Module: Redlock::Scripts

Included in:

Redlock

Defined in:

lib/redlock/scripts.rb

Constant Summary

UNLOCK_SCRIPT =

<<-eos
  if redis.call("get",KEYS[1]) == ARGV[1] then
    return redis.call("del",KEYS[1])
  else
    return 0
  end
eos

LOCK_SCRIPT =

thanks to github.com/sbertrang/redis-distlock/blob/master/lib/Redis/DistLock.pm also github.com/sbertrang/redis-distlock/issues/2 which proposes the value-checking and @maltoe for github.com/leandromoreira/redlock-rb/pull/20#discussion_r38903633

<<-eos
  if (redis.call("exists", KEYS[1]) == 0 and ARGV[3] == "yes") or redis.call("get", KEYS[1]) == ARGV[1] then
    return redis.call("set", KEYS[1], ARGV[1], "PX", ARGV[2])
  end
eos

PTTL_SCRIPT =

<<-eos
  return { redis.call("get", KEYS[1]), redis.call("pttl", KEYS[1]) }
eos

UNLOCK_SCRIPT_SHA =

We do not want to load the scripts on every Redlock::Client initialization. Hence, we rely on Redis handing out SHA1 hashes of the cached scripts and pre-calculate them instead of loading the scripts unconditionally. If the scripts have not been cached on Redis, ‘recover_from_script_flush` has our backs.

Digest::SHA1.hexdigest(UNLOCK_SCRIPT)

LOCK_SCRIPT_SHA =

Digest::SHA1.hexdigest(LOCK_SCRIPT)

PTTL_SCRIPT_SHA =

Digest::SHA1.hexdigest(PTTL_SCRIPT)