chore: Setup code skeleton of datanode

src/datanode/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+snafu = "0.7"

src/datanode/src/catalog.rs

@@ -0,0 +1 @@
+

src/datanode/src/error.rs

@@ -0,0 +1,8 @@
+use snafu::Snafu;
+
+/// business error of datanode.
+#[derive(Debug, Snafu)]
+#[snafu(display("DataNode error"))]
+pub struct Error;
+
+pub type Result<T> = std::result::Result<T, Error>;

src/datanode/src/lib.rs

@@ -1 +1,21 @@
+mod catalog;
+mod error;
+mod processors;
+mod rpc;
 
+use crate::error::Result;
+use crate::rpc::Services;
+
+/// DataNode service.
+pub struct DataNode {
+    services: Services,
+}
+
+impl DataNode {
+    /// Shutdown the datanode service gracefully.
+    pub async fn shutdown(&self) -> Result<()> {
+        self.services.shutdown().await?;
+
+        unimplemented!()
+    }
+}

src/datanode/src/processors.rs

@@ -0,0 +1 @@
+

src/datanode/src/rpc.rs

@@ -0,0 +1,10 @@
+use crate::error::Result;
+
+/// All rpc services.
+pub struct Services {}
+
+impl Services {
+    pub async fn shutdown(&self) -> Result<()> {
+        unimplemented!()
+    }
+}