Re: [Qemu-devel] [PATCH 1/3] Introduce threadlets

[Avi Kivity <avi@redhat.com>]

  On 10/14/2010 11:15 AM, Stefan Hajnoczi wrote:
> I forgot to add that the semantics of cancellation make it difficult
> to write correct user code.  Every cancellation user needs to add
> extra synchronization after the cancel call to handle the case where
> the work is currently executing.
>
> This seems tricky to me and I suspect code using this interface will
> be buggy.  How about the following?
> 1. Add a return value indicating that the work is currently executing
> (this still requires the caller to add extra synchronization but is at
> least explicit) versus work is no longer on the list.
> 2. Add a flag to block until the work has been cancelled or completed.
>   This is useful to callers who are allowed to block.

Blocking is somewhat against the spirit of the thing, no?  While I agree 
that the current cancel API is hard to use correctly, blocking defeats 
the purpose of the API.

-- 
error compiling committee.c: too many arguments to function