feat: add DatanodeManager trait

src/common/meta/src/flownode_manager.rs

@@ -0,0 +1,37 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed 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.
+
+use std::sync::Arc;
+
+use api::v1::flow::{FlowRequest, FlowResponse};
+
+use crate::error::Result;
+use crate::peer::Peer;
+
+/// The trait fo handling requests to flownode
+#[async_trait::async_trait]
+pub trait Flownode: Send + Sync {
+    async fn handle(&self, request: FlowRequest) -> Result<FlowResponse>;
+}
+
+pub type FlownodeRef = Arc<dyn Flownode>;
+
+/// Flownode manager
+#[async_trait::async_trait]
+pub trait FlownodeManager: Send + Sync {
+    /// Retrieves a target `flownode`.
+    async fn flownode(&self, datanode: &Peer) -> FlownodeRef;
+}
+
+pub type FlownodeManagerRef = Arc<dyn FlownodeManager>;

src/common/meta/src/lib.rs

@@ -25,6 +25,7 @@ pub mod ddl;
 pub mod ddl_manager;
 pub mod distributed_time_constants;
 pub mod error;
+pub mod flownode_manager;
 pub mod heartbeat;
 pub mod instruction;
 pub mod key;