feat: add metrics for region server (#2552)

* feat: add metircs for region server

* fix: add comment and remove unused code

src/datanode/src/metrics.rs

@@ -14,5 +14,7 @@
 
 //! datanode metrics
 
-pub const HANDLE_SQL_ELAPSED: &str = "datanode.handle_sql_elapsed";
-pub const HANDLE_PROMQL_ELAPSED: &str = "datanode.handle_promql_elapsed";
+/// The elapsed time of handling a request in the region_server.
+pub const HANDLE_REGION_REQUEST_ELAPSED: &str = "datanode.handle_region_request_elapsed";
+/// Region request type label.
+pub const REGION_REQUEST_TYPE: &str = "datanode.region_request_type";

src/datanode/src/region_server.rs

@@ -28,7 +28,7 @@ use common_query::physical_plan::DfPhysicalPlanAdapter;
 use common_query::{DfPhysicalPlan, Output};
 use common_recordbatch::SendableRecordBatchStream;
 use common_runtime::Runtime;
-use common_telemetry::{info, warn};
+use common_telemetry::{info, timer, warn};
 use dashmap::DashMap;
 use datafusion::catalog::schema::SchemaProvider;
 use datafusion::catalog::{CatalogList, CatalogProvider};
@@ -227,7 +227,11 @@ impl RegionServerInner {
         region_id: RegionId,
         request: RegionRequest,
     ) -> Result<Output> {
-        // TODO(ruihang): add some metrics
+        let request_type = request.request_type();
+        let _timer = timer!(
+            crate::metrics::HANDLE_REGION_REQUEST_ELAPSED,
+            &[(crate::metrics::REGION_REQUEST_TYPE, request_type),]
+        );
 
         let region_change = match &request {
             RegionRequest::Create(create) => RegionChange::Register(create.engine.clone()),

src/store-api/src/region_request.rs

@@ -43,6 +43,23 @@ pub enum RegionRequest {
 }
 
 impl RegionRequest {
+    /// Returns the type name of the [RegionRequest].
+    #[inline]
+    pub fn request_type(&self) -> &'static str {
+        match &self {
+            RegionRequest::Put(_) => "put",
+            RegionRequest::Delete(_) => "delete",
+            RegionRequest::Create(_) => "create",
+            RegionRequest::Drop(_) => "drop",
+            RegionRequest::Open(_) => "open",
+            RegionRequest::Close(_) => "close",
+            RegionRequest::Alter(_) => "alter",
+            RegionRequest::Flush(_) => "flush",
+            RegionRequest::Compact(_) => "compact",
+            RegionRequest::Truncate(_) => "truncate",
+        }
+    }
+
     /// Convert [Body](region_request::Body) to a group of [RegionRequest] with region id.
     /// Inserts/Deletes request might become multiple requests. Others are one-to-one.
     pub fn try_from_request_body(body: region_request::Body) -> Result<Vec<(RegionId, Self)>> {