Add | Use Minimum Login Timeout as 1 sec in .NET Core and enable behavior by default

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

@@ -1263,7 +1263,14 @@ private void Login(ServerInfo server, TimeoutTimer timeout, string newPassword,
             if (!timeout.IsInfinite)
             {
                 long t = timeout.MillisecondsRemaining / 1000;
-                if ((long)int.MaxValue > t)
+                if (t == 0 && LocalAppContextSwitches.UseMinimumLoginTimeout)
+                {
+                    // Take 1 as the minimum value, since 0 is treated as an infinite timeout
+                    // to allow 1 second more for login to complete, since it should take only a few milliseconds.
+                    t = 1;
+                }
+
+                if (int.MaxValue > t)
                 {
                     timeoutInSeconds = (int)t;
                 }
@@ -1279,7 +1286,8 @@ private void Login(ServerInfo server, TimeoutTimer timeout, string newPassword,
 
             login.language = _currentLanguage;
             if (!login.userInstance)
-            { // Do not send attachdbfilename or database to SSE primary instance
+            {
+                // Do not send attachdbfilename or database to SSE primary instance
                 login.database = CurrentDatabase;
                 login.attachDBFilename = ConnectionOptions.AttachDBFilename;
             }

src/Microsoft.Data.SqlClient/netfx/src/Microsoft.Data.SqlClient.csproj

@@ -621,7 +621,6 @@
     <Compile Include="Microsoft\Data\RelationshipConverter.cs" />
     <Compile Include="Microsoft\Data\SqlClient\AlwaysEncryptedKeyConverter.Cng.cs" />
     <Compile Include="Microsoft\Data\SqlClient\assemblycache.cs" />
-    <Compile Include="Microsoft\Data\SqlClient\LocalAppContextSwitches.netfx.cs" />
     <Compile Include="Microsoft\Data\SqlClient\LocalDBAPI.cs" />
     <Compile Include="Microsoft\Data\SqlClient\LocalDBConfig.cs" />
     <Compile Include="Microsoft\Data\SqlClient\Reliability\SqlConfigurableRetryLogicManager.LoadType.cs" />
@@ -735,4 +734,4 @@
   <Import Project="$(NetFxSource)tools\targets\GenerateThisAssemblyCs.targets" />
   <Import Project="$(NetFxSource)tools\targets\GenerateAssemblyRef.targets" />
   <Import Project="$(NetFxSource)tools\targets\GenerateAssemblyInfo.targets" />
-</Project>
+</Project>

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

@@ -1530,10 +1530,11 @@ private void Login(ServerInfo server, TimeoutTimer timeout, string newPassword,
                 if (t == 0 && LocalAppContextSwitches.UseMinimumLoginTimeout)
                 {
                     // Take 1 as the minimum value, since 0 is treated as an infinite timeout
+                    // to allow 1 second more for login to complete, since it should take only a few milliseconds.
                     t = 1;
                 }
 
-                if ((long)Int32.MaxValue > t)
+                if (int.MaxValue > t)
                 {
                     timeoutInSeconds = (int)t;
                 }

src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/LocalAppContextSwitches.cs

@@ -3,8 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Reflection;
-using System.Runtime.CompilerServices;
 
 namespace Microsoft.Data.SqlClient
 {
@@ -13,10 +11,12 @@ internal static partial class LocalAppContextSwitches
         internal const string MakeReadAsyncBlockingString = @"Switch.Microsoft.Data.SqlClient.MakeReadAsyncBlocking";
         internal const string LegacyRowVersionNullString = @"Switch.Microsoft.Data.SqlClient.LegacyRowVersionNullBehavior";
         internal const string SuppressInsecureTLSWarningString = @"Switch.Microsoft.Data.SqlClient.SuppressInsecureTLSWarning";
+        internal const string UseMinimumLoginTimeoutString = @"Switch.Microsoft.Data.SqlClient.UseOneSecFloorInTimeoutCalculationDuringLogin";
 
+        private static bool? s_legacyRowVersionNullBehavior;
+        private static bool? s_suppressInsecureTLSWarning;
         private static bool s_makeReadAsyncBlocking;
-        private static bool? s_LegacyRowVersionNullBehavior;
-        private static bool? s_SuppressInsecureTLSWarning;
+        private static bool s_useMinimumLoginTimeout;
 
 #if !NETFRAMEWORK
         static LocalAppContextSwitches()
@@ -34,46 +34,81 @@ static LocalAppContextSwitches()
         }
 #endif
 
+#if NETFRAMEWORK
+        internal const string DisableTNIRByDefaultString = @"Switch.Microsoft.Data.SqlClient.DisableTNIRByDefaultInConnectionString";
+        private static bool s_disableTNIRByDefault;
+
+        /// <summary>
+        /// Transparent Network IP Resolution (TNIR) is a revision of the existing MultiSubnetFailover feature.
+        /// TNIR affects the connection sequence of the driver in the case where the first resolved IP of the hostname
+        /// doesn't respond and there are multiple IPs associated with the hostname.
+        /// 
+        /// TNIR interacts with MultiSubnetFailover to provide the following three connection sequences:
+        /// 0: One IP is attempted, followed by all IPs in parallel
+        /// 1: All IPs are attempted in parallel
+        /// 2: All IPs are attempted one after another
+        /// 
+        /// TransparentNetworkIPResolution is enabled by default. MultiSubnetFailover is disabled by default.
+        /// To disable TNIR, you can enable the app context switch.
+        /// 
+        /// This app context switch defaults to 'false'.
+        /// </summary>
+        public static bool DisableTNIRByDefault
+            => AppContext.TryGetSwitch(DisableTNIRByDefaultString, out s_disableTNIRByDefault) && s_disableTNIRByDefault;
+#endif
+
+        /// <summary>
+        /// When using Encrypt=false in the connection string, a security warning is output to the console if the TLS version is 1.2 or lower.
+        /// This warning can be suppressed by enabling this AppContext switch.
+        /// This app context switch defaults to 'false'.
+        /// </summary>
         public static bool SuppressInsecureTLSWarning
         {
             get
             {
-                if (s_SuppressInsecureTLSWarning is null)
+                if (s_suppressInsecureTLSWarning is null)
                 {
                     bool result;
-                    result = AppContext.TryGetSwitch(SuppressInsecureTLSWarningString, out result) ? result : false;
-                    s_SuppressInsecureTLSWarning = result;
+                    result = AppContext.TryGetSwitch(SuppressInsecureTLSWarningString, out result) && result;
+                    s_suppressInsecureTLSWarning = result;
                 }
-                return s_SuppressInsecureTLSWarning.Value;
-            }
-        }
-
-        public static bool MakeReadAsyncBlocking
-        {
-            [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            get
-            {
-                return AppContext.TryGetSwitch(MakeReadAsyncBlockingString, out s_makeReadAsyncBlocking) ? s_makeReadAsyncBlocking : false;
+                return s_suppressInsecureTLSWarning.Value;
             }
         }
 
         /// <summary>
         /// In System.Data.SqlClient and Microsoft.Data.SqlClient prior to 3.0.0 a field with type Timestamp/RowVersion
         /// would return an empty byte array. This switch contols whether to preserve that behaviour on newer versions
-        /// of Microsoft.Data.SqlClient, if this switch returns false an appropriate null value will be returned
+        /// of Microsoft.Data.SqlClient, if this switch returns false an appropriate null value will be returned.
+        /// This app context switch defaults to 'false'.
         /// </summary>
         public static bool LegacyRowVersionNullBehavior
         {
             get
             {
-                if (s_LegacyRowVersionNullBehavior is null)
+                if (s_legacyRowVersionNullBehavior is null)
                 {
                     bool result;
-                    result = AppContext.TryGetSwitch(LegacyRowVersionNullString, out result) ? result : false;
-                    s_LegacyRowVersionNullBehavior = result;
+                    result = AppContext.TryGetSwitch(LegacyRowVersionNullString, out result) && result;
+                    s_legacyRowVersionNullBehavior = result;
                 }
-                return s_LegacyRowVersionNullBehavior.Value;
+                return s_legacyRowVersionNullBehavior.Value;
             }
         }
+
+        /// <summary>
+        /// When enabled, ReadAsync runs asynchronously and does not block the calling thread.
+        /// This app context switch defaults to 'false'.
+        /// </summary>
+        public static bool MakeReadAsyncBlocking
+            => AppContext.TryGetSwitch(MakeReadAsyncBlockingString, out s_makeReadAsyncBlocking) && s_makeReadAsyncBlocking;
+
+        /// <summary>
+        /// Specifies minimum login timeout to be set to 1 second instead of 0 seconds,
+        /// to prevent a login attempt from waiting indefinitely.
+        /// This app context switch defaults to 'true'.
+        /// </summary>
+        public static bool UseMinimumLoginTimeout
+            => !AppContext.TryGetSwitch(UseMinimumLoginTimeoutString, out s_useMinimumLoginTimeout) || s_useMinimumLoginTimeout;
     }
 }

src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/DataReaderTest/DataReaderTest.cs

@@ -332,7 +332,7 @@ public static void CheckLegacyNullRowVersionIsEmptyArray()
         private static bool? SetLegacyRowVersionNullBehavior(bool? value)
         {
             Type switchesType = typeof(SqlCommand).Assembly.GetType("Microsoft.Data.SqlClient.LocalAppContextSwitches");
-            FieldInfo switchField = switchesType.GetField("s_LegacyRowVersionNullBehavior", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
+            FieldInfo switchField = switchesType.GetField("s_legacyRowVersionNullBehavior", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Static);
             bool? originalValue = (bool?)switchField.GetValue(null);
             switchField.SetValue(null, value);
             return originalValue;