feat: define remote table engine trait (#502)

table_engine/src/lib.rs

@@ -10,6 +10,7 @@ pub mod memory;
 pub mod partition;
 pub mod predicate;
 pub mod provider;
+pub mod remote;
 pub mod stream;
 pub mod table;
 

table_engine/src/remote/mock_impl.rs

@@ -0,0 +1,19 @@
+// Copyright 2022 CeresDB Project Authors. Licensed under Apache-2.0.
+
+//! Mock impl for remote table engine
+
+use async_trait::async_trait;
+pub struct MockImpl;
+
+#[async_trait]
+impl RemoteEngine for MockImpl {
+    /// Read from the remote engine
+    async fn read(&self, request: ReadRequest) -> Result<SendableRecordBatchStream> {
+        todo!()
+    }
+
+    /// Write to the remote engine
+    async fn write(&self, request: WriteRequest) -> Result<usize> {
+        todo!()
+    }
+}

table_engine/src/remote/mod.rs

@@ -0,0 +1,27 @@
+// Copyright 2022 CeresDB Project Authors. Licensed under Apache-2.0.
+
+//! Remote table engine
+
+pub mod model;
+
+use async_trait::async_trait;
+use common_util::define_result;
+use model::{ReadRequest, WriteRequest};
+use snafu::Snafu;
+
+use crate::stream::SendableRecordBatchStream;
+
+#[derive(Debug, Snafu)]
+pub enum Error {}
+
+define_result!(Error);
+
+/// Remote table engine interface
+#[async_trait]
+pub trait RemoteEngine {
+    /// Read from the remote engine
+    async fn read(&self, request: ReadRequest) -> Result<SendableRecordBatchStream>;
+
+    /// Write to the remote engine
+    async fn write(&self, request: WriteRequest) -> Result<usize>;
+}

table_engine/src/remote/model.rs

@@ -0,0 +1,24 @@
+// Copyright 2022 CeresDB Project Authors. Licensed under Apache-2.0.
+
+//! Model for remote table engine
+
+use crate::table::{ReadRequest as TableReadRequest, WriteRequest as TableWriteRequest};
+
+#[allow(dead_code)]
+pub struct TableIdentifier {
+    pub catalog: String,
+    pub schema: String,
+    pub table: String,
+}
+
+#[allow(dead_code)]
+pub struct ReadRequest {
+    pub table: TableIdentifier,
+    pub table_request: TableReadRequest,
+}
+
+#[allow(dead_code)]
+pub struct WriteRequest {
+    pub table: TableIdentifier,
+    pub table_request: TableWriteRequest,
+}