Add evalLua method in RedisAPI

[liuchong]

Motivation:

Add a convenient method to eval lua script directly, avoid the load-evalsha steps.

Because redis use sha1 to compute script hash, so we can compute it in our client and directly try it wit a evalsha. If failed with a NOSCRIPT error, we can retry with eval and it will cache script, so next time we try evalsha will success.

[liuchong]

Please check when you have time @pmlopes @vietj 👀

[pmlopes]

I'm not sure this is the right way. The client was build with idea of being as close to the protocol as possible so there's just a send and batch to interact, custom APIs should go under the *API wrappers.

The LuaScript probably should be vert.x gen annotated and just have helper method to return a Request instance so you use the current:

redis.send(LuaScript.create("script", args))

To perform hashing it's better to use vertx-auth-common as a single point of codec code:

https://github.com/eclipse-vertx/vertx-auth/blob/master/vertx-auth-common/src/main/java/io/vertx/ext/auth/impl/Codec.java

[pmlopes]

Also the automatic recovery NOSCRIPT is opionated (and not according to the philosophy of the client) it should belong at a different level of abstraction.

[liuchong]

Thanks for the comments, here I have some questions or descriptions:

1. where do you think is better to put these methods?
2. send(Request) is method of Redis and RedisConnection but not RedisAPI
3. class LuaScript is mainly for keep the sha1 hash so we do not need to recreate sha1 for every call of evalLua method
4. NOSCRIPT is beginning string of command EVALSHA, should be ok?
5. seems we did not added vertx-auth-common dep in this project?

Also, if add evalLua for automatic run eval/evalsha, maybe we could also add evalLuaRo for eval_ro/evalsha_ro.

@pmlopes @tsegismont Could you provide some suggestions? Thanks!