v4.0: Ignores ancestors in snapshot (backport of #10835)

accounts-db/src/ancestors.rs

@@ -5,8 +5,6 @@ use {
     std::collections::HashMap,
 };
 
-pub type AncestorsForSerialization = HashMap<Slot, usize>;
-
 #[cfg_attr(feature = "frozen-abi", derive(AbiExample))]
 #[derive(Clone, PartialEq)]
 pub struct Ancestors {

runtime/src/bank.rs

@@ -95,7 +95,7 @@ use {
         accounts_hash::AccountsLtHash,
         accounts_index::{IndexKey, ScanConfig, ScanResult},
         accounts_update_notifier_interface::AccountsUpdateNotifier,
-        ancestors::{Ancestors, AncestorsForSerialization},
+        ancestors::Ancestors,
         blockhash_queue::BlockhashQueue,
         storable_accounts::StorableAccounts,
         utils::create_account_shared_data,
@@ -455,7 +455,6 @@ impl TransactionLogCollector {
 #[derive(Clone, Debug)]
 pub struct BankFieldsToDeserialize {
     pub(crate) blockhash_queue: BlockhashQueue,
-    pub(crate) ancestors: AncestorsForSerialization,
     pub(crate) hash: Hash,
     pub(crate) parent_hash: Hash,
     pub(crate) parent_slot: Slot,
@@ -499,7 +498,6 @@ pub struct BankFieldsToDeserialize {
 #[derive(Debug)]
 pub struct BankFieldsToSerialize {
     pub blockhash_queue: BlockhashQueue,
-    pub ancestors: AncestorsForSerialization,
     pub hash: Hash,
     pub parent_hash: Hash,
     pub parent_slot: Slot,
@@ -650,7 +648,6 @@ impl BankFieldsToSerialize {
     pub fn default_for_tests() -> Self {
         Self {
             blockhash_queue: BlockhashQueue::default(),
-            ancestors: AncestorsForSerialization::default(),
             hash: Hash::default(),
             parent_hash: Hash::default(),
             parent_slot: Slot::default(),
@@ -1846,7 +1843,8 @@ impl Bank {
         epoch_stakes: HashMap<Epoch, VersionedEpochStakes>,
     ) -> Self {
         let now = Instant::now();
-        let ancestors = Ancestors::from(&fields.ancestors);
+        let slot = fields.slot;
+        let ancestors = Ancestors::from(vec![slot]);
         // For backward compatibility, we can only serialize and deserialize
         // Stakes<Delegation> in BankFieldsTo{Serialize,Deserialize}. But Bank
         // caches Stakes<StakeAccount>. Below Stakes<StakeAccount> is obtained
@@ -1902,7 +1900,7 @@ impl Bank {
             ns_per_slot: fields.ns_per_slot,
             genesis_creation_time: fields.genesis_creation_time,
             slots_per_year: fields.slots_per_year,
-            slot: fields.slot,
+            slot,
             bank_id: 0,
             epoch: fields.epoch,
             block_height: fields.block_height,
@@ -2008,7 +2006,6 @@ impl Bank {
     pub(crate) fn get_fields_to_serialize(&self) -> BankFieldsToSerialize {
         BankFieldsToSerialize {
             blockhash_queue: self.blockhash_queue.read().unwrap().clone(),
-            ancestors: AncestorsForSerialization::from(&self.ancestors),
             hash: *self.hash.read().unwrap(),
             parent_hash: self.parent_hash,
             parent_slot: self.parent_slot,

runtime/src/bank/serde_snapshot.rs

@@ -345,7 +345,7 @@ mod tests {
         #[cfg_attr(
             feature = "frozen-abi",
             derive(AbiExample),
-            frozen_abi(digest = "FCDuswxZnGvvJURSkrQPshX45a25CR6UAmPgzGeUfMFv")
+            frozen_abi(digest = "HKTVanoy2iLbtAVwrt2y8HxH8YaWsgw4LZC9B76X6EL4")
         )]
         #[derive(serde::Serialize)]
         pub struct BankAbiTestWrapper {

runtime/src/serde_snapshot.rs

@@ -29,7 +29,6 @@ use {
         accounts_file::{AccountsFile, StorageAccess},
         accounts_hash::AccountsLtHash,
         accounts_update_notifier_interface::AccountsUpdateNotifier,
-        ancestors::AncestorsForSerialization,
         blockhash_queue::BlockhashQueue,
     },
     solana_clock::{Epoch, Slot, UnixTimestamp},
@@ -155,7 +154,7 @@ struct UnusedAccounts {
 #[derive(Clone, Deserialize)]
 struct DeserializableVersionedBank {
     blockhash_queue: BlockhashQueue,
-    ancestors: AncestorsForSerialization,
+    _unused_ancestors: HashMap<Slot, usize>,
     hash: Hash,
     parent_hash: Hash,
     parent_slot: Slot,
@@ -195,7 +194,6 @@ impl From<DeserializableVersionedBank> for BankFieldsToDeserialize {
         const LT_HASH_CANARY: LtHash = LtHash([0xCAFE; LtHash::NUM_ELEMENTS]);
         BankFieldsToDeserialize {
             blockhash_queue: dvb.blockhash_queue,
-            ancestors: dvb.ancestors,
             hash: dvb.hash,
             parent_hash: dvb.parent_hash,
             parent_slot: dvb.parent_slot,
@@ -233,7 +231,7 @@ impl From<DeserializableVersionedBank> for BankFieldsToDeserialize {
 #[derive(Serialize)]
 struct SerializableVersionedBank {
     blockhash_queue: BlockhashQueue,
-    ancestors: AncestorsForSerialization,
+    unused_ancestors: HashMap<Slot, usize>,
     hash: Hash,
     parent_hash: Hash,
     parent_slot: Slot,
@@ -271,7 +269,7 @@ impl From<BankFieldsToSerialize> for SerializableVersionedBank {
     fn from(rhs: BankFieldsToSerialize) -> Self {
         Self {
             blockhash_queue: rhs.blockhash_queue,
-            ancestors: rhs.ancestors,
+            unused_ancestors: HashMap::default(),
             hash: rhs.hash,
             parent_hash: rhs.parent_hash,
             parent_slot: rhs.parent_slot,