fix race condition

Author: KirillKurdyukov

src/Ydb.Sdk/src/Ado/PoolManager.cs

@@ -29,12 +29,7 @@ CancellationToken cancellationToken
             }
 
             var newSessionPool = new PoolingSessionSource<PoolingSession>(
-                new PoolingSessionFactory(
-                    await settings.BuildDriver(),
-                    settings,
-                    settings.LoggerFactory ?? NullLoggerFactory.Instance
-                ),
-                settings
+                await PoolingSessionFactory.Create(settings), settings
             );
 
             Pools[settings.ConnectionString] = newSessionPool;

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

@@ -1,4 +1,5 @@
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
 
 namespace Ydb.Sdk.Ado.Session;
 
@@ -8,13 +9,16 @@ internal class PoolingSessionFactory : IPoolingSessionFactory<PoolingSession>
     private readonly bool _disableServerBalancer;
     private readonly ILogger<PoolingSession> _logger;
 
-    public PoolingSessionFactory(IDriver driver, YdbConnectionStringBuilder settings, ILoggerFactory loggerFactory)
+    private PoolingSessionFactory(IDriver driver, YdbConnectionStringBuilder settings, ILoggerFactory loggerFactory)
     {
         _driver = driver;
         _disableServerBalancer = settings.DisableServerBalancer;
         _logger = loggerFactory.CreateLogger<PoolingSession>();
     }
 
+    public static async Task<PoolingSessionFactory> Create(YdbConnectionStringBuilder settings) =>
+        new(await settings.BuildDriver(), settings, settings.LoggerFactory ?? NullLoggerFactory.Instance);
+
     public PoolingSession NewSession(PoolingSessionSource<PoolingSession> source) =>
         new(_driver, source, _disableServerBalancer, _logger);
 }

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

@@ -99,14 +99,14 @@ private async ValueTask<ISession> RentAsync(CancellationToken cancellationToken)
             _waiters.Enqueue(waiterTcs);
             if (_idleSessions.TryPop(out session))
             {
-                if (!waiterTcs.TrySetResult(null) && waiterTcs.Task.IsCompleted)
+                if (!waiterTcs.TrySetResult(null))
                 {
-                    var sessionFromRace = waiterTcs.Task.Result;
-
-                    if (CheckIdleSession(sessionFromRace))
+                    if (waiterTcs.Task.IsCompleted && CheckIdleSession(waiterTcs.Task.Result))
                     {
-                        _idleSessions.Push(sessionFromRace);
+                        _idleSessions.Push(waiterTcs.Task.Result);
                     }
+
+                    WakeUpWaiter();
                 }
 
                 if (CheckIdleSession(session))
@@ -167,7 +167,7 @@ private async ValueTask<ISession> RentAsync(CancellationToken cancellationToken)
 
     private void WakeUpWaiter()
     {
-        if (_waiters.TryDequeue(out var waiter) && waiter.TrySetResult(null))
+        while (_waiters.TryDequeue(out var waiter) && waiter.TrySetResult(null))
         {
         } // wake up waiter!
     }