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
- TextAutomationPeer.cs
- ISAPIRuntime.cs
- LogEntrySerializer.cs
- RowToParametersTransformer.cs
- GeneralTransform2DTo3D.cs
- XmlUtil.cs
- TableProviderWrapper.cs
- AsyncResult.cs
- AsymmetricKeyExchangeFormatter.cs
- RegexReplacement.cs
- XhtmlConformanceSection.cs
- PlainXmlWriter.cs
- PeerTransportSecuritySettings.cs
- ListCommandEventArgs.cs
- Pair.cs
- SerializationObjectManager.cs
- DataGridViewDataConnection.cs
- SymmetricAlgorithm.cs
- ProcessHostMapPath.cs
- GradientStop.cs
- DrawingCollection.cs
- SpinWait.cs
- ColorContextHelper.cs
- Soap12FormatExtensions.cs
- ValueUtilsSmi.cs
- ComplexBindingPropertiesAttribute.cs
- TextParagraph.cs
- SqlSupersetValidator.cs
- HttpEncoderUtility.cs
- SqlMethodCallConverter.cs
- ClientOptions.cs
- ExpressionBuilder.cs
- DataSourceControl.cs
- DataGridViewCheckBoxColumn.cs
- ConstraintEnumerator.cs
- BitmapEffectGroup.cs
- BamlBinaryReader.cs
- RetrieveVirtualItemEventArgs.cs
- TriggerActionCollection.cs
- SizeAnimationUsingKeyFrames.cs
- DBConcurrencyException.cs
- EventToken.cs
- ExpressionBindings.cs
- Duration.cs
- OleServicesContext.cs
- ViewCellSlot.cs
- FrameSecurityDescriptor.cs
- SemaphoreSecurity.cs
- ManagementEventArgs.cs
- DockingAttribute.cs
- FileVersionInfo.cs
- DataSourceConverter.cs
- CatalogZoneBase.cs
- TreeNodeStyleCollection.cs
- InputProviderSite.cs
- BaseCAMarshaler.cs
- RSAOAEPKeyExchangeFormatter.cs
- XPathPatternBuilder.cs
- SqlPersistenceProviderFactory.cs
- TdsParserSessionPool.cs
- WindowsRichEditRange.cs
- SmtpCommands.cs
- InternalBufferOverflowException.cs
- BitmapDecoder.cs
- Rotation3D.cs
- CollaborationHelperFunctions.cs
- DataGridRow.cs
- COM2ComponentEditor.cs
- MenuAdapter.cs
- TypeDescriptorFilterService.cs
- DataBoundLiteralControl.cs
- ObjectDataSourceStatusEventArgs.cs
- XmlResolver.cs
- FrameworkContentElement.cs
- EntityTransaction.cs
- ContextItem.cs
- BinHexDecoder.cs
- CompilerTypeWithParams.cs
- StorageEntityContainerMapping.cs
- DeploymentSection.cs
- PriorityBindingExpression.cs
- GridViewRow.cs
- _NestedSingleAsyncResult.cs
- CLRBindingWorker.cs
- BaseResourcesBuildProvider.cs
- _NetworkingPerfCounters.cs
- MachineKeyConverter.cs
- SchemeSettingElementCollection.cs
- DateTimeOffsetStorage.cs
- Span.cs
- PhysicalAddress.cs
- WindowsMenu.cs
- StorageInfo.cs
- WCFModelStrings.Designer.cs
- CustomWebEventKey.cs
- ArcSegment.cs
- DockingAttribute.cs
- ProcessHostServerConfig.cs
- ToolboxItemFilterAttribute.cs
- PropertyPathWorker.cs