Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Data / System / Data / SqlClient / SqlCachedBuffer.cs / 1305376 / SqlCachedBuffer.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- namespace System.Data.SqlClient { using System; using System.Collections; using System.ComponentModel; using System.Data; using System.Data.Common; using System.Diagnostics; using System.Globalization; using System.Text; using System.Xml; using System.Data.SqlTypes; using System.IO; using System.Runtime.InteropServices; using System.Reflection; // Caches the bytes returned from partial length prefixed datatypes, like XML sealed internal class SqlCachedBuffer : System.Data.SqlTypes.INullable{ ArrayList _cachedBytes; const int _maxChunkSize = 2048; // Arbitrary value for chunk size. Revisit this later for better perf // Reads off from the network buffer and caches bytes. Only reads one column value in the current row. internal SqlCachedBuffer(SqlMetaDataPriv metadata, TdsParser parser, TdsParserStateObject stateObj ) { int cb = 0; ulong plplength; byte[] byteArr; Debug.Assert(_cachedBytes == null, "Cache is already filled!"); _cachedBytes = new ArrayList(); // the very first length is already read. plplength = parser.PlpBytesLeft(stateObj);; // For now we only handle Plp data from the parser directly. Debug.Assert(metadata.metaType.IsPlp, "SqlCachedBuffer call on a non-plp data"); do { if (plplength == 0) break; do { cb = (plplength > (ulong) _maxChunkSize) ? _maxChunkSize : (int)plplength ; byteArr = new byte[cb]; cb = stateObj.ReadPlpBytes(ref byteArr, 0, cb); Debug.Assert(cb == byteArr.Length); if (_cachedBytes.Count == 0) { // Add the Byte order mark if needed if we read the first array AddByteOrderMark(byteArr); } _cachedBytes.Add(byteArr); plplength -= (ulong)cb; } while (plplength > 0); plplength = parser.PlpBytesLeft(stateObj); } while (plplength > 0); Debug.Assert(stateObj._longlen == 0 && stateObj._longlenleft == 0); } // Reads off from a reader and caches bytes. Only reads the first column of each row. internal SqlCachedBuffer(SqlDataReader dataRdr, int columnOrdinal, long startPosition) { byte[] byteArr; long bytesRead; int cbread; Debug.Assert(_cachedBytes == null, "Cache is already filled!"); _cachedBytes = new ArrayList(); bytesRead = startPosition; do { // Allocate buffer and read a new chunk byteArr = new byte[_maxChunkSize]; cbread = (int)dataRdr.GetBytesInternal(columnOrdinal, bytesRead, byteArr, 0, _maxChunkSize); bytesRead += cbread; if (_cachedBytes.Count == 0) { // Add the Byte order mark if needed if we read the first array AddByteOrderMark(byteArr, cbread); } if (0 < cbread) { // Handle reading less than we requested if (cbread < byteArr.Length) { byte[] newByteArr = new byte[cbread]; Buffer.BlockCopy(byteArr, 0, newByteArr, 0, cbread); byteArr = newByteArr; } // Add new buffer to the list _cachedBytes.Add(byteArr); } } while (0 < cbread); } private void AddByteOrderMark(byte[] byteArr ) { AddByteOrderMark(byteArr, byteArr.Length); } private void AddByteOrderMark(byte[] byteArr, int length ) { Debug.Assert(byteArr.Length >= length); int bom = 0xfeff; // Need to find out if we should add byte order mark or not. // We need to add this if we are getting ntext xml, not if we are getting binary xml // Binary Xml always begins with the bytes 0xDF and 0xFF // If we aren't getting these, then we are getting unicode xml if ((length >= 2 ) && (byteArr[0] == 0xDF) && (byteArr[1] == 0xFF)){ bom = 0; } if (bom != 0) { byte[] b = new byte[2]; b[0] = (byte)bom; bom >>= 8; b[1] = (byte)bom; Debug.Assert(_cachedBytes.Count == 0); _cachedBytes.Add(b); } return; } private SqlCachedBuffer() { // For constructing Null } public static readonly SqlCachedBuffer Null = new SqlCachedBuffer(); internal ArrayList CachedBytes { get { return _cachedBytes; } } override public string ToString() { if (IsNull) throw new SqlNullValueException(); if (_cachedBytes.Count == 0) { return String.Empty; } SqlCachedStream fragment = new SqlCachedStream(this); SqlXml sxml = new SqlXml((Stream)fragment); return sxml.Value; } internal SqlString ToSqlString() { if (IsNull) return SqlString.Null; string str = ToString(); return new SqlString(str); } internal SqlXml ToSqlXml() { SqlCachedStream fragment = new SqlCachedStream(this); SqlXml sx = new SqlXml((Stream)fragment); return sx; } internal XmlReader ToXmlReader() { SqlCachedStream fragment = new SqlCachedStream(this); //XmlTextReader xr = new XmlTextReader(fragment, XmlNodeType.Element, null); XmlReaderSettings readerSettings = new XmlReaderSettings(); readerSettings.ConformanceLevel = ConformanceLevel.Fragment; // Call internal XmlReader.CreateSqlReader from System.Xml. // Signature: internal static XmlReader CreateSqlReader(Stream input, XmlReaderSettings settings, XmlParserContext inputContext); MethodInfo createSqlReaderMethodInfo = typeof(System.Xml.XmlReader).GetMethod("CreateSqlReader", BindingFlags.Static | BindingFlags.NonPublic); object[] args = new object[3] { (Stream)fragment, readerSettings, null }; XmlReader xr; new System.Security.Permissions.ReflectionPermission(System.Security.Permissions.ReflectionPermissionFlag.MemberAccess).Assert(); try { xr = (XmlReader)createSqlReaderMethodInfo.Invoke(null, args); } finally { System.Security.Permissions.ReflectionPermission.RevertAssert(); } return xr; } public bool IsNull { get { return (_cachedBytes == null) ? true : false ; } } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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