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From "David Jencks (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FELIX-3661) Scr sometimes does not invoke Reference bind method
Date Thu, 13 Sep 2012 07:24:11 GMT

    [ https://issues.apache.org/jira/browse/FELIX-3661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13454708#comment-13454708
] 

David Jencks commented on FELIX-3661:
-------------------------------------

Well, we agree on how the components and services are related :-).  Since A registers B from
it's activate method, this is approximately equivalent to just A and C, with C having a reference
to A (instead of B).  This is a circular dependency that is not expected to work with DS.
 Just because you added some code to register some of the services doesn't make it any less
circular :-)  The spec can't enumerate all possible circular dependency situations, it just
says that in general at best you will get all the components created and some of the references
set up, but you shouldn't expect all the references to get set up.

I'm fairly sure this is one of the situations that used to work when we were not spec compliant
about registering immediate components before creating the implementation object, which is
why you code worked with the old DS.

Your code might work if you registered B in a different thread. (but returned immediately
from the activate method.  If you wait for the other thread you'll get a deadlock).  Then
the other thread wouldn't be able to get a read lock until the write lock is released after
the component instance is set for A.  This is roughly what I propose in FELIX-3557

                
> Scr sometimes does not invoke Reference bind method
> ---------------------------------------------------
>
>                 Key: FELIX-3661
>                 URL: https://issues.apache.org/jira/browse/FELIX-3661
>             Project: Felix
>          Issue Type: Bug
>          Components: Declarative Services (SCR)
>            Reporter: Pierre De Rop
>            Assignee: David Jencks
>         Attachments: msg2.log, msg.log
>
>
> With scr from trunk: sometimes, a satisfied Reference bind method is not invoked.
> I'm not sure, but this might be related to the FELIX-3659 issue and/or when Reference
types are org.osgi.service.ComponentFactory types.
> The use case is the following:
> - I have a DS component (name="agent"), which depends on the CompositeFactory service
(ref is dynamic, optional, cardinality=0..N).
> - the "agent" component is started (at this point), the CompositeFactory is not yet available
> - next, the implementation bundle for the CompositeFactory service starts and registers
the service, using bundleContext.registerService.
> - but the "agent" component is not invoked in its bindCompositeFactory(CompositeFactory)
method.
> I have attached a logfile which illustrates the problem.
> 1) Line 8491: the '"agent" component is being created, and some bind method are successfully
invoked, except the "bindCompositeFactory" method (but this is normal since the service is
optional, and not yet available):
> 2012-09-11 23:09:21,147 ProxyAppReporter-FastCacheListener DEBUG osgi  - [agent] For
dependency loggerRepository, optional: false; to bind: {[org.apache.log4j.spi.LoggerRepository]=org.apache.felix.scr.impl.manager.AbstractComponentManager$RefPair@1b7a875}
> 2012-09-11 23:09:21,147 ProxyAppReporter-FastCacheListener DEBUG osgi  - [agent] invoking
bind: bindLoggerRepository
> 2012-09-11 23:09:21,147 ProxyAppReporter-FastCacheListener DEBUG osgi  - [agent] For
dependency compositeFactory, optional: true; to bind: {}
> (here the bind for loggerRepository is invoked, but not for compositeFactory ... normal
behavior for now.
> 2) at line 8644, the CompositeFactory service is being registered, but we see the "component
not yet created, assuming bind method call succeeded" log and the bindCompositeFactory method
on the "agent" component is not invoked. 
> However, another "com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand"
DS component is succesfully bound with the CompositeFactory, but this component depends on
the CompositeService, using a ServiceReference type, instead of the actual CompositeFactory
type, in the bind method signature ...
> 2012-09-11 23:09:21,222 ProxyAppReporter-FastCacheListener WARN  com.alcatel_lucent.as.service.composite.impl.CompositeFactoryImpl
 - Registering CompositeFactory ...
> 2012-09-11 23:09:21,222 ProxyAppReporter-FastCacheListener DEBUG osgi  - [agent] Dependency
Manager: Adding Service com.alcatel_lucent.as.service.composite.CompositeFactory/565
> 2012-09-11 23:09:21,222 ProxyAppReporter-FastCacheListener DEBUG osgi  - [agent] DependencyManager
: component not yet created, assuming bind method call succeeded
> 2012-09-11 23:09:21,223 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.GogoCompositeCommand]
Dependency Manager: Adding Service com.alcatel_lucent.as.service.composite.CompositeFactory/565
> 2012-09-11 23:09:21,223 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.GogoCompositeCommand]
DependencyManager : component not yet created, assuming bind method call succeeded
> 2012-09-11 23:09:21,223 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
Dependency Manager: Adding Service com.alcatel_lucent.as.service.composite.CompositeFactory/565
> 2012-09-11 23:09:21,223 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
getting bind: bindCompositeFactory
> 2012-09-11 23:09:21,224 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
Locating method bindCompositeFactory in class com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand
> 2012-09-11 23:09:21,224 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
doFindMethod: Looking for method com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand.bindCompositeFactory
> 2012-09-11 23:09:21,224 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
doFindMethod: Found Method public void com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand.bindCompositeFactory(org.osgi.framework.ServiceReference)
> 2012-09-11 23:09:21,224 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
Found bind method: public void com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand.bindCompositeFactory(org.osgi.framework.ServiceReference)
> 2012-09-11 23:09:21,224 ProxyAppReporter-FastCacheListener DEBUG osgi  - [com.alcatel_lucent.as.service.composite.impl.shell.FelixCompositeCommand]
invoking bind: bindCompositeFactory
> 2012-09-11 23:09:21,224 ProxyAppReporter-FastCacheListener INFO  osgi.event.service 
- Service registered by bundle com.alcatel_lucent.as.service.composite.impl(1.1100.01)
>  {objectClass=[com.alcatel_lucent.as.service.composite.CompositeFactory],service.id=565}
> Hope that the log file will be enough to understand the issue ?

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