[infinispan-dev] Command cancellation

[Manik Surtani]

Looks good, except that the pseudocode for dealing with a CancellableCommand (on the recipient node) should look like:

* Receive command
* if CancellableCommand, register with CancellationService
* Perform command
* If CancellableCommand, un-register from CancellationService

That last step was missing from your detail below.  I presume that would require a CancellationService#unregisterThread(UUID u) ?

- Manik

On 21 Sep 2012, at 11:42, Vladimir Blagojevic <vblagoje at redhat.com> wrote:

> Hi,
> 
> I wanted to run by you guys design of command cancellation Manik and I 
> talked about recently. For more background regarding this task read 
> https://issues.jboss.org/browse/ISPN-1042
> 
> At originating node I would have each Cancellable command create its 
> UUID as part of constructor. After that command gets sent away to remote 
> VMs but just before it gets executed there we associated thread with 
> UUID by calling CancellationService.registerThread (as a first line of 
> code in Command#perform). After registration has been setup Cancellable 
> command goes into potentially lengthy (in seconds) execution. If needed 
> we would be able to send CancelCommand which would call 
> CancellationService#cancelTask with UUID. CancelTask would interrupt the 
> associated thread.
> 
> WDYT?
> 
> Regards,
> Vladimir
> 
> Cancellation of tasks:
> 
> class CancellationService {
>  UUID registerThread(Thread t, UUID uuid) {
>     // put thread in map, associate with newly give UUID
>    }
>  void cancelTask(UUID uuid) {
> //     look up thread, interrupt if exists.
>   }
> }
> 
> interface CancellableCommand {
>   UUID getCommandUUID();
> }
> 
> command CancelCommand {
>   Object perform() {
> //      Calls CancellationService.cancelTask with UUID.  The UUID is a 
> parameter of this command.
>  }
> }
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--
Manik Surtani
manik at jboss.org
twitter.com/maniksurtani

Platform Architect, JBoss Data Grid
http://red.ht/data-grid

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