allow more redis connection options

[metachris]

📝 Summary

Inspired by https://github.com/bloXroute-Labs/mev-relay/blob/develop/datastore/redis.go

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✅ I have run these commands

• make lint
• make test-race
• go mod tidy
• I have seen and agree to CONTRIBUTING.md

[codecov-commenter]

Codecov Report

Merging #419 (7aae7f4) into main (eec12f7) will decrease coverage by 0.14%.
The diff coverage is 18.75%.

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@@            Coverage Diff             @@
##             main     #419      +/-   ##
==========================================
- Coverage   30.77%   30.63%   -0.14%     
==========================================
  Files          24       24              
  Lines        4569     4579      +10     
==========================================
- Hits         1406     1403       -3     
- Misses       2987     2996       +9     
- Partials      176      180       +4     

Flag	Coverage Δ
unittests	30.63% <18.75%> (-0.14%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
datastore/redis.go	61.90% <18.75%> (-2.37%)	⬇️

[benhenryhunter]

You might want to add some more information about this value. If the PoolSize value is high and the redis service is shared across multiple instances you could end up maxing out the available connections on redis and see random connection errors.

Results from a quick google, but probably better resources out there to explain this:

Redis nodes can have up to either 10,000 simultaneous connections or 4 simultaneous connections per megabyte of memory, whichever is larger.

[metachris]

Good idea. What I could find was

In Redis 2.6 and newer, this limit is dynamic: by default it is set to 10000 clients, unless otherwise stated by the maxclients directive in redis.conf.

However, Redis checks with the kernel what the maximum number of file descriptors that we are able to open is (the soft limit is checked). If the limit is less than the maximum number of clients we want to handle, plus 32 (that is the number of file descriptors Redis reserves for internal uses), then the maximum number of clients is updated to match the number of clients it is really able to handle under the current operating system limit.

https://redis.io/docs/reference/clients/

[metachris]

maybe it would be better to configure poolSize and minIdleConnections separately 🤔