serialize epoch_accounts_hash (solana-labs#27516)

core/src/accounts_hash_verifier.rs

@@ -214,6 +214,7 @@ impl AccountsHashVerifier {
             accounts_package.slot,
             &accounts_hash,
             None,
+            None,
         );
         datapoint_info!(
             "accounts_hash_verifier",

core/tests/snapshots.rs

@@ -258,6 +258,7 @@ fn run_bank_forks_snapshot_n<F>(
         accounts_package.slot,
         &last_bank.get_accounts_hash(),
         None,
+        None,
     );
     let snapshot_package = SnapshotPackage::new(accounts_package, last_bank.get_accounts_hash());
     snapshot_utils::archive_snapshot_package(
@@ -494,6 +495,7 @@ fn test_concurrent_snapshot_packaging(
                 accounts_package.slot,
                 &Hash::default(),
                 None,
+                None,
             );
             let snapshot_package = SnapshotPackage::new(accounts_package, Hash::default());
             pending_snapshot_package
@@ -538,6 +540,7 @@ fn test_concurrent_snapshot_packaging(
         saved_slot,
         &Hash::default(),
         None,
+        None,
     );
 
     snapshot_utils::verify_snapshot_archive(

runtime/src/accounts_db.rs

@@ -1190,7 +1190,11 @@ pub struct AccountsDb {
     /// debug feature to scan every append vec and verify refcounts are equal
     exhaustively_verify_refcounts: bool,
 
-    /// A special accounts hash that occurs once per epoch
+    /// the full accounts hash calculation as of a predetermined block height 'N'
+    /// to be included in the bank hash at a predetermined block height 'M'
+    /// The cadence is once per epoch, all nodes calculate a full accounts hash as of a known slot calculated using 'N'
+    /// Some time later (to allow for slow calculation time), the bank hash at a slot calculated using 'M' includes the full accounts hash.
+    /// Thus, the state of all accounts on a validator is known to be correct at least once per epoch.
     pub(crate) epoch_accounts_hash: Mutex<Option<EpochAccountsHash>>,
 }
 

runtime/src/bank.rs

@@ -2285,6 +2285,19 @@ impl Bank {
         bank
     }
 
+    /// if we were to serialize THIS bank, what value should be saved for the prior accounts hash?
+    /// This depends on the proximity to the time to take the snapshot and the time to use the snapshot.
+    pub(crate) fn get_epoch_accounts_hash_to_serialize(&self) -> Option<Hash> {
+        self.rc
+            .accounts
+            .accounts_db
+            .epoch_accounts_hash
+            .lock()
+            .unwrap()
+            .as_ref()
+            .map(|hash| *hash.as_ref())
+    }
+
     /// Return subset of bank fields representing serializable state
     pub(crate) fn get_fields_to_serialize<'a>(
         &'a self,

runtime/src/epoch_accounts_hash.rs

@@ -23,6 +23,14 @@ impl AsRef<Hash> for EpochAccountsHash {
     }
 }
 
+impl EpochAccountsHash {
+    /// Make an EpochAccountsHash from a regular accounts hash
+    #[must_use]
+    pub fn new(accounts_hash: Hash) -> Self {
+        Self(accounts_hash)
+    }
+}
+
 /// Calculation of the EAH occurs once per epoch.  All nodes in the cluster must agree on which
 /// slot the EAH is based on.  This slot will be at an offset into the epoch, and referred to as
 /// the "start" slot for the EAH calculation.

runtime/src/serde_snapshot.rs

@@ -11,6 +11,7 @@ use {
         bank::{Bank, BankFieldsToDeserialize, BankIncrementalSnapshotPersistence, BankRc},
         blockhash_queue::BlockhashQueue,
         builtins::Builtins,
+        epoch_accounts_hash::EpochAccountsHash,
         epoch_stakes::EpochStakes,
         rent_collector::RentCollector,
         runtime_config::RuntimeConfig,
@@ -193,6 +194,7 @@ trait TypeContext<'a>: PartialEq {
         stream_writer: &mut BufWriter<W>,
         accounts_hash: &Hash,
         incremental_snapshot_persistence: Option<&BankIncrementalSnapshotPersistence>,
+        epoch_accounts_hash: Option<&Hash>,
     ) -> std::result::Result<(), Box<bincode::ErrorKind>>
     where
         R: Read,
@@ -390,6 +392,7 @@ fn reserialize_bank_fields_with_new_hash<W, R>(
     stream_writer: &mut BufWriter<W>,
     accounts_hash: &Hash,
     incremental_snapshot_persistence: Option<&BankIncrementalSnapshotPersistence>,
+    epoch_accounts_hash: Option<&Hash>,
 ) -> Result<(), Error>
 where
     W: Write,
@@ -400,6 +403,7 @@ where
         stream_writer,
         accounts_hash,
         incremental_snapshot_persistence,
+        epoch_accounts_hash,
     )
 }
 
@@ -413,6 +417,7 @@ pub fn reserialize_bank_with_new_accounts_hash(
     slot: Slot,
     accounts_hash: &Hash,
     incremental_snapshot_persistence: Option<&BankIncrementalSnapshotPersistence>,
+    epoch_accounts_hash: Option<&Hash>,
 ) -> bool {
     let bank_post = snapshot_utils::get_bank_snapshots_dir(bank_snapshots_dir, slot);
     let bank_post = bank_post.join(snapshot_utils::get_snapshot_file_name(slot));
@@ -431,6 +436,7 @@ pub fn reserialize_bank_with_new_accounts_hash(
                 &mut BufWriter::new(file_out),
                 accounts_hash,
                 incremental_snapshot_persistence,
+                epoch_accounts_hash,
             )
             .unwrap();
         }
@@ -541,6 +547,7 @@ where
         verify_index,
         accounts_db_config,
         accounts_update_notifier,
+        bank_fields.epoch_accounts_hash,
     )?;
 
     let bank_rc = BankRc::new(Accounts::new_empty(accounts_db), bank_fields.slot);
@@ -661,6 +668,7 @@ fn reconstruct_accountsdb_from_fields<E>(
     verify_index: bool,
     accounts_db_config: Option<AccountsDbConfig>,
     accounts_update_notifier: Option<AccountsUpdateNotifier>,
+    epoch_accounts_hash: Option<Hash>,
 ) -> Result<(AccountsDb, ReconstructedAccountsDbInfo), Error>
 where
     E: SerializableStorage + std::marker::Sync,
@@ -674,6 +682,8 @@ where
         accounts_db_config,
         accounts_update_notifier,
     );
+    *accounts_db.epoch_accounts_hash.lock().unwrap() =
+        epoch_accounts_hash.map(EpochAccountsHash::new);
 
     let AccountsDbFields(
         _snapshot_storages,

runtime/src/serde_snapshot/newer.rs

@@ -212,6 +212,9 @@ impl<'a> TypeContext<'a> for Context {
             // TODO: if we do a snapshot version bump, consider moving this out.
             lamports_per_signature,
             None::<BankIncrementalSnapshotPersistence>,
+            serializable_bank
+                .bank
+                .get_epoch_accounts_hash_to_serialize(),
         )
             .serialize(serializer)
     }
@@ -344,6 +347,7 @@ impl<'a> TypeContext<'a> for Context {
         stream_writer: &mut BufWriter<W>,
         accounts_hash: &Hash,
         incremental_snapshot_persistence: Option<&BankIncrementalSnapshotPersistence>,
+        epoch_accounts_hash: Option<&Hash>,
     ) -> std::result::Result<(), Box<bincode::ErrorKind>>
     where
         R: Read,
@@ -356,6 +360,7 @@ impl<'a> TypeContext<'a> for Context {
         let blockhash_queue = RwLock::new(rhs.blockhash_queue.clone());
         let hard_forks = RwLock::new(rhs.hard_forks.clone());
         let lamports_per_signature = rhs.fee_rate_governor.lamports_per_signature;
+        let epoch_accounts_hash = epoch_accounts_hash.or(rhs.epoch_accounts_hash.as_ref());
 
         let bank = SerializableVersionedBank {
             blockhash_queue: &blockhash_queue,
@@ -399,6 +404,7 @@ impl<'a> TypeContext<'a> for Context {
                 accounts_db_fields,
                 lamports_per_signature,
                 incremental_snapshot_persistence,
+                epoch_accounts_hash,
             ),
         )
     }

runtime/src/serde_snapshot/tests.rs

@@ -116,6 +116,7 @@ where
         false,
         Some(crate::accounts_db::ACCOUNTS_DB_CONFIG_FOR_TESTING),
         None,
+        None,
     )
     .map(|(accounts_db, _)| accounts_db)
 }
@@ -217,6 +218,8 @@ fn test_bank_serialize_style(
     reserialize_accounts_hash: bool,
     update_accounts_hash: bool,
     incremental_snapshot_persistence: bool,
+    epoch_accounts_hash: bool,
+    initial_epoch_accounts_hash: bool,
 ) {
     solana_logger::setup();
     let (genesis_config, _) = create_genesis_config(500);
@@ -245,6 +248,22 @@ fn test_bank_serialize_style(
     let snapshot_storages = bank2.get_snapshot_storages(None);
     let mut buf = vec![];
     let mut writer = Cursor::new(&mut buf);
+
+    let mut expected_epoch_accounts_hash = None;
+
+    if initial_epoch_accounts_hash {
+        expected_epoch_accounts_hash = Some(Hash::new(&[7; 32]));
+        *bank2
+            .rc
+            .accounts
+            .accounts_db
+            .epoch_accounts_hash
+            .lock()
+            .unwrap() = Some(EpochAccountsHash::new(
+            expected_epoch_accounts_hash.unwrap(),
+        ));
+    }
+
     crate::serde_snapshot::bank_to_stream(
         serde_style,
         &mut std::io::BufWriter::new(&mut writer),
@@ -274,7 +293,7 @@ fn test_bank_serialize_style(
             incremental_capitalization: 32,
         });
 
-    if reserialize_accounts_hash || incremental_snapshot_persistence {
+    if reserialize_accounts_hash || incremental_snapshot_persistence || epoch_accounts_hash {
         let temp_dir = TempDir::new().unwrap();
         let slot_dir = temp_dir.path().join(slot.to_string());
         let post_path = slot_dir.join(slot.to_string());
@@ -286,36 +305,71 @@ fn test_bank_serialize_style(
             f.write_all(&buf).unwrap();
         }
 
+        let reserialized_epoch_accounts_hash = if epoch_accounts_hash {
+            expected_epoch_accounts_hash = Some(Hash::new(&[3; 32]));
+            expected_epoch_accounts_hash
+        } else {
+            None
+        };
+
         assert!(reserialize_bank_with_new_accounts_hash(
             temp_dir.path(),
             slot,
             &accounts_hash,
             incremental.as_ref(),
+            reserialized_epoch_accounts_hash.as_ref(),
         ));
-        let previous_len = buf.len();
-        // larger buffer than expected to make sure the file isn't larger than expected
-        let sizeof_none = std::mem::size_of::<u64>();
-        let sizeof_incremental_snapshot_persistence =
-            std::mem::size_of::<Option<BankIncrementalSnapshotPersistence>>();
-        let mut buf_reserialized =
-            vec![0; previous_len + sizeof_incremental_snapshot_persistence + 1];
+        let mut buf_reserialized;
         {
+            let previous_len = buf.len();
+            let expected = previous_len
+                + if incremental_snapshot_persistence {
+                    // previously saved a none (size = sizeof_None), now added a Some
+                    let sizeof_none = std::mem::size_of::<u64>();
+                    let sizeof_incremental_snapshot_persistence =
+                        std::mem::size_of::<Option<BankIncrementalSnapshotPersistence>>();
+                    sizeof_incremental_snapshot_persistence - sizeof_none
+                } else {
+                    // no change
+                    0
+                }
+                + if epoch_accounts_hash && !initial_epoch_accounts_hash {
+                    // previously saved a none (size 1), now added a Some
+                    let sizeof_epoch_accounts_hash_persistence =
+                        std::mem::size_of::<Option<Hash>>();
+                    sizeof_epoch_accounts_hash_persistence - 1
+                } else {
+                    // no change
+                    0
+                };
+
+            // +1: larger buffer than expected to make sure the file isn't larger than expected
+            buf_reserialized = vec![0; expected + 1];
             let mut f = std::fs::File::open(post_path).unwrap();
             let size = f.read(&mut buf_reserialized).unwrap();
-            let expected = if !incremental_snapshot_persistence {
-                previous_len
-            } else {
-                previous_len + sizeof_incremental_snapshot_persistence - sizeof_none
-            };
-            assert_eq!(size, expected);
+
+            assert_eq!(
+                size,
+                expected,
+                "(reserialize_accounts_hash, incremental_snapshot_persistence, epoch_accounts_hash, update_accounts_hash, initial_epoch_accounts_hash): {:?}, previous_len: {previous_len}",
+                (
+                    reserialize_accounts_hash,
+                    incremental_snapshot_persistence,
+                    epoch_accounts_hash,
+                    update_accounts_hash,
+                    initial_epoch_accounts_hash,
+                )
+            );
             buf_reserialized.truncate(size);
         }
-        if update_accounts_hash || incremental_snapshot_persistence {
+        if update_accounts_hash {
             // We cannot guarantee buffer contents are exactly the same if hash is the same.
             // Things like hashsets/maps have randomness in their in-mem representations.
-            // This make serialized bytes not deterministic.
+            // This makes serialized bytes not deterministic.
             // But, we can guarantee that the buffer is different if we change the hash!
             assert_ne!(buf, buf_reserialized);
+        }
+        if update_accounts_hash || incremental_snapshot_persistence || epoch_accounts_hash {
             buf = buf_reserialized;
         }
     }
@@ -360,6 +414,16 @@ fn test_bank_serialize_style(
     assert_eq!(dbank.get_accounts_hash(), accounts_hash);
     assert!(bank2 == dbank);
     assert_eq!(dbank.incremental_snapshot_persistence, incremental);
+    assert_eq!(dbank.rc.accounts.accounts_db.epoch_accounts_hash.lock().unwrap().map(|hash| *hash.as_ref()), expected_epoch_accounts_hash,
+        "(reserialize_accounts_hash, incremental_snapshot_persistence, epoch_accounts_hash, update_accounts_hash, initial_epoch_accounts_hash): {:?}",
+        (
+            reserialize_accounts_hash,
+            incremental_snapshot_persistence,
+            epoch_accounts_hash,
+            update_accounts_hash,
+            initial_epoch_accounts_hash,
+        )
+    );
 }
 
 pub(crate) fn reconstruct_accounts_db_via_serialization(
@@ -413,17 +477,24 @@ fn test_bank_serialize_newer() {
     for (reserialize_accounts_hash, update_accounts_hash) in
         [(false, false), (true, false), (true, true)]
     {
-        for incremental_snapshot_persistence in if reserialize_accounts_hash {
+        let parameters = if reserialize_accounts_hash {
             [false, true].to_vec()
         } else {
             [false].to_vec()
-        } {
-            test_bank_serialize_style(
-                SerdeStyle::Newer,
-                reserialize_accounts_hash,
-                update_accounts_hash,
-                incremental_snapshot_persistence,
-            )
+        };
+        for incremental_snapshot_persistence in parameters.clone() {
+            for epoch_accounts_hash in parameters.clone() {
+                for initial_epoch_accounts_hash in parameters.clone() {
+                    test_bank_serialize_style(
+                        SerdeStyle::Newer,
+                        reserialize_accounts_hash,
+                        update_accounts_hash,
+                        incremental_snapshot_persistence,
+                        epoch_accounts_hash,
+                        initial_epoch_accounts_hash,
+                    )
+                }
+            }
         }
     }
 }
@@ -616,7 +687,7 @@ mod test_bank_serialize {
 
     // This some what long test harness is required to freeze the ABI of
     // Bank's serialization due to versioned nature
-    #[frozen_abi(digest = "5py4Wkuj5fV2sLyA1MrPg4pGNwMEaygQLnpLyY8MMLGC")]
+    #[frozen_abi(digest = "7SZNRErAktC7sRcpChrcHfsr9Uw7XXoSzNbYzoNtoQCr")]
     #[derive(Serialize, AbiExample)]
     pub struct BankAbiTestWrapperNewer {
         #[serde(serialize_with = "wrapper_newer")]

runtime/src/snapshot_utils.rs

@@ -2297,6 +2297,7 @@ pub fn package_and_archive_full_snapshot(
         accounts_package.slot,
         &bank.get_accounts_hash(),
         None,
+        None, // todo: this needs to be passed through
     );
 
     let snapshot_package = SnapshotPackage::new(accounts_package, bank.get_accounts_hash());
@@ -2350,6 +2351,7 @@ pub fn package_and_archive_incremental_snapshot(
         accounts_package.slot,
         &bank.get_accounts_hash(),
         None,
+        None, // todo: this needs to be passed through
     );
 
     let snapshot_package = SnapshotPackage::new(accounts_package, bank.get_accounts_hash());