SNOW-902611 move control over creation of session to session pool (#783)

Moving a code responsible for establishing a new session to the session
pool class as a prerequisite step to introduction of a new connection
pool implementation.
Fixed some flaky tests which were unrelated to the pool but were failing
when mocked connection (with some intentional throw exception behavior)
was put back to the pool by another test.

- [x] Code compiles correctly
- [x] Code is formatted according to [Coding
Conventions](../CodingConventions.md)
- [ ] Created tests which fail without the change (if possible)
- [x] All tests passing (`dotnet test`)
- [x] Extended the README / documentation, if necessary
- [x] Provide JIRA issue id (if possible) or GitHub issue id in PR name

Snowflake.Data.Tests/IntegrationTests/SFConnectionIT.cs

@@ -41,7 +41,6 @@ public void TestBasicConnection()
         {
             using (IDbConnection conn = new SnowflakeDbConnection())
             {
-                SnowflakeDbConnectionPool.SetPooling(false);
                 conn.ConnectionString = ConnectionString;
                 conn.Open();
                 Assert.AreEqual(ConnectionState.Open, conn.State);
@@ -150,7 +149,6 @@ public void TestIncorrectUserOrPasswordBasicConnection()
         [TestCase(false)]
         public void TestConnectionIsNotMarkedAsOpenWhenWasNotCorrectlyOpenedBefore(bool explicitClose)
         {
-            SnowflakeDbConnectionPool.SetPooling(true);
             for (int i = 0; i < 2; ++i)
             {
                 s_logger.Debug($"Running try #{i}");

Snowflake.Data.Tests/IntegrationTests/SFConnectionPoolT.cs

@@ -16,11 +16,26 @@ namespace Snowflake.Data.Tests.IntegrationTests
     using System.Data.Common;
     using Moq;
 
+        public PoolConfig()
+        {
+            _maxPoolSize = SnowflakeDbConnectionPool.GetMaxPoolSize();
+            _timeout = SnowflakeDbConnectionPool.GetTimeout();
+            _pooling = SnowflakeDbConnectionPool.GetPooling();
+        }
+
+        public void Reset()
+        {
+            SnowflakeDbConnectionPool.SetMaxPoolSize(_maxPoolSize);
+            SnowflakeDbConnectionPool.SetTimeout(_timeout);
+            SnowflakeDbConnectionPool.SetPooling(_pooling);
+        }
+    }
+
     [TestFixture, NonParallelizable]
     class SFConnectionPoolT : SFBaseTest
     {
-        private static readonly PoolConfigRestorer s_previousPoolConfig = new PoolConfigRestorer();
-
+        private static readonly PoolConfig s_previousPoolConfig = new PoolConfig();
+        
         [SetUp]
         public void BeforeTest()
         {
@@ -414,7 +429,7 @@ public void TestConnectionPoolTurnOff()
     class SFConnectionPoolITAsync : SFBaseTestAsync
     {
         private static SFLogger logger = SFLoggerFactory.GetLogger<SFConnectionPoolITAsync>();
-        private static readonly PoolConfigRestorer s_previousPoolConfigRestorer = new PoolConfigRestorer();
+        private static readonly PoolConfig s_previousPoolConfigRestorer = new PoolConfig();
 
         [SetUp]
         public void BeforeTest()

Snowflake.Data.Tests/IntegrationTests/SFDbCommandIT.cs

@@ -229,9 +229,6 @@ public void TestSimpleLargeResultSet()
         }
 
 
-        /*
-         * Disabled to make sure that configuration changes does not cause problems with appveyor
-         */
         [Test, NonParallelizable]
         public void TestUseV1ResultParser()
         {

Snowflake.Data.Tests/Mock/MockRetryUntilRestTimeout.cs

@@ -31,7 +31,7 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
                                                               string sid = "")
         {
             // Override the http timeout and set to 1ms to force all http request to timeout and retry
-            message.Properties[BaseRestRequest.HTTP_REQUEST_TIMEOUT_KEY] = TimeSpan.FromMilliseconds(1);
+            message.Properties[BaseRestRequest.HTTP_REQUEST_TIMEOUT_KEY] = TimeSpan.FromTicks(0);
             return await (base.SendAsync(message, restTimeout, externalCancellationToken).ConfigureAwait(false));
         }
     }

Snowflake.Data.Tests/Mock/MockSnowflakeDbConnection.cs

@@ -92,5 +92,10 @@ private void OnSessionEstablished()
         {
             _connectionState = ConnectionState.Open;
         }
+
+        protected override bool CanReuseSession(TransactionRollbackStatus transactionRollbackStatus)
+        {
+            return false;
+        }
     }
 }

Snowflake.Data/Client/SnowflakeDbConnection.cs

@@ -37,7 +37,7 @@ public class SnowflakeDbConnection : DbConnection
         // Will fix that in a separated PR though as it's a different issue
         private static Boolean _isArrayBindStageCreated;
 
-        private enum TransactionRollbackStatus
+        protected enum TransactionRollbackStatus
         {
             Undefined, // used to indicate ignored transaction status when pool disabled
             Success,
@@ -232,7 +232,7 @@ public Task CloseAsync(CancellationToken cancellationToken)
             return taskCompletionSource.Task;
         }
 
-        private bool CanReuseSession(TransactionRollbackStatus transactionRollbackStatus)
+        protected virtual bool CanReuseSession(TransactionRollbackStatus transactionRollbackStatus)
         {
             return SnowflakeDbConnectionPool.GetPooling() && 
                    transactionRollbackStatus == TransactionRollbackStatus.Success;

Snowflake.Data/Core/HttpUtil.cs

@@ -364,7 +364,10 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
                         if (!httpTimeout.Equals(Timeout.InfiniteTimeSpan))
                         {
                             childCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-                            childCts.CancelAfter(httpTimeout);
+                            if (httpTimeout.Ticks == 0)
+                                childCts.Cancel();
+                            else
+                                childCts.CancelAfter(httpTimeout);                        
                         }
                         response = await base.SendAsync(requestMessage, childCts == null ?
                             cancellationToken : childCts.Token).ConfigureAwait(false);