Move Bank::get_incremental_snapshot_storages() into snapshot_utils (#19155)

Filtering out storages for incremental snapshots will be needed by the
background services for incremental snapshot support, but there is not a
Bank at that point.  Since the filtering doesn't apply only to Bank, and
more to snapshots, move the functionality into snapshot_utils.

core/tests/snapshots.rs

@@ -771,13 +771,21 @@ mod tests {
             .into_iter()
             .find(|elem| elem.slot == slot)
             .ok_or_else(|| Error::new(ErrorKind::Other, "did not find snapshot with this path"))?;
+        let storages = {
+            let mut storages = bank.get_snapshot_storages();
+            snapshot_utils::filter_snapshot_storages_for_incremental_snapshot(
+                &mut storages,
+                incremental_snapshot_base_slot,
+            );
+            storages
+        };
         snapshot_utils::package_process_and_archive_incremental_snapshot(
             bank,
             incremental_snapshot_base_slot,
             &bank_snapshot_info,
             &snapshot_config.snapshot_path,
             &snapshot_config.snapshot_package_output_path,
-            bank.get_incremental_snapshot_storages(incremental_snapshot_base_slot),
+            storages,
             snapshot_config.archive_format,
             snapshot_config.snapshot_version,
             None,

runtime/src/bank.rs

@@ -38,7 +38,7 @@ use crate::{
         AccountAddressFilter, Accounts, TransactionAccounts, TransactionLoadResult,
         TransactionLoaders,
     },
-    accounts_db::{AccountShrinkThreshold, ErrorCounters, SnapshotStorage, SnapshotStorages},
+    accounts_db::{AccountShrinkThreshold, ErrorCounters, SnapshotStorages},
     accounts_index::{
         AccountSecondaryIndexes, IndexKey, ScanResult, BINS_FOR_BENCHMARKS, BINS_FOR_TESTING,
     },
@@ -4877,21 +4877,6 @@ impl Bank {
         self.rc.get_snapshot_storages(self.slot())
     }
 
-    /// Get the snapshot storages _higher than_ the `full_snapshot_slot`.  This is used when making an
-    /// incremental snapshot.
-    pub fn get_incremental_snapshot_storages(&self, full_snapshot_slot: Slot) -> SnapshotStorages {
-        self.get_snapshot_storages()
-            .into_iter()
-            .map(|storage| {
-                storage
-                    .into_iter()
-                    .filter(|entry| entry.slot() > full_snapshot_slot)
-                    .collect::<SnapshotStorage>()
-            })
-            .filter(|storage| !storage.is_empty())
-            .collect()
-    }
-
     #[must_use]
     fn verify_hash(&self) -> bool {
         assert!(self.is_frozen());

runtime/src/snapshot_utils.rs

@@ -1536,7 +1536,7 @@ pub fn snapshot_bank(
     archive_format: &ArchiveFormat,
     hash_for_testing: Option<Hash>,
 ) -> Result<()> {
-    let storages: Vec<_> = root_bank.get_snapshot_storages();
+    let storages = root_bank.get_snapshot_storages();
     let mut add_snapshot_time = Measure::start("add-snapshot-ms");
     add_bank_snapshot(snapshots_dir, root_bank, &storages, snapshot_version)?;
     add_snapshot_time.stop();
@@ -1630,7 +1630,11 @@ pub fn bank_to_incremental_snapshot_archive(
     bank.rehash(); // Bank accounts may have been manually modified by the caller
 
     let temp_dir = tempfile::tempdir_in(snapshots_dir)?;
-    let storages = bank.get_incremental_snapshot_storages(full_snapshot_slot);
+    let storages = {
+        let mut storages = bank.get_snapshot_storages();
+        filter_snapshot_storages_for_incremental_snapshot(&mut storages, full_snapshot_slot);
+        storages
+    };
     let bank_snapshot_info = add_bank_snapshot(&temp_dir, bank, &storages, snapshot_version)?;
 
     package_process_and_archive_incremental_snapshot(
@@ -1795,6 +1799,19 @@ pub fn process_accounts_package_pre(
     )
 }
 
+/// Filter snapshot storages and retain only the ones with slots _higher than_
+/// `incremental_snapshot_base_slot`.
+pub fn filter_snapshot_storages_for_incremental_snapshot(
+    snapshot_storages: &mut SnapshotStorages,
+    incremental_snapshot_base_slot: Slot,
+) {
+    snapshot_storages.retain(|storage| {
+        storage
+            .first()
+            .map_or(false, |entry| entry.slot() > incremental_snapshot_base_slot)
+    });
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;