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I submitted a rough draft for review @
https://review.openstack.org/#/c/81941/.  Instead of using the pecan hook,
I added a class property for the transport in the abstract engine class.
 On the pecan app setup, I passed the shared transport to the engine on
load.  Please provide feedback.  Thanks.


On Mon, Mar 17, 2014 at 9:37 AM, Ryan Petrello
<ryan.petrello at dreamhost.com>wrote:

> Changing the configuration object at runtime is not thread-safe.  If you
> want to share objects with controllers, I'd suggest checking out Pecan's
> hook functionality.
>
>
> http://pecan.readthedocs.org/en/latest/hooks.html#implementating-a-pecan-hook
>
> e.g.,
>
> class SpecialContextHook(object):
>
>     def __init__(self, some_obj):
>         self.some_obj = some_obj
>
>     def before(self, state):
>         # In any pecan controller, `pecan.request` is a thread-local
> webob.Request instance,
>         # allowing you to access `pecan.request.context['foo']` in your
> controllers.  In this example,
>         # self.some_obj could be just about anything - a Python primitive,
> or an instance of some class
>         state.request.context = {
>             'foo': self.some_obj
>         }
>
> ...
>
> wsgi_app = pecan.Pecan(
>     my_package.controllers.root.RootController(),
>     hooks=[SpecialContextHook(SomeObj(1, 2, 3))]
> )
>
> ---
> Ryan Petrello
> Senior Developer, DreamHost
> ryan.petrello at dreamhost.com
>
> On Mar 14, 2014, at 8:53 AM, Renat Akhmerov <rakhmerov at mirantis.com>
> wrote:
>
> > Take a look at method get_pecan_config() in mistral/api/app.py. It's
> where you can pass any parameters into pecan app (see a dictionary
> 'cfg_dict' initialization). They can be then accessed via pecan.conf as
> described here:
> http://pecan.readthedocs.org/en/latest/configuration.html#application-configuration.
> If I understood the problem correctly this should be helpful.
> >
> > Renat Akhmerov
> > @ Mirantis Inc.
> >
> >
> >
> > On 14 Mar 2014, at 05:14, Dmitri Zimine <dz at stackstorm.com> wrote:
> >
> >> We have access to all configuration parameters in the context of
> api.py. May be you don't pass it but just instantiate it where you need it?
> Or I may misunderstand what you're trying to do...
> >>
> >> DZ>
> >>
> >> PS: can you generate and update mistral.config.example to include new
> oslo messaging options? I forgot to mention it on review on time.
> >>
> >>
> >> On Mar 13, 2014, at 11:15 AM, W Chan <m4d.coder at gmail.com> wrote:
> >>
> >>> On the transport variable, the problem I see isn't with passing the
> variable to the engine and executor.  It's passing the transport into the
> API layer.  The API layer is a pecan app and I currently don't see a way
> where the transport variable can be passed to it directly.  I'm looking at
> https://github.com/stackforge/mistral/blob/master/mistral/cmd/api.py#L50and
> https://github.com/stackforge/mistral/blob/master/mistral/api/app.py#L44.
>  Do you have any suggestion?  Thanks.
> >>>
> >>>
> >>> On Thu, Mar 13, 2014 at 1:30 AM, Renat Akhmerov <
> rakhmerov at mirantis.com> wrote:
> >>>
> >>> On 13 Mar 2014, at 10:40, W Chan <m4d.coder at gmail.com> wrote:
> >>>
> >>>>    * I can write a method in base test to start local executor.  I
> will do that as a separate bp.
> >>> Ok.
> >>>
> >>>>    * After the engine is made standalone, the API will communicate to
> the engine and the engine to the executor via the oslo.messaging transport.
>  This means that for the "local" option, we need to start all three
> components (API, engine, and executor) on the same process.  If the long
> term goal as you stated above is to use separate launchers for these
> components, this means that the API launcher needs to duplicate all the
> logic to launch the engine and the executor. Hence, my proposal here is to
> move the logic to launch the components into a common module and either
> have a single generic launch script that launch specific components based
> on the CLI options or have separate launch scripts that reference the
> appropriate launch function from the common module.
> >>> Ok, I see your point. Then I would suggest we have one script which we
> could use to run all the components (any subset of of them). So for those
> components we specified when launching the script we use this local
> transport. Btw, scheduler eventually should become a standalone component
> too, so we have 4 components.
> >>>
> >>>>    * The RPC client/server in oslo.messaging do not determine the
> transport.  The transport is determine via oslo.config and then given
> explicitly to the RPC client/server.
> https://github.com/stackforge/mistral/blob/master/mistral/engine/scalable/engine.py#L31and
> https://github.com/stackforge/mistral/blob/master/mistral/cmd/task_executor.py#L63are examples for the client and server respectively.  The in process Queue
> is instantiated within this transport object from the fake driver.  For the
> "local" option, all three components need to share the same transport in
> order to have the Queue in scope. Thus, we will need some method to have
> this transport object visible to all three components and hence my proposal
> to use a global variable and a factory method.
> >>> I'm still not sure I follow your point here.. Looking at the links you
> provided I see this:
> >>>
> >>> transport = messaging.get_transport(cfg.CONF)
> >>>
> >>> So my point here is we can make this call once in the launching script
> and pass it to engine/executor (and now API too if we want it to be
> launched by the same script). Of course, we'll have to change the way how
> we initialize these components, but I believe we can do it. So it's just a
> dependency injection. And in this case we wouldn't need to use a global
> variable. Am I still missing something?
> >>>
> >>>
> >>> Renat Akhmerov
> >>> @ Mirantis Inc.
> >>>
> >>>
> >>> _______________________________________________
> >>> OpenStack-dev mailing list
> >>> OpenStack-dev at lists.openstack.org
> >>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >>>
> >>>
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