chore: add manifest related metrics (#3634)

* chore: add two manifest related metrics

* Update src/mito2/src/manifest/manager.rs

Co-authored-by: Yingwen <realevenyag@gmail.com>

* Update src/mito2/src/metrics.rs

Co-authored-by: Yingwen <realevenyag@gmail.com>

* fix: resolve PR comments

* update cargo lock

---------

Co-authored-by: Yingwen <realevenyag@gmail.com>

src/mito2/src/manifest/action.rs

@@ -22,13 +22,14 @@ use snafu::{OptionExt, ResultExt};
 use store_api::manifest::ManifestVersion;
 use store_api::metadata::RegionMetadataRef;
 use store_api::storage::{RegionId, SequenceNumber};
+use strum::Display;
 
 use crate::error::{RegionMetadataNotFoundSnafu, Result, SerdeJsonSnafu, Utf8Snafu};
 use crate::sst::file::{FileId, FileMeta};
 use crate::wal::EntryId;
 
 /// Actions that can be applied to region manifest.
-#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq)]
+#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, Display)]
 pub enum RegionMetaAction {
     /// Change region's metadata for request like ALTER
     Change(RegionChange),

src/mito2/src/manifest/manager.rs

@@ -29,6 +29,7 @@ use crate::manifest::action::{
     RegionMetaActionList,
 };
 use crate::manifest::storage::{file_version, is_delta_file, ManifestObjectStore};
+use crate::metrics::MANIFEST_OP_ELAPSED;
 
 /// Options for [RegionManifestManager].
 #[derive(Debug, Clone)]
@@ -141,6 +142,10 @@ impl RegionManifestManager {
 
     /// Update the manifest. Return the current manifest version number.
     pub async fn update(&self, action_list: RegionMetaActionList) -> Result<ManifestVersion> {
+        let _t = MANIFEST_OP_ELAPSED
+            .with_label_values(&["update"])
+            .start_timer();
+
         let mut inner = self.inner.write().await;
         inner.update(action_list).await
     }
@@ -245,6 +250,10 @@ impl RegionManifestManagerInner {
     ///
     /// Returns `Ok(None)` if no such manifest.
     async fn open(options: RegionManifestOptions) -> Result<Option<Self>> {
+        let _t = MANIFEST_OP_ELAPSED
+            .with_label_values(&["open"])
+            .start_timer();
+
         // construct storage
         let mut store = ManifestObjectStore::new(
             &options.manifest_dir,
@@ -395,6 +404,10 @@ impl RegionManifestManagerInner {
 
     /// Makes a new checkpoint. Return the fresh one if there are some actions to compact.
     async fn do_checkpoint(&mut self) -> Result<Option<RegionCheckpoint>> {
+        let _t = MANIFEST_OP_ELAPSED
+            .with_label_values(&["checkpoint"])
+            .start_timer();
+
         let last_checkpoint = Self::last_checkpoint(&mut self.store).await?;
         let current_version = self.last_version;
 

src/mito2/src/metrics.rs

@@ -297,4 +297,14 @@ lazy_static! {
     .unwrap();
 
     // ------- End of partition tree memtable metrics.
+
+
+    // Manifest related metrics:
+
+    /// Elapsed time of manifest operation. Labeled with "op".
+    pub static ref MANIFEST_OP_ELAPSED: HistogramVec = register_histogram_vec!(
+        "greptime_manifest_op_elapsed",
+        "mito manifest operation elapsed",
+        &["op"]
+    ).unwrap();
 }