[ENHANCEMENT] Retry API calls

[russcam]

All Elasticsearch clients are intended to retry API calls whose response is a 502, 503 or 504 HTTP status code when there is another node that the client knows about against which the request can be retried. The .NET client documentation summarizes the behaviour well.

Retries should also be implemented for the client, once ConnectionPool implementations that accept multiple urls have been implemented.

@russcam C# guy here, seemed like something good to pick up as I want to expand my Rust skills.

So, if there is only one node running Elasticsearch no retry should be attempted with a 502, 503, or 504?
Has the ConnectionPool implementations that you are speaking of been implemented?

[russcam]

Hi @WingZer0o,

That's correct. The multi node connection pool is in PR #189, which remains to be reviewed.

Since I no longer work at Elastic, I no longer have commit rights to this repository, so am unable to merge PRs. @swallez may be able to advise on the best course of action.

@russcam No worries.

[shenshouer]

Doesn't support multi node connection pool at this crate ?