falvaradorodriguez commented on code in PR #12605:
URL: https://github.com/apache/apisix/pull/12605#discussion_r2736393769
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apisix/plugins/limit-req/util.lua:
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@@ -14,61 +14,97 @@
-- See the License for the specific language governing permissions and
-- limitations under the License.
--
-local math = require "math"
-local abs = math.abs
-local max = math.max
local ngx_now = ngx.now
-local ngx_null = ngx.null
local tonumber = tonumber
+local tostring = tostring
+local type = type
+local core = require("apisix.core")
+local resty_string = require("resty.string")
local _M = {version = 0.1}
+local script = core.string.compress_script([=[
+ local state_key = KEYS[1] -- state_key (hash), fields:
"excess", "last"
+ local rate = tonumber(ARGV[1]) -- req/s
+ local now = tonumber(ARGV[2]) -- ms
+ local burst = tonumber(ARGV[3]) -- req/s
+ local commit = tonumber(ARGV[4]) -- 1/0
+
+ local vals = redis.call("HMGET", state_key, "excess", "last")
+ local prev_excess = tonumber(vals[1] or "0")
+ local prev_last = tonumber(vals[2] or "0")
+
+ local new_excess
+ if prev_last > 0 then
+ local elapsed = math.abs(now - prev_last)
+ new_excess = math.max(prev_excess - rate * (elapsed) / 1000 + 1000, 0)
+ else
+ new_excess = 0
+ end
+
+ if new_excess > burst then
+ return {0, new_excess}
+ end
+
+ if commit == 1 then
+ redis.call("HMSET", state_key, "excess", new_excess, "last", now)
+ local ttl = math.ceil(burst / rate) + 1
+ redis.call("EXPIRE", state_key, ttl)
+ end
+
+ return {1, new_excess}
+]=])
+
+-- Pre-calculate SHA1 for EVALSHA optimization
+local script_sha1 = resty_string.to_hex(ngx.sha1_bin(script))
+
+
+local function is_noscript_error(err)
+ if not err then
+ return false
+ end
+
+ local s
+ if type(err) == "table" then
+ s = tostring(err[1] or err.err or err.message or err.msg or err)
+ else
+ s = tostring(err)
+ end
+
+ return s:find("NOSCRIPT", 1, true) ~= nil
+end
+
+
-- the "commit" argument controls whether should we record the event in shm.
function _M.incoming(self, red, key, commit)
local rate = self.rate
local now = ngx_now() * 1000
- key = "limit_req" .. ":" .. key
- local excess_key = key .. "excess"
- local last_key = key .. "last"
+ local state_key = "limit_req:{" .. key .. "}:state"
- local excess, err = red:get(excess_key)
- if err then
- return nil, err
- end
- local last, err = red:get(last_key)
- if err then
- return nil, err
- end
+ local commit_flag = commit and "1" or "0"
- if excess ~= ngx_null and last ~= ngx_null then
- excess = tonumber(excess)
- last = tonumber(last)
- local elapsed = now - last
- excess = max(excess - rate * abs(elapsed) / 1000 + 1000, 0)
+ -- Try EVALSHA first (fast path).
+ local res, err = red:evalsha(script_sha1, 1, state_key,
+ rate, now, self.burst, commit_flag)
- if excess > self.burst then
- return nil, "rejected"
- end
- else
- excess = 0
+ -- If the script isn't cached on this Redis node, fall back to EVAL.
+ if not res and is_noscript_error(err) then
Review Comment:
Makes sense, and it is also good practice to keep the logic of the plugins
aligned. I have tried to replicate the functionality you mention here:
https://github.com/apache/apisix/pull/12605/changes/05657f67151416b4af9bd37937bc3b76e9fa5b27
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