Code:
/ Net / Net / 3.5.50727.3053 / DEVDIV / depot / DevDiv / releases / whidbey / netfxsp / ndp / fx / src / Data / System / Data / Odbc / DbDataRecord.cs / 1 / DbDataRecord.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- using System; using System.ComponentModel; //Component using System.Data; using System.Runtime.InteropServices; //Marshal using System.Reflection; //Missing namespace System.Data.Odbc { sealed internal class DbSchemaInfo { internal DbSchemaInfo() { } internal string _name; internal string _typename; internal Type _type; internal ODBC32.SQL_TYPE? _dbtype; internal object _scale; internal object _precision; // extension to allow BindCol // internal int _columnlength; // internal int _valueOffset; // offset to the data in the row buffer internal int _lengthOffset; // offset to the length in the row buffer internal ODBC32.SQL_C _sqlctype; // need this to bind the value internal ODBC32.SQL_TYPE _sql_type; // need that to properly marshal the value } ///////////////////////////////////////////////////////////////////////////// // Cache // // This is a on-demand cache, only caching what the user requests. // The reational is that for ForwardOnly access (the default and LCD of drivers) // we cannot obtain the data more than once, and even GetData(0) (to determine is-null) // still obtains data for fixed lenght types. // So simple code like: // if(!rReader.IsDBNull(i)) // rReader.GetInt32(i) // // Would fail, unless we cache on the IsDBNull call, and return the cached // item for GetInt32. This actually improves perf anyway, (even if the driver could // support it), since we are not making a seperate interop call... // We do not cache all columns, so reading out of order is still not // ///////////////////////////////////////////////////////////////////////////// sealed internal class DbCache { //Data private bool[] _isBadValue; private DbSchemaInfo[] _schema; private object[] _values; private OdbcDataReader _record; internal int _count; internal bool _randomaccess = true; //Constructor internal DbCache(OdbcDataReader record, int count) { _count = count; _record = record; _randomaccess = (!record.IsBehavior(CommandBehavior.SequentialAccess)); _values = new object[count]; _isBadValue = new bool[count]; } //Accessor internal object this[int i] { get { if(_isBadValue[i]) { OverflowException innerException = (OverflowException)Values[i]; throw new OverflowException(innerException.Message, innerException); } return Values[i]; } set { Values[i] = value; _isBadValue[i] = false; } } internal int Count { get { return _count; } } internal void InvalidateValue(int i) { _isBadValue[i] = true; } internal object[] Values { get { return _values; } } internal object AccessIndex(int i) { //Note: We could put this directly in this[i], instead of having an explicit overload. //However that means that EVERY access into the cache takes the hit of checking, so //something as simple as the following code would take two hits. It's nice not to //have to take the hit when you know what your doing. // // if(cache[i] == null) // .... // return cache[i]; object[] values = this.Values; if(_randomaccess) { //Random //Means that the user can ask for the values int any order (ie: out of order). // In order to acheive this on a forward only stream, we need to actually // retreive all the value in between so they can go back to values they've skipped for(int c = 0; c < i; c++) { if(values[c] == null) { values[c] = _record.GetValue(c); } } } return values[i]; } internal DbSchemaInfo GetSchema(int i) { if(_schema == null) { _schema = new DbSchemaInfo[Count]; } if(_schema[i] == null) { _schema[i] = new DbSchemaInfo(); } return _schema[i]; } internal void FlushValues() { //Set all objects to null (to explcitly release them) //Note: SchemaInfo remains the same for all rows - no need to reget those... int count = _values.Length; for(int i = 0; i < count; ++i) { _values[i] = null; } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. //------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- using System; using System.ComponentModel; //Component using System.Data; using System.Runtime.InteropServices; //Marshal using System.Reflection; //Missing namespace System.Data.Odbc { sealed internal class DbSchemaInfo { internal DbSchemaInfo() { } internal string _name; internal string _typename; internal Type _type; internal ODBC32.SQL_TYPE? _dbtype; internal object _scale; internal object _precision; // extension to allow BindCol // internal int _columnlength; // internal int _valueOffset; // offset to the data in the row buffer internal int _lengthOffset; // offset to the length in the row buffer internal ODBC32.SQL_C _sqlctype; // need this to bind the value internal ODBC32.SQL_TYPE _sql_type; // need that to properly marshal the value } ///////////////////////////////////////////////////////////////////////////// // Cache // // This is a on-demand cache, only caching what the user requests. // The reational is that for ForwardOnly access (the default and LCD of drivers) // we cannot obtain the data more than once, and even GetData(0) (to determine is-null) // still obtains data for fixed lenght types. // So simple code like: // if(!rReader.IsDBNull(i)) // rReader.GetInt32(i) // // Would fail, unless we cache on the IsDBNull call, and return the cached // item for GetInt32. This actually improves perf anyway, (even if the driver could // support it), since we are not making a seperate interop call... // We do not cache all columns, so reading out of order is still not // ///////////////////////////////////////////////////////////////////////////// sealed internal class DbCache { //Data private bool[] _isBadValue; private DbSchemaInfo[] _schema; private object[] _values; private OdbcDataReader _record; internal int _count; internal bool _randomaccess = true; //Constructor internal DbCache(OdbcDataReader record, int count) { _count = count; _record = record; _randomaccess = (!record.IsBehavior(CommandBehavior.SequentialAccess)); _values = new object[count]; _isBadValue = new bool[count]; } //Accessor internal object this[int i] { get { if(_isBadValue[i]) { OverflowException innerException = (OverflowException)Values[i]; throw new OverflowException(innerException.Message, innerException); } return Values[i]; } set { Values[i] = value; _isBadValue[i] = false; } } internal int Count { get { return _count; } } internal void InvalidateValue(int i) { _isBadValue[i] = true; } internal object[] Values { get { return _values; } } internal object AccessIndex(int i) { //Note: We could put this directly in this[i], instead of having an explicit overload. //However that means that EVERY access into the cache takes the hit of checking, so //something as simple as the following code would take two hits. It's nice not to //have to take the hit when you know what your doing. // // if(cache[i] == null) // .... // return cache[i]; object[] values = this.Values; if(_randomaccess) { //Random //Means that the user can ask for the values int any order (ie: out of order). // In order to acheive this on a forward only stream, we need to actually // retreive all the value in between so they can go back to values they've skipped for(int c = 0; c < i; c++) { if(values[c] == null) { values[c] = _record.GetValue(c); } } } return values[i]; } internal DbSchemaInfo GetSchema(int i) { if(_schema == null) { _schema = new DbSchemaInfo[Count]; } if(_schema[i] == null) { _schema[i] = new DbSchemaInfo(); } return _schema[i]; } internal void FlushValues() { //Set all objects to null (to explcitly release them) //Note: SchemaInfo remains the same for all rows - no need to reget those... int count = _values.Length; for(int i = 0; i < count; ++i) { _values[i] = null; } } } } // 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
- SystemResourceKey.cs
- OperandQuery.cs
- RowToParametersTransformer.cs
- TimelineCollection.cs
- TabPanel.cs
- TextEditorThreadLocalStore.cs
- Substitution.cs
- Context.cs
- DebugView.cs
- GenerateTemporaryTargetAssembly.cs
- ArrayConverter.cs
- Group.cs
- LinkLabelLinkClickedEvent.cs
- HandleCollector.cs
- BigIntegerStorage.cs
- SynchronizationLockException.cs
- GridViewHeaderRowPresenter.cs
- Models.cs
- Command.cs
- CounterCreationDataCollection.cs
- AutomationElement.cs
- Camera.cs
- ConfigurationManagerHelperFactory.cs
- IApplicationTrustManager.cs
- CollectionViewGroupRoot.cs
- SmtpAuthenticationManager.cs
- Serializer.cs
- Memoizer.cs
- UnsafeNativeMethods.cs
- controlskin.cs
- PenThreadWorker.cs
- SerialPinChanges.cs
- DesignTimeHTMLTextWriter.cs
- ExpressionConverter.cs
- ResourceAssociationType.cs
- IDispatchConstantAttribute.cs
- StylusPoint.cs
- ExtendedPropertyDescriptor.cs
- ZipIOCentralDirectoryBlock.cs
- _UriTypeConverter.cs
- VScrollBar.cs
- LocatorPart.cs
- NullExtension.cs
- Internal.cs
- ExceptionRoutedEventArgs.cs
- InfiniteTimeSpanConverter.cs
- SecUtil.cs
- AnnotationComponentManager.cs
- XComponentModel.cs
- XomlCompilerParameters.cs
- TrackingMemoryStreamFactory.cs
- MasterPage.cs
- IODescriptionAttribute.cs
- TypeUtil.cs
- SecurityTokenParameters.cs
- Parameter.cs
- MemoryFailPoint.cs
- FrameDimension.cs
- FontStretchConverter.cs
- DbParameterCollectionHelper.cs
- EventPrivateKey.cs
- XmlQueryRuntime.cs
- TaiwanCalendar.cs
- RowBinding.cs
- FilteredDataSetHelper.cs
- XmlSchemaAnnotated.cs
- PersonalizationProviderHelper.cs
- TimeSpanSecondsConverter.cs
- DesignerProperties.cs
- EntityParameter.cs
- _HeaderInfo.cs
- CatalogZoneAutoFormat.cs
- SystemIPInterfaceStatistics.cs
- PolicyManager.cs
- RoutedEvent.cs
- AnimationStorage.cs
- backend.cs
- MasterPageParser.cs
- EncoderParameter.cs
- HtmlTextViewAdapter.cs
- XmlILIndex.cs
- JsonByteArrayDataContract.cs
- PropertyRecord.cs
- CollectionViewProxy.cs
- DependencyPropertyValueSerializer.cs
- MouseButton.cs
- BookmarkEventArgs.cs
- DefaultValidator.cs
- ImageClickEventArgs.cs
- KeySpline.cs
- CodeLinePragma.cs
- ConnectionStringsSection.cs
- Selection.cs
- CompositeCollectionView.cs
- UserUseLicenseDictionaryLoader.cs
- NonBatchDirectoryCompiler.cs
- DataGridViewColumnTypeEditor.cs
- Byte.cs
- ResXResourceSet.cs
- ResourceDisplayNameAttribute.cs