feat/objbench:

### Update Metrics and Command Output

 - **`objbench.rs`**:
   - Renamed "Write time" to "Total time" in output.
   - Enhanced metrics output to include a sum of all metrics.

 - **`access_layer.rs`**:
   - Split `index` duration into `index_update` and `index_finish`.
   - Added a `sum` method to `Metrics` to calculate the total duration.

 - **`writer.rs`**:
   - Updated metrics to use `index_update` and `index_finish` for more granular tracking of index operations.

Signed-off-by: Lei, HUANG <mrsatangel@gmail.com>

src/cmd/src/bin/objbench.rs

@@ -227,10 +227,15 @@ impl Command {
             "Reader build time".bold(),
             reader_build_elapsed
         );
-        println!("  {}: {:?}", "Write time".bold(), write_elapsed);
+        println!("  {}: {:?}", "Total time".bold(), write_elapsed);
 
         // Print metrics in a formatted way
-        println!("  {}: {:?}", "Metrics".bold(), metrics);
+        println!(
+            "  {}: {:?}, sum: {:?}",
+            "Metrics".bold(),
+            metrics,
+            metrics.sum()
+        );
 
         // Cleanup
         println!("\n{}", "Cleaning up...".yellow());

src/mito2/src/access_layer.rs

@@ -48,10 +48,17 @@ pub struct Metrics {
     pub read: Duration,
     pub write: Duration,
     pub convert: Duration,
-    pub index: Duration,
+    pub index_update: Duration,
+    pub index_finish: Duration,
     pub close: Duration,
 }
 
+impl Metrics {
+    pub fn sum(&self) -> Duration {
+        self.read + self.write + self.convert + self.index_update + self.index_finish + self.close
+    }
+}
+
 /// A layer to access SST files under the same directory.
 pub struct AccessLayer {
     region_dir: String,

src/mito2/src/sst/parquet/writer.rs

@@ -174,7 +174,7 @@ where
                     stats.update(&batch);
                     let index_start = Instant::now();
                     self.get_or_create_indexer().await.update(&mut batch).await;
-                    metrics.index += index_start.elapsed();
+                    metrics.index_update += index_start.elapsed();
                 }
                 Err(e) => {
                     self.get_or_create_indexer().await.abort().await;
@@ -183,7 +183,9 @@ where
             }
         }
 
+        let index_finish_start = Instant::now();
         let index_output = self.get_or_create_indexer().await.finish().await;
+        metrics.index_finish += index_finish_start.elapsed();
 
         if stats.num_rows == 0 {
             return Ok(smallvec![]);