add redis implement of datasource

[tigerMoon]

Describe what this PR does / why we need it

Add Redis implementation of Datasource

Does this pull request fix one issue?

Resolves #37

Describe how you did it

Use Lettuce Redis client and Redis pub/sub feature.

Describe how to verify it

Run the test cases.

Special notes for reviews

no

[codecov-io]

Codecov Report

Merging #102 into master will increase coverage by 0.5%.
The diff coverage is 54.06%.

@@             Coverage Diff             @@
##             master     #102     +/-   ##
===========================================
+ Coverage     45.74%   46.24%   +0.5%     
- Complexity      556      589     +33     
===========================================
  Files           114      118      +4     
  Lines          3817     4063    +246     
  Branches        531      559     +28     
===========================================
+ Hits           1746     1879    +133     
- Misses         1857     1950     +93     
- Partials        214      234     +20

Impacted Files	Coverage Δ	Complexity Δ
...csp/sentinel/datasource/redis/util/AssertUtil.java	33.33% <33.33%> (ø)	4 <4> (?)
...inel/datasource/redis/config/RedisHostAndPort.java	33.33% <33.33%> (ø)	6 <6> (?)
...csp/sentinel/datasource/redis/RedisDataSource.java	56.92% <56.92%> (ø)	6 <6> (?)
...datasource/redis/config/RedisConnectionConfig.java	58.45% <58.45%> (ø)	17 <17> (?)

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[sczyh30]

Here the constructor should not directly accept a RedisClient as users don't have to know the internal client here. Users can provide host and port, then we create the client internal. So even if we changed the Redis client library, users don't have to care about that.

The constructor can be like this:

public RedisDataSource(String host, int port, String ruleKey, String channel, ConfigParser<String, T> parser)

[tigerMoon]

yes. it should be decoupled. but when build RedisClient with lettuce. it has different mode to build like this:

Standalone mode build:

RedisURI masterUri = RedisURI.Builder.redis("master-host", 6379).build();

Sentinel mode build:

RedisURI sentinelUri = RedisURI.Builder.sentinel("sentinel-host", 26379, "master-name").build();

case i build a own constructor to compatible to all:

MyRedisURI{host,port,password,RedisConnectionType,ClientResources}

[sczyh30]

That's okay, you can implement a universal RedisConfig class including these attributes, then users can pass a RedisConfig to the constructor.

[sczyh30]

You can add a log here like this:

RecordLog.info(String.format("[RedisDataSource] New property value received for (%s:%d, %s): %s", host, port, channel, message));

[sczyh30]

Also add license header here.

[sczyh30]

The method name should follow camel-case naming style like: testPubMessageAndReceiveSuccess.

[sczyh30]

Using pub-sub feature is a good idea, but for consistency users should publish the value and save the value to the ruleKey simultaneously like this (using Redis transaction):

MULTI
PUBLISH channel value
SET ruleKey value
EXEC

We cannot ensure users will do that, but it's better to mention it in the document, and provide a helper publisher to do that.

[sczyh30]

Hi, any progress on this?

[tigerMoon]

yes. I will finish it at this weekend.

[tigerMoon]

Hi, any progress on this?

I'm done

[sczyh30]

Nice! It may take some time to review the code. I'll do the review these days.

[sczyh30]

Hi, please re-sign the CLA as there may be some update on it.

[sczyh30]

It's better to rename sentinel to redisSentinel as our project's name is also Sentinel, so the name of the method may be confusing.

[sczyh30]

Thanks for your contribution! I'll rearrange some code later.