Question

how to monitor the file growth on the server side before rebex sftp client can actually pick the file.

Answer 1

using var client = new Sftp();

client.Connect("test.rebex.net");
client.Login("demo", "password");

var files = new List<RemoteFile>()
{
    new RemoteFile("/pub/example/readme.txt", client),
    new RemoteFile("/pub/example/KeyGenerator.png", client),
    new RemoteFile("/pub/example/ResumableTransfer.png", client)
};

TimeSpan delay = TimeSpan.FromSeconds(5); // set a safe value for you
while (files.Count > 0)
{
    Thread.Sleep(delay); // wait a while 

    files = TryDownload(files, @"c:\data", client);
}

List<RemoteFile> TryDownload(List<RemoteFile> files, string targetFolder, Sftp client)
{
    List<RemoteFile> updatedFiles = new List<RemoteFile>();

    foreach (var file in files)
    {
        var size = client.GetFileLength(file.Path);
        if (size == file.Size)
        {
            client.Download(file.Path, targetFolder);
        }
        else
        {
            file.Size = size;
            updatedFiles.Add(file);
        }
    }

    return updatedFiles;
}

class RemoteFile
{
    public string Path;
    public long Size;

    public RemoteFile(string path, Sftp client)
    {
        Path = path;
        Size = client.GetFileLength(path);
    }
}