Redesign chunk LRU with a simpler design

.gitignore

@@ -6,4 +6,5 @@ nvme-loop.json
 /eval/data/
 /eval/plots/
 user-data
-/eval/tables/
+/eval/tables/
+/logs-compressed

cortes.server.block.toml

@@ -19,7 +19,7 @@ remote_artificial_delay_microsec = 40632
 eviction_policy = "promotional"
 high_water_evict = 1 # Number remaining from end, evicts if reaches here
 low_water_evict = 3  # Evict until below mark
-eviction_interval_ms = 1000  # Evict every 1s
+eviction_interval_ms = 100  # Evict every 0.1s
 
 [metrics]
 ip_addr = "127.0.0.1"

cortes.server.zns.toml

@@ -19,7 +19,7 @@ remote_artificial_delay_microsec = 40632
 eviction_policy = "promotional"
 high_water_evict = 1 # Number remaining from end, evicts if reaches here
 low_water_evict = 3  # Evict until below mark
-eviction_interval_ms = 1000  # Evict every 1s
+eviction_interval_ms = 100  # Evict every 0.1s
 
 [metrics]
 ip_addr = "127.0.0.1"

oxcache/src/cache/mod.rs

@@ -37,7 +37,7 @@ pub struct Cache {
     num_shards: usize,
     // Shared reverse mapping (zone, chunk_index) -> key
     // This needs to be shared because we look up by location, not by key
-    zone_to_entry: RwLock<Array2<Option<Chunk>>>,
+    pub zone_to_entry: RwLock<Array2<Option<Chunk>>>,
 }
 
 impl Cache {

oxcache/src/device.rs

@@ -8,6 +8,7 @@ use crate::writerpool::{BatchWriteRequest, WriterPool};
 use crate::zone_state::zone_list::{ZoneList, ZoneObtainFailure};
 use aligned_vec::{AVec, RuntimeAlign};
 use bytes::Bytes;
+use ndarray::s;
 use flume::Sender;
 use nvme::info::{get_active_zones, get_lba_at, is_zoned_device, nvme_get_info, report_zones_all};
 use nvme::ops::{close_zone, finish_zone, reset_zone, zns_append};
@@ -215,10 +216,6 @@ fn check_first_evict_bench() {
 }
 
 fn trigger_eviction(eviction_channel: Sender<EvictorMessage>) -> io::Result<()> {
-    tracing::debug!(
-        "DEVICE: [Thread {:?}] Sending eviction trigger",
-        std::thread::current().id()
-    );
     let (resp_tx, resp_rx) = flume::bounded(1);
     if let Err(e) = eviction_channel.send(EvictorMessage { sender: resp_tx }) {
         tracing::error!("[append] Failed to send eviction message: {}", e);
@@ -230,15 +227,10 @@ fn trigger_eviction(eviction_channel: Sender<EvictorMessage>) -> io::Result<()>
 
     match resp_rx.recv() {
         Ok(result) => match result {
-            Ok(_) => {
-                tracing::debug!(
-                    "DEVICE: [Thread {:?}] Eviction completed successfully",
-                    std::thread::current().id()
-                );
-            }
+            Ok(_) => { }
             Err(e) => {
                 tracing::error!(
-                    "DEVICE: [Thread {:?}] Eviction failed: {}",
+                    "[trigger_eviction] Thread {:?} eviction FAILED: {}",
                     std::thread::current().id(),
                     e
                 );
@@ -250,7 +242,7 @@ fn trigger_eviction(eviction_channel: Sender<EvictorMessage>) -> io::Result<()>
         },
         Err(e) => {
             tracing::error!(
-                "DEVICE: [Thread {:?}] Failed to receive eviction response: {}",
+                "[trigger_eviction] Thread {:?} failed to receive eviction response: {}",
                 std::thread::current().id(),
                 e
             );
@@ -275,29 +267,45 @@ impl Zoned {
                 <= self.config.max_active_resources as usize
         );
 
+        tracing::trace!("[get_free_zone] Thread {:?} requesting zone (is_eviction={}, free={}, open={}, writing={})",
+            std::thread::current().id(), is_eviction, zone_list.free_zones.len(),
+            zone_list.open_zones.len(), zone_list.writing_zones.len());
+
         match zone_list.remove_with_eviction_bypass(is_eviction) {
-            Ok(zone_idx) => Ok(zone_idx),
+            Ok(zone_idx) => {
+                tracing::trace!("[get_free_zone] Thread {:?} got zone {} (is_eviction={})",
+                    std::thread::current().id(), zone_idx, is_eviction);
+                Ok(zone_idx)
+            },
             Err(error) => match error {
                 ZoneObtainFailure::EvictNow => {
                     Err(io::Error::new(ErrorKind::StorageFull, "Cache is full"))
                 }
-                ZoneObtainFailure::Wait => loop {
-                    zone_list = wait_notify.wait(zone_list).unwrap();
-                    match zone_list.remove_with_eviction_bypass(is_eviction) {
-                        Ok(idx) => return Ok(idx),
-                        Err(err) => match err {
-                            ZoneObtainFailure::EvictNow => {
-                                return Err(io::Error::new(ErrorKind::Other, "Cache is full"));
-                            }
-                            ZoneObtainFailure::Wait => continue,
-                        },
+                ZoneObtainFailure::Wait => {
+                    loop {
+                        zone_list = wait_notify.wait(zone_list).unwrap();
+                        match zone_list.remove_with_eviction_bypass(is_eviction) {
+                            Ok(idx) => {
+                                return Ok(idx);
+                            },
+                            Err(err) => match err {
+                                ZoneObtainFailure::EvictNow => {
+                                    tracing::warn!("[get_free_zone] Thread {:?} got EvictNow after wait",
+                                        std::thread::current().id());
+                                    return Err(io::Error::new(ErrorKind::Other, "Cache is full"));
+                                }
+                                ZoneObtainFailure::Wait => {
+                                    continue;
+                                },
+                            },
+                        }
                     }
                 },
             },
         }
     }
 
-    fn complete_write(&self, zone_idx: Zone, finish_zone: bool) -> io::Result<()> {
+    fn complete_write(&self, zone_idx: Zone, finish_zone: bool, suppress_notify: bool) -> io::Result<()> {
         let (mtx, notify) = &*self.zones;
         let mut zone_list = mtx.lock().unwrap();
         // assert!(zone_list.get_open_zones() == active_zones, "{} vs {}", zone_list.get_open_zones(), active_zones);
@@ -309,7 +317,10 @@ impl Zoned {
         zone_list.write_finish(zone_idx, self, finish_zone)?;
         // Tell other threads that we finished writing, so they can
         // come and try to open a new zone if needed.
-        notify.notify_all();
+        // Skip notification during eviction batch writes to avoid race condition
+        if !suppress_notify {
+            notify.notify_all();
+        }
 
         Ok(())
     }
@@ -409,21 +420,24 @@ impl Zoned {
         chunk_ind
     }
 
-    fn chunked_append(&self, data: Bytes, zone_index: Zone) -> io::Result<ChunkLocation> {
-        tracing::debug!("Chunk appending to zone {}", zone_index);
+    fn chunked_append(&self, data: Bytes, zone_index: Zone, suppress_notify: bool) -> io::Result<ChunkLocation> {
+        tracing::trace!("[chunked_append] Thread {:?} appending to zone {} (suppress_notify={})",
+            std::thread::current().id(), zone_index, suppress_notify);
 
         let total_sz = data.len() as Byte;
         let write_sz = total_sz.min(self.max_write_size);
 
-        tracing::debug!(
-            "[Device]: Total size = {}, Write size = {}, max_write_size = {}",
+        tracing::trace!(
+            "[chunked_append]: Total size = {}, Write size = {}, max_write_size = {}",
             total_sz,
             write_sz,
             self.max_write_size
         );
 
         // Only locks if needed
         // this is AWFUL
+        tracing::trace!("[chunked_append] Thread {:?} acquiring zone_append_lock for zone {}",
+            std::thread::current().id(), zone_index);
         let _maybe_guard = if total_sz > self.max_write_size {
             (
                 None,
@@ -435,6 +449,8 @@ impl Zoned {
                 None,
             )
         };
+        tracing::trace!("[chunked_append] Thread {:?} acquired zone_append_lock for zone {}",
+            std::thread::current().id(), zone_index);
 
         // Sequentially write looped
 
@@ -507,7 +523,7 @@ impl Zoned {
 
         // println!("Finished writing to zone {} - {:?} - finish_zone={:?}", zone_index, cl, finish_zone);
 
-        self.complete_write(zone_index, finish_zone)?;
+        self.complete_write(zone_index, finish_zone, suppress_notify)?;
         Ok(cl)
     }
 }
@@ -552,7 +568,7 @@ impl Device for Zoned {
         );
 
         let start = std::time::Instant::now();
-        let res = self.chunked_append(data, zone_index);
+        let res = self.chunked_append(data, zone_index, is_eviction);
         METRICS.update_metric_histogram_latency(
             "disk_write_latency_ms",
             start.elapsed(),
@@ -683,12 +699,36 @@ impl Device for Zoned {
                 // Remove from map (invalidation)
                 RUNTIME.block_on(cache.remove_entries(&chunk_locations))?;
 
+                // Lock zones to prevent new writes during cleaning
+                {
+                    let (zone_mtx, _) = &*self.zones;
+                    let mut zones = zone_mtx.lock().unwrap();
+                    for zone in &clean_locations {
+                        // Remove from open_zones so no new chunks can be allocated from this zone
+                        zones.open_zones.retain(|z| z != zone);
+                    }
+                }
+
                 // Cleaning
                 let self_clone = self.clone();
                 for zone in clean_locations.iter() {
+                    // Collect old chunk locations in this zone BEFORE cleaning starts
+                    let old_chunks = RUNTIME.block_on(async {
+                        let zone_mapping = cache.zone_to_entry.read().await;
+                        let zone_slice = s![*zone as usize, ..];
+                        zone_mapping.slice(zone_slice)
+                            .iter()
+                            .enumerate()
+                            .filter_map(|(chunk_idx, opt_key)| {
+                                opt_key.as_ref().map(|_| ChunkLocation::new(*zone, chunk_idx as Chunk))
+                            })
+                            .collect::<Vec<_>>()
+                    });
+
                     let cache_clone = cache.clone();
                     let self_clone = self_clone.clone();
                     let writer_pool = writer_pool.clone();
+                    let eviction_policy_clone = eviction_policy.clone();
 
                     RUNTIME.block_on(cache_clone.clean_zone_and_update_map(
                         zone.clone(),
@@ -716,30 +756,38 @@ impl Device for Zoned {
                         {
                             let writer_pool = writer_pool.clone();
                             let self_clone = self_clone;
+                            let eviction_policy = eviction_policy_clone;
+                            let old_locations = old_chunks; // Capture old locations
 
                             // Writer callback
                             |payloads: Vec<(CacheKey, bytes::Bytes)>| {
                                 async move {
+                                    // Remove old LRU entries FIRST, before reset_zone makes the zone available again
+                                    // This prevents relocated chunks from being accidentaly added then removed
                                     {
+                                        let mut policy = eviction_policy.lock().unwrap();
+                                        if let EvictionPolicyWrapper::Chunk(c) = &mut *policy {
+                                            c.chunks_relocated(&old_locations);
+                                        }
+                                    }
+
+                                    let cv = {
                                         // Return zones back to the zone list and reset the zone
                                         let _guard = self_clone.zone_append_lock[*zone as usize]
                                             .write()
                                             .unwrap();
                                         let (zone_mtx, cv) = &*self_clone.zones;
                                         let mut zones = zone_mtx.lock().unwrap();
                                         zones.reset_zone(*zone, &*self_clone)?;
-                                        cv.notify_all();
-                                    } // Drop the mutex, so we don't have to put it in an await
+                                        cv
+                                    }; // Drop the mutex, so we don't have to put it in an await
 
                                     // Use prioritized batch write for eviction
                                     let keys: Vec<_> =
                                         payloads.iter().map(|(key, _)| key.clone()).collect();
                                     let data_vec: Vec<_> =
                                         payloads.iter().map(|(_, data)| data.clone()).collect();
 
-                                    // Used to verify no RACE, TODO: Remove!
-                                    // tokio::time::sleep(Duration::from_secs(5)).await;
-
                                     let (batch_tx, batch_rx) = flume::bounded(1);
 
                                     let batch_request = BatchWriteRequest {
@@ -775,6 +823,9 @@ impl Device for Zoned {
 
                                     let write_results = write_results?;
 
+                                    // Notify waiting writers AFTER batch write completes successfully
+                                    cv.notify_all();
+
                                     Ok(write_results) // Vec<(Chunk, ChunkLocation)>
                                 }
                             }
@@ -792,9 +843,13 @@ impl Device for Zoned {
 
                 RUNTIME.block_on(cache.remove_zones(&zones_to_evict))?;
 
-                let (zone_mtx, _) = &*self.zones;
+                let (zone_mtx, cv) = &*self.zones;
                 let mut zones = zone_mtx.lock().unwrap();
                 zones.reset_zones(&zones_to_evict, &*self)?;
+                drop(zones);
+
+                // Notify waiting writers after zones are reset
+                cv.notify_all();
 
                 // Reset atomic counters for evicted zones
                 let policy = eviction_policy.lock().unwrap();