chore(disk-cache): remove unnecessary doc comment on random_value

disk_cache.rs

@@ -26,7 +26,6 @@ const CACHE_DIR_RELATIVE: &str = "+gitks-cache/cache";
 /// Info-refs cache directory relative path under repo prefix.
 const INFO_REFS_DIR_RELATIVE: &str = "+gitks-cache/info_refs";
 
-/// Generate a random value for the `latest` file.
 fn random_value() -> String {
     use std::fmt::Write;
     use std::sync::atomic::{AtomicU64, Ordering};
@@ -270,8 +269,10 @@ impl DiskCache {
         if !self.enabled {
             return Ok(None);
         }
+        let start = std::time::Instant::now();
         let path = self.cache_file_path(namespace, digest);
         if !path.exists() {
+            crate::metrics::record_cache_op("disk", "miss", start.elapsed());
             return Ok(None);
         }
         if let Ok(metadata) = std::fs::metadata(&path)
@@ -288,6 +289,7 @@ impl DiskCache {
             if let Some(parent) = path.parent() {
                 std::fs::remove_dir(parent).ok();
             }
+            crate::metrics::record_cache_op("disk", "expired", start.elapsed());
             return Ok(None);
         }
         let data = std::fs::read(&path).map_err(GitError::Io)?;
@@ -295,8 +297,10 @@ impl DiskCache {
             namespace = %namespace,
             digest = %digest,
             size = data.len(),
+            elapsed_ms = start.elapsed().as_millis() as u64,
             "cache hit"
         );
+        crate::metrics::record_cache_op("disk", "hit", start.elapsed());
         Ok(Some(data))
     }
 
@@ -305,6 +309,7 @@ impl DiskCache {
         if !self.enabled {
             return Ok(());
         }
+        let start = std::time::Instant::now();
         let path = self.cache_file_path(namespace, digest);
         if let Some(parent) = path.parent() {
             std::fs::create_dir_all(parent).map_err(GitError::Io)?;
@@ -316,8 +321,10 @@ impl DiskCache {
             namespace = %namespace,
             digest = %digest,
             size = data.len(),
+            elapsed_ms = start.elapsed().as_millis() as u64,
             "cache entry written"
         );
+        crate::metrics::record_cache_op("disk", "write", start.elapsed());
         Ok(())
     }