CSHARP-3884: Driver calls SemaphoreSlim.WaitAsync with negative timeout values

Author: BorisDog

src/MongoDB.Driver.Core/Core/ConnectionPools/ExclusiveConnectionPool.Helpers.cs

@@ -64,7 +64,7 @@ private static class State
             public const int Disposed = 2;
         }
 
-        private sealed class AcquireConnectionHelper
+        internal sealed class AcquireConnectionHelper
         {
             // private fields
             private readonly ExclusiveConnectionPool _pool;
@@ -106,8 +106,8 @@ public IConnectionHandle EnteredPool(bool enteredPool, CancellationToken cancell
 
                 if (enteredPool)
                 {
-                    var timeSpentInWaitQueue = _stopwatch.Elapsed;
-                    using (var connectionCreator = new ConnectionCreator(_pool, _pool._settings.WaitQueueTimeout - timeSpentInWaitQueue))
+                    var timeout = EnsureTimeout();
+                    using (var connectionCreator = new ConnectionCreator(_pool, timeout))
                     {
                         connection = connectionCreator.CreateOpenedOrReuse(cancellationToken);
                     }
@@ -123,8 +123,8 @@ public async Task<IConnectionHandle> EnteredPoolAsync(bool enteredPool, Cancella
 
                 if (enteredPool)
                 {
-                    var timeSpentInWaitQueue = _stopwatch.Elapsed;
-                    using (var connectionCreator = new ConnectionCreator(_pool, _pool._settings.WaitQueueTimeout - timeSpentInWaitQueue))
+                    var timeout = EnsureTimeout();
+                    using (var connectionCreator = new ConnectionCreator(_pool, timeout))
                     {
                         connection = await connectionCreator.CreateOpenedOrReuseAsync(cancellationToken).ConfigureAwait(false);
                     }
@@ -154,6 +154,19 @@ private AcquiredConnection FinalizePoolEnterance(PooledConnection pooledConnecti
                 }
             }
 
+            private TimeSpan EnsureTimeout()
+            {
+                var timeSpentInWaitQueue = _stopwatch.Elapsed;
+                var timeout = _pool._settings.WaitQueueTimeout - timeSpentInWaitQueue;
+
+                if (timeout <= TimeSpan.Zero)
+                {
+                    throw _pool.CreateTimeoutException(_stopwatch, $"Timed out waiting for a connection after {timeSpentInWaitQueue.TotalMilliseconds}ms.");
+                }
+
+                return timeout;
+            }
+
             public void Finally()
             {
                 if (_enteredWaitQueue)

tests/MongoDB.Driver.Core.Tests/Core/ConnectionPools/ExclusiveConnectionPoolTests.cs

@@ -679,6 +679,37 @@ public void AquireConnection_should_timeout_when_no_sufficient_reused_connection
             subject.PendingCount.Should().Be(0);
         }
 
+        [Theory]
+        [ParameterAttributeData]
+        public async Task AcquireConnectionHelper_EnteredPool_should_not_create_connection_if_timed_out([Values(true, false)] bool async)
+        {
+            var settings = _settings.With(
+                maintenanceInterval: Timeout.InfiniteTimeSpan,
+                minConnections: 0,
+                waitQueueSize: 1,
+                waitQueueTimeout: TimeSpan.FromMilliseconds(2));
+
+            var mockConnectionFactory = new Mock<IConnectionFactory>();
+            using var pool = CreateSubject(settings, mockConnectionFactory.Object);
+
+            var acquireConnectionHelper = new ExclusiveConnectionPool.AcquireConnectionHelper(pool);
+
+            acquireConnectionHelper.EnterWaitQueue();
+            await Task.Delay(10);
+
+            Exception exception;
+            if (async)
+            {
+                exception = await Record.ExceptionAsync(() => acquireConnectionHelper.EnteredPoolAsync(true, default));
+            }
+            else
+            {
+                exception = Record.Exception(() => acquireConnectionHelper.EnteredPool(true, default));
+            }
+
+            exception.Should().BeOfType<TimeoutException>();
+        }
+
         [Fact]
         public void Clear_should_throw_an_InvalidOperationException_if_not_initialized()
         {