SmiContextFactory.cs source code in C# .NET

                        Code:
                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / Microsoft / SqlServer / Server / SmiContextFactory.cs / 3 / SmiContextFactory.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
//----------------------------------------------------------------------------- 
 
namespace Microsoft.SqlServer.Server {
 
    using System;
    using System.Data.Common;
    using System.Data.SqlClient;
    using System.Diagnostics; 

    sealed internal class SmiContextFactory  { 
        public static readonly SmiContextFactory Instance = new SmiContextFactory(); 

        private readonly SmiLink                _smiLink; 
        private readonly ulong                  _negotiatedSmiVersion;
        private readonly byte                   _majorVersion;
        private readonly byte                   _minorVersion;
        private readonly short                  _buildNum; 
        private readonly string                 _serverVersion;
        private readonly SmiEventSink_Default   _eventSinkForGetCurrentContext; 
 
        internal const ulong YukonVersion = 100;
        internal const ulong KatmaiVersion = 210; 
        internal const ulong LatestVersion = KatmaiVersion;

        private readonly ulong[]                  __supportedSmiVersions = new ulong[] {YukonVersion, KatmaiVersion};
 
        // Used as the key for SmiContext.GetContextValue()
        internal enum ContextKey { 
            Connection = 0, 
            SqlContext = 1
        } 


        private SmiContextFactory() {
            if (InOutOfProcHelper.InProc) { 
                Type smiLinkType = Type.GetType("Microsoft.SqlServer.Server.InProcLink, SqlAccess, PublicKeyToken=89845dcd8080cc91");
 
                if (null == smiLinkType) { 
                    Debug.Assert(false, "could not get InProcLink type");
                    throw SQL.ContextUnavailableOutOfProc();    // Must not be a valid version of Sql Server. 
                }

                System.Reflection.FieldInfo instanceField = GetStaticField(smiLinkType, "Instance");
                if (instanceField != null) { 
                    _smiLink = (SmiLink)GetValue(instanceField);
                } 
                else { 
                    Debug.Assert(false, "could not get InProcLink.Instance");
                    throw SQL.ContextUnavailableOutOfProc();    // Must not be a valid version of Sql Server. 
                }

                System.Reflection.FieldInfo buildVersionField = GetStaticField(smiLinkType, "BuildVersion");
                if (buildVersionField != null) { 
                    UInt32 buildVersion = (UInt32)GetValue(buildVersionField);
 
                    _majorVersion = (byte)(buildVersion >> 24); 
                    _minorVersion = (byte)((buildVersion >> 16) & 0xff);
                    _buildNum     = (short)(buildVersion & 0xffff); 
                    _serverVersion = (String.Format((IFormatProvider)null, "{0:00}.{1:00}.{2:0000}", _majorVersion, (short) _minorVersion, _buildNum));
                }
                else {
                    _serverVersion = String.Empty;  // default value if nothing exists. 
                }
                _negotiatedSmiVersion          = _smiLink.NegotiateVersion(SmiLink.InterfaceVersion); 
                bool isSupportedVersion = false; 
                for(int i=0; !isSupportedVersion && i<__supportedSmiVersions.Length; i++) {
                    if (__supportedSmiVersions[i] == _negotiatedSmiVersion) { 
                        isSupportedVersion = true;
                    }
                }
 
                // Disconnect if we didn't get a supported version!!
                if (!isSupportedVersion) { 
                    _smiLink = null; 
                }
 
                _eventSinkForGetCurrentContext = new SmiEventSink_Default();
            }
        }
 
        internal ulong NegotiatedSmiVersion {
            get { 
                if (null == _smiLink) { 
                    throw SQL.ContextUnavailableOutOfProc();    // Must not be a valid version of Sql Server, or not be SqlCLR
                } 

                return _negotiatedSmiVersion;
            }
        } 

        internal string ServerVersion { 
            get { 
                if (null == _smiLink) {
                    throw SQL.ContextUnavailableOutOfProc();    // Must not be a valid version of Sql Server, or not be SqlCLR 
                }

                return _serverVersion;
            } 
        }
 
        internal SmiContext GetCurrentContext() { 
            if (null == _smiLink) {
                throw SQL.ContextUnavailableOutOfProc();    // Must not be a valid version of Sql Server, or not be SqlCLR 
            }

            object result = _smiLink.GetCurrentContext(_eventSinkForGetCurrentContext);
            _eventSinkForGetCurrentContext.ProcessMessagesAndThrow(); 

 			if (null == result) { 
				throw SQL.ContextUnavailableWhileInProc(); 
			}
 
            Debug.Assert(typeof(SmiContext).IsInstanceOfType(result), "didn't get SmiContext from GetCurrentContext?");
            return (SmiContext)result;
        }
 
        [System.Security.Permissions.ReflectionPermission(System.Security.Permissions.SecurityAction.Assert, MemberAccess=true)]
        private object GetValue(System.Reflection.FieldInfo fieldInfo) { 
            object result = fieldInfo.GetValue(null); 
            return result;
        } 

        [System.Security.Permissions.ReflectionPermission(System.Security.Permissions.SecurityAction.Assert, MemberAccess=true)]
        private System.Reflection.FieldInfo GetStaticField(Type aType, string fieldName) {
            System.Reflection.FieldInfo result = aType.GetField(fieldName, System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.GetField); 
            return result;
        } 
 
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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