Redis cluster refactoring

[hofrob]

Q	A
Is bugfix?	yes
New feature?	yes
Breaks BC?	no
Tests pass?	yes
Fixed issues	#147 #143 #142 #136 #135 #134 #66

[hofrob]

Connections to redis are now pooled, to enable redirects without opening and closing connections during a request.

If redis is running in cluster mode, it is possible to supply a hashtag for MGET and MSET operations. If there are now hashtags, it falls back to GET and SET.

To test this locally I used a ready-to-use docker cluster container:

docker run --network=some_local_network --network-alias=redis-cluster grokzen/redis-cluster:redis_version

Put a PHP container with Yii in the same network (some_local_network), select a redis version (redis_version), and try the example.

[hofrob]

I should implement some tests for this change. Probably by using the aforementioned docker container. But to be honest, I have no idea where to start. If someone could point me in the right direction, I'd be happy to get started.

[hofrob]

@cebe

This PR would fix the problem you mentioned here: #147 (comment)

[cebe]

Thanks for your work on this. I am planning to use a redis cluster in the near future and will review this PR when I get to that.

[hofrob]

I can give you an update from what we're using now. Turns out this solution works, but somehow it was the slowest of all the solutions we tried (our production env runs on AWS EB with extensive use of redis ElastiCache). Our requests were just about 10-15% slower than before. But it was noticeable.

And yes, weirdly enough opening and closing the connections after redirects was faster. But I did not do any more research on that because....

We then tried the redis pecl extension. It supports cluster mode completely and we're now at about the same request duration we were before.

To be able to use the pecl extension with \yii\caching\Cache I just had to write a very simple wrapper (about 80 lines). The only thing left for us to completely switch to this extension is rewriting the yii2-queue. It's unfortunate that the method names are written differently.

• hdel vs hDel
• lpush vs lPush
• zadd vs zAdd

So I've not yet tackled this. I think it would be great if you could switch from yii2-redis to the pecl extension without having to change something in yii2-queue. If you or the yii devs in general are interested in implementing this, maybe I can help.

[samdark]

That is interesting, especially for 3.0.

[samdark]

@cebe did you have a chance to use Redis cluster?

[pacifier17]

@samdark do you think we can get this merged soon? We are looking to use cluster Redis for our use case. We did test out the fork and it works with cluster redis config.

[samdark]

Overall it looks OK. Some minor adjustments and changelog line are needed.

[samdark]

Unit tests would be awesome as well.

[samdark]

@hofrob would you please apply suggestions?

[hofrob]

changelog line are needed.

Since this is a really old branch, is there a preferred way how to update it? I'd just rebase it (and then add the changelog).

[samdark]

Either merging master into it or rebasing.

[hofrob]

Unit tests would be awesome as well.

After a quick look at the sources I'm not really sure how to configure/start/use a redis cluster for tests.

[samdark]

Merged. Thank you very much!

[pacifier17]

Thanks a lot @samdark and @hofrob for merging these changes in so quickly. I really appreciate it.

[samdark]

Not so quickly. Look how much time it took me to get to it and review/merge it :) @hofrob sorry for that btw.