Prevent ObjectDisposedException if Key Vault config provider disposed twice (Azure#24769)

Author: martincostello

sdk/extensions/Azure.Extensions.AspNetCore.Configuration.Secrets/src/AzureKeyVaultConfigurationProvider.cs

@@ -23,6 +23,7 @@ public class AzureKeyVaultConfigurationProvider : ConfigurationProvider, IDispos
         private Dictionary<string, KeyVaultSecret> _loadedSecrets;
         private Task _pollingTask;
         private readonly CancellationTokenSource _cancellationToken;
+        private bool _disposed;
 
         /// <summary>
         /// Creates a new instance of <see cref="AzureKeyVaultConfigurationProvider"/>.
@@ -148,8 +149,13 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposing)
             {
-                _cancellationToken.Cancel();
-                _cancellationToken.Dispose();
+                if (!_disposed)
+                {
+                    _cancellationToken.Cancel();
+                    _cancellationToken.Dispose();
+                }
+
+                _disposed = true;
             }
         }
 

sdk/extensions/Azure.Extensions.AspNetCore.Configuration.Secrets/tests/AzureKeyVaultConfigurationTests.cs

@@ -628,6 +628,21 @@ public void ConstructorThrowsForNegativeRefreshPeriodValue()
             Assert.Throws<ArgumentOutOfRangeException>(() => new AzureKeyVaultConfigurationProvider(Mock.Of<SecretClient>(),  new AzureKeyVaultConfigurationOptions() { ReloadInterval = TimeSpan.FromMilliseconds(-1) }));
         }
 
+        [Test]
+        public void DisposeCanBeCalledMultipleTimes()
+        {
+            // Arrange
+            var client = new Mock<SecretClient>();
+
+            using (var provider = new AzureKeyVaultConfigurationProvider(client.Object, new AzureKeyVaultConfigurationOptions() { Manager = new KeyVaultSecretManager() }))
+            {
+                provider.Dispose();
+
+                // Act & Assert
+                Assert.DoesNotThrow(() => provider.Dispose());
+            }
+        }
+
         private class EndsWithOneKeyVaultSecretManager : KeyVaultSecretManager
         {
             public override bool Load(SecretProperties secret)