Merge DisposePacketCache

This also allows _writePacketCache to be migrated to TdsParserStateObjectNative in netfx.

Author: edwardneal

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParserStateObject.netcore.cs

@@ -96,8 +96,6 @@ internal abstract void CreatePhysicalSNIHandle(
 
         internal abstract void Dispose();
 
-        internal abstract void DisposePacketCache();
-
         internal abstract uint CheckConnection();
 
         internal int DecrementPendingCallbacks(bool release)

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/TdsParserStateObjectNative.cs

@@ -445,8 +445,16 @@ internal override void DisposePacketCache()
         {
             lock (_writePacketLockObject)
             {
-                _writePacketCache.Dispose();
-                // Do not set _writePacketCache to null, just in case a WriteAsyncCallback completes after this point
+#if NETFRAMEWORK
+                RuntimeHelpers.PrepareConstrainedRegions();
+#endif
+                try
+                { }
+                finally
+                {
+                    _writePacketCache.Dispose();
+                    // Do not set _writePacketCache to null, just in case a WriteAsyncCallback completes after this point
+                }
             }
         }
 

src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/TdsParserStateObject.netfx.cs

@@ -25,7 +25,6 @@ internal partial class TdsParserStateObject
         // SNI variables                                                     // multiple resultsets in one batch.
         protected SNIPacket _sniPacket = null;                // Will have to re-vamp this for MARS
         internal SNIPacket _sniAsyncAttnPacket = null;                // Packet to use to send Attn
-        protected readonly WritePacketCache _writePacketCache = new WritePacketCache(); // Store write packets that are ready to be re-used
 
         // Async variables
         private GCHandle _gcHandle;                                    // keeps this object alive until we're closed.
@@ -196,20 +195,7 @@ internal void Dispose()
                 }
             }
 
-            if (_writePacketCache != null)
-            {
-                lock (_writePacketLockObject)
-                {
-                    RuntimeHelpers.PrepareConstrainedRegions();
-                    try
-                    { }
-                    finally
-                    {
-                        _writePacketCache.Dispose();
-                        // Do not set _writePacketCache to null, just in case a WriteAsyncCallback completes after this point
-                    }
-                }
-            }
+            DisposePacketCache();
         }
 
         /// <summary>

src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/TdsParserStateObjectNative.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 using Interop.Windows.Sni;
 using Microsoft.Data.Common;
@@ -13,6 +14,8 @@ namespace Microsoft.Data.SqlClient
 {
     internal class TdsParserStateObjectNative : TdsParserStateObject
     {
+        private readonly WritePacketCache _writePacketCache = new WritePacketCache(); // Store write packets that are ready to be re-used
+
         private readonly Dictionary<IntPtr, SNIPacket> _pendingWritePackets = new Dictionary<IntPtr, SNIPacket>(); // Stores write packets that have been sent to SNI, but have not yet finished writing (i.e. we are waiting for SNI's callback)
 
         internal TdsParserStateObjectNative(TdsParser parser, TdsParserStateObject physicalConnection, bool async)
@@ -172,6 +175,23 @@ internal override uint EnableMars(ref uint info)
         internal override uint SetConnectionBufferSize(ref uint unsignedPacketSize)
             => SniNativeWrapper.SniSetInfo(Handle, QueryType.SNI_QUERY_CONN_BUFSIZE, ref unsignedPacketSize);
 
+        internal override void DisposePacketCache()
+        {
+            lock (_writePacketLockObject)
+            {
+#if NETFRAMEWORK
+                RuntimeHelpers.PrepareConstrainedRegions();
+#endif
+                try
+                { }
+                finally
+                {
+                    _writePacketCache.Dispose();
+                    // Do not set _writePacketCache to null, just in case a WriteAsyncCallback completes after this point
+                }
+            }
+        }
+
         internal override SspiContextProvider CreateSspiContextProvider() => new NativeSspiContextProvider();
     }
 }

src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParserStateObject.cs

@@ -519,6 +519,8 @@ internal long TimeoutTime
 
         internal abstract uint SetConnectionBufferSize(ref uint unsignedPacketSize);
 
+        internal abstract void DisposePacketCache();
+
         internal int GetTimeoutRemaining()
         {
             int remaining;