Get/Return pooled connections

src/Directory.Packages.props

@@ -10,6 +10,7 @@
         <PackageVersion Include="System.Memory" Version="4.5.5" />
         <PackageVersion Include="System.Data.Common" Version="4.3.0" />
         <PackageVersion Include="System.Text.Encodings.Web" Version="8.0.0" />
+        <PackageVersion Include="System.Threading.Channels" Version="8.0.0" />
     </ItemGroup>
     <!-- NetFx and NetCore project dependencies -->
     <ItemGroup>

src/Microsoft.Data.SqlClient/netcore/ref/Microsoft.Data.SqlClient.csproj

@@ -45,6 +45,11 @@
     <!-- Transitive dependencies that would otherwise bring in older, vulnerable versions. -->
     <PackageReference Include="System.Text.Json" />
   </ItemGroup>
+
+  <!-- netstandard dependencies -->
+  <ItemGroup Condition="'$(TargetGroup)' != 'netcoreapp'">
+    <PackageReference Include="System.Threading.Channels" />
+  </ItemGroup>
 
   <Import Project="$(ToolsDir)targets\ResolveContract.targets" Condition="'$(OSGroup)' == 'AnyOS' AND '$(TargetGroup)' != 'netcoreapp'" />
   <Import Project="$(ToolsDir)targets\NotSupported.targets" Condition="'$(OSGroup)' == 'AnyOS' AND '$(TargetGroup)' != 'netcoreapp'" />

src/Microsoft.Data.SqlClient/netcore/src/Microsoft.Data.SqlClient.csproj

@@ -105,6 +105,9 @@
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ConnectionPool\ChannelDbConnectionPool.cs">
       <Link>Microsoft\Data\SqlClient\ConnectionPool\ChannelDbConnectionPool.cs</Link>
     </Compile>
+    <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ConnectionPool\ConnectionPoolSlots.cs">
+      <Link>Microsoft\Data\SqlClient\ConnectionPool\ConnectionPoolSlots.cs</Link>
+    </Compile>
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ConnectionPool\DbConnectionPoolAuthenticationContext.cs">
       <Link>Microsoft\Data\SqlClient\ConnectionPool\DbConnectionPoolAuthenticationContext.cs</Link>
     </Compile>

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

@@ -46,6 +46,7 @@
     <PackageReference Include="System.Security.Cryptography.Pkcs" />
     <PackageReference Include="System.Text.Encodings.Web" />
     <PackageReference Include="System.Text.Json" />
+    <PackageReference Include="System.Threading.Channels" />
   </ItemGroup>
   <Import Project="$(ToolsDir)targets\TrimDocsForIntelliSense.targets" />
 </Project>

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

@@ -294,6 +294,9 @@
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ConnectionPool\ChannelDbConnectionPool.cs">
       <Link>Microsoft\Data\SqlClient\ConnectionPool\ChannelDbConnectionPool.cs</Link>
     </Compile>
+    <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ConnectionPool\ConnectionPoolSlots.cs">
+      <Link>Microsoft\Data\SqlClient\ConnectionPool\ConnectionPoolSlots.cs</Link>
+    </Compile>
     <Compile Include="$(CommonSourceRoot)Microsoft\Data\SqlClient\ConnectionPool\DbConnectionPoolAuthenticationContext.cs">
       <Link>Microsoft\Data\SqlClient\ConnectionPool\DbConnectionPoolAuthenticationContext.cs</Link>
     </Compile>
@@ -974,6 +977,7 @@
     <PackageReference Include="System.Security.Cryptography.Pkcs" />
     <PackageReference Include="System.Text.Encodings.Web" />
     <PackageReference Include="System.Text.Json" />
+	  <PackageReference Include="System.Threading.Channels" />
   </ItemGroup>
   <Import Project="$(CommonSourceRoot)tools\targets\GenerateResourceStringsSource.targets" />
   <Import Project="$(NetFxSource)tools\targets\GenerateThisAssemblyCs.targets" />

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

@@ -20,7 +20,8 @@
     <Reference Include="System.Configuration.ConfigurationManager" />
     <Reference Include="System.Transactions" />
     <PackageReference Include="System.Data.Common" />
-	</ItemGroup>
+    <PackageReference Include="System.Threading.Channels" />
+  </ItemGroup>
   <ItemGroup Condition="'$(TargetFramework)' != 'net462'">
     <!-- References that only apply to netcore -->
     <PackageReference Include="System.Configuration.ConfigurationManager" />

src/Microsoft.Data.SqlClient/src/Microsoft/Data/ProviderBase/DbConnectionInternal.cs

@@ -46,11 +46,6 @@ internal abstract class DbConnectionInternal
         /// </summary>
         private bool _cannotBePooled;
 
-        /// <summary>
-        /// When the connection was created.
-        /// </summary>
-        private DateTime _createTime;
-
         /// <summary>
         /// [usage must be thread-safe] the transaction that we're enlisted in, either manually or automatically.
         /// </summary>
@@ -93,10 +88,16 @@ internal DbConnectionInternal(ConnectionState state, bool hidePassword, bool all
             AllowSetConnectionString = allowSetConnectionString;
             ShouldHidePassword = hidePassword;
             State = state;
+            CreateTime = DateTime.UtcNow;
         }
 
         #region Properties
 
+        /// <summary>
+        /// When the connection was created.
+        /// </summary>
+        internal DateTime CreateTime { get; }
+
         internal bool AllowSetConnectionString { get; }
 
         internal bool CanBePooled => !IsConnectionDoomed && !_cannotBePooled && !_owningObject.TryGetTarget(out _);
@@ -531,7 +532,7 @@ internal void DeactivateConnection()
                 // If we're not already doomed, check the connection's lifetime and
                 // doom it if it's lifetime has elapsed.
                 DateTime now = DateTime.UtcNow;
-                if (now.Ticks - _createTime.Ticks > Pool.LoadBalanceTimeout.Ticks)
+                if (now.Ticks - CreateTime.Ticks > Pool.LoadBalanceTimeout.Ticks)
                 {
                     DoNotPoolThisConnection();
                 }
@@ -701,7 +702,6 @@ internal void MakeNonPooledObject(DbConnection owningObject)
         /// <param name="connectionPool"></param>
         internal void MakePooledConnection(IDbConnectionPool connectionPool)
         {
-            _createTime = DateTime.UtcNow;
             Pool = connectionPool;
         }
 
@@ -756,7 +756,7 @@ internal virtual void PrepareForReplaceConnection()
             // By default, there is no preparation required
         }
 
-        internal void PrePush(object expectedOwner)
+        internal void PrePush(DbConnection expectedOwner)
         {
             // Called by IDbConnectionPool when we're about to be put into it's pool, we take this
             // opportunity to ensure ownership and pool counts are legit.