lib/redlock/scripts.rb
require 'digest'
module Redlock
module Scripts
UNLOCK_SCRIPT = <<-eos
if redis.call("get",KEYS[1]) == ARGV[1] then
return redis.call("del",KEYS[1])
else
return 0
end
eos
# thanks to https://github.com/sbertrang/redis-distlock/blob/master/lib/Redis/DistLock.pm
# also https://github.com/sbertrang/redis-distlock/issues/2 which proposes the value-checking
# and @maltoe for https://github.com/leandromoreira/redlock-rb/pull/20#discussion_r38903633
LOCK_SCRIPT = <<-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
# 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.
UNLOCK_SCRIPT_SHA = Digest::SHA1.hexdigest(UNLOCK_SCRIPT)
LOCK_SCRIPT_SHA = Digest::SHA1.hexdigest(LOCK_SCRIPT)
PTTL_SCRIPT_SHA = Digest::SHA1.hexdigest(PTTL_SCRIPT)
end
end