Update taurus doc

taurus/README.md

@@ -1,2 +1,21 @@
 # Message Queue Module
+
+## Intro
 This module offers mega the ability to send and handle specific events.
+
+After sending the event you created into a global message queue, it will be received in a handler thread and run the callback function defined in trait `EventBase`.
+
+The events would also be asynchronously flush into database for further investigation.
+
+## New Customized Event
+
+If you want to make a new event type and use it in other modules, you should do as follows.
+
+- Create a event struct which implements trait `EventBase`.
+- Give your new event a way to enqueue itself into the message queue.
+- Add a enum variation in `EventType` which is defined in `src/event/mod.rs`.
+- Fill the missing match arms in `src/event/mod.rs` and `src/queue.rs`.
+- Import and use it.
+
+> Tips:
+> Check `src/event/api_request.rs` for a brief example.

taurus/src/event/api_request.rs

@@ -5,13 +5,13 @@ use async_trait::async_trait;
 use crate::{event::EventBase, event::EventType, queue::get_mq};
 
 /// # Api Request Event
-/// ---
-/// This is a example event definition for using message queue.     \
 ///
-/// Your customized event should implement `EventBase` trait.       \
-/// Then the event can be wrapped and put into message queue.       \
-/// The message `id` and `create_time` will be attached to your event
-/// and then wrapped as a `Message`.                                \
+/// This is a example event definition for using message queue.
+///
+/// Your customized event should implement `EventBase` trait.
+/// Then the event can be wrapped and put into message queue.
+/// The message `id` and `create_time` will be attached to your
+/// event and then wrapped as a `Message`.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ApiRequestEvent {
     pub api: ApiType,