| -- |
| -- 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. |
| -- |
| |
| -- limit define |
| local ELEMENT_MAX_NUMBER = 3 |
| local VALUE_MAX_LENGTH = 128 |
| |
| local Util = require('skywalking.util') |
| local Base64 = require('skywalking.dependencies.base64') |
| local encode_base64 = Base64.encode |
| local decode_base64 = Base64.decode |
| |
| if Util.is_ngx_lua then |
| encode_base64 = ngx.encode_base64 |
| decode_base64 = ngx.decode_base64 |
| end |
| |
| local _M = {} |
| |
| function _M.new() |
| return {} |
| end |
| |
| -- Deserialze value from the correlation context and initalize the context |
| function _M.fromSW8Value(value) |
| local context = _M.new() |
| |
| if value == nil or #value == 0 then |
| return context |
| end |
| |
| local data = Util.split(value, ',') |
| if #data == 0 then |
| return context |
| end |
| |
| for i, per_data in ipairs(data) |
| do |
| if #data > ELEMENT_MAX_NUMBER then |
| return context |
| end |
| |
| local parts = Util.split(per_data, ':') |
| if #parts == 2 then |
| local key = decode_base64(parts[1]) |
| local value = decode_base64(parts[2]) |
| |
| context[key] = value |
| end |
| end |
| |
| return context |
| end |
| |
| -- Return string to represent this correlation context |
| function _M.serialize(context) |
| local encoded = '' |
| for name, value in pairs(context) do |
| if #encoded > 0 then |
| encoded = encoded .. ',' |
| end |
| |
| encoded = encoded .. encode_base64(name) .. ':' .. encode_base64(value) |
| end |
| |
| return encoded |
| end |
| |
| -- Put the custom key/value into correlation context. |
| function _M.put(context, key, value) |
| -- key must not null |
| if not key then |
| return |
| end |
| |
| -- remove and return previous value when value is empty |
| if not value or #value == 0 then |
| context[key] = nil |
| return |
| end |
| |
| -- check value length |
| if #value > VALUE_MAX_LENGTH then |
| return |
| end |
| |
| -- already contain key, overwrite it |
| if context[key] then |
| context[key] = value |
| return |
| end |
| |
| |
| -- check keys count |
| local contextLength = 0 |
| for k,v in pairs(context) do |
| contextLength = contextLength + 1 |
| end |
| if contextLength >= ELEMENT_MAX_NUMBER then |
| return |
| end |
| |
| -- setting |
| context[key] = value |
| end |
| |
| return _M |