Ruby<->Redisson Interop Investigation

This document describes the differences between the implementations of Redisson's Lock mechanisms, and a redlock implementation in Ruby. The objective is to find a common ground so that two heterogenous applications can share the same redis-lock mechanism.

Standard Redlock documentation algorythm https://redis.io/docs/reference/patterns/distributed-locks/

(Ruby) Redlock-rb format (Redlock)

Command Impl: https://github.com/leandromoreira/redlock-rb/blob/main/lib/redlock/scripts.rb

• Simple, if-exists lock.
• Returns true if thread already has a lock.
• Unlocks by deleting key.
• Driver long-polls for key to be deleted in order to acquire new lock.

GET lock_key1 => "8aa49485-fa83-4a0e-ade6-e5c6f77d291d"
TYPE lock_key1 => string

(Java) Redisson-format (RedissonLock)

Command Impl: https://github.com/redisson/redisson/blob/master/redisson/src/main/java/org/redisson/RedissonLock.java

• Complex, reentrant lock.
  • If thread acquires new lock, a lock counter is incremented.
• Watchdog to extend lock TTL to avoid hang locks.
  • If thread crashes, TTL is not extended, lock is released.
• Relies on Redis PubSub for lock release notification.

GET lock_key2 => (error) WRONGTYPE Operation against a key holding the wrong kind of value
TYPE lock_key2 => hash
HGETALL lock_key2 =>
    "a13acce4-72d7-4ab6-9d8c-4b7f8fd39b35:1"
    "1"