Move rate limiter logic to Lua scripts

service/src/main/resources/lua/validate_rate_limit.lua

@@ -0,0 +1,33 @@
+local bucketId = KEYS[1]
+
+local bucketSize = tonumber(ARGV[1])
+local leakRatePerMillis = tonumber(ARGV[2])
+local currentTimeMillis = tonumber(ARGV[3])
+local amount = tonumber(ARGV[4])
+
+local leakyBucket
+
+if redis.call("EXISTS", bucketId) == 1 then
+    leakyBucket = cjson.decode(redis.call("GET", bucketId))
+else
+    leakyBucket = {
+        bucketSize = bucketSize,
+        leakRatePerMillis = leakRatePerMillis,
+        spaceRemaining = bucketSize,
+        lastUpdateTimeMillis = currentTimeMillis
+    }
+end
+
+local elapsedTime = currentTimeMillis - leakyBucket["lastUpdateTimeMillis"]
+local updatedSpaceRemaining = math.min(leakyBucket["bucketSize"], math.floor(leakyBucket["spaceRemaining"] + (elapsedTime * leakyBucket["leakRatePerMillis"])))
+
+redis.call("SET", "elapsedTime", elapsedTime)
+redis.call("SET", "updatedSpaceRemaining", updatedSpaceRemaining)
+
+if updatedSpaceRemaining >= amount then
+    leakyBucket["spaceRemaining"] = updatedSpaceRemaining - amount
+    redis.call("SET", bucketId, cjson.encode(leakyBucket))
+    return true
+else
+    return false
+end