refactor: expose space_amp directly

src/lib.rs

@@ -62,7 +62,7 @@
 //! value_log.register_writer(writer)?;
 //!
 //! // Get some stats
-//! assert_eq!(1.0, value_log.manifest.space_amp());
+//! assert_eq!(1.0, value_log.space_amp());
 //! #
 //! # Ok(())
 //! # }

src/value_log.rs

@@ -248,7 +248,7 @@ impl ValueLog {
     /// merge to reach a certain space amplification.
     #[must_use]
     pub fn select_segments_for_space_amp_reduction(&self, space_amp_target: f32) -> Vec<SegmentId> {
-        let current_space_amp = self.manifest.space_amp();
+        let current_space_amp = self.space_amp();
 
         if current_space_amp < space_amp_target {
             log::trace!("Space amp is <= target {space_amp_target}, nothing to do");
@@ -348,6 +348,14 @@ impl ValueLog {
         }
     }
 
+    /// Returns the approximate space amplification
+    ///
+    /// Returns 0.0 if there are no items.
+    #[must_use]
+    pub fn space_amp(&self) -> f32 {
+        self.manifest.space_amp()
+    }
+
     /// Scans the given index and collecting GC statistics.
     ///
     /// # Errors
@@ -441,7 +449,7 @@ impl ValueLog {
 
         log::info!("Total bytes: {}", self.manifest.total_bytes());
         log::info!("Stale bytes: {}", self.manifest.stale_bytes());
-        log::info!("Space amp: {}", self.manifest.space_amp());
+        log::info!("Space amp: {}", self.space_amp());
         log::info!("--- GC report done ---");
 
         Ok(())

tests/gc_space_amp.rs

@@ -10,7 +10,7 @@ fn gc_space_amp_target_1() -> value_log::Result<()> {
 
     let value_log = ValueLog::open(vl_path, Config::default())?;
 
-    assert_eq!(0.0, value_log.manifest.space_amp());
+    assert_eq!(0.0, value_log.space_amp());
     assert_eq!(0.0, value_log.manifest.stale_ratio());
 
     let key = "key";
@@ -36,7 +36,7 @@ fn gc_space_amp_target_1() -> value_log::Result<()> {
 
     value_log.scan_for_stats(index.read().unwrap().values().cloned().map(Ok))?;
 
-    assert!(value_log.manifest.space_amp() > 2.0);
+    assert!(value_log.space_amp() > 2.0);
 
     {
         let target_space_amp = 8.0;
@@ -46,7 +46,7 @@ fn gc_space_amp_target_1() -> value_log::Result<()> {
         value_log.drop_stale_segments()?;
 
         value_log.scan_for_stats(index.read().unwrap().values().cloned().map(Ok))?;
-        assert!(value_log.manifest.space_amp() <= target_space_amp);
+        assert!(value_log.space_amp() <= target_space_amp);
     }
 
     {
@@ -57,7 +57,7 @@ fn gc_space_amp_target_1() -> value_log::Result<()> {
         value_log.drop_stale_segments()?;
 
         value_log.scan_for_stats(index.read().unwrap().values().cloned().map(Ok))?;
-        assert!(value_log.manifest.space_amp() <= target_space_amp);
+        assert!(value_log.space_amp() <= target_space_amp);
     }
 
     Ok(())

tests/space_amp.rs

@@ -10,7 +10,7 @@ fn worst_case_space_amp() -> value_log::Result<()> {
 
     let value_log = ValueLog::open(vl_path, Config::default())?;
 
-    assert_eq!(0.0, value_log.manifest.space_amp());
+    assert_eq!(0.0, value_log.space_amp());
     assert_eq!(0.0, value_log.manifest.stale_ratio());
 
     let key = "key";
@@ -28,7 +28,7 @@ fn worst_case_space_amp() -> value_log::Result<()> {
 
         value_log.scan_for_stats(index.read().unwrap().values().cloned().map(Ok))?;
 
-        assert_eq!(x as f32, value_log.manifest.space_amp());
+        assert_eq!(x as f32, value_log.space_amp());
 
         if x > 1 {
             assert!((1.0 - (1.0 / x as f32) - value_log.manifest.stale_ratio()) < 0.00001);
@@ -48,7 +48,7 @@ fn no_overlap_space_amp() -> value_log::Result<()> {
     let value_log = ValueLog::open(vl_path, Config::default())?;
 
     assert_eq!(0.0, value_log.manifest.stale_ratio());
-    assert_eq!(0.0, value_log.manifest.space_amp());
+    assert_eq!(0.0, value_log.space_amp());
 
     // NOTE: No blobs overlap, so there are no dead blobs => space amp = 1.0 => perfect space amp
     for i in 0..100 {
@@ -63,7 +63,7 @@ fn no_overlap_space_amp() -> value_log::Result<()> {
 
         value_log.scan_for_stats(index.read().unwrap().values().cloned().map(Ok))?;
 
-        assert_eq!(1.0, value_log.manifest.space_amp());
+        assert_eq!(1.0, value_log.space_amp());
         assert_eq!(0.0, value_log.manifest.stale_ratio());
     }