log write cache contents from purge_slots_from_cache_and_store (#24948)

runtime/src/accounts_db.rs

@@ -4104,12 +4104,21 @@ impl AccountsDb {
     /// entries in the accounts index, cache entries, and any backing storage entries.
     fn purge_slots_from_cache_and_store<'a>(
         &self,
-        removed_slots: impl Iterator<Item = &'a Slot>,
+        removed_slots: impl Iterator<Item = &'a Slot> + Clone,
         purge_stats: &PurgeStats,
+        log_accounts: bool,
     ) {
         let mut remove_cache_elapsed_across_slots = 0;
         let mut num_cached_slots_removed = 0;
         let mut total_removed_cached_bytes = 0;
+        if log_accounts {
+            if let Some(min) = removed_slots.clone().min() {
+                info!(
+                    "purge_slots_from_cache_and_store: {:?}",
+                    self.get_pubkey_hash_for_slot(*min).0
+                );
+            }
+        }
         for remove_slot in removed_slots {
             // This function is only currently safe with respect to `flush_slot_cache()` because
             // both functions run serially in AccountsBackgroundService.
@@ -4314,7 +4323,7 @@ impl AccountsDb {
     }
 
     #[allow(clippy::needless_collect)]
-    fn purge_slots<'a>(&self, slots: impl Iterator<Item = &'a Slot>) {
+    fn purge_slots<'a>(&self, slots: impl Iterator<Item = &'a Slot> + Clone) {
         // `add_root()` should be called first
         let mut safety_checks_elapsed = Measure::start("safety_checks_elapsed");
         let non_roots = slots
@@ -4332,7 +4341,7 @@ impl AccountsDb {
         self.external_purge_slots_stats
             .safety_checks_elapsed
             .fetch_add(safety_checks_elapsed.as_us(), Ordering::Relaxed);
-        self.purge_slots_from_cache_and_store(non_roots, &self.external_purge_slots_stats);
+        self.purge_slots_from_cache_and_store(non_roots, &self.external_purge_slots_stats, false);
         self.external_purge_slots_stats
             .report("external_purge_slots_stats", Some(1000));
     }
@@ -4415,6 +4424,7 @@ impl AccountsDb {
         self.purge_slots_from_cache_and_store(
             remove_slots.iter().map(|(slot, _)| slot),
             &remove_unrooted_purge_stats,
+            true,
         );
         remove_unrooted_purge_stats.report("remove_unrooted_slots_purge_slots_stats", Some(0));
 
@@ -6061,11 +6071,12 @@ impl AccountsDb {
     pub fn get_accounts_delta_hash(&self, slot: Slot) -> Hash {
         self.get_accounts_delta_hash_with_rewrites(slot, &Rewrites::default())
     }
-    pub fn get_accounts_delta_hash_with_rewrites(
-        &self,
-        slot: Slot,
-        skipped_rewrites: &Rewrites,
-    ) -> Hash {
+
+    /// helper to return
+    /// 1. pubkey, hash pairs for the slot
+    /// 2. us spent scanning
+    /// 3. Measure started when we began accumulating
+    fn get_pubkey_hash_for_slot(&self, slot: Slot) -> (Vec<(Pubkey, Hash)>, u64, Measure) {
         let mut scan = Measure::start("scan");
 
         let scan_result: ScanStorageResult<(Pubkey, Hash), DashMapVersionHash> = self
@@ -6094,14 +6105,23 @@ impl AccountsDb {
             );
         scan.stop();
 
-        let mut accumulate = Measure::start("accumulate");
-        let mut hashes: Vec<_> = match scan_result {
+        let accumulate = Measure::start("accumulate");
+        let hashes: Vec<_> = match scan_result {
             ScanStorageResult::Cached(cached_result) => cached_result,
             ScanStorageResult::Stored(stored_result) => stored_result
                 .into_iter()
                 .map(|(pubkey, (_latest_write_version, hash))| (pubkey, hash))
                 .collect(),
         };
+        (hashes, scan.as_us(), accumulate)
+    }
+
+    pub fn get_accounts_delta_hash_with_rewrites(
+        &self,
+        slot: Slot,
+        skipped_rewrites: &Rewrites,
+    ) -> Hash {
+        let (mut hashes, scan_us, mut accumulate) = self.get_pubkey_hash_for_slot(slot);
         let dirty_keys = hashes.iter().map(|(pubkey, _hash)| *pubkey).collect();
 
         if self.filler_accounts_enabled() {
@@ -6122,7 +6142,7 @@ impl AccountsDb {
 
         self.stats
             .delta_hash_scan_time_total_us
-            .fetch_add(scan.as_us(), Ordering::Relaxed);
+            .fetch_add(scan_us, Ordering::Relaxed);
         self.stats
             .delta_hash_accumulate_time_total_us
             .fetch_add(accumulate.as_us(), Ordering::Relaxed);