Add device usage indicator

Author: sam cheng

oxcache/src/device.rs

@@ -221,6 +221,8 @@ impl Device for Zoned {
     }
 
     fn evict(&self, locations: EvictTarget, cache: Arc<Cache>) -> io::Result<()> {
+        println!("Current device usage is at: {}", self.get_use_percentage());
+
         match locations {
             EvictTarget::Chunk(mut chunk_locations) => {
                 // Check all zones are the same, this isn't a
@@ -304,6 +306,14 @@ impl Device for Zoned {
     fn get_block_size(&self) -> usize {
         self.nvme_config.logical_block_size as usize
     }
+
+    fn get_use_percentage(&self) -> f32 {
+        let (zones, _) = &*self.zones;
+        let zones = zones.lock().unwrap();
+        let total_chunks = (self.config.chunks_per_zone * self.config.num_zones) as f32;
+        let available_chunks = zones.get_num_available_chunks() as f32;
+        (total_chunks - available_chunks) / total_chunks
+    }
 }
 
 impl BlockInterface {
@@ -445,4 +455,11 @@ impl Device for BlockInterface {
     fn get_block_size(&self) -> usize {
         self.nvme_config.logical_block_size as usize
     }
+
+    fn get_use_percentage(&self) -> f32 {
+        let state = &*self.state.lock().unwrap();
+        let total_chunks = (self.chunks_per_zone * self.num_zones) as f32;
+        let available_chunks = state.active_zones.get_num_available_chunks() as f32;
+        (total_chunks - available_chunks) / total_chunks
+    }
 }

oxcache/src/eviction.rs

@@ -15,6 +15,7 @@ pub enum EvictionPolicyWrapper {
     Chunk(ChunkEvictionPolicy),
 }
 
+#[derive(Debug)]
 pub enum EvictTarget {
     Chunk(Vec<ChunkLocation>),
     Zone(Vec<usize>),

oxcache/src/zone_state/zone_list.rs

@@ -176,6 +176,12 @@ impl ZoneList {
             chunks_available: remaining,
         });
     }
+
+    pub fn get_num_available_chunks(&self) -> usize {
+        self.open_zones.iter().fold(0, |avail, zone| {
+            avail + zone.chunks_available
+        }) + self.free_zones.len() * self.chunks_per_zone
+    }
 }
 
 #[cfg(test)]