[GitHub] [skywalking-nginx-lua] wu-sheng commented on a change in pull request #35: Implement correlation protocol

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

wu-sheng commented on a change in pull request #35: Implement correlation protocol
URL: https://github.com/apache/skywalking-nginx-lua/pull/35#discussion_r407284255
 
 

 ##########
 File path: lib/skywalking/correlation_context.lua
 ##########
 @@ -0,0 +1,119 @@
+--
+-- 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('util')
+local Base64 = require('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 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, ':')
+        local key = decode_base64(parts[1])
+        local value = #parts > 1 and decode_base64(parts[2]) or ""
 
 Review comment:
   Reading the `#serialize`, I didn't see it coming.

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