Re: [akka-user] Get ActorSystem as part of a stream materialization process

[Alexey S]

I'm trying to bind stream life-cycle to an actor life-cycle (let's call it
master actor). In a sense that if the stream is destroyed - the master
actor receives some Termination message but stays alive, but if the actor
is destroyed - the stream has to be shut down as well.
When I construct part of the stream flow, that has to be responsible for
the logic above, I have only an ActorRef of the master actor I want bind
the stream life-cycle to.

Originally I wanted to do the following: during stream materialization I
get its KillSwitch and create an aux actor with KillSwitch and master
ActorRef as parameters. The aux actor will create a watch for the master
actor and kill the stream using KillSwitch, once master actor shuts down.

As an alternative I can probably create a branch in the flow, filter off
all the possible events/messages and attach the master actor as a
Sink.actorRef.

WDYT?

Thanks.

WBR,
Alexey

On Sat, Jul 30, 2016 at 1:41 PM, Konrad Malawski <
konrad.malaw...@lightbend.com> wrote:

> Not using safe APIs.
> But instead I'd turn around the question and ask what you're trying to
> achieve?
> Perhaps there's a cleaner way than reaching out to the ActorSystem.
>
> --
> Konrad `ktoso` Malawski
> Akka  @ Lightbend 
>
> On 30 July 2016 at 22:39:47, oleksiys (kvr...@gmail.com) wrote:
>
> Hi,
>
> is it possible to get access to the ActorSystem, that is being used to
> materialize the stream during materialization?
>
> Something like:
>
> Flow[String].viaMat(*ExposeActorSystemMat.instance*).mapMaterializedValue(actorSystem
> => doSomethingWithActorSystem(actorSystem))
>
> Thanks.
>
> WBR,
> Alexey
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Re: [akka-user] Dynamically move proxied journal (PersistencePluginProxy) to another node

[Alexey S]

>
>> The problem with the PersistencePluginProxy.start(system) is that AFAIU
>> it checks the actual actor system config before it decides how exactly to
>> start the plugin, and if in the config it say "start-target-journal=false"
>> (as in my case) it won't start the underlying journal.
>>
>
> No, it doesn't. See here: https://github.com/akka/akka/blob/master/akka-
> persistence/src/main/scala/akka/persistence/journal/
> PersistencePluginProxy.scala#L26
>
> Note that it only works for the default plugin (null). I think there are
> other places in the PersistencePluginProxy where it only works for the
> default plugin.
>

I understand the code you mentioned above as "PersistencePluginProxy only
works *as* default plugin".
Otherwise why does it need the target plugin ids config for the journal and
snapshot?

And this is
https://github.com/akka/akka/blob/master/akka-persistence/src/main/scala/akka/persistence/journal/PersistencePluginProxy.scala#L80

where it decides whether to start the target plugin or not.

Thanks!

WBR,
Alexey.





>
>
>>
>> That's why I'm using that semi-hacky way to force the underlying journal
>> plugin to start.
>>
>> Thanks.
>>
>> WBR,
>> Alexey
>>
>> On Sunday, August 7, 2016 at 8:40:19 AM UTC-7, Patrik Nordwall wrote:
>>>
>>> As far as I can see the PersistencePluginProxy can only be used with the
>>> default journal plugin and then you would use PersistencePluginProxy.sta
>>> rt(system).
>>>
>>> I hope you need this for testing. PersistencePluginProxy is not intended
>>> for production usage.
>>>
>>> Regards,
>>> Patrik
>>>
>>> On Sat, Aug 6, 2016 at 12:46 AM, oleksiys  wrote:
>>>
 Hi,

 I have a usecase, where I'd like to be able to move the proxied journal
 from one cluster node to another.
 Looks like I can redirect all the journal clients using:

 *PersistencePluginProxy.setTargetLocation(someNewLocation)*

 But now on the cluster node, that has to host the journal I need to
 actually start the actual journal plugin (considering the default journal
 plugin is proxied-journal).
 So I need a way to start a non-default journal plugin at runtime.

 The closest I could get to it was:

 *Persistence(system).adaptersFor(journalPluginId)*

 it looks a bit hacky, but unfortunately:

 *Persistence(system).journalFor(journalPluginId)*
 *Persistence(system).snapshotStoreFor(snapshotStorePluginId)*

 are all in the private[akka] scope.

 Any suggestions?

 Thank you.

 WBR,
 Alexey

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>>>
>>>
>>>
>>> --
>>>
>>> Patrik Nordwall
>>> Akka Tech Lead
>>> Lightbend  -  Reactive apps on the JVM
>>> Twitter: @patriknw
>>>
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>
>
>
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> Lightbend  -  Reactive apps on the JVM
> Twitter: @patriknw
>
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>>  Re