-- implement GitHub request rate limiting: -- https://developer.github.com/v3/#rate-limiting local ngx_shared = ngx.shared local setmetatable = setmetatable local assert = assert local _M = { _VERSION = '0.08' } local mt = { __index = _M } local incr_support_init_ttl local ngx_config = ngx.config local ngx_lua_v = ngx.config.ngx_lua_version if not ngx_config or not ngx_lua_v or (ngx_lua_v < 10012) then incr_support_init_ttl = false else incr_support_init_ttl = true end -- the "limit" argument controls number of request allowed in a time window. -- time "window" argument controls the time window in seconds. function _M.new(dict_name, limit, window) local dict = ngx_shared[dict_name] if not dict then return nil, "shared dict not found" end assert(limit > 0 and window > 0) local self = { dict = dict, limit = limit, window = window, } return setmetatable(self, mt) end -- incoming function using incr with init_ttl -- need OpenResty version > v0.10.12rc2 local function incoming_new(self, key, commit) local dict = self.dict local limit = self.limit local window = self.window local remaining, err if commit then remaining, err = dict:incr(key, -1, limit, window) if not remaining then return nil, err end else remaining = (dict:get(key) or limit) - 1 end if remaining < 0 then return nil, "rejected" end return 0, remaining end -- incoming function using incr and expire local function incoming_old(self, key, commit) local dict = self.dict local limit = self.limit local window = self.window local remaining, ok, err if commit then remaining, err = dict:incr(key, -1, limit) if not remaining then return nil, err end if remaining == limit - 1 then ok, err = dict:expire(key, window) if not ok then if err == "not found" then remaining, err = dict:incr(key, -1, limit) if not remaining then return nil, err end ok, err = dict:expire(key, window) if not ok then return nil, err end else return nil, err end end end else remaining = (dict:get(key) or limit) - 1 end if remaining < 0 then return nil, "rejected" end return 0, remaining end _M.incoming = incr_support_init_ttl and incoming_new or incoming_old -- uncommit remaining and return remaining value function _M.uncommit(self, key) assert(key) local dict = self.dict local limit = self.limit local remaining, err = dict:incr(key, 1) if not remaining then if err == "not found" then remaining = limit else return nil, err end end return remaining end return _M SIMPAN PERUBAHAN