Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Runtime / Serialization / ObjectIDGenerator.cs / 1305376 / ObjectIDGenerator.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== /*============================================================ ** ** Class: ObjectIDGenerator ** ** ** Purpose: ObjectIDGenerator is a simple id generator that keeps track of ** objects with a hashtable. ** ** ===========================================================*/ namespace System.Runtime.Serialization { using System; using System.Runtime.CompilerServices; using System.Runtime.Remoting; using System.Diagnostics.Contracts; [Serializable] [System.Runtime.InteropServices.ComVisible(true)] public class ObjectIDGenerator { private const int numbins = 4; internal int m_currentCount; internal int m_currentSize; internal long []m_ids; internal Object []m_objs; // Table of prime numbers to use as hash table sizes. Each entry is the // smallest prime number larger than twice the previous entry. private static readonly int[] sizes = { 5, 11, 29, 47, 97, 197, 397, 797, 1597, 3203, 6421, 12853, 25717, 51437, 102877, 205759, 411527, 823117, 1646237, 3292489, 6584983}; // Constructs a new ObjectID generator, initalizing all of the necessary variables. public ObjectIDGenerator() { m_currentCount=1; m_currentSize = sizes[0]; m_ids = new long[m_currentSize*numbins]; m_objs = new Object[m_currentSize*numbins]; } // Determines where element obj lives, or should live, // within the table. It calculates the hashcode and searches all of the // bins where the given object could live. If it's not found within the bin, // we rehash and go look for it in another bin. If we find the object, we // set found to true and return it's position. If we can't find the object, // we set found to false and return the position where the object should be inserted. // private int FindElement(Object obj, out bool found) { //This double-hashing algorithm is recomended by CLR, pg 236. //We're hosed if somebody rehashes the table while we're doing the lookup, but that's //generally true for most of these operations. int hashcode = RuntimeHelpers.GetHashCode(obj); int hashIncrement = (1+((hashcode&0x7FFFFFFF)%(m_currentSize-2))); do { int pos = ((hashcode&0x7FFFFFFF)%m_currentSize)*numbins; for (int i=pos; i(m_currentSize*numbins)/2) { Rehash(); } } else { BCLDebug.Trace("SER", "[ObjectIDGenerator.GetID] Found objectid: ", (m_ids[pos]), " with hashcode: ", RuntimeHelpers.GetHashCode(obj), " Type: ", obj); foundID = m_ids[pos]; } firstTime = !found; return foundID; } // Checks to see if obj has already been assigned an id. If it has, // we return that id, otherwise we return 0. // public virtual long HasId(Object obj, out bool firstTime) { bool found; if (obj==null) { throw new ArgumentNullException("obj", Environment.GetResourceString("ArgumentNull_Obj")); } Contract.EndContractBlock(); int pos = FindElement(obj, out found); if (found) { firstTime = false; return m_ids[pos]; } firstTime=true; return 0; } // Rehashes the table by finding the next larger size in the list provided, // allocating two new arrays of that size and rehashing all of the elements in // the old arrays into the new ones. Expensive but necessary. // private void Rehash() { int i,pos; long [] newIds; long [] oldIds; Object[] newObjs; Object[] oldObjs; bool found; int currSize; for (i=0, currSize=m_currentSize; i This double-hashing algorithm is recomended by CLR, pg 236. //We're hosed if somebody rehashes the table while we're doing the lookup, but that's //generally true for most of these operations. int hashcode = RuntimeHelpers.GetHashCode(obj); int hashIncrement = (1+((hashcode&0x7FFFFFFF)%(m_currentSize-2))); do { int pos = ((hashcode&0x7FFFFFFF)%m_currentSize)*numbins; for (int i=pos; i (m_currentSize*numbins)/2) { Rehash(); } } else { BCLDebug.Trace("SER", "[ObjectIDGenerator.GetID] Found objectid: ", (m_ids[pos]), " with hashcode: ", RuntimeHelpers.GetHashCode(obj), " Type: ", obj); foundID = m_ids[pos]; } firstTime = !found; return foundID; } // Checks to see if obj has already been assigned an id. If it has, // we return that id, otherwise we return 0. // public virtual long HasId(Object obj, out bool firstTime) { bool found; if (obj==null) { throw new ArgumentNullException("obj", Environment.GetResourceString("ArgumentNull_Obj")); } Contract.EndContractBlock(); int pos = FindElement(obj, out found); if (found) { firstTime = false; return m_ids[pos]; } firstTime=true; return 0; } // Rehashes the table by finding the next larger size in the list provided, // allocating two new arrays of that size and rehashing all of the elements in // the old arrays into the new ones. Expensive but necessary. // private void Rehash() { int i,pos; long [] newIds; long [] oldIds; Object[] newObjs; Object[] oldObjs; bool found; int currSize; for (i=0, currSize=m_currentSize; i
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- ActivationWorker.cs
- UnmanagedMemoryStream.cs
- ImageCodecInfoPrivate.cs
- RoleService.cs
- InstancePersistenceCommand.cs
- _ConnectionGroup.cs
- TextServicesCompartmentContext.cs
- CaseKeyBox.ViewModel.cs
- Msmq4SubqueuePoisonHandler.cs
- DataFormats.cs
- PrimitiveSchema.cs
- ParserExtension.cs
- TableLayoutSettings.cs
- SqlDataSourceFilteringEventArgs.cs
- HitTestFilterBehavior.cs
- ExecutionScope.cs
- MessageQueueInstaller.cs
- SchemaImporter.cs
- cookieexception.cs
- Line.cs
- CodePageUtils.cs
- XmlSchemaType.cs
- IntersectQueryOperator.cs
- WmlValidatorAdapter.cs
- WhitespaceRuleReader.cs
- UnmanagedBitmapWrapper.cs
- TraceUtils.cs
- ContainerParagraph.cs
- UnsafeNativeMethods.cs
- X509UI.cs
- JoinElimination.cs
- SystemBrushes.cs
- NameSpaceExtractor.cs
- XhtmlTextWriter.cs
- DefaultTextStore.cs
- PostBackOptions.cs
- _DigestClient.cs
- CrossSiteScriptingValidation.cs
- ProvidersHelper.cs
- DataGridLinkButton.cs
- FormatConvertedBitmap.cs
- EntityKey.cs
- DesignerWithHeader.cs
- ArrangedElement.cs
- RegexMatchCollection.cs
- NamedPipeTransportManager.cs
- CustomActivityDesigner.cs
- TypeResolvingOptions.cs
- GrabHandleGlyph.cs
- ParallelActivityDesigner.cs
- SystemIPv6InterfaceProperties.cs
- ResourceManagerWrapper.cs
- ServiceModelActivationSectionGroup.cs
- FormattedTextSymbols.cs
- ProgressBar.cs
- MemberExpression.cs
- QilVisitor.cs
- PageEventArgs.cs
- StsCommunicationException.cs
- Attributes.cs
- tibetanshape.cs
- SafeCancelMibChangeNotify.cs
- InlineUIContainer.cs
- SBCSCodePageEncoding.cs
- GridViewColumnCollectionChangedEventArgs.cs
- AsyncResult.cs
- ServiceMemoryGates.cs
- AsyncPostBackErrorEventArgs.cs
- TimelineCollection.cs
- ScriptReferenceEventArgs.cs
- RtfControlWordInfo.cs
- BindingSource.cs
- CapabilitiesPattern.cs
- ExternalCalls.cs
- StorageBasedPackageProperties.cs
- Timer.cs
- DesignerSerializationVisibilityAttribute.cs
- SQLBytes.cs
- CultureTable.cs
- DataGridParentRows.cs
- ClientBuildManagerCallback.cs
- NumberAction.cs
- FlatButtonAppearance.cs
- SocketElement.cs
- DBAsyncResult.cs
- ParseElement.cs
- NotImplementedException.cs
- SqlGatherConsumedAliases.cs
- DropDownButton.cs
- Vertex.cs
- AnnotationStore.cs
- RoleManagerEventArgs.cs
- Pair.cs
- OletxDependentTransaction.cs
- EraserBehavior.cs
- EditingCommands.cs
- XmlReader.cs
- TypeResolver.cs
- SafeViewOfFileHandle.cs
- ExpressionBuilderContext.cs