Hi,

A bit later than initially planned I finally restarted looking at this KIP.

I made a few significant changes to the proposed APIs.
I considered Chris' idea of automatically removing metrics but decided
to leave that responsibility to the plugins. All plugins that will
support this feature have close/stop methods and will need to close
their PluginMetrics instance. This simplifies the required changes a
lot and I think it's not a big ask on users implementing plugins.

Thanks,
Mickael

On Tue, May 30, 2023 at 11:32 AM Mickael Maison
<mickael.mai...@gmail.com> wrote:
>
> Hi Jorge,
>
> There are a few issues with the current proposal. Once 3.5 is out, I
> plan to start looking at this again.
>
> Thanks,
> Mickael
>
> On Mon, May 15, 2023 at 3:19 PM Jorge Esteban Quilcate Otoya
> <quilcate.jo...@gmail.com> wrote:
> >
> > Hi Mickael,
> >
> > Just to check the status of this KIP as it looks very useful. I can see how
> > new Tiered Storage interfaces and plugins may benefit from this.
> >
> > Cheers,
> > Jorge.
> >
> > On Mon, 6 Feb 2023 at 23:00, Chris Egerton <chr...@aiven.io.invalid> wrote:
> >
> > > Hi Mickael,
> > >
> > > I agree that adding a getter method for Monitorable isn't great. A few
> > > alternatives come to mind:
> > >
> > > 1. Introduce a new ConfiguredInstance<T> (name subject to change) 
> > > interface
> > > that wraps an instance of type T, but also contains a getter method for 
> > > any
> > > PluginMetrics instances that the plugin was instantiated with (which may
> > > return null either if no PluginMetrics instance could be created for the
> > > plugin, or if it did not implement the Monitorable interface). This can be
> > > the return type of the new AbstractConfig::getConfiguredInstance variants.
> > > It would give us room to move forward with other plugin-for-your-plugin
> > > style interfaces without cluttering things up with getter methods. We 
> > > could
> > > even add a close method to this interface which would handle cleanup of 
> > > all
> > > extra resources allocated for the plugin by the runtime, and even possibly
> > > the plugin itself.
> > >
> > > 2. Break out the instantiation logic into two separate steps. The first
> > > step, creating a PluginMetrics instance, can be either private or public
> > > API. The second step, providing that PluginMetrics instance to a
> > > newly-created object, can be achieved with a small tweak of the proposed
> > > new methods for the AbstractConfig class; instead of accepting a Metrics
> > > instance, they would now accept a PluginMetrics instance. For the first
> > > step, we might even introduce a new CloseablePluginMetrics interface which
> > > would be the return type of whatever method we use to create the
> > > PluginMetrics instance. We can track that CloseablePluginMetrics instance
> > > in tandem with the plugin it applies to, and close it when we're done with
> > > the plugin.
> > >
> > > I know that this adds some complexity to the API design and some
> > > bookkeeping responsibilities for our implementation, but I can't shake the
> > > feeling that if we don't feel comfortable taking on the responsibility to
> > > clean up these resources ourselves, it's not really fair to ask users to
> > > handle it for us instead. And with the case of Connect, sometimes 
> > > Connector
> > > or Task instances that are scheduled for shutdown block for a while, at
> > > which point we abandon them and bring up new instances in their place; 
> > > it'd
> > > be nice to have a way to forcibly clear out all the metrics allocated by
> > > that Connector or Task instance before bringing up a new one, in order to
> > > prevent issues due to naming conflicts.
> > >
> > > Regardless, and whether or not it ends up being relevant to this KIP, I'd
> > > love to see a new Converter::close method. It's irked me for quite a while
> > > that we don't have one already.
> > >
> > > Cheers,
> > >
> > > Chris
> > >
> > > On Mon, Feb 6, 2023 at 1:50 PM Mickael Maison <mickael.mai...@gmail.com>
> > > wrote:
> > >
> > > > Hi Chris,
> > > >
> > > > I envisioned plugins to be responsible for closing the PluginMetrics
> > > > instance. This is mostly important for Connect connector plugins as
> > > > they can be closed while the runtime keeps running (and keeps its
> > > > Metrics instance). As far as I can tell, other plugins should only be
> > > > closed when their runtime closes, so we should not be leaking metrics
> > > > even if those don't explicitly call close().
> > > >
> > > > For Connect plugin, as you said, it would be nice to automatically
> > > > close their associated PluginMetrics rather than relying on user
> > > > logic. The issue is that with the current API there's no way to
> > > > retrieve the PluginMetrics instance once it's passed to the plugin.
> > > > I'm not super keen on having a getter method on the Monitorable
> > > > interface and tracking PluginMetrics instances associated with each
> > > > plugin would require a lot of changes. I just noticed Converter does
> > > > not have a close() method so it's problematic for that type of plugin.
> > > > The other Connect plugins all have close() or stop() methods. I wonder
> > > > if the simplest is to make Converter extend Closeable. WDYT?
> > > >
> > > > Thanks,
> > > > Mickael
> > > >
> > > > On Mon, Feb 6, 2023 at 6:39 PM Mickael Maison <mickael.mai...@gmail.com>
> > > > wrote:
> > > > >
> > > > > Hi Yash,
> > > > >
> > > > > I added a sentence to the sensor() method mentioning the sensor name
> > > > > must only be unique per plugin. Regarding having getters for sensors
> > > > > and metrics I considered this not strictly necessary as I expect the
> > > > > metrics logic in most plugins to be relatively simple. If you have a
> > > > > use case that would benefit from these methods, let me know I will
> > > > > reconsider.
> > > > >
> > > > > Thanks,
> > > > > Mickael
> > > > >
> > > > >
> > > > > On Fri, Feb 3, 2023 at 9:16 AM Yash Mayya <yash.ma...@gmail.com>
> > > wrote:
> > > > > >
> > > > > > Hi Mickael,
> > > > > >
> > > > > > Thanks for the updates.
> > > > > >
> > > > > > > the PluginMetrics implementation will append a
> > > > > > > suffix to sensor names to unique identify
> > > > > > > the plugin (based on the class name and tags).
> > > > > >
> > > > > > Can we call this out explicitly in the KIP, since it is important to
> > > > avoid
> > > > > > clashes in sensor naming? Also, should we allow plugins to retrieve
> > > > sensors
> > > > > > from `PluginMetrics` if we can check / verify that they own the
> > > sensor
> > > > > > (based on the suffix)?
> > > > > >
> > > > > > Other than the above minor points, this looks good to me now!
> > > > > >
> > > > > > Thanks,
> > > > > > Yash
> > > > > >
> > > > > > On Fri, Feb 3, 2023 at 2:29 AM Chris Egerton 
> > > > > > <chr...@aiven.io.invalid
> > > >
> > > > > > wrote:
> > > > > >
> > > > > > > Hi Mickael,
> > > > > > >
> > > > > > > This is looking great. I have one small question left but I do not
> > > > consider
> > > > > > > it a blocker.
> > > > > > >
> > > > > > > What is the intended use case for PluginMetrics::close? To me at
> > > > least, it
> > > > > > > implies that plugin developers will be responsible for invoking
> > > that
> > > > method
> > > > > > > themselves in order to clean up metrics that they've created, but
> > > > wouldn't
> > > > > > > we want the runtime (i.e., KafkaProducer class, Connect framework,
> > > > etc.) to
> > > > > > > handle that automatically when the resource that the plugin 
> > > > > > > applies
> > > > to is
> > > > > > > closed?
> > > > > > >
> > > > > > > Cheers,
> > > > > > >
> > > > > > > Chris
> > > > > > >
> > > > > > > On Thu, Jan 26, 2023 at 10:22 AM Mickael Maison <
> > > > mickael.mai...@gmail.com>
> > > > > > > wrote:
> > > > > > >
> > > > > > > > Hi Yash,
> > > > > > > >
> > > > > > > > 1) To avoid conflicts with other sensors, the PluginMetrics
> > > > > > > > implementation will append a suffix to sensor names to unique
> > > > identify
> > > > > > > > the plugin (based on the class name and tags). Also I changed 
> > > > > > > > the
> > > > > > > > semantics of the sensor() method to only create sensors
> > > > (originally it
> > > > > > > > was get or create). If a sensor with the same name already
> > > exists,
> > > > the
> > > > > > > > method will throw.
> > > > > > > > 2) Tags will be automatically added to metrics and sensors to
> > > > unique
> > > > > > > > identify the plugin. For Connect plugins, the connector name,
> > > task
> > > > id
> > > > > > > > and alias can be added if available. The class implementing
> > > > > > > > PluginMetrics will be similar to ConnectMetrics, as in it will
> > > > provide
> > > > > > > > a simplified API wrapping Metrics. I'm planning to use
> > > > PluginMetrics
> > > > > > > > for Connect plugin too and should not need to interact with
> > > > > > > > ConnectMetrics.
> > > > > > > > 3) Right, I fixed the last rejected alternative.
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Mickael
> > > > > > > >
> > > > > > > > On Thu, Jan 26, 2023 at 4:04 PM Mickael Maison <
> > > > mickael.mai...@gmail.com
> > > > > > > >
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > Hi Federico,
> > > > > > > > >
> > > > > > > > > - The metricName() method does not register anything, it just
> > > > builds a
> > > > > > > > > MetricName instance which is just a container holding a name,
> > > > group,
> > > > > > > > > description and tags for a metric. Each time it is called, it
> > > > returns
> > > > > > > > > a new instance. If called with the same arguments, the 
> > > > > > > > > returned
> > > > value
> > > > > > > > > will be equal.
> > > > > > > > > - Initially I just copied the API of Metrics. I made some 
> > > > > > > > > small
> > > > > > > > > changes so the metric and sensor methods are a bit more 
> > > > > > > > > similar
> > > > > > > > > - Good catch! I fixed the example.
> > > > > > > > >
> > > > > > > > > Thanks,
> > > > > > > > > Mickael
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > On Thu, Jan 26, 2023 at 3:54 PM Mickael Maison <
> > > > > > > mickael.mai...@gmail.com>
> > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > Hi Chris,
> > > > > > > > > >
> > > > > > > > > > 1) I updated the KIP to only mention the interface.
> > > > > > > > > > 2) This was a mistake. I've added ReplicationPolicy to the
> > > > list of
> > > > > > > > plugins.
> > > > > > > > > >
> > > > > > > > > > Thanks,
> > > > > > > > > > Mickael
> > > > > > > > > >
> > > > > > > > > > On Tue, Jan 24, 2023 at 11:16 AM Yash Mayya <
> > > > yash.ma...@gmail.com>
> > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > Hi Mickael,
> > > > > > > > > > >
> > > > > > > > > > > Thanks for the updated KIP, this is looking really good! I
> > > > had a
> > > > > > > > couple
> > > > > > > > > > > more questions -
> > > > > > > > > > >
> > > > > > > > > > > 1) Sensor names need to be unique across all groups for a
> > > > `Metrics`
> > > > > > > > > > > instance. How are we planning to avoid naming clashes 
> > > > > > > > > > > (both
> > > > between
> > > > > > > > > > > different plugins as well as with pre-defined sensors)?
> > > > > > > > > > >
> > > > > > > > > > > 2) Connect has a `ConnectMetrics` wrapper around `Metrics`
> > > > via
> > > > > > > which
> > > > > > > > > > > rebalance / worker / connector / task metrics are 
> > > > > > > > > > > recorded.
> > > > Could
> > > > > > > you
> > > > > > > > > > > please elaborate in the KIP how the plugin metrics for
> > > > connectors /
> > > > > > > > tasks
> > > > > > > > > > > will inter-operate with this?
> > > > > > > > > > >
> > > > > > > > > > > Another minor point is that the third rejected alternative
> > > > appears
> > > > > > > > to be an
> > > > > > > > > > > incomplete sentence?
> > > > > > > > > > >
> > > > > > > > > > > Thanks,
> > > > > > > > > > > Yash
> > > > > > > > > > >
> > > > > > > > > > > On Fri, Jan 13, 2023 at 10:56 PM Mickael Maison <
> > > > > > > > mickael.mai...@gmail.com>
> > > > > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > > Hi,
> > > > > > > > > > > >
> > > > > > > > > > > > I've updated the KIP based on the feedback.
> > > > > > > > > > > >
> > > > > > > > > > > > Now instead of receiving a Metrics instance, plugins get
> > > > access
> > > > > > > to
> > > > > > > > > > > > PluginMetrics that exposes a much smaller API. I've
> > > > removed the
> > > > > > > > > > > > special handling for connectors and tasks and they must
> > > now
> > > > > > > > implement
> > > > > > > > > > > > the Monitorable interface as well to use this feature.
> > > > Finally
> > > > > > > the
> > > > > > > > > > > > goal is to allow all plugins (apart from metrics
> > > > reporters) to
> > > > > > > use
> > > > > > > > > > > > this feature. I've listed them all (there are over 30
> > > > pluggable
> > > > > > > > APIs)
> > > > > > > > > > > > but I've not added the list in the KIP. The reason is
> > > that
> > > > new
> > > > > > > > plugins
> > > > > > > > > > > > could be added in the future and instead I'll focus on
> > > > adding
> > > > > > > > support
> > > > > > > > > > > > in all the place that instantiate classes.
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks,
> > > > > > > > > > > > Mickael
> > > > > > > > > > > >
> > > > > > > > > > > > On Tue, Jan 10, 2023 at 7:00 PM Mickael Maison <
> > > > > > > > mickael.mai...@gmail.com>
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > Hi Chris/Yash,
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks for taking a look and providing feedback.
> > > > > > > > > > > > >
> > > > > > > > > > > > > 1) Yes you're right, when using incompatible version,
> > > > metrics()
> > > > > > > > would
> > > > > > > > > > > > > trigger NoSuchMethodError. I thought using the context
> > > > to pass
> > > > > > > > the
> > > > > > > > > > > > > Metrics object would be more idiomatic for Connect but
> > > > maybe
> > > > > > > > > > > > > implementing Monitorable would be simpler. It would
> > > also
> > > > allow
> > > > > > > > other
> > > > > > > > > > > > > Connect plugins (transformations, converters, etc) to
> > > > register
> > > > > > > > > > > > > metrics. So I'll make that change.
> > > > > > > > > > > > >
> > > > > > > > > > > > > 2) As mentioned in the rejected alternatives, I
> > > > considered
> > > > > > > > having a
> > > > > > > > > > > > > PluginMetrics class/interface with a limited API. But
> > > > since
> > > > > > > > Metrics is
> > > > > > > > > > > > > part of the public API, I thought it would be simpler
> > > to
> > > > reuse
> > > > > > > > it.
> > > > > > > > > > > > > That said you bring interesting points so I took
> > > another
> > > > look
> > > > > > > > today.
> > > > > > > > > > > > > It's true that the Metrics API is pretty complex and
> > > most
> > > > > > > > methods are
> > > > > > > > > > > > > useless for plugin authors. I'd expect most use cases
> > > > only need
> > > > > > > > one
> > > > > > > > > > > > > addMetric and one sensor methods. Rather than
> > > subclassing
> > > > > > > > Metrics, I
> > > > > > > > > > > > > think a delegate/forwarding pattern might work well
> > > > here. A
> > > > > > > > > > > > > PluginMetric class would forward its method to the
> > > > Metrics
> > > > > > > > instance
> > > > > > > > > > > > > and could perform some basic validations such as only
> > > > letting
> > > > > > > > plugins
> > > > > > > > > > > > > delete metrics they created, or automatically 
> > > > > > > > > > > > > injecting
> > > > tags
> > > > > > > > with the
> > > > > > > > > > > > > class name for example.
> > > > > > > > > > > > >
> > > > > > > > > > > > > 3) Between the clients, brokers, streams and connect,
> > > > Kafka has
> > > > > > > > quite
> > > > > > > > > > > > > a lot! In practice I think registering metrics should
> > > be
> > > > > > > > beneficial
> > > > > > > > > > > > > for all plugins, I think the only exception would be
> > > > metrics
> > > > > > > > reporters
> > > > > > > > > > > > > (which are instantiated before the Metrics object).
> > > I'll
> > > > try to
> > > > > > > > build
> > > > > > > > > > > > > a list of all plugin types and add that to the KIP.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > Mickael
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > > > On Tue, Dec 27, 2022 at 4:54 PM Chris Egerton
> > > > > > > > <chr...@aiven.io.invalid>
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Hi Yash,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Yes, a default no-op is exactly what I had in mind
> > > > should the
> > > > > > > > > > > > Connector and
> > > > > > > > > > > > > > Task classes implement the Monitorable interface.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Cheers,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Chris
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Tue, Dec 20, 2022 at 2:46 AM Yash Mayya <
> > > > > > > > yash.ma...@gmail.com>
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hi Mickael,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks for creating this KIP, this will be a super
> > > > useful
> > > > > > > > feature to
> > > > > > > > > > > > > > > enhance existing connectors in the Kafka Connect
> > > > ecosystem.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I have some similar concerns to the ones that 
> > > > > > > > > > > > > > > Chris
> > > > has
> > > > > > > > outlined
> > > > > > > > > > > > above,
> > > > > > > > > > > > > > > especially with regard to directly exposing
> > > Connect's
> > > > > > > > Metrics object
> > > > > > > > > > > > to
> > > > > > > > > > > > > > > plugins. I believe it would be a lot friendlier to
> > > > > > > > developers if we
> > > > > > > > > > > > instead
> > > > > > > > > > > > > > > exposed wrapper methods in the context classes -
> > > > such as
> > > > > > > one
> > > > > > > > for
> > > > > > > > > > > > > > > registering a new metric, one for recording metric
> > > > values
> > > > > > > > and so on.
> > > > > > > > > > > > This
> > > > > > > > > > > > > > > would also have the added benefit of minimizing 
> > > > > > > > > > > > > > > the
> > > > surface
> > > > > > > > area for
> > > > > > > > > > > > > > > potential misuse by custom plugins.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > for connectors and tasks they should handle the
> > > > > > > > > > > > > > > > metrics() method returning null when deployed on
> > > > > > > > > > > > > > > > an older runtime.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I believe this won't be the case, and instead
> > > > they'll need
> > > > > > > > to handle
> > > > > > > > > > > > a
> > > > > > > > > > > > > > > `NoSuchMethodError` right? This is similar to
> > > > previous KIPs
> > > > > > > > that
> > > > > > > > > > > > added
> > > > > > > > > > > > > > > methods to connector context classes and will 
> > > > > > > > > > > > > > > arise
> > > > due to
> > > > > > > an
> > > > > > > > > > > > > > > incompatibility between the `connect-api`
> > > dependency
> > > > that a
> > > > > > > > plugin
> > > > > > > > > > > > will be
> > > > > > > > > > > > > > > compiled against versus what it will actually get
> > > at
> > > > > > > runtime.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Hi Chris,
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > WDYT about having the Connector and Task classes
> > > > > > > > > > > > > > > > implement the Monitorable interface, both for
> > > > > > > > > > > > > > > > consistency's sake, and to prevent classloading
> > > > > > > > > > > > > > > > headaches?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Are you suggesting that the framework should
> > > > configure
> > > > > > > > connectors /
> > > > > > > > > > > > tasks
> > > > > > > > > > > > > > > with a Metrics instance during their startup 
> > > > > > > > > > > > > > > rather
> > > > than
> > > > > > > the
> > > > > > > > > > > > connector /
> > > > > > > > > > > > > > > task asking the framework to provide one? In this
> > > > case, I'm
> > > > > > > > guessing
> > > > > > > > > > > > you're
> > > > > > > > > > > > > > > envisioning a default no-op implementation for the
> > > > metrics
> > > > > > > > > > > > configuration
> > > > > > > > > > > > > > > method rather than the framework having to handle
> > > > the case
> > > > > > > > where the
> > > > > > > > > > > > > > > connector was compiled against an older version of
> > > > Connect
> > > > > > > > right?
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > > Yash
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > On Wed, Nov 30, 2022 at 1:38 AM Chris Egerton
> > > > > > > > > > > > <chr...@aiven.io.invalid>
> > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Hi Mickael,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Thanks for the KIP! This seems especially useful
> > > to
> > > > > > > reduce
> > > > > > > > the
> > > > > > > > > > > > > > > > implementation cost and divergence in behavior
> > > for
> > > > > > > > connectors that
> > > > > > > > > > > > choose
> > > > > > > > > > > > > > > > to publish their own metrics.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > My initial thoughts:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 1. Are you certain that the default
> > > implementation
> > > > of the
> > > > > > > > "metrics"
> > > > > > > > > > > > > > > method
> > > > > > > > > > > > > > > > for the various connector/task context classes
> > > > will be
> > > > > > > > used on
> > > > > > > > > > > > older
> > > > > > > > > > > > > > > > versions of the Connect runtime? My 
> > > > > > > > > > > > > > > > understanding
> > > > was
> > > > > > > that
> > > > > > > > a
> > > > > > > > > > > > > > > > NoSuchMethodError (or some similar classloading
> > > > > > > exception)
> > > > > > > > would be
> > > > > > > > > > > > > > > thrown
> > > > > > > > > > > > > > > > in that case. If that turns out to be true, WDYT
> > > > about
> > > > > > > > having the
> > > > > > > > > > > > > > > Connector
> > > > > > > > > > > > > > > > and Task classes implement the Monitorable
> > > > interface,
> > > > > > > both
> > > > > > > > for
> > > > > > > > > > > > > > > > consistency's sake, and to prevent classloading
> > > > > > > headaches?
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 2. Although I agree that administrators should 
> > > > > > > > > > > > > > > > be
> > > > careful
> > > > > > > > about
> > > > > > > > > > > > which
> > > > > > > > > > > > > > > > plugins they run on their clients, Connect
> > > > clusters,
> > > > > > > etc.,
> > > > > > > > I
> > > > > > > > > > > > wonder if
> > > > > > > > > > > > > > > > there might still be value in wrapping the
> > > Metrics
> > > > class
> > > > > > > > behind a
> > > > > > > > > > > > new
> > > > > > > > > > > > > > > > interface, for a few reasons:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >   a. Developers and administrators may still 
> > > > > > > > > > > > > > > > make
> > > > > > > > mistakes, and if
> > > > > > > > > > > > we can
> > > > > > > > > > > > > > > > reduce the blast radius by preventing plugins
> > > > from, e.g.,
> > > > > > > > closing
> > > > > > > > > > > > the
> > > > > > > > > > > > > > > > Metrics instance we give them, it may be worth
> > > it.
> > > > This
> > > > > > > > could also
> > > > > > > > > > > > be
> > > > > > > > > > > > > > > > accomplished by forbidding plugins from invoking
> > > > these
> > > > > > > > methods, and
> > > > > > > > > > > > > > > giving
> > > > > > > > > > > > > > > > them a subclass of Metrics that throws
> > > > > > > > > > > > UnsupportedOperationException from
> > > > > > > > > > > > > > > > these methods.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >   b. If we don't know of any reasonable use 
> > > > > > > > > > > > > > > > cases
> > > > for
> > > > > > > > closing the
> > > > > > > > > > > > > > > instance,
> > > > > > > > > > > > > > > > adding new reporters, removing metrics, etc., it
> > > > can make
> > > > > > > > the API
> > > > > > > > > > > > cleaner
> > > > > > > > > > > > > > > > and easier for developers to grok if they don't
> > > > even have
> > > > > > > > the
> > > > > > > > > > > > option to
> > > > > > > > > > > > > > > do
> > > > > > > > > > > > > > > > any of those things.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >   c. Interoperability between plugins that
> > > > implement
> > > > > > > > Monitorable
> > > > > > > > > > > > and
> > > > > > > > > > > > > > > their
> > > > > > > > > > > > > > > > runtime becomes complicated. For example, a
> > > > connector may
> > > > > > > > be built
> > > > > > > > > > > > > > > against
> > > > > > > > > > > > > > > > a version of Kafka that introduces new methods
> > > for
> > > > the
> > > > > > > > Metrics
> > > > > > > > > > > > class,
> > > > > > > > > > > > > > > which
> > > > > > > > > > > > > > > > introduces risks of incompatibility if its
> > > > developer
> > > > > > > > chooses to
> > > > > > > > > > > > take
> > > > > > > > > > > > > > > > advantage of these methods without realizing 
> > > > > > > > > > > > > > > > that
> > > > they
> > > > > > > > will not be
> > > > > > > > > > > > > > > > available on Connect runtimes built against an
> > > > older
> > > > > > > > version of
> > > > > > > > > > > > Kafka.
> > > > > > > > > > > > > > > With
> > > > > > > > > > > > > > > > a wrapper interface, we at least have a chance 
> > > > > > > > > > > > > > > > to
> > > > isolate
> > > > > > > > these
> > > > > > > > > > > > issues so
> > > > > > > > > > > > > > > > that the Metrics class can be expanded without
> > > > adding
> > > > > > > > footguns for
> > > > > > > > > > > > > > > plugins
> > > > > > > > > > > > > > > > that implement Monitorable, and to call out
> > > > potential
> > > > > > > > compatibility
> > > > > > > > > > > > > > > > problems in documentation more clearly if/when 
> > > > > > > > > > > > > > > > we
> > > > do
> > > > > > > > expand the
> > > > > > > > > > > > wrapper
> > > > > > > > > > > > > > > > interface.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > 3. It'd be nice to see a list of exactly which
> > > > plugins
> > > > > > > > will be
> > > > > > > > > > > > able to
> > > > > > > > > > > > > > > take
> > > > > > > > > > > > > > > > advantage of the new Monitorable interface.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Looking forward to your thoughts!
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Cheers,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Chris
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > On Mon, Nov 7, 2022 at 11:42 AM Mickael Maison <
> > > > > > > > > > > > mickael.mai...@gmail.com
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Hi,
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > I have opened KIP-877 to make it easy for
> > > > plugins and
> > > > > > > > connectors
> > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > register their own metrics:
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > >
> > > > > > >
> > > >
> > > https://eu01.z.antigena.com/l/9lWv8kbU9CKs2LajwgfKF~yMNQVM7rWRxYmYVNrHU_2nQbisTiXYZdowNfQ-NcgF1uai2lk-sv6hJASnbdr_gqVwyVae_~y-~oq5yQFgO_-IHD3UGDn3lsIyauAG2tG6giPJH-9yCYg3Hwe26sm7nep258qB6SNXRwpaVxbU3SaVTybfLQVvTn_uUlHKMhmVnpnc1dUnusK6x4j8JPPQQ1Ce~rrg-nsSLouHHMf0ewmpsFNy4BcbMaqHd4Y
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Let me know if you have any feedback or
> > > > suggestions.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > > > > Mickael
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > >
> > > > > > >
> > > >
> > >

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