Re: [osgi-dev] Correct way to handle error/recovery in PushStream
Thanks Tim. We'll go with that for now as we are matching the default
behavior and will just add a note documenting to be careful if we do change
that.
Alain
On Thu, Nov 29, 2018 at 6:23 AM Tim Ward wrote:
> That looks reasonable to me. You could also do it using an error handler
> on the promise returned by forEach(), but what you’re doing is also fine.
>
> Depending on your threading model you may lose some events, specifically
> if there’s a buffer in the SimplePushEventSource that you are using (which
> there is unless you’ve worked to avoid it) with a parallelism greater than
> 1 (the default is one) then some events may be delivered into the failed
> push stream by other threads (if they are available) and discarded. If
> there is only one worker thread, or a parallelism of one, then this won’t
> happen and as your “onError” connects a new listener *before* the old one
> returns its back pressure to the SimplePushEventSource.
>
> Note that this whole reasoning goes out of the window if you add another
> buffer between the SimplePushEventSource and your error handler.
>
> I hope this helps,
>
> Tim
>
> > On 28 Nov 2018, at 23:32, Alain Picard via osgi-dev <
> osgi-dev@mail.osgi.org> wrote:
> >
> > We ended up with an exception thrown in the forEach of our stream, which
> is a stream to manage notifications and that should be always on. Nothing
> got reported, but the stream stopped working. Finally testing isConnected
> reported false and then found the source of the exception.
> >
> > Now digging, we found out that there are onError and onClose, but
> couldn't find any example. First time tried to insert after the
> createStream but debugging found that this seemed to be tied to the filter
> intermediate stream. Now moving the onClose, is working but very unsure if
> the pattern is correct.
> >
> > private void handleEvents() {
> >psp.createStream(spes) //NOSONAR as we don't close it
> > .filter(isOfInterest())
> > .onError(e -> {
> > log.error(Messages.CNCI_0, e);
> > handleEvents(); // start a new stream
> > })
> > .forEach(entry -> entry.listener.notify(entry.notification)
> >);
> > }
> >
> > Thanks
> > Alain
> > ___
> > OSGi Developer Mail List
> > osgi-dev@mail.osgi.org
> > https://mail.osgi.org/mailman/listinfo/osgi-dev
>
>
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Re: [osgi-dev] Correct way to handle error/recovery in PushStream
That looks reasonable to me. You could also do it using an error handler on the
promise returned by forEach(), but what you’re doing is also fine.
Depending on your threading model you may lose some events, specifically if
there’s a buffer in the SimplePushEventSource that you are using (which there
is unless you’ve worked to avoid it) with a parallelism greater than 1 (the
default is one) then some events may be delivered into the failed push stream
by other threads (if they are available) and discarded. If there is only one
worker thread, or a parallelism of one, then this won’t happen and as your
“onError” connects a new listener *before* the old one returns its back
pressure to the SimplePushEventSource.
Note that this whole reasoning goes out of the window if you add another buffer
between the SimplePushEventSource and your error handler.
I hope this helps,
Tim
> On 28 Nov 2018, at 23:32, Alain Picard via osgi-dev
> wrote:
>
> We ended up with an exception thrown in the forEach of our stream, which is a
> stream to manage notifications and that should be always on. Nothing got
> reported, but the stream stopped working. Finally testing isConnected
> reported false and then found the source of the exception.
>
> Now digging, we found out that there are onError and onClose, but couldn't
> find any example. First time tried to insert after the createStream but
> debugging found that this seemed to be tied to the filter intermediate
> stream. Now moving the onClose, is working but very unsure if the pattern is
> correct.
>
> private void handleEvents() {
>psp.createStream(spes) //NOSONAR as we don't close it
> .filter(isOfInterest())
> .onError(e -> {
> log.error(Messages.CNCI_0, e);
> handleEvents(); // start a new stream
> })
> .forEach(entry -> entry.listener.notify(entry.notification)
>);
> }
>
> Thanks
> Alain
> ___
> OSGi Developer Mail List
> osgi-dev@mail.osgi.org
> https://mail.osgi.org/mailman/listinfo/osgi-dev
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[osgi-dev] Correct way to handle error/recovery in PushStream
We ended up with an exception thrown in the forEach of our stream, which is
a stream to manage notifications and that should be always on. Nothing got
reported, but the stream stopped working. Finally testing isConnected
reported false and then found the source of the exception.
Now digging, we found out that there are onError and onClose, but couldn't
find any example. First time tried to insert after the createStream but
debugging found that this seemed to be tied to the filter intermediate
stream. Now moving the onClose, is working but very unsure if the pattern
is correct.
private void handleEvents() {
psp.createStream(spes) //NOSONAR as we don't close it
.filter(isOfInterest())
.onError(e -> {
log.error(Messages.CNCI_0, e);
handleEvents(); // start a new stream
})
.forEach(entry -> entry.listener.notify(entry.notification)
);
}
Thanks
Alain
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