configurable topology refresh duration

[rishabharyal]

This pull requests a configurable way to topology refresh duration. Two files session.rs and cluster.rs have been modified to set the session configuration and consume the duration configuration respectively.

Note: I am not sure if we need any test cases in this case as the duration is still provided from where its called.

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.

Fixes: #232

[piodul]

To be precise, the parameter that you introduced affects how frequently the whole cluster metadata is refreshed. Cluster metadata not only contains information about the cluster topology, but also information about the cluster schema. The issue #232 was created long ago, when the only metadata that the driver used to fetch in ClusterWorker::perform_refresh() was indeed cluster topology, but it has changed since.

I think the current behavior of the parameter is fine and it can control fetching of the whole metadata, but the names used in the code and in the documentation should be adjusted.

Apart from that and some other small comments - looks good.

[piodul]

Note: I am not sure if we need any test cases in this case as the duration is still provided from where its called.

I don't have a good idea on how to write a good test for this. Usually, a SessionBuilder test + a manual test to see whether the parameter is properly propagated is sufficient for us.

[rishabharyal]

Hi @piodul, are any further changes needed? Let me know in case you missed this.

[wprzytula]

There are a number of places with names still containing "topology refresh" instead of "metadata refresh". Please fix them.

[wprzytula]

Thanks, LGTM.
Whoever maintainer is going to merge this, I highly recommend squash&merge.

[piodul]

Hi @piodul, are any further changes needed? Let me know in case you missed this.

@rishabharyal Sorry, I was out on vacation for the last two weeks.

[piodul]

LGTM, and thanks for the contribution!