[DRAFT] Fix connection getting disposed due to 'Using'

[KathanS]

In the current design, we face the issue of connection getting disposed, when it is needed by publisher. As we leverage 'Using', there can be cases where async function call - publisher.PublishAsync is still running and needs to get feature flag by passing connection and connection has been disposed.

I am removing 'Using' block and doing disposal manually in the 'finally' block as 'finally' block will only be called after all async operations in try block are done.

In the error cases we currently receive error logs as per below,

##[warning]Failed to get FF TestManagement.Agent.PTR.EnableFlakyCheck Value. Error: System.AggregateException: One or more errors occurred. (A task was canceled.)
---> System.Threading.Tasks.TaskCanceledException: A task was canceled.
at System.Threading.Tasks.Task.GetExceptions(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task1.GetResultCore(Boolean waitCompletionNotification) at System.Threading.Tasks.Task1.get_Result()
at Microsoft.VisualStudio.Services.Agent.Worker.TestResults.Utils.FeatureFlagService.GetFeatureFlagState(String featureFlagName, Guid serviceInstanceId) in D:\a_work\1\s\src\Agent.Worker\TestResults\Utils\FeatureFlagService.cs:line 39
at Microsoft.VisualStudio.Services.Agent.Worker.TestResults.TestDataPublisher.PublishAsync(TestRunContext runContext, List1 testResultFiles, PublishOptions publishOptions, CancellationToken cancellationToken) in D:\a\_work\1\s\src\Agent.Worker\TestResults\TestDataPublisher.cs:line 101 at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox1.ExecutionContextCallback(Object s) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox1.MoveNext(Thread threadPoolThread) at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox1.MoveNext() at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining) at System.Threading.Tasks.Task.RunContinuations(Object continuationObject) at System.Threading.Tasks.Task.TrySetResult() at System.Threading.Tasks.Task.WhenAllPromise.Invoke(Task completedTask) at System.Threading.Tasks.Task.RunContinuations(Object continuationObject) at System.Threading.Tasks.Task1.TrySetResult(TResult result)
at System.Threading.Tasks.UnwrapPromise1.TrySetFromTask(Task task, Boolean lookForOce) at System.Threading.Tasks.UnwrapPromise1.Invoke(Task completingTask)
at System.Threading.Tasks.Task.RunContinuations(Object continuationObject)
at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.SetExistingTaskResult(Task1 task, TResult result)
at Microsoft.TeamFoundation.TestClient.PublishTestResults.TestRunPublisher.PublishTestRunDataAsync(TestRunContext runContext, String projectName, IList1 testRuns, PublishOptions publishOptions, CancellationToken cancellationToken) at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox1.ExecutionContextCallback(Object s) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox1.MoveNext(Thread threadPoolThread) at System.Runtime.CompilerServices.AsyncTaskMethodBuilder1.AsyncStateMachineBox`1.MoveNext()
at System.Threading.Tasks.AwaitTaskContinuation.RunOrScheduleAction(IAsyncStateMachineBox box, Boolean allowInlining)
...
at System.Threading._IOCompletionCallback.PerformIOCompletionCallback(UInt32 errorCode, UInt32 numBytes, NativeOverlapped* pNativeOverlapped)
--- End of stack trace from previous location ---

--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task1.GetResultCore(Boolean waitCompletionNotification) at System.Threading.Tasks.Task1.get_Result()
at Microsoft.VisualStudio.Services.Agent.Worker.TestResults.Utils.FeatureFlagService.GetFeatureFlagState(String featureFlagName, Guid serviceInstanceId) in D:\a_work\1\s\src\Agent.Worker\TestResults\Utils\FeatureFlagService.cs:line 39

##[warning]Failed to get FF TestManagement.PTR.CalculateTestRunSummary Value. Error: System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'VssConnection'.
at Microsoft.VisualStudio.Services.WebApi.VssConnection.CheckForDisposed()
at Microsoft.VisualStudio.Services.WebApi.VssConnection.GetClientServiceImplAsync(Type requestedType, Guid serviceIdentifier, Func4 getInstanceAsync, CancellationToken cancellationToken) at Microsoft.VisualStudio.Services.WebApi.VssConnection.GetClientAsync[T](Guid serviceIdentifier, CancellationToken cancellationToken) at Microsoft.VisualStudio.Services.WebApi.TaskExtensions.SyncResult[T](Task1 task)
at Microsoft.VisualStudio.Services.WebApi.VssConnection.GetClient[T](Guid serviceIdentifier)
at Microsoft.VisualStudio.Services.Agent.Worker.TestResults.Utils.FeatureFlagService.GetFeatureFlagState(String featureFlagName, Guid serviceInstanceId

[dougbu]

I am removing 'Using' block and doing disposal manually in the 'finally' block as 'finally' block will only be called after all async operations in try block are done.

@jaredpar do you think try / finally is going to change anything compared to a using block containing unchanged async / await code❓ if not you, who would know❓