solana_accounts_db/

accounts.rs

use {
    crate::{
        accounts_db::{
            AccountsAddRootTiming, AccountsDb, LoadHint, LoadedAccount, ScanStorageResult,
            VerifyAccountsHashAndLamportsConfig,
        },
        accounts_index::{IndexKey, ScanConfig, ScanError, ScanResult, ZeroLamport},
        ancestors::Ancestors,
        nonce_info::{NonceFull, NonceInfo},
        rent_collector::RentCollector,
        rent_debits::RentDebits,
        storable_accounts::StorableAccounts,
        transaction_results::TransactionExecutionResult,
    },
    dashmap::DashMap,
    log::*,
    solana_sdk::{
        account::{AccountSharedData, ReadableAccount},
        account_utils::StateMut,
        address_lookup_table::{self, error::AddressLookupError, state::AddressLookupTable},
        clock::{BankId, Slot},
        message::v0::{LoadedAddresses, MessageAddressTableLookup},
        nonce::{
            state::{DurableNonce, Versions as NonceVersions},
            State as NonceState,
        },
        pubkey::Pubkey,
        slot_hashes::SlotHashes,
        transaction::{Result, SanitizedTransaction, TransactionAccountLocks, TransactionError},
        transaction_context::{IndexOfAccount, TransactionAccount},
    },
    std::{
        cmp::Reverse,
        collections::{
            hash_map::{self},
            BinaryHeap, HashMap, HashSet,
        },
        ops::RangeBounds,
        sync::{
            atomic::{AtomicUsize, Ordering},
            Arc, Mutex,
        },
    },
};

pub type PubkeyAccountSlot = (Pubkey, AccountSharedData, Slot);

#[derive(Debug, Default, AbiExample)]
pub struct AccountLocks {
    write_locks: HashSet<Pubkey>,
    readonly_locks: HashMap<Pubkey, u64>,
}

impl AccountLocks {
    fn is_locked_readonly(&self, key: &Pubkey) -> bool {
        self.readonly_locks
            .get(key)
            .map_or(false, |count| *count > 0)
    }

    fn is_locked_write(&self, key: &Pubkey) -> bool {
        self.write_locks.contains(key)
    }

    fn insert_new_readonly(&mut self, key: &Pubkey) {
        assert!(self.readonly_locks.insert(*key, 1).is_none());
    }

    fn lock_readonly(&mut self, key: &Pubkey) -> bool {
        self.readonly_locks.get_mut(key).map_or(false, |count| {
            *count += 1;
            true
        })
    }

    fn unlock_readonly(&mut self, key: &Pubkey) {
        if let hash_map::Entry::Occupied(mut occupied_entry) = self.readonly_locks.entry(*key) {
            let count = occupied_entry.get_mut();
            *count -= 1;
            if *count == 0 {
                occupied_entry.remove_entry();
            }
        }
    }

    fn unlock_write(&mut self, key: &Pubkey) {
        self.write_locks.remove(key);
    }
}

/// This structure handles synchronization for db
#[derive(Debug, AbiExample)]
pub struct Accounts {
    /// Single global AccountsDb
    pub accounts_db: Arc<AccountsDb>,

    /// set of read-only and writable accounts which are currently
    /// being processed by banking/replay threads
    pub(crate) account_locks: Mutex<AccountLocks>,
}

// for the load instructions
pub type TransactionRent = u64;
pub type TransactionProgramIndices = Vec<Vec<IndexOfAccount>>;
#[derive(PartialEq, Eq, Debug, Clone)]
pub struct LoadedTransaction {
    pub accounts: Vec<TransactionAccount>,
    pub program_indices: TransactionProgramIndices,
    pub rent: TransactionRent,
    pub rent_debits: RentDebits,
}

pub type TransactionLoadResult = (Result<LoadedTransaction>, Option<NonceFull>);

pub enum AccountAddressFilter {
    Exclude, // exclude all addresses matching the filter
    Include, // only include addresses matching the filter
}

impl Accounts {
    pub fn new(accounts_db: Arc<AccountsDb>) -> Self {
        Self {
            accounts_db,
            account_locks: Mutex::new(AccountLocks::default()),
        }
    }

    pub fn load_lookup_table_addresses(
        &self,
        ancestors: &Ancestors,
        address_table_lookup: &MessageAddressTableLookup,
        slot_hashes: &SlotHashes,
    ) -> std::result::Result<LoadedAddresses, AddressLookupError> {
        let table_account = self
            .accounts_db
            .load_with_fixed_root(ancestors, &address_table_lookup.account_key)
            .map(|(account, _rent)| account)
            .ok_or(AddressLookupError::LookupTableAccountNotFound)?;

        if table_account.owner() == &address_lookup_table::program::id() {
            let current_slot = ancestors.max_slot();
            let lookup_table = AddressLookupTable::deserialize(table_account.data())
                .map_err(|_ix_err| AddressLookupError::InvalidAccountData)?;

            Ok(LoadedAddresses {
                writable: lookup_table.lookup(
                    current_slot,
                    &address_table_lookup.writable_indexes,
                    slot_hashes,
                )?,
                readonly: lookup_table.lookup(
                    current_slot,
                    &address_table_lookup.readonly_indexes,
                    slot_hashes,
                )?,
            })
        } else {
            Err(AddressLookupError::InvalidAccountOwner)
        }
    }

    /// Slow because lock is held for 1 operation instead of many
    /// This always returns None for zero-lamport accounts.
    fn load_slow(
        &self,
        ancestors: &Ancestors,
        pubkey: &Pubkey,
        load_hint: LoadHint,
    ) -> Option<(AccountSharedData, Slot)> {
        self.accounts_db.load(ancestors, pubkey, load_hint)
    }

    pub fn load_with_fixed_root(
        &self,
        ancestors: &Ancestors,
        pubkey: &Pubkey,
    ) -> Option<(AccountSharedData, Slot)> {
        self.load_slow(ancestors, pubkey, LoadHint::FixedMaxRoot)
    }

    pub fn load_without_fixed_root(
        &self,
        ancestors: &Ancestors,
        pubkey: &Pubkey,
    ) -> Option<(AccountSharedData, Slot)> {
        self.load_slow(ancestors, pubkey, LoadHint::Unspecified)
    }

    /// scans underlying accounts_db for this delta (slot) with a map function
    ///   from LoadedAccount to B
    /// returns only the latest/current version of B for this slot
    pub fn scan_slot<F, B>(&self, slot: Slot, func: F) -> Vec<B>
    where
        F: Fn(LoadedAccount) -> Option<B> + Send + Sync,
        B: Sync + Send + Default + std::cmp::Eq,
    {
        let scan_result = self.accounts_db.scan_account_storage(
            slot,
            |loaded_account: LoadedAccount| {
                // Cache only has one version per key, don't need to worry about versioning
                func(loaded_account)
            },
            |accum: &DashMap<Pubkey, B>, loaded_account: LoadedAccount| {
                let loaded_account_pubkey = *loaded_account.pubkey();
                if let Some(val) = func(loaded_account) {
                    accum.insert(loaded_account_pubkey, val);
                }
            },
        );

        match scan_result {
            ScanStorageResult::Cached(cached_result) => cached_result,
            ScanStorageResult::Stored(stored_result) => stored_result
                .into_iter()
                .map(|(_pubkey, val)| val)
                .collect(),
        }
    }

    /// Returns all the accounts from `slot`
    ///
    /// If `program_id` is `Some`, filter the results to those whose owner matches `program_id`
    pub fn load_by_program_slot(
        &self,
        slot: Slot,
        program_id: Option<&Pubkey>,
    ) -> Vec<TransactionAccount> {
        self.scan_slot(slot, |stored_account| {
            program_id
                .map(|program_id| program_id == stored_account.owner())
                .unwrap_or(true)
                .then(|| (*stored_account.pubkey(), stored_account.take_account()))
        })
    }

    pub fn load_largest_accounts(
        &self,
        ancestors: &Ancestors,
        bank_id: BankId,
        num: usize,
        filter_by_address: &HashSet<Pubkey>,
        filter: AccountAddressFilter,
    ) -> ScanResult<Vec<(Pubkey, u64)>> {
        if num == 0 {
            return Ok(vec![]);
        }
        let mut account_balances = BinaryHeap::new();
        self.accounts_db.scan_accounts(
            ancestors,
            bank_id,
            |option| {
                if let Some((pubkey, account, _slot)) = option {
                    if account.lamports() == 0 {
                        return;
                    }
                    let contains_address = filter_by_address.contains(pubkey);
                    let collect = match filter {
                        AccountAddressFilter::Exclude => !contains_address,
                        AccountAddressFilter::Include => contains_address,
                    };
                    if !collect {
                        return;
                    }
                    if account_balances.len() == num {
                        let Reverse(entry) = account_balances
                            .peek()
                            .expect("BinaryHeap::peek should succeed when len > 0");
                        if *entry >= (account.lamports(), *pubkey) {
                            return;
                        }
                        account_balances.pop();
                    }
                    account_balances.push(Reverse((account.lamports(), *pubkey)));
                }
            },
            &ScanConfig::default(),
        )?;
        Ok(account_balances
            .into_sorted_vec()
            .into_iter()
            .map(|Reverse((balance, pubkey))| (pubkey, balance))
            .collect())
    }

    /// Only called from startup or test code.
    #[must_use]
    pub fn verify_accounts_hash_and_lamports(
        &self,
        slot: Slot,
        total_lamports: u64,
        base: Option<(Slot, /*capitalization*/ u64)>,
        config: VerifyAccountsHashAndLamportsConfig,
    ) -> bool {
        if let Err(err) =
            self.accounts_db
                .verify_accounts_hash_and_lamports(slot, total_lamports, base, config)
        {
            warn!("verify_accounts_hash failed: {err:?}, slot: {slot}");
            false
        } else {
            true
        }
    }

    pub fn is_loadable(lamports: u64) -> bool {
        // Don't ever load zero lamport accounts into runtime because
        // the existence of zero-lamport accounts are never deterministic!!
        lamports > 0
    }

    fn load_while_filtering<F: Fn(&AccountSharedData) -> bool>(
        collector: &mut Vec<TransactionAccount>,
        some_account_tuple: Option<(&Pubkey, AccountSharedData, Slot)>,
        filter: F,
    ) {
        if let Some(mapped_account_tuple) = some_account_tuple
            .filter(|(_, account, _)| Self::is_loadable(account.lamports()) && filter(account))
            .map(|(pubkey, account, _slot)| (*pubkey, account))
        {
            collector.push(mapped_account_tuple)
        }
    }

    fn load_with_slot(
        collector: &mut Vec<PubkeyAccountSlot>,
        some_account_tuple: Option<(&Pubkey, AccountSharedData, Slot)>,
    ) {
        if let Some(mapped_account_tuple) = some_account_tuple
            .filter(|(_, account, _)| Self::is_loadable(account.lamports()))
            .map(|(pubkey, account, slot)| (*pubkey, account, slot))
        {
            collector.push(mapped_account_tuple)
        }
    }

    pub fn load_by_program(
        &self,
        ancestors: &Ancestors,
        bank_id: BankId,
        program_id: &Pubkey,
        config: &ScanConfig,
    ) -> ScanResult<Vec<TransactionAccount>> {
        let mut collector = Vec::new();
        self.accounts_db
            .scan_accounts(
                ancestors,
                bank_id,
                |some_account_tuple| {
                    Self::load_while_filtering(&mut collector, some_account_tuple, |account| {
                        account.owner() == program_id
                    })
                },
                config,
            )
            .map(|_| collector)
    }

    pub fn load_by_program_with_filter<F: Fn(&AccountSharedData) -> bool>(
        &self,
        ancestors: &Ancestors,
        bank_id: BankId,
        program_id: &Pubkey,
        filter: F,
        config: &ScanConfig,
    ) -> ScanResult<Vec<TransactionAccount>> {
        let mut collector = Vec::new();
        self.accounts_db
            .scan_accounts(
                ancestors,
                bank_id,
                |some_account_tuple| {
                    Self::load_while_filtering(&mut collector, some_account_tuple, |account| {
                        account.owner() == program_id && filter(account)
                    })
                },
                config,
            )
            .map(|_| collector)
    }

    fn calc_scan_result_size(account: &AccountSharedData) -> usize {
        account.data().len()
            + std::mem::size_of::<AccountSharedData>()
            + std::mem::size_of::<Pubkey>()
    }

    /// Accumulate size of (pubkey + account) into sum.
    /// Return true iff sum > 'byte_limit_for_scan'
    fn accumulate_and_check_scan_result_size(
        sum: &AtomicUsize,
        account: &AccountSharedData,
        byte_limit_for_scan: &Option<usize>,
    ) -> bool {
        if let Some(byte_limit_for_scan) = byte_limit_for_scan.as_ref() {
            let added = Self::calc_scan_result_size(account);
            sum.fetch_add(added, Ordering::Relaxed)
                .saturating_add(added)
                > *byte_limit_for_scan
        } else {
            false
        }
    }

    fn maybe_abort_scan(
        result: ScanResult<Vec<TransactionAccount>>,
        config: &ScanConfig,
    ) -> ScanResult<Vec<TransactionAccount>> {
        if config.is_aborted() {
            ScanResult::Err(ScanError::Aborted(
                "The accumulated scan results exceeded the limit".to_string(),
            ))
        } else {
            result
        }
    }

    pub fn load_by_index_key_with_filter<F: Fn(&AccountSharedData) -> bool>(
        &self,
        ancestors: &Ancestors,
        bank_id: BankId,
        index_key: &IndexKey,
        filter: F,
        config: &ScanConfig,
        byte_limit_for_scan: Option<usize>,
    ) -> ScanResult<Vec<TransactionAccount>> {
        let sum = AtomicUsize::default();
        let config = config.recreate_with_abort();
        let mut collector = Vec::new();
        let result = self
            .accounts_db
            .index_scan_accounts(
                ancestors,
                bank_id,
                *index_key,
                |some_account_tuple| {
                    Self::load_while_filtering(&mut collector, some_account_tuple, |account| {
                        let use_account = filter(account);
                        if use_account
                            && Self::accumulate_and_check_scan_result_size(
                                &sum,
                                account,
                                &byte_limit_for_scan,
                            )
                        {
                            // total size of results exceeds size limit, so abort scan
                            config.abort();
                        }
                        use_account
                    });
                },
                &config,
            )
            .map(|_| collector);
        Self::maybe_abort_scan(result, &config)
    }

    pub fn account_indexes_include_key(&self, key: &Pubkey) -> bool {
        self.accounts_db.account_indexes.include_key(key)
    }

    pub fn load_all(
        &self,
        ancestors: &Ancestors,
        bank_id: BankId,
    ) -> ScanResult<Vec<PubkeyAccountSlot>> {
        let mut collector = Vec::new();
        self.accounts_db
            .scan_accounts(
                ancestors,
                bank_id,
                |some_account_tuple| {
                    if let Some((pubkey, account, slot)) = some_account_tuple
                        .filter(|(_, account, _)| Self::is_loadable(account.lamports()))
                    {
                        collector.push((*pubkey, account, slot))
                    }
                },
                &ScanConfig::default(),
            )
            .map(|_| collector)
    }

    pub fn scan_all<F>(
        &self,
        ancestors: &Ancestors,
        bank_id: BankId,
        scan_func: F,
    ) -> ScanResult<()>
    where
        F: FnMut(Option<(&Pubkey, AccountSharedData, Slot)>),
    {
        self.accounts_db
            .scan_accounts(ancestors, bank_id, scan_func, &ScanConfig::default())
    }

    pub fn hold_range_in_memory<R>(
        &self,
        range: &R,
        start_holding: bool,
        thread_pool: &rayon::ThreadPool,
    ) where
        R: RangeBounds<Pubkey> + std::fmt::Debug + Sync,
    {
        self.accounts_db
            .accounts_index
            .hold_range_in_memory(range, start_holding, thread_pool)
    }

    pub fn load_to_collect_rent_eagerly<R: RangeBounds<Pubkey> + std::fmt::Debug>(
        &self,
        ancestors: &Ancestors,
        range: R,
    ) -> Vec<PubkeyAccountSlot> {
        let mut collector = Vec::new();
        self.accounts_db.range_scan_accounts(
            "", // disable logging of this. We now parallelize it and this results in multiple parallel logs
            ancestors,
            range,
            &ScanConfig::new(true),
            |option| Self::load_with_slot(&mut collector, option),
        );
        collector
    }

    /// Slow because lock is held for 1 operation instead of many.
    /// WARNING: This noncached version is only to be used for tests/benchmarking
    /// as bypassing the cache in general is not supported
    pub fn store_slow_uncached(&self, slot: Slot, pubkey: &Pubkey, account: &AccountSharedData) {
        self.accounts_db.store_uncached(slot, &[(pubkey, account)]);
    }

    fn lock_account(
        &self,
        account_locks: &mut AccountLocks,
        writable_keys: Vec<&Pubkey>,
        readonly_keys: Vec<&Pubkey>,
    ) -> Result<()> {
        for k in writable_keys.iter() {
            if account_locks.is_locked_write(k) || account_locks.is_locked_readonly(k) {
                debug!("Writable account in use: {:?}", k);
                return Err(TransactionError::AccountInUse);
            }
        }
        for k in readonly_keys.iter() {
            if account_locks.is_locked_write(k) {
                debug!("Read-only account in use: {:?}", k);
                return Err(TransactionError::AccountInUse);
            }
        }

        for k in writable_keys {
            account_locks.write_locks.insert(*k);
        }

        for k in readonly_keys {
            if !account_locks.lock_readonly(k) {
                account_locks.insert_new_readonly(k);
            }
        }

        Ok(())
    }

    fn unlock_account(
        &self,
        account_locks: &mut AccountLocks,
        writable_keys: Vec<&Pubkey>,
        readonly_keys: Vec<&Pubkey>,
    ) {
        for k in writable_keys {
            account_locks.unlock_write(k);
        }
        for k in readonly_keys {
            account_locks.unlock_readonly(k);
        }
    }

    /// This function will prevent multiple threads from modifying the same account state at the
    /// same time
    #[must_use]
    #[allow(clippy::needless_collect)]
    pub fn lock_accounts<'a>(
        &self,
        txs: impl Iterator<Item = &'a SanitizedTransaction>,
        tx_account_lock_limit: usize,
    ) -> Vec<Result<()>> {
        let tx_account_locks_results: Vec<Result<_>> = txs
            .map(|tx| tx.get_account_locks(tx_account_lock_limit))
            .collect();
        self.lock_accounts_inner(tx_account_locks_results)
    }

    #[must_use]
    #[allow(clippy::needless_collect)]
    pub fn lock_accounts_with_results<'a>(
        &self,
        txs: impl Iterator<Item = &'a SanitizedTransaction>,
        results: impl Iterator<Item = Result<()>>,
        tx_account_lock_limit: usize,
    ) -> Vec<Result<()>> {
        let tx_account_locks_results: Vec<Result<_>> = txs
            .zip(results)
            .map(|(tx, result)| match result {
                Ok(()) => tx.get_account_locks(tx_account_lock_limit),
                Err(err) => Err(err),
            })
            .collect();
        self.lock_accounts_inner(tx_account_locks_results)
    }

    #[must_use]
    fn lock_accounts_inner(
        &self,
        tx_account_locks_results: Vec<Result<TransactionAccountLocks>>,
    ) -> Vec<Result<()>> {
        let account_locks = &mut self.account_locks.lock().unwrap();
        tx_account_locks_results
            .into_iter()
            .map(|tx_account_locks_result| match tx_account_locks_result {
                Ok(tx_account_locks) => self.lock_account(
                    account_locks,
                    tx_account_locks.writable,
                    tx_account_locks.readonly,
                ),
                Err(err) => Err(err),
            })
            .collect()
    }

    /// Once accounts are unlocked, new transactions that modify that state can enter the pipeline
    #[allow(clippy::needless_collect)]
    pub fn unlock_accounts<'a>(
        &self,
        txs: impl Iterator<Item = &'a SanitizedTransaction>,
        results: &[Result<()>],
    ) {
        let keys: Vec<_> = txs
            .zip(results)
            .filter(|(_, res)| res.is_ok())
            .map(|(tx, _)| tx.get_account_locks_unchecked())
            .collect();
        let mut account_locks = self.account_locks.lock().unwrap();
        debug!("bank unlock accounts");
        keys.into_iter().for_each(|keys| {
            self.unlock_account(&mut account_locks, keys.writable, keys.readonly);
        });
    }

    /// Store the accounts into the DB
    // allow(clippy) needed for various gating flags
    #[allow(clippy::too_many_arguments)]
    pub fn store_cached(
        &self,
        slot: Slot,
        txs: &[SanitizedTransaction],
        res: &[TransactionExecutionResult],
        loaded: &mut [TransactionLoadResult],
        rent_collector: &RentCollector,
        durable_nonce: &DurableNonce,
        lamports_per_signature: u64,
    ) {
        let (accounts_to_store, transactions) = self.collect_accounts_to_store(
            txs,
            res,
            loaded,
            rent_collector,
            durable_nonce,
            lamports_per_signature,
        );
        self.accounts_db
            .store_cached_inline_update_index((slot, &accounts_to_store[..]), Some(&transactions));
    }

    pub fn store_accounts_cached<'a, T: ReadableAccount + Sync + ZeroLamport + 'a>(
        &self,
        accounts: impl StorableAccounts<'a, T>,
    ) {
        self.accounts_db.store_cached(accounts, None)
    }

    /// Add a slot to root.  Root slots cannot be purged
    pub fn add_root(&self, slot: Slot) -> AccountsAddRootTiming {
        self.accounts_db.add_root(slot)
    }

    #[allow(clippy::too_many_arguments)]
    fn collect_accounts_to_store<'a>(
        &self,
        txs: &'a [SanitizedTransaction],
        execution_results: &'a [TransactionExecutionResult],
        load_results: &'a mut [TransactionLoadResult],
        _rent_collector: &RentCollector,
        durable_nonce: &DurableNonce,
        lamports_per_signature: u64,
    ) -> (
        Vec<(&'a Pubkey, &'a AccountSharedData)>,
        Vec<Option<&'a SanitizedTransaction>>,
    ) {
        let mut accounts = Vec::with_capacity(load_results.len());
        let mut transactions = Vec::with_capacity(load_results.len());
        for (i, ((tx_load_result, nonce), tx)) in load_results.iter_mut().zip(txs).enumerate() {
            if tx_load_result.is_err() {
                // Don't store any accounts if tx failed to load
                continue;
            }

            let execution_status = match &execution_results[i] {
                TransactionExecutionResult::Executed { details, .. } => &details.status,
                // Don't store any accounts if tx wasn't executed
                TransactionExecutionResult::NotExecuted(_) => continue,
            };

            let maybe_nonce = match (execution_status, &*nonce) {
                (Ok(_), _) => None, // Success, don't do any additional nonce processing
                (Err(_), Some(nonce)) => {
                    Some((nonce, true /* rollback */))
                }
                (Err(_), None) => {
                    // Fees for failed transactions which don't use durable nonces are
                    // deducted in Bank::filter_program_errors_and_collect_fee
                    continue;
                }
            };

            let message = tx.message();
            let loaded_transaction = tx_load_result.as_mut().unwrap();
            let mut fee_payer_index = None;
            for (i, (address, account)) in (0..message.account_keys().len())
                .zip(loaded_transaction.accounts.iter_mut())
                .filter(|(i, _)| message.is_non_loader_key(*i))
            {
                if fee_payer_index.is_none() {
                    fee_payer_index = Some(i);
                }
                let is_fee_payer = Some(i) == fee_payer_index;
                if message.is_writable(i) {
                    let is_nonce_account = prepare_if_nonce_account(
                        address,
                        account,
                        execution_status,
                        is_fee_payer,
                        maybe_nonce,
                        durable_nonce,
                        lamports_per_signature,
                    );

                    if execution_status.is_ok() || is_nonce_account || is_fee_payer {
                        // Add to the accounts to store
                        accounts.push((&*address, &*account));
                        transactions.push(Some(tx));
                    }
                }
            }
        }
        (accounts, transactions)
    }
}

fn prepare_if_nonce_account(
    address: &Pubkey,
    account: &mut AccountSharedData,
    execution_result: &Result<()>,
    is_fee_payer: bool,
    maybe_nonce: Option<(&NonceFull, bool)>,
    &durable_nonce: &DurableNonce,
    lamports_per_signature: u64,
) -> bool {
    if let Some((nonce, rollback)) = maybe_nonce {
        if address == nonce.address() {
            if rollback {
                // The transaction failed which would normally drop the account
                // processing changes, since this account is now being included
                // in the accounts written back to the db, roll it back to
                // pre-processing state.
                *account = nonce.account().clone();
            }

            // Advance the stored blockhash to prevent fee theft by someone
            // replaying nonce transactions that have failed with an
            // `InstructionError`.
            //
            // Since we know we are dealing with a valid nonce account,
            // unwrap is safe here
            let nonce_versions = StateMut::<NonceVersions>::state(nonce.account()).unwrap();
            if let NonceState::Initialized(ref data) = nonce_versions.state() {
                let nonce_state = NonceState::new_initialized(
                    &data.authority,
                    durable_nonce,
                    lamports_per_signature,
                );
                let nonce_versions = NonceVersions::new(nonce_state);
                account.set_state(&nonce_versions).unwrap();
            }
            true
        } else {
            if execution_result.is_err() && is_fee_payer {
                if let Some(fee_payer_account) = nonce.fee_payer_account() {
                    // Instruction error and fee-payer for this nonce tx is not
                    // the nonce account itself, rollback the fee payer to the
                    // fee-paid original state.
                    *account = fee_payer_account.clone();
                }
            }

            false
        }
    } else {
        false
    }
}

#[cfg(test)]
mod tests {
    use {
        super::*,
        crate::{
            rent_collector::RentCollector,
            transaction_results::{DurableNonceFee, TransactionExecutionDetails},
        },
        assert_matches::assert_matches,
        solana_program_runtime::loaded_programs::LoadedProgramsForTxBatch,
        solana_sdk::{
            account::{AccountSharedData, WritableAccount},
            address_lookup_table::state::LookupTableMeta,
            hash::Hash,
            instruction::{CompiledInstruction, InstructionError},
            message::{Message, MessageHeader},
            native_loader, nonce, nonce_account,
            signature::{keypair_from_seed, signers::Signers, Keypair, Signer},
            system_instruction, system_program,
            transaction::{Transaction, MAX_TX_ACCOUNT_LOCKS},
        },
        std::{
            borrow::Cow,
            sync::atomic::{AtomicBool, AtomicU64, Ordering},
            thread, time,
        },
    };

    fn new_sanitized_tx<T: Signers>(
        from_keypairs: &T,
        message: Message,
        recent_blockhash: Hash,
    ) -> SanitizedTransaction {
        SanitizedTransaction::from_transaction_for_tests(Transaction::new(
            from_keypairs,
            message,
            recent_blockhash,
        ))
    }

    fn new_execution_result(
        status: Result<()>,
        nonce: Option<&NonceFull>,
    ) -> TransactionExecutionResult {
        TransactionExecutionResult::Executed {
            details: TransactionExecutionDetails {
                status,
                log_messages: None,
                inner_instructions: None,
                durable_nonce_fee: nonce.map(DurableNonceFee::from),
                return_data: None,
                executed_units: 0,
                accounts_data_len_delta: 0,
            },
            programs_modified_by_tx: Box::<LoadedProgramsForTxBatch>::default(),
        }
    }

    #[test]
    fn test_hold_range_in_memory() {
        let accounts_db = AccountsDb::default_for_tests();
        let accts = Accounts::new(Arc::new(accounts_db));
        let range = Pubkey::from([0; 32])..=Pubkey::from([0xff; 32]);
        accts.hold_range_in_memory(&range, true, &test_thread_pool());
        accts.hold_range_in_memory(&range, false, &test_thread_pool());
        accts.hold_range_in_memory(&range, true, &test_thread_pool());
        accts.hold_range_in_memory(&range, true, &test_thread_pool());
        accts.hold_range_in_memory(&range, false, &test_thread_pool());
        accts.hold_range_in_memory(&range, false, &test_thread_pool());
    }

    #[test]
    fn test_hold_range_in_memory2() {
        let accounts_db = AccountsDb::default_for_tests();
        let accts = Accounts::new(Arc::new(accounts_db));
        let range = Pubkey::from([0; 32])..=Pubkey::from([0xff; 32]);
        let idx = &accts.accounts_db.accounts_index;
        let bins = idx.account_maps.len();
        // use bins * 2 to get the first half of the range within bin 0
        let bins_2 = bins * 2;
        let binner = crate::pubkey_bins::PubkeyBinCalculator24::new(bins_2);
        let range2 =
            binner.lowest_pubkey_from_bin(0, bins_2)..binner.lowest_pubkey_from_bin(1, bins_2);
        let range2_inclusive = range2.start..=range2.end;
        assert_eq!(0, idx.bin_calculator.bin_from_pubkey(&range2.start));
        assert_eq!(0, idx.bin_calculator.bin_from_pubkey(&range2.end));
        accts.hold_range_in_memory(&range, true, &test_thread_pool());
        idx.account_maps.iter().for_each(|map| {
            assert_eq!(
                map.cache_ranges_held.read().unwrap().to_vec(),
                vec![range.clone()]
            );
        });
        accts.hold_range_in_memory(&range2, true, &test_thread_pool());
        idx.account_maps.iter().enumerate().for_each(|(bin, map)| {
            let expected = if bin == 0 {
                vec![range.clone(), range2_inclusive.clone()]
            } else {
                vec![range.clone()]
            };
            assert_eq!(
                map.cache_ranges_held.read().unwrap().to_vec(),
                expected,
                "bin: {bin}"
            );
        });
        accts.hold_range_in_memory(&range, false, &test_thread_pool());
        accts.hold_range_in_memory(&range2, false, &test_thread_pool());
    }

    fn test_thread_pool() -> rayon::ThreadPool {
        crate::accounts_db::make_min_priority_thread_pool()
    }

    #[test]
    fn test_load_lookup_table_addresses_account_not_found() {
        let ancestors = vec![(0, 0)].into_iter().collect();
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        let invalid_table_key = Pubkey::new_unique();
        let address_table_lookup = MessageAddressTableLookup {
            account_key: invalid_table_key,
            writable_indexes: vec![],
            readonly_indexes: vec![],
        };

        assert_eq!(
            accounts.load_lookup_table_addresses(
                &ancestors,
                &address_table_lookup,
                &SlotHashes::default(),
            ),
            Err(AddressLookupError::LookupTableAccountNotFound),
        );
    }

    #[test]
    fn test_load_lookup_table_addresses_invalid_account_owner() {
        let ancestors = vec![(0, 0)].into_iter().collect();
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        let invalid_table_key = Pubkey::new_unique();
        let mut invalid_table_account = AccountSharedData::default();
        invalid_table_account.set_lamports(1);
        accounts.store_slow_uncached(0, &invalid_table_key, &invalid_table_account);

        let address_table_lookup = MessageAddressTableLookup {
            account_key: invalid_table_key,
            writable_indexes: vec![],
            readonly_indexes: vec![],
        };

        assert_eq!(
            accounts.load_lookup_table_addresses(
                &ancestors,
                &address_table_lookup,
                &SlotHashes::default(),
            ),
            Err(AddressLookupError::InvalidAccountOwner),
        );
    }

    #[test]
    fn test_load_lookup_table_addresses_invalid_account_data() {
        let ancestors = vec![(0, 0)].into_iter().collect();
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        let invalid_table_key = Pubkey::new_unique();
        let invalid_table_account =
            AccountSharedData::new(1, 0, &address_lookup_table::program::id());
        accounts.store_slow_uncached(0, &invalid_table_key, &invalid_table_account);

        let address_table_lookup = MessageAddressTableLookup {
            account_key: invalid_table_key,
            writable_indexes: vec![],
            readonly_indexes: vec![],
        };

        assert_eq!(
            accounts.load_lookup_table_addresses(
                &ancestors,
                &address_table_lookup,
                &SlotHashes::default(),
            ),
            Err(AddressLookupError::InvalidAccountData),
        );
    }

    #[test]
    fn test_load_lookup_table_addresses() {
        let ancestors = vec![(1, 1), (0, 0)].into_iter().collect();
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        let table_key = Pubkey::new_unique();
        let table_addresses = vec![Pubkey::new_unique(), Pubkey::new_unique()];
        let table_account = {
            let table_state = AddressLookupTable {
                meta: LookupTableMeta::default(),
                addresses: Cow::Owned(table_addresses.clone()),
            };
            AccountSharedData::create(
                1,
                table_state.serialize_for_tests().unwrap(),
                address_lookup_table::program::id(),
                false,
                0,
            )
        };
        accounts.store_slow_uncached(0, &table_key, &table_account);

        let address_table_lookup = MessageAddressTableLookup {
            account_key: table_key,
            writable_indexes: vec![0],
            readonly_indexes: vec![1],
        };

        assert_eq!(
            accounts.load_lookup_table_addresses(
                &ancestors,
                &address_table_lookup,
                &SlotHashes::default(),
            ),
            Ok(LoadedAddresses {
                writable: vec![table_addresses[0]],
                readonly: vec![table_addresses[1]],
            }),
        );
    }

    #[test]
    fn test_load_by_program_slot() {
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        // Load accounts owned by various programs into AccountsDb
        let pubkey0 = solana_sdk::pubkey::new_rand();
        let account0 = AccountSharedData::new(1, 0, &Pubkey::from([2; 32]));
        accounts.store_slow_uncached(0, &pubkey0, &account0);
        let pubkey1 = solana_sdk::pubkey::new_rand();
        let account1 = AccountSharedData::new(1, 0, &Pubkey::from([2; 32]));
        accounts.store_slow_uncached(0, &pubkey1, &account1);
        let pubkey2 = solana_sdk::pubkey::new_rand();
        let account2 = AccountSharedData::new(1, 0, &Pubkey::from([3; 32]));
        accounts.store_slow_uncached(0, &pubkey2, &account2);

        let loaded = accounts.load_by_program_slot(0, Some(&Pubkey::from([2; 32])));
        assert_eq!(loaded.len(), 2);
        let loaded = accounts.load_by_program_slot(0, Some(&Pubkey::from([3; 32])));
        assert_eq!(loaded, vec![(pubkey2, account2)]);
        let loaded = accounts.load_by_program_slot(0, Some(&Pubkey::from([4; 32])));
        assert_eq!(loaded, vec![]);
    }

    #[test]
    fn test_accounts_empty_bank_hash_stats() {
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        assert!(accounts.accounts_db.get_bank_hash_stats(0).is_some());
        assert!(accounts.accounts_db.get_bank_hash_stats(1).is_none());
    }

    #[test]
    fn test_lock_accounts_with_duplicates() {
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        let keypair = Keypair::new();
        let message = Message {
            header: MessageHeader {
                num_required_signatures: 1,
                ..MessageHeader::default()
            },
            account_keys: vec![keypair.pubkey(), keypair.pubkey()],
            ..Message::default()
        };

        let tx = new_sanitized_tx(&[&keypair], message, Hash::default());
        let results = accounts.lock_accounts([tx].iter(), MAX_TX_ACCOUNT_LOCKS);
        assert_eq!(results[0], Err(TransactionError::AccountLoadedTwice));
    }

    #[test]
    fn test_lock_accounts_with_too_many_accounts() {
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        let keypair = Keypair::new();

        // Allow up to MAX_TX_ACCOUNT_LOCKS
        {
            let num_account_keys = MAX_TX_ACCOUNT_LOCKS;
            let mut account_keys: Vec<_> = (0..num_account_keys)
                .map(|_| Pubkey::new_unique())
                .collect();
            account_keys[0] = keypair.pubkey();
            let message = Message {
                header: MessageHeader {
                    num_required_signatures: 1,
                    ..MessageHeader::default()
                },
                account_keys,
                ..Message::default()
            };

            let txs = vec![new_sanitized_tx(&[&keypair], message, Hash::default())];
            let results = accounts.lock_accounts(txs.iter(), MAX_TX_ACCOUNT_LOCKS);
            assert_eq!(results[0], Ok(()));
            accounts.unlock_accounts(txs.iter(), &results);
        }

        // Disallow over MAX_TX_ACCOUNT_LOCKS
        {
            let num_account_keys = MAX_TX_ACCOUNT_LOCKS + 1;
            let mut account_keys: Vec<_> = (0..num_account_keys)
                .map(|_| Pubkey::new_unique())
                .collect();
            account_keys[0] = keypair.pubkey();
            let message = Message {
                header: MessageHeader {
                    num_required_signatures: 1,
                    ..MessageHeader::default()
                },
                account_keys,
                ..Message::default()
            };

            let txs = vec![new_sanitized_tx(&[&keypair], message, Hash::default())];
            let results = accounts.lock_accounts(txs.iter(), MAX_TX_ACCOUNT_LOCKS);
            assert_eq!(results[0], Err(TransactionError::TooManyAccountLocks));
        }
    }

    #[test]
    fn test_accounts_locks() {
        let keypair0 = Keypair::new();
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();
        let keypair3 = Keypair::new();

        let account0 = AccountSharedData::new(1, 0, &Pubkey::default());
        let account1 = AccountSharedData::new(2, 0, &Pubkey::default());
        let account2 = AccountSharedData::new(3, 0, &Pubkey::default());
        let account3 = AccountSharedData::new(4, 0, &Pubkey::default());

        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        accounts.store_for_tests(0, &keypair0.pubkey(), &account0);
        accounts.store_for_tests(0, &keypair1.pubkey(), &account1);
        accounts.store_for_tests(0, &keypair2.pubkey(), &account2);
        accounts.store_for_tests(0, &keypair3.pubkey(), &account3);

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair0.pubkey(), keypair1.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx = new_sanitized_tx(&[&keypair0], message, Hash::default());
        let results0 = accounts.lock_accounts([tx.clone()].iter(), MAX_TX_ACCOUNT_LOCKS);

        assert!(results0[0].is_ok());
        assert_eq!(
            *accounts
                .account_locks
                .lock()
                .unwrap()
                .readonly_locks
                .get(&keypair1.pubkey())
                .unwrap(),
            1
        );

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair2.pubkey(), keypair1.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx0 = new_sanitized_tx(&[&keypair2], message, Hash::default());
        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair1.pubkey(), keypair3.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx1 = new_sanitized_tx(&[&keypair1], message, Hash::default());
        let txs = vec![tx0, tx1];
        let results1 = accounts.lock_accounts(txs.iter(), MAX_TX_ACCOUNT_LOCKS);

        assert!(results1[0].is_ok()); // Read-only account (keypair1) can be referenced multiple times
        assert!(results1[1].is_err()); // Read-only account (keypair1) cannot also be locked as writable
        assert_eq!(
            *accounts
                .account_locks
                .lock()
                .unwrap()
                .readonly_locks
                .get(&keypair1.pubkey())
                .unwrap(),
            2
        );

        accounts.unlock_accounts([tx].iter(), &results0);
        accounts.unlock_accounts(txs.iter(), &results1);
        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair1.pubkey(), keypair3.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx = new_sanitized_tx(&[&keypair1], message, Hash::default());
        let results2 = accounts.lock_accounts([tx].iter(), MAX_TX_ACCOUNT_LOCKS);
        assert!(results2[0].is_ok()); // Now keypair1 account can be locked as writable

        // Check that read-only lock with zero references is deleted
        assert!(accounts
            .account_locks
            .lock()
            .unwrap()
            .readonly_locks
            .get(&keypair1.pubkey())
            .is_none());
    }

    #[test]
    fn test_accounts_locks_multithreaded() {
        let counter = Arc::new(AtomicU64::new(0));
        let exit = Arc::new(AtomicBool::new(false));

        let keypair0 = Keypair::new();
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();

        let account0 = AccountSharedData::new(1, 0, &Pubkey::default());
        let account1 = AccountSharedData::new(2, 0, &Pubkey::default());
        let account2 = AccountSharedData::new(3, 0, &Pubkey::default());

        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        accounts.store_for_tests(0, &keypair0.pubkey(), &account0);
        accounts.store_for_tests(0, &keypair1.pubkey(), &account1);
        accounts.store_for_tests(0, &keypair2.pubkey(), &account2);

        let accounts_arc = Arc::new(accounts);

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let readonly_message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair0.pubkey(), keypair1.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let readonly_tx = new_sanitized_tx(&[&keypair0], readonly_message, Hash::default());

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let writable_message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair1.pubkey(), keypair2.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let writable_tx = new_sanitized_tx(&[&keypair1], writable_message, Hash::default());

        let counter_clone = counter.clone();
        let accounts_clone = accounts_arc.clone();
        let exit_clone = exit.clone();
        thread::spawn(move || loop {
            let txs = vec![writable_tx.clone()];
            let results = accounts_clone
                .clone()
                .lock_accounts(txs.iter(), MAX_TX_ACCOUNT_LOCKS);
            for result in results.iter() {
                if result.is_ok() {
                    counter_clone.clone().fetch_add(1, Ordering::SeqCst);
                }
            }
            accounts_clone.unlock_accounts(txs.iter(), &results);
            if exit_clone.clone().load(Ordering::Relaxed) {
                break;
            }
        });
        let counter_clone = counter;
        for _ in 0..5 {
            let txs = vec![readonly_tx.clone()];
            let results = accounts_arc
                .clone()
                .lock_accounts(txs.iter(), MAX_TX_ACCOUNT_LOCKS);
            if results[0].is_ok() {
                let counter_value = counter_clone.clone().load(Ordering::SeqCst);
                thread::sleep(time::Duration::from_millis(50));
                assert_eq!(counter_value, counter_clone.clone().load(Ordering::SeqCst));
            }
            accounts_arc.unlock_accounts(txs.iter(), &results);
            thread::sleep(time::Duration::from_millis(50));
        }
        exit.store(true, Ordering::Relaxed);
    }

    #[test]
    fn test_demote_program_write_locks() {
        let keypair0 = Keypair::new();
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();
        let keypair3 = Keypair::new();

        let account0 = AccountSharedData::new(1, 0, &Pubkey::default());
        let account1 = AccountSharedData::new(2, 0, &Pubkey::default());
        let account2 = AccountSharedData::new(3, 0, &Pubkey::default());
        let account3 = AccountSharedData::new(4, 0, &Pubkey::default());

        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        accounts.store_for_tests(0, &keypair0.pubkey(), &account0);
        accounts.store_for_tests(0, &keypair1.pubkey(), &account1);
        accounts.store_for_tests(0, &keypair2.pubkey(), &account2);
        accounts.store_for_tests(0, &keypair3.pubkey(), &account3);

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            0, // All accounts marked as writable
            vec![keypair0.pubkey(), keypair1.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx = new_sanitized_tx(&[&keypair0], message, Hash::default());
        let results0 = accounts.lock_accounts([tx].iter(), MAX_TX_ACCOUNT_LOCKS);

        assert!(results0[0].is_ok());
        // Instruction program-id account demoted to readonly
        assert_eq!(
            *accounts
                .account_locks
                .lock()
                .unwrap()
                .readonly_locks
                .get(&native_loader::id())
                .unwrap(),
            1
        );
        // Non-program accounts remain writable
        assert!(accounts
            .account_locks
            .lock()
            .unwrap()
            .write_locks
            .contains(&keypair0.pubkey()));
        assert!(accounts
            .account_locks
            .lock()
            .unwrap()
            .write_locks
            .contains(&keypair1.pubkey()));
    }

    impl Accounts {
        /// callers used to call store_uncached. But, this is not allowed anymore.
        pub fn store_for_tests(&self, slot: Slot, pubkey: &Pubkey, account: &AccountSharedData) {
            self.accounts_db.store_for_tests(slot, &[(pubkey, account)])
        }

        /// useful to adapt tests written prior to introduction of the write cache
        /// to use the write cache
        pub fn add_root_and_flush_write_cache(&self, slot: Slot) {
            self.add_root(slot);
            self.accounts_db.flush_accounts_cache_slot_for_tests(slot);
        }
    }

    #[test]
    fn test_accounts_locks_with_results() {
        let keypair0 = Keypair::new();
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();
        let keypair3 = Keypair::new();

        let account0 = AccountSharedData::new(1, 0, &Pubkey::default());
        let account1 = AccountSharedData::new(2, 0, &Pubkey::default());
        let account2 = AccountSharedData::new(3, 0, &Pubkey::default());
        let account3 = AccountSharedData::new(4, 0, &Pubkey::default());

        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        accounts.store_for_tests(0, &keypair0.pubkey(), &account0);
        accounts.store_for_tests(0, &keypair1.pubkey(), &account1);
        accounts.store_for_tests(0, &keypair2.pubkey(), &account2);
        accounts.store_for_tests(0, &keypair3.pubkey(), &account3);

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair1.pubkey(), keypair0.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx0 = new_sanitized_tx(&[&keypair1], message, Hash::default());
        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair2.pubkey(), keypair0.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx1 = new_sanitized_tx(&[&keypair2], message, Hash::default());
        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair3.pubkey(), keypair0.pubkey(), native_loader::id()],
            Hash::default(),
            instructions,
        );
        let tx2 = new_sanitized_tx(&[&keypair3], message, Hash::default());
        let txs = vec![tx0, tx1, tx2];

        let qos_results = vec![
            Ok(()),
            Err(TransactionError::WouldExceedMaxBlockCostLimit),
            Ok(()),
        ];

        let results = accounts.lock_accounts_with_results(
            txs.iter(),
            qos_results.into_iter(),
            MAX_TX_ACCOUNT_LOCKS,
        );

        assert!(results[0].is_ok()); // Read-only account (keypair0) can be referenced multiple times
        assert!(results[1].is_err()); // is not locked due to !qos_results[1].is_ok()
        assert!(results[2].is_ok()); // Read-only account (keypair0) can be referenced multiple times

        // verify that keypair0 read-only lock twice (for tx0 and tx2)
        assert_eq!(
            *accounts
                .account_locks
                .lock()
                .unwrap()
                .readonly_locks
                .get(&keypair0.pubkey())
                .unwrap(),
            2
        );
        // verify that keypair2 (for tx1) is not write-locked
        assert!(accounts
            .account_locks
            .lock()
            .unwrap()
            .write_locks
            .get(&keypair2.pubkey())
            .is_none());

        accounts.unlock_accounts(txs.iter(), &results);

        // check all locks to be removed
        assert!(accounts
            .account_locks
            .lock()
            .unwrap()
            .readonly_locks
            .is_empty());
        assert!(accounts
            .account_locks
            .lock()
            .unwrap()
            .write_locks
            .is_empty());
    }

    #[test]
    fn test_collect_accounts_to_store() {
        let keypair0 = Keypair::new();
        let keypair1 = Keypair::new();
        let pubkey = solana_sdk::pubkey::new_rand();
        let account0 = AccountSharedData::new(1, 0, &Pubkey::default());
        let account1 = AccountSharedData::new(2, 0, &Pubkey::default());
        let account2 = AccountSharedData::new(3, 0, &Pubkey::default());

        let rent_collector = RentCollector::default();

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair0.pubkey(), pubkey, native_loader::id()],
            Hash::default(),
            instructions,
        );
        let transaction_accounts0 = vec![
            (message.account_keys[0], account0),
            (message.account_keys[1], account2.clone()),
        ];
        let tx0 = new_sanitized_tx(&[&keypair0], message, Hash::default());

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let message = Message::new_with_compiled_instructions(
            1,
            0,
            2,
            vec![keypair1.pubkey(), pubkey, native_loader::id()],
            Hash::default(),
            instructions,
        );
        let transaction_accounts1 = vec![
            (message.account_keys[0], account1),
            (message.account_keys[1], account2),
        ];
        let tx1 = new_sanitized_tx(&[&keypair1], message, Hash::default());

        let loaded0 = (
            Ok(LoadedTransaction {
                accounts: transaction_accounts0,
                program_indices: vec![],
                rent: 0,
                rent_debits: RentDebits::default(),
            }),
            None,
        );

        let loaded1 = (
            Ok(LoadedTransaction {
                accounts: transaction_accounts1,
                program_indices: vec![],
                rent: 0,
                rent_debits: RentDebits::default(),
            }),
            None,
        );

        let mut loaded = vec![loaded0, loaded1];

        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        {
            accounts
                .account_locks
                .lock()
                .unwrap()
                .insert_new_readonly(&pubkey);
        }
        let txs = vec![tx0.clone(), tx1.clone()];
        let execution_results = vec![new_execution_result(Ok(()), None); 2];
        let (collected_accounts, transactions) = accounts.collect_accounts_to_store(
            &txs,
            &execution_results,
            loaded.as_mut_slice(),
            &rent_collector,
            &DurableNonce::default(),
            0,
        );
        assert_eq!(collected_accounts.len(), 2);
        assert!(collected_accounts
            .iter()
            .any(|(pubkey, _account)| *pubkey == &keypair0.pubkey()));
        assert!(collected_accounts
            .iter()
            .any(|(pubkey, _account)| *pubkey == &keypair1.pubkey()));

        assert_eq!(transactions.len(), 2);
        assert!(transactions.iter().any(|txn| txn.unwrap().eq(&tx0)));
        assert!(transactions.iter().any(|txn| txn.unwrap().eq(&tx1)));

        // Ensure readonly_lock reflects lock
        assert_eq!(
            *accounts
                .account_locks
                .lock()
                .unwrap()
                .readonly_locks
                .get(&pubkey)
                .unwrap(),
            1
        );
    }

    #[test]
    fn huge_clean() {
        solana_logger::setup();
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        let mut old_pubkey = Pubkey::default();
        let zero_account = AccountSharedData::new(0, 0, AccountSharedData::default().owner());
        info!("storing..");
        for i in 0..2_000 {
            let pubkey = solana_sdk::pubkey::new_rand();
            let account = AccountSharedData::new(i + 1, 0, AccountSharedData::default().owner());
            accounts.store_for_tests(i, &pubkey, &account);
            accounts.store_for_tests(i, &old_pubkey, &zero_account);
            old_pubkey = pubkey;
            accounts.add_root_and_flush_write_cache(i);

            if i % 1_000 == 0 {
                info!("  store {}", i);
            }
        }
        info!("done..cleaning..");
        accounts.accounts_db.clean_accounts_for_tests();
    }

    fn create_accounts_prepare_if_nonce_account() -> (
        Pubkey,
        AccountSharedData,
        AccountSharedData,
        DurableNonce,
        u64,
        Option<AccountSharedData>,
    ) {
        let data = NonceVersions::new(NonceState::Initialized(nonce::state::Data::default()));
        let account = AccountSharedData::new_data(42, &data, &system_program::id()).unwrap();
        let mut pre_account = account.clone();
        pre_account.set_lamports(43);
        let durable_nonce = DurableNonce::from_blockhash(&Hash::new(&[1u8; 32]));
        (
            Pubkey::default(),
            pre_account,
            account,
            durable_nonce,
            1234,
            None,
        )
    }

    fn run_prepare_if_nonce_account_test(
        account_address: &Pubkey,
        account: &mut AccountSharedData,
        tx_result: &Result<()>,
        is_fee_payer: bool,
        maybe_nonce: Option<(&NonceFull, bool)>,
        durable_nonce: &DurableNonce,
        lamports_per_signature: u64,
        expect_account: &AccountSharedData,
    ) -> bool {
        // Verify expect_account's relationship
        if !is_fee_payer {
            match maybe_nonce {
                Some((nonce, _)) if nonce.address() == account_address => {
                    assert_ne!(expect_account, nonce.account())
                }
                _ => assert_eq!(expect_account, account),
            }
        }

        prepare_if_nonce_account(
            account_address,
            account,
            tx_result,
            is_fee_payer,
            maybe_nonce,
            durable_nonce,
            lamports_per_signature,
        );
        assert_eq!(expect_account, account);
        expect_account == account
    }

    #[test]
    fn test_prepare_if_nonce_account_expected() {
        let (
            pre_account_address,
            pre_account,
            mut post_account,
            blockhash,
            lamports_per_signature,
            maybe_fee_payer_account,
        ) = create_accounts_prepare_if_nonce_account();
        let post_account_address = pre_account_address;
        let nonce = NonceFull::new(
            pre_account_address,
            pre_account.clone(),
            maybe_fee_payer_account,
        );

        let mut expect_account = pre_account;
        expect_account
            .set_state(&NonceVersions::new(NonceState::Initialized(
                nonce::state::Data::new(Pubkey::default(), blockhash, lamports_per_signature),
            )))
            .unwrap();

        assert!(run_prepare_if_nonce_account_test(
            &post_account_address,
            &mut post_account,
            &Ok(()),
            false,
            Some((&nonce, true)),
            &blockhash,
            lamports_per_signature,
            &expect_account,
        ));
    }

    #[test]
    fn test_prepare_if_nonce_account_not_nonce_tx() {
        let (
            pre_account_address,
            _pre_account,
            _post_account,
            blockhash,
            lamports_per_signature,
            _maybe_fee_payer_account,
        ) = create_accounts_prepare_if_nonce_account();
        let post_account_address = pre_account_address;

        let mut post_account = AccountSharedData::default();
        let expect_account = post_account.clone();
        assert!(run_prepare_if_nonce_account_test(
            &post_account_address,
            &mut post_account,
            &Ok(()),
            false,
            None,
            &blockhash,
            lamports_per_signature,
            &expect_account,
        ));
    }

    #[test]
    fn test_prepare_if_nonce_account_not_nonce_address() {
        let (
            pre_account_address,
            pre_account,
            mut post_account,
            blockhash,
            lamports_per_signature,
            maybe_fee_payer_account,
        ) = create_accounts_prepare_if_nonce_account();

        let nonce = NonceFull::new(pre_account_address, pre_account, maybe_fee_payer_account);

        let expect_account = post_account.clone();
        // Wrong key
        assert!(run_prepare_if_nonce_account_test(
            &Pubkey::from([1u8; 32]),
            &mut post_account,
            &Ok(()),
            false,
            Some((&nonce, true)),
            &blockhash,
            lamports_per_signature,
            &expect_account,
        ));
    }

    #[test]
    fn test_prepare_if_nonce_account_tx_error() {
        let (
            pre_account_address,
            pre_account,
            mut post_account,
            blockhash,
            lamports_per_signature,
            maybe_fee_payer_account,
        ) = create_accounts_prepare_if_nonce_account();
        let post_account_address = pre_account_address;
        let mut expect_account = pre_account.clone();

        let nonce = NonceFull::new(pre_account_address, pre_account, maybe_fee_payer_account);

        expect_account
            .set_state(&NonceVersions::new(NonceState::Initialized(
                nonce::state::Data::new(Pubkey::default(), blockhash, lamports_per_signature),
            )))
            .unwrap();

        assert!(run_prepare_if_nonce_account_test(
            &post_account_address,
            &mut post_account,
            &Err(TransactionError::InstructionError(
                0,
                InstructionError::InvalidArgument,
            )),
            false,
            Some((&nonce, true)),
            &blockhash,
            lamports_per_signature,
            &expect_account,
        ));
    }

    #[test]
    fn test_rollback_nonce_fee_payer() {
        let nonce_account = AccountSharedData::new_data(1, &(), &system_program::id()).unwrap();
        let pre_fee_payer_account =
            AccountSharedData::new_data(42, &(), &system_program::id()).unwrap();
        let mut post_fee_payer_account =
            AccountSharedData::new_data(84, &[1, 2, 3, 4], &system_program::id()).unwrap();
        let nonce = NonceFull::new(
            Pubkey::new_unique(),
            nonce_account,
            Some(pre_fee_payer_account.clone()),
        );

        assert!(run_prepare_if_nonce_account_test(
            &Pubkey::new_unique(),
            &mut post_fee_payer_account.clone(),
            &Err(TransactionError::InstructionError(
                0,
                InstructionError::InvalidArgument,
            )),
            false,
            Some((&nonce, true)),
            &DurableNonce::default(),
            1,
            &post_fee_payer_account,
        ));

        assert!(run_prepare_if_nonce_account_test(
            &Pubkey::new_unique(),
            &mut post_fee_payer_account.clone(),
            &Ok(()),
            true,
            Some((&nonce, true)),
            &DurableNonce::default(),
            1,
            &post_fee_payer_account,
        ));

        assert!(run_prepare_if_nonce_account_test(
            &Pubkey::new_unique(),
            &mut post_fee_payer_account.clone(),
            &Err(TransactionError::InstructionError(
                0,
                InstructionError::InvalidArgument,
            )),
            true,
            None,
            &DurableNonce::default(),
            1,
            &post_fee_payer_account,
        ));

        assert!(run_prepare_if_nonce_account_test(
            &Pubkey::new_unique(),
            &mut post_fee_payer_account,
            &Err(TransactionError::InstructionError(
                0,
                InstructionError::InvalidArgument,
            )),
            true,
            Some((&nonce, true)),
            &DurableNonce::default(),
            1,
            &pre_fee_payer_account,
        ));
    }

    #[test]
    fn test_nonced_failure_accounts_rollback_from_pays() {
        let rent_collector = RentCollector::default();

        let nonce_address = Pubkey::new_unique();
        let nonce_authority = keypair_from_seed(&[0; 32]).unwrap();
        let from = keypair_from_seed(&[1; 32]).unwrap();
        let from_address = from.pubkey();
        let to_address = Pubkey::new_unique();
        let durable_nonce = DurableNonce::from_blockhash(&Hash::new_unique());
        let nonce_state = NonceVersions::new(NonceState::Initialized(nonce::state::Data::new(
            nonce_authority.pubkey(),
            durable_nonce,
            0,
        )));
        let nonce_account_post =
            AccountSharedData::new_data(43, &nonce_state, &system_program::id()).unwrap();
        let from_account_post = AccountSharedData::new(4199, 0, &Pubkey::default());
        let to_account = AccountSharedData::new(2, 0, &Pubkey::default());
        let nonce_authority_account = AccountSharedData::new(3, 0, &Pubkey::default());
        let recent_blockhashes_sysvar_account = AccountSharedData::new(4, 0, &Pubkey::default());

        let instructions = vec![
            system_instruction::advance_nonce_account(&nonce_address, &nonce_authority.pubkey()),
            system_instruction::transfer(&from_address, &to_address, 42),
        ];
        let message = Message::new(&instructions, Some(&from_address));
        let blockhash = Hash::new_unique();
        let transaction_accounts = vec![
            (message.account_keys[0], from_account_post),
            (message.account_keys[1], nonce_authority_account),
            (message.account_keys[2], nonce_account_post),
            (message.account_keys[3], to_account),
            (message.account_keys[4], recent_blockhashes_sysvar_account),
        ];
        let tx = new_sanitized_tx(&[&nonce_authority, &from], message, blockhash);

        let durable_nonce = DurableNonce::from_blockhash(&Hash::new_unique());
        let nonce_state = NonceVersions::new(NonceState::Initialized(nonce::state::Data::new(
            nonce_authority.pubkey(),
            durable_nonce,
            0,
        )));
        let nonce_account_pre =
            AccountSharedData::new_data(42, &nonce_state, &system_program::id()).unwrap();
        let from_account_pre = AccountSharedData::new(4242, 0, &Pubkey::default());

        let nonce = Some(NonceFull::new(
            nonce_address,
            nonce_account_pre.clone(),
            Some(from_account_pre.clone()),
        ));

        let loaded = (
            Ok(LoadedTransaction {
                accounts: transaction_accounts,
                program_indices: vec![],
                rent: 0,
                rent_debits: RentDebits::default(),
            }),
            nonce.clone(),
        );

        let mut loaded = vec![loaded];

        let durable_nonce = DurableNonce::from_blockhash(&Hash::new_unique());
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        let txs = vec![tx];
        let execution_results = vec![new_execution_result(
            Err(TransactionError::InstructionError(
                1,
                InstructionError::InvalidArgument,
            )),
            nonce.as_ref(),
        )];
        let (collected_accounts, _) = accounts.collect_accounts_to_store(
            &txs,
            &execution_results,
            loaded.as_mut_slice(),
            &rent_collector,
            &durable_nonce,
            0,
        );
        assert_eq!(collected_accounts.len(), 2);
        assert_eq!(
            collected_accounts
                .iter()
                .find(|(pubkey, _account)| *pubkey == &from_address)
                .map(|(_pubkey, account)| *account)
                .cloned()
                .unwrap(),
            from_account_pre,
        );
        let collected_nonce_account = collected_accounts
            .iter()
            .find(|(pubkey, _account)| *pubkey == &nonce_address)
            .map(|(_pubkey, account)| *account)
            .cloned()
            .unwrap();
        assert_eq!(
            collected_nonce_account.lamports(),
            nonce_account_pre.lamports(),
        );
        assert_matches!(
            nonce_account::verify_nonce_account(&collected_nonce_account, durable_nonce.as_hash()),
            Some(_)
        );
    }

    #[test]
    fn test_nonced_failure_accounts_rollback_nonce_pays() {
        let rent_collector = RentCollector::default();

        let nonce_authority = keypair_from_seed(&[0; 32]).unwrap();
        let nonce_address = nonce_authority.pubkey();
        let from = keypair_from_seed(&[1; 32]).unwrap();
        let from_address = from.pubkey();
        let to_address = Pubkey::new_unique();
        let durable_nonce = DurableNonce::from_blockhash(&Hash::new_unique());
        let nonce_state = NonceVersions::new(NonceState::Initialized(nonce::state::Data::new(
            nonce_authority.pubkey(),
            durable_nonce,
            0,
        )));
        let nonce_account_post =
            AccountSharedData::new_data(43, &nonce_state, &system_program::id()).unwrap();
        let from_account_post = AccountSharedData::new(4200, 0, &Pubkey::default());
        let to_account = AccountSharedData::new(2, 0, &Pubkey::default());
        let nonce_authority_account = AccountSharedData::new(3, 0, &Pubkey::default());
        let recent_blockhashes_sysvar_account = AccountSharedData::new(4, 0, &Pubkey::default());

        let instructions = vec![
            system_instruction::advance_nonce_account(&nonce_address, &nonce_authority.pubkey()),
            system_instruction::transfer(&from_address, &to_address, 42),
        ];
        let message = Message::new(&instructions, Some(&nonce_address));
        let blockhash = Hash::new_unique();
        let transaction_accounts = vec![
            (message.account_keys[0], from_account_post),
            (message.account_keys[1], nonce_authority_account),
            (message.account_keys[2], nonce_account_post),
            (message.account_keys[3], to_account),
            (message.account_keys[4], recent_blockhashes_sysvar_account),
        ];
        let tx = new_sanitized_tx(&[&nonce_authority, &from], message, blockhash);

        let durable_nonce = DurableNonce::from_blockhash(&Hash::new_unique());
        let nonce_state = NonceVersions::new(NonceState::Initialized(nonce::state::Data::new(
            nonce_authority.pubkey(),
            durable_nonce,
            0,
        )));
        let nonce_account_pre =
            AccountSharedData::new_data(42, &nonce_state, &system_program::id()).unwrap();

        let nonce = Some(NonceFull::new(
            nonce_address,
            nonce_account_pre.clone(),
            None,
        ));

        let loaded = (
            Ok(LoadedTransaction {
                accounts: transaction_accounts,
                program_indices: vec![],
                rent: 0,
                rent_debits: RentDebits::default(),
            }),
            nonce.clone(),
        );

        let mut loaded = vec![loaded];

        let durable_nonce = DurableNonce::from_blockhash(&Hash::new_unique());
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));
        let txs = vec![tx];
        let execution_results = vec![new_execution_result(
            Err(TransactionError::InstructionError(
                1,
                InstructionError::InvalidArgument,
            )),
            nonce.as_ref(),
        )];
        let (collected_accounts, _) = accounts.collect_accounts_to_store(
            &txs,
            &execution_results,
            loaded.as_mut_slice(),
            &rent_collector,
            &durable_nonce,
            0,
        );
        assert_eq!(collected_accounts.len(), 1);
        let collected_nonce_account = collected_accounts
            .iter()
            .find(|(pubkey, _account)| *pubkey == &nonce_address)
            .map(|(_pubkey, account)| *account)
            .cloned()
            .unwrap();
        assert_eq!(
            collected_nonce_account.lamports(),
            nonce_account_pre.lamports()
        );
        assert_matches!(
            nonce_account::verify_nonce_account(&collected_nonce_account, durable_nonce.as_hash()),
            Some(_)
        );
    }

    #[test]
    fn test_load_largest_accounts() {
        let accounts_db = AccountsDb::new_single_for_tests();
        let accounts = Accounts::new(Arc::new(accounts_db));

        /* This test assumes pubkey0 < pubkey1 < pubkey2.
         * But the keys created with new_unique() does not guarantee this
         * order because of the endianness.  new_unique() calls add 1 at each
         * key generaration as the little endian integer.  A pubkey stores its
         * value in a 32-byte array bytes, and its eq-partial trait considers
         * the lower-address bytes more significant, which is the big-endian
         * order.
         * So, sort first to ensure the order assumption holds.
         */
        let mut keys = vec![];
        for _idx in 0..3 {
            keys.push(Pubkey::new_unique());
        }
        keys.sort();
        let pubkey2 = keys.pop().unwrap();
        let pubkey1 = keys.pop().unwrap();
        let pubkey0 = keys.pop().unwrap();
        let account0 = AccountSharedData::new(42, 0, &Pubkey::default());
        accounts.store_for_tests(0, &pubkey0, &account0);
        let account1 = AccountSharedData::new(42, 0, &Pubkey::default());
        accounts.store_for_tests(0, &pubkey1, &account1);
        let account2 = AccountSharedData::new(41, 0, &Pubkey::default());
        accounts.store_for_tests(0, &pubkey2, &account2);

        let ancestors = vec![(0, 0)].into_iter().collect();
        let all_pubkeys: HashSet<_> = vec![pubkey0, pubkey1, pubkey2].into_iter().collect();

        // num == 0 should always return empty set
        let bank_id = 0;
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    0,
                    &HashSet::new(),
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    0,
                    &all_pubkeys,
                    AccountAddressFilter::Include
                )
                .unwrap(),
            vec![]
        );

        // list should be sorted by balance, then pubkey, descending
        assert!(pubkey1 > pubkey0);
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    1,
                    &HashSet::new(),
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey1, 42)]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    2,
                    &HashSet::new(),
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey1, 42), (pubkey0, 42)]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    3,
                    &HashSet::new(),
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey1, 42), (pubkey0, 42), (pubkey2, 41)]
        );

        // larger num should not affect results
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    6,
                    &HashSet::new(),
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey1, 42), (pubkey0, 42), (pubkey2, 41)]
        );

        // AccountAddressFilter::Exclude should exclude entry
        let exclude1: HashSet<_> = vec![pubkey1].into_iter().collect();
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    1,
                    &exclude1,
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey0, 42)]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    2,
                    &exclude1,
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey0, 42), (pubkey2, 41)]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    3,
                    &exclude1,
                    AccountAddressFilter::Exclude
                )
                .unwrap(),
            vec![(pubkey0, 42), (pubkey2, 41)]
        );

        // AccountAddressFilter::Include should limit entries
        let include1_2: HashSet<_> = vec![pubkey1, pubkey2].into_iter().collect();
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    1,
                    &include1_2,
                    AccountAddressFilter::Include
                )
                .unwrap(),
            vec![(pubkey1, 42)]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    2,
                    &include1_2,
                    AccountAddressFilter::Include
                )
                .unwrap(),
            vec![(pubkey1, 42), (pubkey2, 41)]
        );
        assert_eq!(
            accounts
                .load_largest_accounts(
                    &ancestors,
                    bank_id,
                    3,
                    &include1_2,
                    AccountAddressFilter::Include
                )
                .unwrap(),
            vec![(pubkey1, 42), (pubkey2, 41)]
        );
    }

    fn zero_len_account_size() -> usize {
        std::mem::size_of::<AccountSharedData>() + std::mem::size_of::<Pubkey>()
    }

    #[test]
    fn test_calc_scan_result_size() {
        for len in 0..3 {
            assert_eq!(
                Accounts::calc_scan_result_size(&AccountSharedData::new(
                    0,
                    len,
                    &Pubkey::default()
                )),
                zero_len_account_size() + len
            );
        }
    }

    #[test]
    fn test_maybe_abort_scan() {
        assert!(Accounts::maybe_abort_scan(ScanResult::Ok(vec![]), &ScanConfig::default()).is_ok());
        let config = ScanConfig::default().recreate_with_abort();
        assert!(Accounts::maybe_abort_scan(ScanResult::Ok(vec![]), &config).is_ok());
        config.abort();
        assert!(Accounts::maybe_abort_scan(ScanResult::Ok(vec![]), &config).is_err());
    }

    #[test]
    fn test_accumulate_and_check_scan_result_size() {
        for (account, byte_limit_for_scan, result) in [
            (AccountSharedData::default(), zero_len_account_size(), false),
            (
                AccountSharedData::new(0, 1, &Pubkey::default()),
                zero_len_account_size(),
                true,
            ),
            (
                AccountSharedData::new(0, 2, &Pubkey::default()),
                zero_len_account_size() + 3,
                false,
            ),
        ] {
            let sum = AtomicUsize::default();
            assert_eq!(
                result,
                Accounts::accumulate_and_check_scan_result_size(
                    &sum,
                    &account,
                    &Some(byte_limit_for_scan)
                )
            );
            // calling a second time should accumulate above the threshold
            assert!(Accounts::accumulate_and_check_scan_result_size(
                &sum,
                &account,
                &Some(byte_limit_for_scan)
            ));
            assert!(!Accounts::accumulate_and_check_scan_result_size(
                &sum, &account, &None
            ));
        }
    }
}