How to create a distributed lock with Redis?

Question

On the redis documentation, I found a primitive lock can be implemented via SETNX:

http://redis.io/commands/setnx

• C4 sends SETNX lo

Answer 1

Using redis >= 2.6 the LUA script solution would be great. Lua script always executed atomically so:

--lockscript, parameters: lock_key, lock_timeout
local lock = redis.call('get', KEYS[1])
if not lock then    
    return redis.call('setex', KEYS[1], ARGV[1], "locked");
end
return false

The another solution based on new options of SET command

SET lock_key "locked" EX lock_timeout NX 

Using redis < 2.6 the pattern with multi can be used:

MULTI
SETNX tmp_unique_lock some_value
EXPIRE tmp_unique_lock
RENAMENX tmp_unique_lock real_lock
EXEC