AcctIdx: add flush remove stat (solana-labs#20625)

runtime/src/bucket_map_holder_stats.rs

@@ -34,6 +34,7 @@ pub struct BucketMapHolderStats {
     pub count_in_mem: AtomicU64,
     pub per_bucket_count: Vec<AtomicU64>,
     pub flush_entries_updated_on_disk: AtomicU64,
+    pub flush_entries_removed_from_mem: AtomicU64,
     pub active_threads: AtomicU64,
     pub get_range_us: AtomicU64,
     last_age: AtomicU8,
@@ -66,13 +67,17 @@ impl BucketMapHolderStats {
     }
 
     pub fn insert_or_delete_mem(&self, insert: bool, bin: usize) {
+        self.insert_or_delete_mem_count(insert, bin, 1)
+    }
+
+    pub fn insert_or_delete_mem_count(&self, insert: bool, bin: usize, count: u64) {
         let per_bucket = self.per_bucket_count.get(bin);
         if insert {
-            self.count_in_mem.fetch_add(1, Ordering::Relaxed);
-            per_bucket.map(|count| count.fetch_add(1, Ordering::Relaxed));
+            self.count_in_mem.fetch_add(count, Ordering::Relaxed);
+            per_bucket.map(|stat| stat.fetch_add(count, Ordering::Relaxed));
         } else {
-            self.count_in_mem.fetch_sub(1, Ordering::Relaxed);
-            per_bucket.map(|count| count.fetch_sub(1, Ordering::Relaxed));
+            self.count_in_mem.fetch_sub(count, Ordering::Relaxed);
+            per_bucket.map(|stat| stat.fetch_sub(count, Ordering::Relaxed));
         }
     }
 
@@ -364,6 +369,12 @@ impl BucketMapHolderStats {
                     .swap(0, Ordering::Relaxed),
                 i64
             ),
+            (
+                "flush_entries_removed_from_mem",
+                self.flush_entries_removed_from_mem
+                    .swap(0, Ordering::Relaxed),
+                i64
+            ),
         );
     }
 }

runtime/src/in_mem_accounts_index.rs

@@ -778,6 +778,7 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
             return false; // range said to hold 'all', so not completed
         }
 
+        let mut removed = 0;
         // consider chunking these so we don't hold the write lock too long
         let mut map = self.map().write().unwrap();
         for k in removes {
@@ -815,10 +816,14 @@ impl<T: IndexValue> InMemAccountsIndex<T> {
                 }
 
                 // all conditions for removing succeeded, so really remove item from in-mem cache
-                self.stats().insert_or_delete_mem(false, self.bin);
+                removed += 1;
                 occupied.remove();
             }
         }
+        self.stats()
+            .insert_or_delete_mem_count(false, self.bin, removed);
+        Self::update_stat(&self.stats().flush_entries_removed_from_mem, removed);
+
         completed_scan
     }