Increase the maximum of ancient slots allowed to be not combined (sol…

…ana-labs#3205)

* Increase the maximum of ancient slots allowed to be not combined

* OFFSET

* Offset

* Fix

* Fix

* Roots

* Comment

accounts-db/src/accounts_db.rs

@@ -145,6 +145,10 @@ const SHRINK_COLLECT_CHUNK_SIZE: usize = 50;
 /// candidates for shrinking.
 const SHRINK_INSERT_ANCIENT_THRESHOLD: usize = 10;
 
+/// Default value for the number of ancient storages the ancient slot
+/// combining should converge to.
+pub const MAX_ANCIENT_SLOTS_DEFAULT: usize = 100_000;
+
 #[derive(Debug, Default, Clone, Copy, PartialEq, Eq)]
 pub enum CreateAncientStorage {
     /// ancient storages are created by appending
@@ -592,9 +596,24 @@ pub struct AccountsAddRootTiming {
     pub store_us: u64,
 }
 
-/// if negative, this many accounts older than # slots in epoch are still treated as modern (ie. non-ancient).
-/// Slots older than # slots in epoch - this # are then treated as ancient and subject to packing.
-const ANCIENT_APPEND_VEC_DEFAULT_OFFSET: Option<i64> = Some(-10_000);
+/// Slots older the "number of slots in an epoch minus this number"
+/// than max root are treated as ancient and subject to packing.
+/// |  older  |<-          slots in an epoch          ->| max root
+/// |  older  |<-    offset   ->|                       |
+/// |          ancient          |        modern         |
+///
+/// If this is negative, this many slots older than the number of
+/// slots in epoch are still treated as modern (ie. non-ancient).
+/// |  older  |<- abs(offset) ->|<- slots in an epoch ->| max root
+/// | ancient |                 modern                  |
+///
+/// Note that another constant MAX_ANCIENT_SLOTS_DEFAULT sets a
+/// threshold for combining ancient storages so that their overall
+/// number is under a certain limit, whereas this constant establishes
+/// the distance from the max root slot beyond which storages holding
+/// the account data for the slots are considered ancient by the
+/// shrinking algorithm.
+const ANCIENT_APPEND_VEC_DEFAULT_OFFSET: Option<i64> = Some(100_000);
 
 #[derive(Debug, Default, Clone)]
 pub struct AccountsDbConfig {
@@ -15201,10 +15220,9 @@ pub mod tests {
         let slots_per_epoch = config.epoch_schedule.slots_per_epoch;
         assert_ne!(slot, 0);
         let offset = 10;
-        // no ancient append vecs, so always 0
         assert_eq!(
             db.get_oldest_non_ancient_slot_for_hash_calc_scan(slots_per_epoch + offset, &config),
-            expected(0)
+            expected(db.ancient_append_vec_offset.unwrap() as u64 + offset + 1)
         );
         // ancient append vecs enabled (but at 0 offset), so can be non-zero
         db.ancient_append_vec_offset = Some(0);
@@ -15929,52 +15947,55 @@ pub mod tests {
         assert!(db
             .get_sorted_potential_ancient_slots(oldest_non_ancient_slot)
             .is_empty());
-        let root0 = 0;
-        db.add_root(root0);
-        let root1 = 1;
+        let root1 = MAX_ANCIENT_SLOTS_DEFAULT as u64 + ancient_append_vec_offset as u64 + 1;
         db.add_root(root1);
+        let root2 = root1 + 1;
+        db.add_root(root2);
         let oldest_non_ancient_slot = db.get_oldest_non_ancient_slot(&epoch_schedule);
         assert!(db
             .get_sorted_potential_ancient_slots(oldest_non_ancient_slot)
             .is_empty());
         let completed_slot = epoch_schedule.slots_per_epoch;
-        db.accounts_index.add_root(completed_slot);
+        db.accounts_index.add_root(AccountsDb::apply_offset_to_slot(
+            completed_slot,
+            ancient_append_vec_offset,
+        ));
         let oldest_non_ancient_slot = db.get_oldest_non_ancient_slot(&epoch_schedule);
         // get_sorted_potential_ancient_slots uses 'less than' as opposed to 'less or equal'
         // so, we need to get more than an epoch away to get the first valid root
         assert!(db
             .get_sorted_potential_ancient_slots(oldest_non_ancient_slot)
             .is_empty());
-        let completed_slot = epoch_schedule.slots_per_epoch + root0;
+        let completed_slot = epoch_schedule.slots_per_epoch + root1;
         db.accounts_index.add_root(AccountsDb::apply_offset_to_slot(
             completed_slot,
-            -ancient_append_vec_offset,
+            ancient_append_vec_offset,
         ));
         let oldest_non_ancient_slot = db.get_oldest_non_ancient_slot(&epoch_schedule);
         assert_eq!(
             db.get_sorted_potential_ancient_slots(oldest_non_ancient_slot),
-            vec![root0]
+            vec![root1, root2]
         );
-        let completed_slot = epoch_schedule.slots_per_epoch + root1;
+        let completed_slot = epoch_schedule.slots_per_epoch + root2;
         db.accounts_index.add_root(AccountsDb::apply_offset_to_slot(
             completed_slot,
-            -ancient_append_vec_offset,
+            ancient_append_vec_offset,
         ));
         let oldest_non_ancient_slot = db.get_oldest_non_ancient_slot(&epoch_schedule);
         assert_eq!(
             db.get_sorted_potential_ancient_slots(oldest_non_ancient_slot),
-            vec![root0, root1]
+            vec![root1, root2]
         );
         db.accounts_index
             .roots_tracker
             .write()
             .unwrap()
             .alive_roots
-            .remove(&root0);
+            .remove(&root1);
         let oldest_non_ancient_slot = db.get_oldest_non_ancient_slot(&epoch_schedule);
         assert_eq!(
             db.get_sorted_potential_ancient_slots(oldest_non_ancient_slot),
-            vec![root1]
+            vec![root2]
         );
     });
 

accounts-db/src/ancient_append_vecs.rs

@@ -11,6 +11,7 @@ use {
             stats::{ShrinkAncientStats, ShrinkStatsSub},
             AccountFromStorage, AccountStorageEntry, AccountsDb, AliveAccounts,
             GetUniqueAccountsResult, ShrinkCollect, ShrinkCollectAliveSeparatedByRefs,
+            MAX_ANCIENT_SLOTS_DEFAULT,
         },
         accounts_file::AccountsFile,
         active_stats::ActiveStatItem,
@@ -343,8 +344,9 @@ impl AccountsDb {
         can_randomly_shrink: bool,
     ) {
         let tuning = PackedAncientStorageTuning {
-            // only allow 10k slots old enough to be ancient
-            max_ancient_slots: 10_000,
+            // Slots old enough to be ancient.  Setting this parameter
+            // to 100k makes ancient storages to be approx 5M.
+            max_ancient_slots: MAX_ANCIENT_SLOTS_DEFAULT,
             // Don't re-pack anything just to shrink.
             // shrink_candidate_slots will handle these old storages.
             percent_of_alive_shrunk_data: 0,