Another operation is pending. error message

Question

Hi,

i'm trying to send bulk of commands to my client (without considering if it's connected nor busy). since there is no event for IsBusy i can't really determine if client can accept my commands.

for example when i'm running:

var task = ftpHandler.Ftp.ChangeDirectoryAsync(dir);

task.ContinueWith(task1 =>
    {
        var listTask = ftpHandler.Ftp.GetListAsync();

        listTask.ContinueWith(task2 =>
            {
                var list = task2.Result;

                foreach (var listItem in list)
                {
                    LoggerRepository.AddMessage(listItem.Name);
                }
            });
    });

i get "Another operation is pending". is there a way to determine if the client is ready to execute commands ?

Answer 1

This error is raised when you are trying to execute two methods simultaneously on the Ftp object. Because the code you provided is logically correct, I suppose that the cause of the problem is somewhere else.

Please note, that you cannot use Ftp object until the specified code is completed. This leads to design like this:

var ftp = new Ftp();
ftp.Connect(...);
ftp.Login(...);

var task = ftp.ChangeDirectoryAsync("/");

task = task.ContinueWith(task1 =>
{
    // simply call synchronous methods, 
    // because continuation task is run asynchronously
    var list = ftp.GetList();
    foreach (var listItem in list)
    {
        LoggerRepository.AddMessage(listItem.Name);
    }
});

task.Wait();

// now you can use Ftp object again 
// ...
ftp.ChangeDirectoryAsync("/home");
...