Add connector name tag for JettyConnectionMetrics and JettySslHandshakeMetricsBinder

[izeye]

This PR adds connector name tag for JettyConnectionMetrics.

See spring-projects/spring-boot#26418 (comment)

/cc @wilkinsona

[shakuzen]

I'm generally in favor of this change, but it makes an asymmetry between the outcome of the two ways the JettyConnectionMetrics can be applied. If you do connector.addBean(new JettyConnectionMetrics(registry)) then the connector.name tag won't be there. Since we don't have a reference to the Connector, we can't do much about that given the current API. I wonder if we shouldn't move the API in the direction of passing the Connector to the constructor so we can add the connector.name tag in either case.

[wilkinsona]

I also wonder if it should be possible not to use the connector’s name as a tag? In the

[izeye]

@wilkinsona I'm not sure if I fully understand your comment. Do you mean a flag to control addition of the tag for connector's name? Maybe, you might mean to provide more context in the following incomplete sentence that seems to have been removed accidentally.

[wilkinsona]

Oops. Sorry, not sure how I managed that. I intended to say the following:

In the single connector case, if things change as suggested above by @shakuzen, that could be done by only setting the name tag if the user just passes in the Connector. If they call a Connector, Iterable<Tag> method then the default name tag could perhaps be skipped. That doesn't work so well for the multi-connector case as there's no way to provide connector-specific tags. Maybe that doesn't matter so much and the user could just call the new single connector method multiple times?

[izeye]

@wilkinsona Thanks for clarification! I can see how it could work, but I'm not sure if it's natural to use them as a signal for adding the tag. Maybe, I might miss something.

[izeye]

I updated this PR to try to apply the suggestion from @shakuzen. I didn't deprecate the previous constructors as they provide a way not to use the connector's name as a tag. I wasn't able to apply the suggestion from @wilkinsona as I don't think I fully understand it.

Let me know what you think.

If it's okay, I'll update this PR to apply the same changes to JettySslHandshakeMetricsBinder as well.

See spring-projects/spring-boot#26418 (comment)

[wilkinsona]

Sorry for the confusion, @izeye. Please ignore my suggested way of achieving the goal. It's really just the goal itself that's important and that is for a user to be able to register metrics for a Connector without the connector.name tag being added automatically. If this isn't a pattern that's followed elsewhere in Micrometer then please disregard this. I'd rather that the connector.name tag was always added than it never was.

[izeye]

@wilkinsona Thanks for the feedback!

I updated this PR to apply the same changes to JettySslHandshakeMetricsBinder.

Please let me know if anything else needs to be done.

[wilkinsona]

Looks good to me, @izeye.

[shakuzen]

Looks good to me.