Created
January 26, 2015 08:49
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Redis Lua script to clamp a value between a min & max
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-- @desc: Clamp a value between a min & max | |
-- @usage: redis-cli EVAL "$(cat SETCLAMP.lua)" 1 <key> <min> <max> | |
-- @return: clamped value | |
local function SETCLAMP(key, min, max) | |
local valStr = redis.call("GET", key) | |
if not valStr then return end | |
local val = tonumber(valStr) | |
if val > max then | |
redis.call("SET", key, max) | |
val = max | |
elseif val < min then | |
redis.call("SET", key, min) | |
val = min | |
end | |
return val | |
end | |
--[[ @TEST | |
redis.call("SET", "test_max", 9) | |
local clampMax = SETCLAMP("test_max", 5, 7) | |
assert(clampMax == 7) | |
assert(redis.call("GET", "test_max") == "7") | |
redis.call("SET", "test_min", 4) | |
local clampMin = SETCLAMP("test_min", 5, 7) | |
assert(clampMin == 5) | |
assert(redis.call("GET", "test_min") == "5") | |
local clampEmpty = SETCLAMP("test_empty", 0, 10) | |
assert(clampEmpty == nil) | |
redis.call("DEL", "test_min", "test_max") | |
--]] | |
return SETCLAMP(KEYS[1], ARGV[1], ARGV[2]) |
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