults.cs
- DocumentApplicationJournalEntry.cs
- KeyValueConfigurationCollection.cs
- BrowserDefinition.cs
- ModuleBuilder.cs
- DetailsViewInsertedEventArgs.cs
- BinaryKeyIdentifierClause.cs
- RootDesignerSerializerAttribute.cs
- SqlFlattener.cs
- ToolStripItemTextRenderEventArgs.cs
- DataAdapter.cs
- CssTextWriter.cs
- SQLDecimalStorage.cs
- DateTimeParse.cs
- ColumnTypeConverter.cs
- UriExt.cs
- DispatcherExceptionEventArgs.cs
- FixedPageProcessor.cs
- UriTemplateQueryValue.cs
- ServicePointManager.cs
- MergeFailedEvent.cs
- MergeLocalizationDirectives.cs
- OleDbRowUpdatingEvent.cs
- XamlFigureLengthSerializer.cs
- SqlConnectionPoolGroupProviderInfo.cs
- GlyphInfoList.cs
- IsolatedStorageFilePermission.cs
- Bitmap.cs
- StyleCollectionEditor.cs
- RelationshipConstraintValidator.cs
- VBCodeProvider.cs
- DataGridViewCheckBoxCell.cs
- hresults.cs
- Utils.cs
- CodeArrayIndexerExpression.cs
- TextContainerChangedEventArgs.cs
- BindingValueChangedEventArgs.cs
- TransformGroup.cs
- CodeDOMUtility.cs
- IPipelineRuntime.cs
- SoapParser.cs
- NavigatingCancelEventArgs.cs
- DesignerOptions.cs
- InputLangChangeRequestEvent.cs
- MatrixValueSerializer.cs
- ScriptDescriptor.cs
- XmlExceptionHelper.cs
- TimeStampChecker.cs
- CultureNotFoundException.cs
- IdentityManager.cs
- CqlWriter.cs
- sortedlist.cs
- List.cs
- PopupRoot.cs
- HandlerMappingMemo.cs
- AnnotationAuthorChangedEventArgs.cs
- RoutedCommand.cs
- InProcStateClientManager.cs
- FontSource.cs
- ObjectSpanRewriter.cs
- XmlReaderSettings.cs
- DataGridViewLayoutData.cs
- WebPartsPersonalization.cs
- ClientConfigPaths.cs
- StickyNoteContentControl.cs
- ActivityCodeDomReferenceService.cs
- BlobPersonalizationState.cs
- Addressing.cs
- ActiveXContainer.cs
- GeometryValueSerializer.cs
- RequiredFieldValidator.cs
- TiffBitmapEncoder.cs
- FillRuleValidation.cs
- SafeSecurityHelper.cs
- CollectionViewGroupInternal.cs
- DBAsyncResult.cs
- XamlStream.cs
- Int16Converter.cs
- DesigntimeLicenseContext.cs
- XmlAttributeProperties.cs
- WebPartTracker.cs
- _ProxyChain.cs
- ConnectivityStatus.cs
- SemanticResolver.cs
- Size3D.cs
- Rijndael.cs
- ToolboxCategory.cs
- elementinformation.cs
- Stylesheet.cs
- Point3DAnimation.cs
- ElementUtil.cs
- UrlAuthorizationModule.cs
- ChangeConflicts.cs
- SqlGatherProducedAliases.cs
- Accessors.cs
- VSWCFServiceContractGenerator.cs
- BasicAsyncResult.cs
- Grant.cs
- Overlapped.cs