Thanks Mike
On Thu, 18 May 2017 at 21:33, Michael André Pearce <
michael.andre.pea...@me.com> wrote:
> Hi Andrew,
>
> There is already a kip discussion exactly around this if you look for KIP
> 141 discuss thread.
>
> Cheers
> Mike
>
> Sent from my iPhone
>
> > On 18 May 2017, at 18:29, Andrew Coates <andy.coa...@apple.com> wrote:
> >
> > Hi all,
> >
> > The `ProducerRecord` type has many optional fields and the list has
> grown over different revisions of Kafka. Kafka supports
> `ProducerInterceptor`s, which often need to construct new
> `ProducerRecord`s, based on those passed in, copying most fields from the
> old to the new record, e.g.:
> >
> > ```java
> > public ProducerRecord<K,V> onSend(ProducerRecord<K,V> record) {
> > return new ProducerRecord<>(record.topic(), record.partition(),
> getSpecificTimestampIWantToSet(), record.key(), record.value())
> > }
> > ```
> >
> > If/when a new field is next added to the `ProducerRecord` all existing
> interceptor implementations will fail to copy across the new field,
> assuming a backwards compatible constructors exist that allow the old code
> to compile, (which the tend to do). This makes the code brittle and leaves
> me with a bad taste in my mouth.
> >
> > Additionally, the set of `ProducerRecord` constructors is multiplying as
> new optional fields are being added and not all combinations are supported,
> though they may be valid.
> >
> > I was wondering what peoples thoughts would be to introducing a builder
> pattern on the producer record? If we did and a pre-initialised builder
> could be obtained from any existing record, then interceptors can just
> set/oeverwrite the fields they care about, without additional fields being
> lost, so the above code becomes:
> >
> > ```java
> > public ProducerRecord<K,V> onSend(ProducerRecord<K,V> record) {
> > return record.asBuilder()
> > .setTimestamp(getSpecificTimestampIWantToSet())
> > .build();
> > }
> > ```
> >
> > This has the benefits of less and more clear interceptor code, and the
> code will pass along new fields, added in a newer version, without
> modification. (Though interceptor authors can still make the choice to use
> a constructor instead, dropping new fields - but now they’d have a choice).
> >
> > If people like this idea then I can create a Jira and a PR. (Would a KIP
> be required also?). If people don’t, I’ll move along quietly…
> >
> > Thanks,
> >
> > Andy
> >
> >
>
