SqlDependencyProcessDispatcherStorage lock fix, use intptr (#3208)

Author: benrr101

src/Microsoft.Data.SqlClient/src/Interop/Windows/Sni/SqlDependencyProcessDispatcherStorage.netfx.cs

@@ -8,27 +8,24 @@
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
-using System.Threading;
 
 namespace Interop.Windows.Sni
 {
-    internal unsafe class SqlDependencyProcessDispatcherStorage
+    internal class SqlDependencyProcessDispatcherStorage
     {
-        private static void* s_data;
+        private static readonly object s_lockObj = new();
+        private static IntPtr s_data;
         private static int s_size;
-        private static volatile int s_lock; // Int used for a spin-lock.
 
         [ResourceExposure(ResourceScope.Process)] // SxS: there is no way to set scope = Instance, using Process which is wider
         [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
         public static byte[] NativeGetData()
         {
-            IntPtr ptr = (IntPtr)s_data;
-            
             byte[] result = null;
-            if (ptr != IntPtr.Zero)
+            if (s_data != IntPtr.Zero)
             {
                 result = new byte[s_size];
-                Marshal.Copy(ptr, result, 0, s_size);
+                Marshal.Copy(s_data, result, 0, s_size);
             }
 
             return result;
@@ -38,29 +35,18 @@ public static byte[] NativeGetData()
         [ResourceConsumption(ResourceScope.Process, ResourceScope.Process)]
         internal static void NativeSetData(byte[] data)
         {
-            fixed (byte* pDispatcher = data)
+            lock (s_lockObj)
             {
-                while (Interlocked.CompareExchange(ref s_lock, 1, 0) != 0)
+                if (s_data == IntPtr.Zero)
                 {
-                    // Spin until we have the lock.
-                    Thread.Sleep(50); // Sleep with short-timeout to prevent starvation.
-                }
-                Trace.Assert(s_lock == 1); // Now that we have the lock, lock should be equal to 1.
-
-                if (s_data == null)
-                {
-                    s_data = Marshal.AllocHGlobal(data.Length).ToPointer();
-
-                    Trace.Assert(s_data != null);
-
-                    Buffer.MemoryCopy(pDispatcher, s_data, data.Length, data.Length);
-
-                    Trace.Assert(0 == s_size); // Size should still be zero at this point.
+                    s_data = Marshal.AllocHGlobal(data.Length);
+                    Trace.Assert(s_data != IntPtr.Zero);
+                    
+                    Marshal.Copy(data, 0, s_data, data.Length);
+                    
+                    Trace.Assert(s_size == 0); // Size should still be zero at this point
                     s_size = data.Length;
                 }
-
-                int result = Interlocked.CompareExchange(ref s_lock, 0, 1);
-                Trace.Assert(1 == result); // The release of the lock should have been successful.  
             }
         }
     }