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Re: [equinox-dev] bug or not

On 4/28/14, 17:37 , Thomas Watson wrote:

Is your ServiceFactory.ungetService getting called each time?  If so then it is likely the felix webconsole is using an anti pattern like this:

HttpService service = bc.getService(httpServiceRef);
/// do some work with http service
bc.ungetService(httpServiceRef);


Is this really an anti-pattern? It doesn't seem so to me. If so, why don't we just deprecate ungetService() and tell all bundle implementers to not worry about ungetting, since they framework will do it for you when the bundle stops?

The fact that ungetting and recreating may be costly is an issue for the service implementer, it would seem, not the service consumer. If it costs a lot to create instances, the service factory could consider doing caching of instances and reusing them on subsequent requests.

Having client bundles call ungetService when they are done with a service that they may not use again for a while seems reasonable to me.

-> richard


If they are getting/ungetting the service each time they are interacting with the service then the usecount for the service goes to zero for each usage which then causes the framework to free the service instance object.  The should be using something like a ServiceTracker to avoid this kind of anti-pattern.

Tom



Inactive hide details for Raymond Auge ---04/28/2014
          04:26:50 PM---I agree that I should NOT have to implement this
          code. HowevRaymond Auge ---04/28/2014 04:26:50 PM---I agree that I should NOT have to implement this code. However, I'm having to do so in order to work

From: Raymond Auge <raymond.auge@xxxxxxxxxxx>
To: Equinox development mailing list <equinox-dev@xxxxxxxxxxx>
Date: 04/28/2014 04:26 PM
Subject: Re: [equinox-dev] bug or not
Sent by: equinox-dev-bounces@xxxxxxxxxxx





I agree that I should NOT have to implement this code. However, I'm having to do so in order to work around this apparent issue.

- Ray


On Mon, Apr 28, 2014 at 5:23 PM, Raymond Auge <raymond.auge@xxxxxxxxxxx> wrote:



    On Mon, Apr 28, 2014 at 5:17 PM, Thomas Watson <tjwatson@xxxxxxxxxx> wrote:
      You seem to be implementing the work that the framework already does for ServiceFactory registrations.  The framework will only call your factory once as long as the use count of the service is greater than zero for a particular bundle.  The framework will then cache that service instance and keep returning it directly to the bundle without calling the ServiceFactory again.

      Am I understanding your observation correctly?  You are stating that your factory is not called multiple times for the same consuming bundle?


    I'm stating that when a single bundle is deployed which requests the same service multiple times the factory method is called multiple times and the bundle gets a different instance of the service each time.

    I'm not sure if there is some sort of race condition but the client bundle (in this case the felix webconsole) is requesting the HttpService mutliple times (in the same thread) and each time the equinox framework is invoking the HttpServiceFactory method returning different HttpServiceImpl instance.

    - Ray
     


      Tom



      Inactive hide details for Raymond Auge ---04/28/2014
            03:24:26 PM---Hey all, I have to write code as follows in a
            ServiceFactoryRaymond Auge ---04/28/2014 03:24:26 PM---Hey all, I have to write code as follows in a ServiceFactory impl in order for my



      From:
      Raymond Auge <raymond.auge@xxxxxxxxxxx>
      To:
      Equinox development mailing list <equinox-dev@xxxxxxxxxxx>
      Date: 04/28/2014 03:24 PM

      Subject:
      [equinox-dev] bug or not
      Sent by:
      equinox-dev-bounces@xxxxxxxxxxx





      Hey all,

      I have to write code as follows in a ServiceFactory impl in order for my factory to always return the same instance per bundle running on equinox 3.8.0.v20120529-1548

      ===============================================
      public HttpService getService(
      Bundle bundle, ServiceRegistration<HttpService> registration) {

      HttpServiceImpl httpServiceImpl = serviceMap.get(bundle);

      if (httpServiceImpl != null) {
      return httpServiceImpl;
      }

      httpServiceImpl = new HttpServiceImpl(
      bundle, contextController, legacyServiceIdGenerator);

      serviceMap.putIfAbsent(bundle, httpServiceImpl);

      return httpServiceImpl;
      }
      ===============================================

      This seems clearly wrong as per the spec. 

      It's certainly calling the getService method of the ServiceFactory which I'm guessing means it's not incorrectly registered.

      What could I be doing wrong? Was this ever a bug in equinox that was later resolved?

      --

      Raymond Augé (@rotty3000)
      Senior Software Architect

      Liferay, Inc. (@Liferay)
      _______________________________________________
      equinox-dev mailing list

      equinox-dev@xxxxxxxxxxx
      https://dev.eclipse.org/mailman/listinfo/equinox-dev


      _______________________________________________
      equinox-dev mailing list

      equinox-dev@xxxxxxxxxxx
      https://dev.eclipse.org/mailman/listinfo/equinox-dev



    --
    Raymond Augé (@rotty3000)
    Senior Software Architect
    Liferay, Inc. (@Liferay)




--
Raymond Augé (@rotty3000)
Senior Software Architect
Liferay, Inc. (@Liferay)
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