fix: flush metric metadata region (GreptimeTeam#4852)

* fix: flush metric metadata region

* chore: apply suggestions from CR

src/metric-engine/src/engine.rs

@@ -17,6 +17,7 @@ mod catchup;
 mod close;
 mod create;
 mod drop;
+mod flush;
 mod open;
 mod options;
 mod put;
@@ -145,7 +146,7 @@ impl RegionEngine for MetricEngine {
                     .alter_region(region_id, alter, &mut extension_return_value)
                     .await
             }
-            RegionRequest::Flush(_) | RegionRequest::Compact(_) => {
+            RegionRequest::Compact(_) => {
                 if self.inner.is_physical_region(region_id) {
                     self.inner
                         .mito
@@ -157,10 +158,11 @@ impl RegionEngine for MetricEngine {
                     UnsupportedRegionRequestSnafu { request }.fail()
                 }
             }
+            RegionRequest::Flush(req) => self.inner.flush_region(region_id, req).await,
             RegionRequest::Delete(_) | RegionRequest::Truncate(_) => {
                 UnsupportedRegionRequestSnafu { request }.fail()
             }
-            RegionRequest::Catchup(ref req) => self.inner.catchup_region(region_id, *req).await,
+            RegionRequest::Catchup(req) => self.inner.catchup_region(region_id, req).await,
         };
 
         result.map_err(BoxedError::new).map(|rows| RegionResponse {

src/metric-engine/src/engine/catchup.rs

@@ -47,9 +47,10 @@ impl MetricEngineInner {
             .await
             .context(MitoCatchupOperationSnafu)?;
 
+        let data_region_id = utils::to_data_region_id(region_id);
         self.mito
             .handle_request(
-                region_id,
+                data_region_id,
                 RegionRequest::Catchup(RegionCatchupRequest {
                     set_writable: req.set_writable,
                     entry_id: req.entry_id,

src/metric-engine/src/engine/flush.rs

@@ -0,0 +1,52 @@
+// 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 snafu::ResultExt;
+use store_api::region_engine::RegionEngine;
+use store_api::region_request::{AffectedRows, RegionFlushRequest, RegionRequest};
+use store_api::storage::RegionId;
+
+use crate::engine::MetricEngineInner;
+use crate::error::{MitoFlushOperationSnafu, Result, UnsupportedRegionRequestSnafu};
+use crate::utils;
+
+impl MetricEngineInner {
+    pub async fn flush_region(
+        &self,
+        region_id: RegionId,
+        req: RegionFlushRequest,
+    ) -> Result<AffectedRows> {
+        if !self.is_physical_region(region_id) {
+            return UnsupportedRegionRequestSnafu {
+                request: RegionRequest::Flush(req),
+            }
+            .fail();
+        }
+
+        let metadata_region_id = utils::to_metadata_region_id(region_id);
+        // Flushes the metadata region as well
+        self.mito
+            .handle_request(metadata_region_id, RegionRequest::Flush(req.clone()))
+            .await
+            .context(MitoFlushOperationSnafu)
+            .map(|response| response.affected_rows)?;
+
+        let data_region_id = utils::to_data_region_id(region_id);
+        self.mito
+            .handle_request(data_region_id, RegionRequest::Flush(req.clone()))
+            .await
+            .context(MitoFlushOperationSnafu)
+            .map(|response| response.affected_rows)
+    }
+}

src/store-api/src/region_request.rs

@@ -639,7 +639,7 @@ impl From<v1::ChangeColumnType> for ChangeColumnType {
     }
 }
 
-#[derive(Debug, Default)]
+#[derive(Debug, Clone, Default)]
 pub struct RegionFlushRequest {
     pub row_group_size: Option<usize>,
 }