Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / ProviderBase / DbReferenceCollection.cs / 2 / DbReferenceCollection.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- namespace System.Data.ProviderBase { using System; using System.Collections; using System.Diagnostics; internal abstract class DbReferenceCollection { #if ORACLE abstract public void Add(object value, int tag); abstract public void Notify(int message); abstract public void Remove(object value); #else private struct CollectionEntry { private int _tag; // information about the reference private WeakReference _weak; // the reference itself. public bool HasTarget { get { Debug.Assert((0 != _tag && null != _weak) || (null == _weak || !_weak.IsAlive), "0 tag with Target"); return ((0 != _tag) && null != _weak && _weak.IsAlive); } } public bool InUse { get { return (null != _weak); } } public int Tag { get { return _tag; } set { _tag = value; } } public object Target { get { if (0 != _tag) { return _weak.Target; } Debug.Assert(!_weak.IsAlive, "0 tag with Target"); return null; } set { if (null == _weak) { _weak = new WeakReference(value, false); } else { _weak.Target = value; } } } } private CollectionEntry[] _items; protected DbReferenceCollection() { _items = new CollectionEntry[5]; } abstract public void Add(object value, int tag); protected void AddItem(object value, int tag) { Debug.Assert(null != value && 0 != tag, "AddItem with null value or 0 tag"); CollectionEntry[] items = _items; for (int i = 0; i < items.Length; ++i) { if (!items[i].HasTarget) { items[i].Target = value; items[i].Tag = tag; Debug.Assert(items[i].HasTarget, "missing expected target"); return; } } int newlength = ((5 == items.Length) ? 15 : (items.Length + 15)); CollectionEntry[] jtems = new CollectionEntry[newlength]; for (int i = 0; i < items.Length; ++i) { jtems[i] = items[i]; } jtems[items.Length].Target = value; jtems[items.Length].Tag = tag; Debug.Assert(jtems[items.Length].HasTarget, "missing expected target"); _items = jtems; } internal IEnumerable Filter(int tag) { return new DbFilteredReferenceCollection (_items, tag); } public void Notify(int message) { CollectionEntry[] items = _items; for (int index = 0; index < items.Length; ++index) { if (items[index].InUse) { object value = items[index].Target; // checks tag & gets target if (null != value) { Debug.Assert(items[index].HasTarget, "missing expected target"); if (!NotifyItem(message, items[index].Tag, value)) { items[index].Tag = 0; items[index].Target = null; Debug.Assert(!items[index].HasTarget, "has unexpected target"); } } // else (0 == Tag) or !IsAlive } else { Debug.Assert(!items[index].HasTarget, "has unexpected target"); break; // we're done as soon as we find the first null in the list } } } abstract protected bool NotifyItem(int message, int tag, object value); public void Purge() { CollectionEntry[] items = _items; #if DEBUG for(int i = 0; i < items.Length; ++i) { Debug.Assert(!items[i].HasTarget, "unexpected target during purge"); } #endif if (100 < items.Length) { _items = new CollectionEntry[5]; // revert back to 5 items if we're really big... } } abstract public void Remove(object value); protected void RemoveItem(object value) { Debug.Assert(null != value, "RemoveItem with null"); CollectionEntry[] items = _items; for (int index = 0; index < items.Length; ++index) { if (items[index].InUse) { if (value == items[index].Target) { // checks tag & gets target items[index].Tag = 0; items[index].Target = null; Debug.Assert(!items[index].HasTarget, "has unexpected target"); break; } // else (0 == Tag) or !IsAlive or (value != Target) } else { break; // we're done as soon as we find the first null in the list } } } private struct DbFilteredReferenceCollection : IEnumerable { private readonly DbReferenceCollection.CollectionEntry[] _items; private readonly int _filterTag; internal DbFilteredReferenceCollection(DbReferenceCollection.CollectionEntry[] items, int filterTag) { _items = items; _filterTag = filterTag; } IEnumerator IEnumerable.GetEnumerator() { return new DbFilteredReferenceCollectionedEnumerator(_items, _filterTag); } private struct DbFilteredReferenceCollectionedEnumerator : IEnumerator { private readonly DbReferenceCollection.CollectionEntry[] _items; private readonly int _filterTag; private int _current; internal DbFilteredReferenceCollectionedEnumerator(DbReferenceCollection.CollectionEntry[] items, int filterTag) { _items = items; _filterTag = filterTag; _current = -1; } object IEnumerator.Current { get { return _items[_current].Target; } } bool IEnumerator.MoveNext() { while (++_current < _items.Length) { if (_items[_current].InUse) { if (_items[_current].Tag == _filterTag) { return true; } } else { break; } } return false; } void IEnumerator.Reset() { _current = -1; } } } #endif } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- BindingRestrictions.cs
- CqlErrorHelper.cs
- XmlILTrace.cs
- EnvironmentPermission.cs
- BitVec.cs
- HTTPNotFoundHandler.cs
- DataObjectCopyingEventArgs.cs
- XmlCompatibilityReader.cs
- QilDataSource.cs
- VideoDrawing.cs
- MethodSignatureGenerator.cs
- AQNBuilder.cs
- UriExt.cs
- XamlToRtfWriter.cs
- CopyOfAction.cs
- EndpointInstanceProvider.cs
- Brush.cs
- BoundingRectTracker.cs
- SqlErrorCollection.cs
- SqlCommandBuilder.cs
- Section.cs
- Blend.cs
- DbProviderFactory.cs
- PtsPage.cs
- XmlHierarchicalEnumerable.cs
- LinkClickEvent.cs
- TypeLoader.cs
- GregorianCalendarHelper.cs
- EntityTypeBase.cs
- TagNameToTypeMapper.cs
- ArrayConverter.cs
- TriggerBase.cs
- AuthenticationServiceManager.cs
- PtsPage.cs
- Update.cs
- ColumnCollection.cs
- TypeBrowserDialog.cs
- ReflectPropertyDescriptor.cs
- SizeValueSerializer.cs
- AuthorizationSection.cs
- webeventbuffer.cs
- counter.cs
- TriggerCollection.cs
- PaperSource.cs
- TextSelection.cs
- MatrixKeyFrameCollection.cs
- SqlCaseSimplifier.cs
- FeatureAttribute.cs
- HttpNamespaceReservationInstallComponent.cs
- Hyperlink.cs
- DispatcherHooks.cs
- _CommandStream.cs
- Icon.cs
- _NetworkingPerfCounters.cs
- complextypematerializer.cs
- XmlSchemaObject.cs
- WindowAutomationPeer.cs
- AnchoredBlock.cs
- __Filters.cs
- SaveFileDialog.cs
- WebPermission.cs
- AutomationPropertyChangedEventArgs.cs
- SqlGatherProducedAliases.cs
- IntSecurity.cs
- SystemIPAddressInformation.cs
- SqlNodeTypeOperators.cs
- AxWrapperGen.cs
- NameValueFileSectionHandler.cs
- Vector3DCollectionConverter.cs
- XmlNodeChangedEventManager.cs
- IconEditor.cs
- GcSettings.cs
- ViewKeyConstraint.cs
- DbParameterCollectionHelper.cs
- EdmSchemaAttribute.cs
- ExpandableObjectConverter.cs
- SafePointer.cs
- Function.cs
- DataSourceSelectArguments.cs
- EntityViewGenerationAttribute.cs
- FrameworkElementFactoryMarkupObject.cs
- HostingEnvironmentSection.cs
- RichListBox.cs
- DataRecordInternal.cs
- Rectangle.cs
- Int64Animation.cs
- ObjectParameter.cs
- SlotInfo.cs
- StructuralCache.cs
- RequestDescription.cs
- GridItem.cs
- NativeMethodsCLR.cs
- SelectionHighlightInfo.cs
- RtfToXamlLexer.cs
- TransformProviderWrapper.cs
- WindowsIPAddress.cs
- PropertyInformation.cs
- AssemblyBuilder.cs
- MILUtilities.cs
- IconBitmapDecoder.cs