feat: PoolingSessionSource 2.0 based on Npgsql pooling algorithm (ydb-platform#477)

Author: KirillKurdyukov

src/Ydb.Sdk/CHANGELOG.md

@@ -1,3 +1,4 @@
+- ADO.NET: PoolingSessionSource 2.0 based on Npgsql pooling algorithm.
 - Added new ADO.NET options:
   - `MinSessionPool`: The minimum connection pool size.
   - `SessionIdleTimeout`: The time (in seconds) to wait before closing idle session in the pool if the count of all sessions exceeds `MinSessionPool`.

src/Ydb.Sdk/src/Ado/Session/ISession.cs

@@ -6,6 +6,8 @@ namespace Ydb.Sdk.Ado.Session;
 
 internal interface ISession
 {
+    bool IsBroken { get; }
+
     ValueTask<IServerStream<ExecuteQueryResponsePart>> ExecuteQuery(
         string query,
         Dictionary<string, YdbValue> parameters,

src/Ydb.Sdk/src/Ado/Session/ISessionSource.cs

@@ -2,7 +2,7 @@ namespace Ydb.Sdk.Ado.Session;
 
 internal interface ISessionSource<TSession> where TSession : ISession
 {
-    ValueTask<TSession> OpenSession();
+    ValueTask<TSession> OpenSession(CancellationToken cancellationToken = default);
 
     void Return(TSession session);
 }

src/Ydb.Sdk/src/Ado/Session/ImplicitSession.cs

@@ -13,6 +13,8 @@ public ImplicitSession(IDriver driver)
         _driver = driver;
     }
 
+    public bool IsBroken => false;
+
     public ValueTask<IServerStream<ExecuteQueryResponsePart>> ExecuteQuery(
         string query,
         Dictionary<string, YdbValue> parameters,

src/Ydb.Sdk/src/Ado/Session/Session.cs renamed to src/Ydb.Sdk/src/Ado/Session/PoolingSession.cs

@@ -8,7 +8,7 @@
 
 namespace Ydb.Sdk.Ado.Session;
 
-internal class Session : IPoolingSession
+internal class PoolingSession : IPoolingSession
 {
     private const string SessionBalancer = "session-balancer";
 
@@ -18,20 +18,20 @@ internal class Session : IPoolingSession
     private readonly IDriver _driver;
     private readonly PoolingSessionSource _poolingSessionSource;
     private readonly YdbConnectionStringBuilder _settings;
-    private readonly ILogger<Session> _logger;
+    private readonly ILogger<PoolingSession> _logger;
 
-    private volatile bool _isActive;
+    private volatile bool _isBroken;
 
     private string SessionId { get; set; } = string.Empty;
     private long NodeId { get; set; }
 
-    public bool IsActive => _isActive;
+    public bool IsBroken => _isBroken;
 
-    internal Session(
+    internal PoolingSession(
         IDriver driver,
         PoolingSessionSource poolingSessionSource,
         YdbConnectionStringBuilder settings,
-        ILogger<Session> logger
+        ILogger<PoolingSession> logger
     )
     {
         _driver = driver;
@@ -109,7 +109,7 @@ StatusCode.Unavailable or
         {
             _logger.LogWarning("Session[{SessionId}] is deactivated. Reason StatusCode: {Code}", SessionId, code);
 
-            _isActive = false;
+            _isBroken = true;
         }
     }
 
@@ -176,7 +176,7 @@ public async Task Open(CancellationToken cancellationToken)
 
                         OnNotSuccessStatusCode(statusCode);
 
-                        if (!IsActive)
+                        if (IsBroken)
                         {
                             return;
                         }
@@ -204,7 +204,7 @@ public async Task Open(CancellationToken cancellationToken)
             }
             finally
             {
-                _isActive = false;
+                _isBroken = true;
             }
         }, cancellationToken);
 
@@ -215,7 +215,12 @@ public async Task DeleteSession()
     {
         try
         {
-            _isActive = false;
+            if (_isBroken)
+            {
+                return;
+            }
+
+            _isBroken = true;
 
             var deleteSessionResponse = await _driver.UnaryCall(
                 QueryService.DeleteSessionMethod,

src/Ydb.Sdk/src/Ado/Session/PoolingSessionFactory.cs

@@ -0,0 +1,20 @@
+using Microsoft.Extensions.Logging;
+
+namespace Ydb.Sdk.Ado.Session;
+
+internal class PoolingSessionFactory : IPoolingSessionFactory
+{
+    private readonly IDriver _driver;
+    private readonly YdbConnectionStringBuilder _settings;
+    private readonly ILogger<PoolingSession> _logger;
+
+    public PoolingSessionFactory(IDriver driver, YdbConnectionStringBuilder settings, ILogger<PoolingSession> logger)
+    {
+        _driver = driver;
+        _settings = settings;
+        _logger = logger;
+    }
+
+    public IPoolingSession NewSession(PoolingSessionSource source) =>
+        new PoolingSession(_driver, source, _settings, _logger);
+}