function plugin_ctx_new(sess, plug_env, sess_context)
    print("now create new ctx example topic, plugin id", plug_env.id)
    sess_context.count = 0
    sess_context.payload_len = 0
    msg = {}
    msg.data = "this is message"
    session_mq.publish_message(sess, plug_env.topic_id, msg)
end

function plugin_ctx_free(sess, sess_context, plug_env)
    print("now begin to free ctx context example topic")
    print("total packet count is", sess_context.count)
    print("total paylaod length is", sess_context.payload_len)
end

function on_message_fn(sess, topic_id, msg, sess_context, env)
    sess_context.count = sess_context.count + 1
    -- print("topic call on message function, id", topic_id)
    payload, payload_len = session.get_payload(sess)
    sess_context.payload_len = sess_context.payload_len + payload_len
end

function free_message(sess, msg, msg_free_arg)
    print("message need to free is", msg.data)
    print("env id is ", msg_free_arg.id)
end

function plugin_load(stellar, plug_env)
    print("now begin to load plugin example topic")
    print("this example aims to test topic functions")

    plug_env.st = stellar
    plug_env.id = session_plugin.register(stellar, plugin_ctx_new, plugin_ctx_free, plug_env)
    plug_env.data = "this is topic example plug env data"

    --[[ 获取TCP topic, 并完成订阅 ]]
    tcp_topic_id = session_mq.get_topic_id(stellar, "TCP")
    print("get TCP topic id is", tcp_topic_id)
    session_mq.subscribe_topic(stellar, tcp_topic_id, on_message_fn, plug_env.id)
    plug_env.tcp_topic_id = tcp_topic_id

    --[[ 创建TOPIC_SESSION_STAT, 并完成函数注册 ]]
    msg_free_arg = {}
    msg_free_arg.data = "this is example topic msg private data"
    test_topic_id = session_mq.get_topic_id(stellar, "LUA_TOPIC_SESSION_STAT")
    if (test_topic_id < 0)
    then
        --[[ 该消息未创建, 创建该topic ]]
        test_topic_id = session_mq.create_topic(stellar, "LUA_TOPIC_SESSION_STAT", free_message, msg_free_arg)
        print("create topic is", test_topic_id)
    else
        --[[ 如果该消息已经注册, 更新其注册函数 ]]
        session_mq.update_topic(stellar, test_topic_id, free_message, msg_free_arg)
        print("topic already created, id is", test_topic_id)
    end
    plug_env.tcp_topic_id = tcp_topic_id
    plug_env.topic_id = test_topic_id
end

function plugin_unload(plug_env)
    print("now unload lua plugin example topic")
    print("plugin env data is", plug_env.data)
    print("now destory topic id is", plug_env.topic_id)
    session_mq.destory_topic(plug_env.st, plug_env.topic_id)
end