Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / ProviderBase / WrappedIUnknown.cs / 1 / WrappedIUnknown.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //[....] //[....] //----------------------------------------------------------------------------- namespace System.Data.ProviderBase { using System; using System.Data.Common; using System.Runtime.CompilerServices; using System.Runtime.ConstrainedExecution; using System.Runtime.InteropServices; using System.Security; using System.Security.Permissions; using System.Threading; // We wrap the interface as a native IUnknown IntPtr so that every // thread that creates a connection will fake the correct context when // in transactions, otherwise everything is marshalled. We do this // for two reasons: first for the connection pooler, this is a significant // performance gain, second for the OLE DB provider, it doesn't marshal. internal class WrappedIUnknown : SafeHandle { internal WrappedIUnknown() : base(IntPtr.Zero, true) { } internal WrappedIUnknown(object unknown) : this() { if (null != unknown) { RuntimeHelpers.PrepareConstrainedRegions(); try {} finally { base.handle = Marshal.GetIUnknownForObject(unknown); // } } } public override bool IsInvalid { get { return (IntPtr.Zero == base.handle); } } internal object ComWrapper() { // NOTE: Method, instead of property, to avoid being evaluated at // runtime in the debugger. object value = null; bool mustRelease = false; RuntimeHelpers.PrepareConstrainedRegions(); try { DangerousAddRef(ref mustRelease); IntPtr handle = DangerousGetHandle(); value = System.Runtime.Remoting.Services.EnterpriseServicesHelper.WrapIUnknownWithComObject(handle); } finally { if (mustRelease) { DangerousRelease(); } } return value; } override protected bool ReleaseHandle() { // NOTE: The SafeHandle class guarantees this will be called exactly once. IntPtr ptr = base.handle; base.handle = IntPtr.Zero; if (IntPtr.Zero != ptr) { Marshal.Release(ptr); } return true; } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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