bank_from_latest_snapshot_dir (solana-labs#31115)

* bank_from_latest_snapshot_dir

* Clear the account paths before constructing a bank from a snapshot dir

* Clear the account paths before constructing a bank from a snapshot dir (solana-labs#31170)

* use the highest POST snapshot dir to construct a bank

* Use POST to fix test_bank_from_latest_snapshot_dir

* Revert "Clear the account paths before constructing a bank from a snapshot dir"

This reverts commit 272bb9f.

* Remove the set_accounts_hash_for_tests call

* Revert "Revert "Clear the account paths before constructing a bank from a snapshot dir""

This reverts commit 2e345d8.

runtime/src/snapshot_utils.rs

@@ -1722,6 +1722,60 @@ pub fn bank_from_snapshot_dir(
     Ok((bank, timings))
 }
 
+/// follow the prototype of fn bank_from_latest_snapshot_archives, implement the from_dir case
+#[allow(clippy::too_many_arguments)]
+pub fn bank_from_latest_snapshot_dir(
+    bank_snapshots_dir: impl AsRef<Path>,
+    genesis_config: &GenesisConfig,
+    runtime_config: &RuntimeConfig,
+    account_paths: &[PathBuf],
+    debug_keys: Option<Arc<HashSet<Pubkey>>>,
+    additional_builtins: Option<&Builtins>,
+    account_secondary_indexes: AccountSecondaryIndexes,
+    limit_load_slot_count_from_snapshot: Option<usize>,
+    shrink_ratio: AccountShrinkThreshold,
+    verify_index: bool,
+    accounts_db_config: Option<AccountsDbConfig>,
+    accounts_update_notifier: Option<AccountsUpdateNotifier>,
+    exit: &Arc<AtomicBool>,
+) -> Result<Bank> {
+    info!("Loading bank from snapshot dir");
+    let bank_snapshot = get_highest_bank_snapshot_post(&bank_snapshots_dir).ok_or_else(|| {
+        SnapshotError::NoSnapshotSlotDir(bank_snapshots_dir.as_ref().to_path_buf())
+    })?;
+
+    let (bank, timings) = bank_from_snapshot_dir(
+        account_paths,
+        &bank_snapshot,
+        genesis_config,
+        runtime_config,
+        debug_keys,
+        additional_builtins,
+        account_secondary_indexes,
+        limit_load_slot_count_from_snapshot,
+        shrink_ratio,
+        verify_index,
+        accounts_db_config,
+        accounts_update_notifier,
+        exit,
+    )?;
+
+    datapoint_info!(
+        "bank_from_snapshot_dir",
+        (
+            "build_storage_from_snapshot_dir_us",
+            timings.build_storage_us,
+            i64
+        ),
+        (
+            "rebuild_bank_from_snapshot_us",
+            timings.rebuild_bank_from_snapshot_us,
+            i64
+        ),
+    );
+    Ok(bank)
+}
+
 /// Check to make sure the deserialized bank's slot and hash matches the snapshot archive's slot
 /// and hash
 fn verify_bank_against_expected_slot_hash(
@@ -5469,4 +5523,70 @@ mod tests {
         let next_id = bank.accounts().accounts_db.next_id.load(Ordering::Relaxed) as usize;
         assert_eq!(max_id, next_id - 1);
     }
+
+    #[test]
+    fn test_bank_from_latest_snapshot_dir() {
+        solana_logger::setup();
+        let genesis_config = GenesisConfig::default();
+        let mut bank = Arc::new(Bank::new_for_tests(&genesis_config));
+
+        let tmp_dir = tempfile::TempDir::new().unwrap();
+        let bank_snapshots_dir = tmp_dir.path();
+        let collecter_id = Pubkey::new_unique();
+        let snapshot_version = SnapshotVersion::default();
+
+        for _ in 0..3 {
+            // prepare the bank
+            bank = Arc::new(Bank::new_from_parent(&bank, &collecter_id, bank.slot() + 1));
+            bank.fill_bank_with_ticks_for_tests();
+            bank.squash();
+            bank.force_flush_accounts_cache();
+
+            // generate the bank snapshot directory for slot+1
+            let snapshot_storages = bank.get_snapshot_storages(None);
+            let slot_deltas = bank.status_cache.read().unwrap().root_slot_deltas();
+            add_bank_snapshot(
+                bank_snapshots_dir,
+                &bank,
+                &snapshot_storages,
+                snapshot_version,
+                slot_deltas,
+            )
+            .unwrap();
+            // Reserialize the snapshot dir to convert it from PRE to POST, because only the POST type can be used
+            // to construct a bank.
+            assert!(
+                crate::serde_snapshot::reserialize_bank_with_new_accounts_hash(
+                    bank_snapshots_dir,
+                    bank.slot(),
+                    &AccountsHash(Hash::new_unique()),
+                    None
+                )
+            );
+        }
+
+        let account_paths = &bank.rc.accounts.accounts_db.paths;
+
+        let deserialized_bank = bank_from_latest_snapshot_dir(
+            bank_snapshots_dir,
+            &genesis_config,
+            &RuntimeConfig::default(),
+            account_paths,
+            None,
+            None,
+            AccountSecondaryIndexes::default(),
+            None,
+            AccountShrinkThreshold::default(),
+            false,
+            Some(ACCOUNTS_DB_CONFIG_FOR_TESTING),
+            None,
+            &Arc::default(),
+        )
+        .unwrap();
+
+        assert_eq!(
+            deserialized_bank, *bank,
+            "Ensure rebuilding bank from the highest snapshot dir results in the highest bank",
+        );
+    }
 }