The async method does not have any callback
Well that's a problem. A very big problem. If at all possible you should fix that; unless there is a very good reason not to, all asynchronous methods should provide some means for the caller to know when they have completed, whether it's a callback, returning a Task
, firing an event, etc. It's particularly troubling for an asynchronous method that is dependent on a disposable resource to do this.
If you really do have no way of being notified when the operation completes, then there is no way for you to call Dispose
after the method completes. The only means you have of ensuring you don't dispose of the resource while the async operation still needs it is to leak the resource and not dispose of it at all. If the disposable resource has a finalizer it's possible it will be cleaned up eventually, but not all disposable resources do so.
If you can modify the asynchronous method somehow then you simply need to call Dispose
in the callback, or in a continuation of the task, or in a handler of the relevant event. You won't be able to use a using
unless you can await
the asynchronous operation (because await
is just awesome like that).
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