[GitHub] [apisix] nic-chen commented on a change in pull request #2406: feature: plugin `limit-count` support to use `redis` cluster

[GitBox <gi...@apache.org>]

nic-chen commented on a change in pull request #2406:
URL: https://github.com/apache/apisix/pull/2406#discussion_r504348516



##########
File path: apisix/plugins/limit-count/limit-count-redis-cluster.lua
##########
@@ -0,0 +1,134 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+
+local rediscluster = require("resty.rediscluster")
+local core = require("apisix.core")
+local resty_lock = require("resty.lock")
+local setmetatable = setmetatable
+local tostring = tostring
+local ipairs = ipairs
+
+local _M = {}
+
+
+local mt = {
+    __index = _M
+}
+
+
+local function new_redis_cluster(conf)
+    local config = {
+        name = "apisix-redis-cluster",
+        serv_list = {},
+        read_timeout = conf.redis_timeout,
+        auth = conf.redis_password,
+        dict_name = "plugin-limit-count-redis-cluster-slot-lock",
+    }
+
+    for i, conf_item in ipairs(conf.redis_cluster_nodes) do
+        local host, port, err = core.utils.parse_addr(conf_item)
+        if err then
+            return nil, "failed to parse address: " .. conf_item
+                        .. " err: " .. err
+        end
+
+        config.serv_list[i] = {ip = host, port = port}
+    end
+
+    local red_cli, err = rediscluster:new(config)
+    if not red_cli then
+        return nil, "failed to new redis cluster: " .. err
+    end
+
+    return red_cli
+end
+
+
+function _M.new(plugin_name, limit, window, conf)
+    local red_cli, err = new_redis_cluster(conf)
+    if not red_cli then
+        return nil, err
+    end
+
+    local self = {
+        limit = limit, window = window, conf = conf,
+        plugin_name = plugin_name, red_cli =red_cli
+    }
+
+    return setmetatable(self, mt)
+end
+
+
+function _M.incoming(self, key)
+    local red = self.red_cli
+    local limit = self.limit
+    local window = self.window
+    local remaining
+    key = self.plugin_name .. tostring(key)
+
+    local ret, err = red:ttl(key)
+    if not ret then
+        return false, "failed to get redis `" .. key .."` ttl: " .. err
+    end
+
+    core.log.info("ttl key: ", key, " ret: ", ret, " err: ", err)
+    if ret < 0 then
+        local lock, err = resty_lock:new("plugin-limit-count")
+        if not lock then
+            return false, "failed to create lock: " .. err
+        end
+
+        local elapsed, err = lock:lock(key)
+        if not elapsed then
+            return false, "failed to acquire the lock: " .. err
+        end
+
+        ret = red:ttl(key)

Review comment:
       why read ttl twice ? a little confuse




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