xenadmin | XenCenter , the Windows management console for XenServer | Command Line Interface library

HTTP_actions.put_import calls HTTP_actions.put calls HTTP.put calls HTTP.CopyStream

The delegate is passed to CopyStream which then checks that the function isn’t null (not passed) or true (return value). However, it only does this at the While statement so the chances are it is the Read of the Stream that is causing the blocking operation. Though it could also occur in the progressDelegate if one is used.

To get around this, put the call to HTTP.put_import() inside a task or background thread and then separately check for cancellation or a return from the task/thread.

Interestingly enough, a quick glance at that CopyStream code revealed a bug to me. If the function that works out if a process has been cancelled returns a different value based off some check it is making, you can actually get the loop to exit without generating a CancelledException(). The result of the CancelledException call should be stored in a local variable.