accounts.rs

use crate::{
    accounts_db::{
        AccountShrinkThreshold, AccountsDb, AccountsDbConfig, BankHashInfo, ErrorCounters,
        LoadHint, LoadedAccount, ScanStorageResult, ACCOUNTS_DB_CONFIG_FOR_BENCHMARKS,
        ACCOUNTS_DB_CONFIG_FOR_TESTING,
    },
    accounts_index::{AccountSecondaryIndexes, IndexKey, ScanConfig, ScanError, ScanResult},
    accounts_update_notifier_interface::AccountsUpdateNotifier,
    ancestors::Ancestors,
    bank::{
        Bank, NonceFull, NonceInfo, RentDebits, TransactionCheckResult, TransactionExecutionResult,
    },
    blockhash_queue::BlockhashQueue,
    rent_collector::RentCollector,
    system_instruction_processor::{get_system_account_kind, SystemAccountKind},
};
use dashmap::{
    mapref::entry::Entry::{Occupied, Vacant},
    DashMap,
};
use log::*;
use rand::{thread_rng, Rng};
use solana_sdk::{
    account::{Account, AccountSharedData, ReadableAccount, WritableAccount},
    account_utils::StateMut,
    bpf_loader_upgradeable::{self, UpgradeableLoaderState},
    clock::{BankId, Slot, INITIAL_RENT_EPOCH},
    feature_set::{self, FeatureSet},
    genesis_config::ClusterType,
    hash::Hash,
    message::SanitizedMessage,
    native_loader,
    nonce::{state::Versions as NonceVersions, State as NonceState, NONCED_TX_MARKER_IX_INDEX},
    pubkey::Pubkey,
    system_program, sysvar,
    sysvar::instructions::construct_instructions_data,
    transaction::{Result, SanitizedTransaction, TransactionError},
};
use std::{
    cmp::Reverse,
    collections::{hash_map, BinaryHeap, HashMap, HashSet},
    ops::RangeBounds,
    path::PathBuf,
    sync::atomic::{AtomicUsize, Ordering},
    sync::{Arc, Mutex},
};

#[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 TransactionAccounts = Vec<(Pubkey, AccountSharedData)>;
pub type TransactionRent = u64;
pub type TransactionProgramIndices = Vec<Vec<usize>>;
#[derive(PartialEq, Debug, Clone)]
pub struct LoadedTransaction {
    pub accounts: TransactionAccounts,
    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 default_for_tests() -> Self {
        Self {
            accounts_db: Arc::new(AccountsDb::default_for_tests()),
            account_locks: Mutex::default(),
        }
    }

    pub fn new_with_config_for_tests(
        paths: Vec<PathBuf>,
        cluster_type: &ClusterType,
        account_indexes: AccountSecondaryIndexes,
        caching_enabled: bool,
        shrink_ratio: AccountShrinkThreshold,
    ) -> Self {
        Self::new_with_config(
            paths,
            cluster_type,
            account_indexes,
            caching_enabled,
            shrink_ratio,
            Some(ACCOUNTS_DB_CONFIG_FOR_TESTING),
            None,
        )
    }

    pub fn new_with_config_for_benches(
        paths: Vec<PathBuf>,
        cluster_type: &ClusterType,
        account_indexes: AccountSecondaryIndexes,
        caching_enabled: bool,
        shrink_ratio: AccountShrinkThreshold,
    ) -> Self {
        Self::new_with_config(
            paths,
            cluster_type,
            account_indexes,
            caching_enabled,
            shrink_ratio,
            Some(ACCOUNTS_DB_CONFIG_FOR_BENCHMARKS),
            None,
        )
    }

    pub fn new_with_config(
        paths: Vec<PathBuf>,
        cluster_type: &ClusterType,
        account_indexes: AccountSecondaryIndexes,
        caching_enabled: bool,
        shrink_ratio: AccountShrinkThreshold,
        accounts_db_config: Option<AccountsDbConfig>,
        accounts_update_notifier: Option<AccountsUpdateNotifier>,
    ) -> Self {
        Self {
            accounts_db: Arc::new(AccountsDb::new_with_config(
                paths,
                cluster_type,
                account_indexes,
                caching_enabled,
                shrink_ratio,
                accounts_db_config,
                accounts_update_notifier,
            )),
            account_locks: Mutex::new(AccountLocks::default()),
        }
    }

    pub fn new_from_parent(parent: &Accounts, slot: Slot, parent_slot: Slot) -> Self {
        let accounts_db = parent.accounts_db.clone();
        accounts_db.set_hash(slot, parent_slot);
        Self {
            accounts_db,
            account_locks: Mutex::new(AccountLocks::default()),
        }
    }

    pub(crate) fn new_empty(accounts_db: AccountsDb) -> Self {
        Self {
            accounts_db: Arc::new(accounts_db),
            account_locks: Mutex::new(AccountLocks::default()),
        }
    }

    fn construct_instructions_account(
        message: &SanitizedMessage,
        is_owned_by_sysvar: bool,
        demote_program_write_locks: bool,
    ) -> AccountSharedData {
        let data = construct_instructions_data(message, demote_program_write_locks);
        let owner = if is_owned_by_sysvar {
            sysvar::id()
        } else {
            system_program::id()
        };
        AccountSharedData::from(Account {
            data,
            owner,
            ..Account::default()
        })
    }

    fn load_transaction(
        &self,
        ancestors: &Ancestors,
        tx: &SanitizedTransaction,
        fee: u64,
        error_counters: &mut ErrorCounters,
        rent_collector: &RentCollector,
        feature_set: &FeatureSet,
    ) -> Result<LoadedTransaction> {
        // Copy all the accounts
        let message = tx.message();
        // NOTE: this check will never fail because `tx` is sanitized
        if tx.signatures().is_empty() && fee != 0 {
            Err(TransactionError::MissingSignatureForFee)
        } else {
            // There is no way to predict what program will execute without an error
            // If a fee can pay for execution then the program will be scheduled
            let mut payer_index = None;
            let mut tx_rent: TransactionRent = 0;
            let mut accounts = Vec::with_capacity(message.account_keys_len());
            let mut account_deps = Vec::with_capacity(message.account_keys_len());
            let mut rent_debits = RentDebits::default();
            let rent_for_sysvars = feature_set.is_active(&feature_set::rent_for_sysvars::id());
            let demote_program_write_locks =
                feature_set.is_active(&feature_set::demote_program_write_locks::id());

            for (i, key) in message.account_keys_iter().enumerate() {
                let account = if !message.is_non_loader_key(i) {
                    // Fill in an empty account for the program slots.
                    AccountSharedData::default()
                } else {
                    if payer_index.is_none() {
                        payer_index = Some(i);
                    }

                    if solana_sdk::sysvar::instructions::check_id(key) {
                        Self::construct_instructions_account(
                            message,
                            feature_set
                                .is_active(&feature_set::instructions_sysvar_owned_by_sysvar::id()),
                            demote_program_write_locks,
                        )
                    } else {
                        let (account, rent) = self
                            .accounts_db
                            .load_with_fixed_root(ancestors, key)
                            .map(|(mut account, _)| {
                                if message.is_writable(i, demote_program_write_locks) {
                                    let rent_due = rent_collector.collect_from_existing_account(
                                        key,
                                        &mut account,
                                        rent_for_sysvars,
                                        self.accounts_db.filler_account_suffix.as_ref(),
                                    );
                                    (account, rent_due)
                                } else {
                                    (account, 0)
                                }
                            })
                            .unwrap_or_default();

                        if bpf_loader_upgradeable::check_id(account.owner()) {
                            if demote_program_write_locks
                                && message.is_writable(i, demote_program_write_locks)
                                && !message.is_upgradeable_loader_present()
                            {
                                error_counters.invalid_writable_account += 1;
                                return Err(TransactionError::InvalidWritableAccount);
                            }

                            if account.executable() {
                                // The upgradeable loader requires the derived ProgramData account
                                if let Ok(UpgradeableLoaderState::Program {
                                    programdata_address,
                                }) = account.state()
                                {
                                    if let Some((programdata_account, _)) = self
                                        .accounts_db
                                        .load_with_fixed_root(ancestors, &programdata_address)
                                    {
                                        account_deps
                                            .push((programdata_address, programdata_account));
                                    } else {
                                        error_counters.account_not_found += 1;
                                        return Err(TransactionError::ProgramAccountNotFound);
                                    }
                                } else {
                                    error_counters.invalid_program_for_execution += 1;
                                    return Err(TransactionError::InvalidProgramForExecution);
                                }
                            }
                        } else if account.executable()
                            && demote_program_write_locks
                            && message.is_writable(i, demote_program_write_locks)
                        {
                            error_counters.invalid_writable_account += 1;
                            return Err(TransactionError::InvalidWritableAccount);
                        }

                        tx_rent += rent;
                        rent_debits.insert(key, rent, account.lamports());

                        account
                    }
                };
                accounts.push((*key, account));
            }
            debug_assert_eq!(accounts.len(), message.account_keys_len());
            // Appends the account_deps at the end of the accounts,
            // this way they can be accessed in a uniform way.
            // At places where only the accounts are needed,
            // the account_deps are truncated using e.g:
            // accounts.iter().take(message.account_keys.len())
            accounts.append(&mut account_deps);

            if let Some(payer_index) = payer_index {
                if payer_index != 0 {
                    warn!("Payer index should be 0! {:?}", tx);
                }
                let payer_account = &mut accounts[payer_index].1;
                if payer_account.lamports() == 0 {
                    error_counters.account_not_found += 1;
                    return Err(TransactionError::AccountNotFound);
                }
                let min_balance = match get_system_account_kind(payer_account).ok_or_else(|| {
                    error_counters.invalid_account_for_fee += 1;
                    TransactionError::InvalidAccountForFee
                })? {
                    SystemAccountKind::System => 0,
                    SystemAccountKind::Nonce => {
                        // Should we ever allow a fees charge to zero a nonce account's
                        // balance. The state MUST be set to uninitialized in that case
                        rent_collector.rent.minimum_balance(NonceState::size())
                    }
                };

                if payer_account.lamports() < fee + min_balance {
                    error_counters.insufficient_funds += 1;
                    return Err(TransactionError::InsufficientFundsForFee);
                }
                payer_account
                    .checked_sub_lamports(fee)
                    .map_err(|_| TransactionError::InsufficientFundsForFee)?;

                let program_indices = message
                    .instructions()
                    .iter()
                    .map(|instruction| {
                        self.load_executable_accounts(
                            ancestors,
                            &mut accounts,
                            instruction.program_id_index as usize,
                            error_counters,
                        )
                    })
                    .collect::<Result<Vec<Vec<usize>>>>()?;
                Ok(LoadedTransaction {
                    accounts,
                    program_indices,
                    rent: tx_rent,
                    rent_debits,
                })
            } else {
                error_counters.account_not_found += 1;
                Err(TransactionError::AccountNotFound)
            }
        }
    }

    fn load_executable_accounts(
        &self,
        ancestors: &Ancestors,
        accounts: &mut Vec<(Pubkey, AccountSharedData)>,
        mut program_account_index: usize,
        error_counters: &mut ErrorCounters,
    ) -> Result<Vec<usize>> {
        let mut account_indices = Vec::new();
        let mut program_id = accounts[program_account_index].0;
        let mut depth = 0;
        while !native_loader::check_id(&program_id) {
            if depth >= 5 {
                error_counters.call_chain_too_deep += 1;
                return Err(TransactionError::CallChainTooDeep);
            }
            depth += 1;

            program_account_index = match self
                .accounts_db
                .load_with_fixed_root(ancestors, &program_id)
            {
                Some((program_account, _)) => {
                    let account_index = accounts.len();
                    accounts.push((program_id, program_account));
                    account_index
                }
                None => {
                    error_counters.account_not_found += 1;
                    return Err(TransactionError::ProgramAccountNotFound);
                }
            };
            let program = &accounts[program_account_index].1;
            if !program.executable() {
                error_counters.invalid_program_for_execution += 1;
                return Err(TransactionError::InvalidProgramForExecution);
            }

            // Add loader to chain
            let program_owner = *program.owner();
            account_indices.insert(0, program_account_index);
            if bpf_loader_upgradeable::check_id(&program_owner) {
                // The upgradeable loader requires the derived ProgramData account
                if let Ok(UpgradeableLoaderState::Program {
                    programdata_address,
                }) = program.state()
                {
                    let programdata_account_index = match self
                        .accounts_db
                        .load_with_fixed_root(ancestors, &programdata_address)
                    {
                        Some((programdata_account, _)) => {
                            let account_index = accounts.len();
                            accounts.push((programdata_address, programdata_account));
                            account_index
                        }
                        None => {
                            error_counters.account_not_found += 1;
                            return Err(TransactionError::ProgramAccountNotFound);
                        }
                    };
                    account_indices.insert(0, programdata_account_index);
                } else {
                    error_counters.invalid_program_for_execution += 1;
                    return Err(TransactionError::InvalidProgramForExecution);
                }
            }

            program_id = program_owner;
        }
        Ok(account_indices)
    }

    pub fn load_accounts(
        &self,
        ancestors: &Ancestors,
        txs: &[SanitizedTransaction],
        lock_results: Vec<TransactionCheckResult>,
        hash_queue: &BlockhashQueue,
        error_counters: &mut ErrorCounters,
        rent_collector: &RentCollector,
        feature_set: &FeatureSet,
    ) -> Vec<TransactionLoadResult> {
        txs.iter()
            .zip(lock_results)
            .map(|etx| match etx {
                (tx, (Ok(()), nonce)) => {
                    let lamports_per_signature = nonce
                        .as_ref()
                        .map(|nonce| nonce.lamports_per_signature())
                        .unwrap_or_else(|| {
                            hash_queue.get_lamports_per_signature(tx.message().recent_blockhash())
                        });
                    let fee = if let Some(lamports_per_signature) = lamports_per_signature {
                        Bank::calculate_fee(tx.message(), lamports_per_signature)
                    } else {
                        return (Err(TransactionError::BlockhashNotFound), None);
                    };

                    let loaded_transaction = match self.load_transaction(
                        ancestors,
                        tx,
                        fee,
                        error_counters,
                        rent_collector,
                        feature_set,
                    ) {
                        Ok(loaded_transaction) => loaded_transaction,
                        Err(e) => return (Err(e), None),
                    };

                    // Update nonce with fee-subtracted accounts
                    let nonce = if let Some(nonce) = nonce {
                        match NonceFull::from_partial(
                            nonce,
                            tx.message(),
                            &loaded_transaction.accounts,
                            &loaded_transaction.rent_debits,
                        ) {
                            Ok(nonce) => Some(nonce),
                            Err(e) => return (Err(e), None),
                        }
                    } else {
                        None
                    };

                    (Ok(loaded_transaction), nonce)
                }
                (_, (Err(e), _nonce)) => (Err(e), None),
            })
            .collect()
    }

    fn filter_zero_lamport_account(
        account: AccountSharedData,
        slot: Slot,
    ) -> Option<(AccountSharedData, Slot)> {
        if account.lamports() > 0 {
            Some((account, slot))
        } else {
            None
        }
    }

    /// Slow because lock is held for 1 operation instead of many
    fn load_slow(
        &self,
        ancestors: &Ancestors,
        pubkey: &Pubkey,
        load_hint: LoadHint,
    ) -> Option<(AccountSharedData, Slot)> {
        let (account, slot) = self.accounts_db.load(ancestors, pubkey, load_hint)?;
        Self::filter_zero_lamport_account(account, slot)
    }

    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, (u64, B)>, loaded_account: LoadedAccount| {
                let loaded_account_pubkey = *loaded_account.pubkey();
                let loaded_write_version = loaded_account.write_version();
                let should_insert = accum
                    .get(&loaded_account_pubkey)
                    .map(|existing_entry| loaded_write_version > existing_entry.value().0)
                    .unwrap_or(true);
                if should_insert {
                    if let Some(val) = func(loaded_account) {
                        // Detected insertion is necessary, grabs the write lock to commit the write,
                        match accum.entry(loaded_account_pubkey) {
                            // Double check in case another thread interleaved a write between the read + write.
                            Occupied(mut occupied_entry) => {
                                if loaded_write_version > occupied_entry.get().0 {
                                    occupied_entry.insert((loaded_write_version, val));
                                }
                            }

                            Vacant(vacant_entry) => {
                                vacant_entry.insert((loaded_write_version, val));
                            }
                        }
                    }
                }
            },
        );

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

    pub fn load_by_program_slot(
        &self,
        slot: Slot,
        program_id: Option<&Pubkey>,
    ) -> Vec<(Pubkey, AccountSharedData)> {
        self.scan_slot(slot, |stored_account| {
            let hit = match program_id {
                None => true,
                Some(program_id) => stored_account.owner() == program_id,
            };

            if hit {
                Some((*stored_account.pubkey(), stored_account.take_account()))
            } else {
                None
            }
        })
    }

    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 account_balances = self.accounts_db.scan_accounts(
            ancestors,
            bank_id,
            |collector: &mut BinaryHeap<Reverse<(u64, Pubkey)>>, 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 collector.len() == num {
                        let Reverse(entry) = collector
                            .peek()
                            .expect("BinaryHeap::peek should succeed when len > 0");
                        if *entry >= (account.lamports(), *pubkey) {
                            return;
                        }
                        collector.pop();
                    }
                    collector.push(Reverse((account.lamports(), *pubkey)));
                }
            },
            &ScanConfig::default(),
        )?;
        Ok(account_balances
            .into_sorted_vec()
            .into_iter()
            .map(|Reverse((balance, pubkey))| (pubkey, balance))
            .collect())
    }

    pub fn calculate_capitalization(
        &self,
        ancestors: &Ancestors,
        slot: Slot,
        can_cached_slot_be_unflushed: bool,
        debug_verify: bool,
    ) -> u64 {
        let use_index = false;
        let is_startup = false; // there may be conditions where this is called at startup.
        self.accounts_db
            .update_accounts_hash_with_index_option(
                use_index,
                debug_verify,
                slot,
                ancestors,
                None,
                can_cached_slot_be_unflushed,
                None,
                is_startup,
            )
            .1
    }

    /// Only called from startup or test code.
    #[must_use]
    pub fn verify_bank_hash_and_lamports(
        &self,
        slot: Slot,
        ancestors: &Ancestors,
        total_lamports: u64,
        test_hash_calculation: bool,
    ) -> bool {
        if let Err(err) = self.accounts_db.verify_bank_hash_and_lamports(
            slot,
            ancestors,
            total_lamports,
            test_hash_calculation,
        ) {
            warn!("verify_bank_hash failed: {:?}", err);
            false
        } else {
            true
        }
    }

    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<(Pubkey, AccountSharedData)>,
        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)
        }
    }

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

    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<(Pubkey, AccountSharedData)>> {
        self.accounts_db.scan_accounts(
            ancestors,
            bank_id,
            |collector: &mut Vec<(Pubkey, AccountSharedData)>, some_account_tuple| {
                Self::load_while_filtering(collector, some_account_tuple, |account| {
                    account.owner() == program_id && filter(account)
                })
            },
            config,
        )
    }

    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<(Pubkey, AccountSharedData)>> {
        let sum = AtomicUsize::default();
        let config = ScanConfig {
            abort: Some(config.abort.as_ref().map(Arc::clone).unwrap_or_default()),
            collect_all_unsorted: config.collect_all_unsorted,
        };
        let result = self
            .accounts_db
            .index_scan_accounts(
                ancestors,
                bank_id,
                *index_key,
                |collector: &mut Vec<(Pubkey, AccountSharedData)>, some_account_tuple| {
                    Self::load_while_filtering(collector, some_account_tuple, |account| {
                        let use_account = filter(account);
                        if use_account {
                            if let Some(byte_limit_for_scan) = byte_limit_for_scan.as_ref() {
                                let added = account.data().len()
                                    + std::mem::size_of::<AccountSharedData>()
                                    + std::mem::size_of::<Pubkey>();
                                if sum
                                    .fetch_add(added, Ordering::Relaxed)
                                    .saturating_add(added)
                                    > *byte_limit_for_scan
                                {
                                    // total size of results exceeds size limit, so abort scan
                                    config.abort();
                                }
                            }
                        }
                        use_account
                    });
                },
                &config,
            )
            .map(|result| result.0);
        if config.is_aborted() {
            ScanResult::Err(ScanError::Aborted(
                "The accumulated scan results exceeded the limit".to_string(),
            ))
        } else {
            result
        }
    }

    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<(Pubkey, AccountSharedData, Slot)>> {
        self.accounts_db.scan_accounts(
            ancestors,
            bank_id,
            |collector: &mut Vec<(Pubkey, AccountSharedData, Slot)>, 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(),
        )
    }

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

    pub fn load_to_collect_rent_eagerly<R: RangeBounds<Pubkey> + std::fmt::Debug>(
        &self,
        ancestors: &Ancestors,
        range: R,
    ) -> Vec<(Pubkey, AccountSharedData)> {
        self.accounts_db.range_scan_accounts(
            "load_to_collect_rent_eagerly_scan_elapsed",
            ancestors,
            range,
            &ScanConfig::new(true),
            |collector: &mut Vec<(Pubkey, AccountSharedData)>, option| {
                Self::load_while_filtering(collector, option, |_| true)
            },
        )
    }

    /// 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)]);
    }

    pub fn store_slow_cached(&self, slot: Slot, pubkey: &Pubkey, account: &AccountSharedData) {
        self.accounts_db.store_cached(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);
        }
    }

    pub fn bank_hash_at(&self, slot: Slot) -> Hash {
        self.bank_hash_info_at(slot).hash
    }

    pub fn bank_hash_info_at(&self, slot: Slot) -> BankHashInfo {
        let delta_hash = self.accounts_db.get_accounts_delta_hash(slot);
        let bank_hashes = self.accounts_db.bank_hashes.read().unwrap();
        let mut hash_info = bank_hashes
            .get(&slot)
            .expect("No bank hash was found for this bank, that should not be possible")
            .clone();
        hash_info.hash = delta_hash;
        hash_info
    }

    /// 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>,
        demote_program_write_locks: bool,
    ) -> Vec<Result<()>> {
        let keys: Vec<_> = txs
            .map(|tx| tx.get_account_locks(demote_program_write_locks))
            .collect();
        let account_locks = &mut self.account_locks.lock().unwrap();
        keys.into_iter()
            .map(|keys| self.lock_account(account_locks, keys.writable, keys.readonly))
            .collect()
    }

    #[allow(clippy::needless_collect)]
    pub fn lock_accounts_with_results<'a>(
        &self,
        txs: impl Iterator<Item = &'a SanitizedTransaction>,
        results: impl Iterator<Item = &'a Result<()>>,
        demote_program_write_locks: bool,
    ) -> Vec<Result<()>> {
        let keys: Vec<_> = txs
            .map(|tx| tx.get_account_locks(demote_program_write_locks))
            .collect();
        let account_locks = &mut self.account_locks.lock().unwrap();
        keys.into_iter()
            .zip(results)
            .map(|(keys, result)| match result {
                Ok(()) => self.lock_account(account_locks, keys.writable, keys.readonly),
                Err(e) => Err(e.clone()),
            })
            .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<()>],
        demote_program_write_locks: bool,
    ) {
        let keys: Vec<_> = txs
            .zip(results)
            .filter_map(|(tx, res)| match res {
                Err(TransactionError::AccountInUse) => None,
                Err(TransactionError::SanitizeFailure) => None,
                Err(TransactionError::AccountLoadedTwice) => None,
                _ => Some(tx.get_account_locks(demote_program_write_locks)),
            })
            .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<'a>(
        &self,
        slot: Slot,
        txs: &'a [SanitizedTransaction],
        res: &'a [TransactionExecutionResult],
        loaded: &'a mut [TransactionLoadResult],
        rent_collector: &RentCollector,
        blockhash: &Hash,
        lamports_per_signature: u64,
        rent_for_sysvars: bool,
        merge_nonce_error_into_system_error: bool,
        demote_program_write_locks: bool,
    ) {
        let accounts_to_store = self.collect_accounts_to_store(
            txs,
            res,
            loaded,
            rent_collector,
            blockhash,
            lamports_per_signature,
            rent_for_sysvars,
            merge_nonce_error_into_system_error,
            demote_program_write_locks,
        );
        self.accounts_db.store_cached(slot, &accounts_to_store);
    }

    /// Purge a slot if it is not a root
    /// Root slots cannot be purged
    /// `is_from_abs` is true if the caller is the AccountsBackgroundService
    pub fn purge_slot(&self, slot: Slot, bank_id: BankId, is_from_abs: bool) {
        self.accounts_db.purge_slot(slot, bank_id, is_from_abs);
    }

    /// Add a slot to root.  Root slots cannot be purged
    pub fn add_root(&self, slot: Slot) {
        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,
        blockhash: &Hash,
        lamports_per_signature: u64,
        rent_for_sysvars: bool,
        merge_nonce_error_into_system_error: bool,
        demote_program_write_locks: bool,
    ) -> Vec<(&'a Pubkey, &'a AccountSharedData)> {
        let mut accounts = Vec::with_capacity(load_results.len());
        for (i, ((tx_load_result, _), 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_result, nonce) = &execution_results[i];
            let maybe_nonce = match (execution_result, nonce) {
                (Ok(_), Some(nonce)) => {
                    let address = nonce.address();
                    let account = nonce.account();
                    let maybe_fee_payer_account = nonce.fee_payer_account();
                    Some((address, account, maybe_fee_payer_account, true))
                }
                (Err(TransactionError::InstructionError(index, _)), Some(nonce)) => {
                    let nonce_marker_ix_failed = if merge_nonce_error_into_system_error {
                        // Don't advance stored blockhash when the nonce marker ix fails
                        *index == NONCED_TX_MARKER_IX_INDEX
                    } else {
                        false
                    };
                    let address = nonce.address();
                    let account = nonce.account();
                    let maybe_fee_payer_account = nonce.fee_payer_account();
                    Some((
                        address,
                        account,
                        maybe_fee_payer_account,
                        !nonce_marker_ix_failed,
                    ))
                }
                (Ok(_), _nonce) => None,
                (Err(_), _nonce) => 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))
            {
                let is_nonce_account = prepare_if_nonce_account(
                    address,
                    account,
                    execution_result,
                    maybe_nonce,
                    blockhash,
                    lamports_per_signature,
                );
                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, demote_program_write_locks)
                    && (execution_result.is_ok()
                        || (maybe_nonce.is_some() && (is_nonce_account || is_fee_payer)))
                {
                    if execution_result.is_err() {
                        match (is_nonce_account, is_fee_payer, maybe_nonce) {
                            // nonce is fee-payer, state updated in `prepare_if_nonce_account()`
                            (true, true, Some((_, _, None, _))) => (),
                            // nonce not fee-payer, state updated in `prepare_if_nonce_account()`
                            (true, false, Some((_, _, Some(_), _))) => (),
                            // not nonce, but fee-payer. rollback to cached state
                            (false, true, Some((_, _, Some(fee_payer_account), _))) => {
                                *account = fee_payer_account.clone();
                            }
                            _ => panic!("unexpected nonce condition"),
                        }
                    }
                    if account.rent_epoch() == INITIAL_RENT_EPOCH {
                        let rent = rent_collector.collect_from_created_account(
                            address,
                            account,
                            rent_for_sysvars,
                        );
                        loaded_transaction.rent += rent;
                        loaded_transaction
                            .rent_debits
                            .insert(address, rent, account.lamports());
                    }

                    // Add to the accounts to store
                    accounts.push((&*address, &*account));
                }
            }
        }
        accounts
    }
}

pub fn prepare_if_nonce_account(
    address: &Pubkey,
    account: &mut AccountSharedData,
    execution_result: &Result<()>,
    maybe_nonce: Option<(
        &Pubkey,
        &AccountSharedData,
        Option<&AccountSharedData>,
        bool,
    )>,
    blockhash: &Hash,
    lamports_per_signature: u64,
) -> bool {
    if let Some((nonce_key, nonce_account, _, advance_blockhash)) = maybe_nonce {
        if address == nonce_key {
            if execution_result.is_err() {
                // 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();
            }

            if advance_blockhash {
                // 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 state = StateMut::<NonceVersions>::state(nonce_account)
                    .unwrap()
                    .convert_to_current();
                if let NonceState::Initialized(ref data) = state {
                    account
                        .set_state(&NonceVersions::new_current(NonceState::new_initialized(
                            &data.authority,
                            blockhash,
                            lamports_per_signature,
                        )))
                        .unwrap();
                }
            }
            return true;
        }
    }
    false
}

pub fn create_test_accounts(
    accounts: &Accounts,
    pubkeys: &mut Vec<Pubkey>,
    num: usize,
    slot: Slot,
) {
    for t in 0..num {
        let pubkey = solana_sdk::pubkey::new_rand();
        let account =
            AccountSharedData::new((t + 1) as u64, 0, AccountSharedData::default().owner());
        accounts.store_slow_uncached(slot, &pubkey, &account);
        pubkeys.push(pubkey);
    }
}

// Only used by bench, not safe to call otherwise accounts can conflict with the
// accounts cache!
pub fn update_accounts_bench(accounts: &Accounts, pubkeys: &[Pubkey], slot: u64) {
    for pubkey in pubkeys {
        let amount = thread_rng().gen_range(0, 10);
        let account = AccountSharedData::new(amount, 0, AccountSharedData::default().owner());
        accounts.store_slow_uncached(slot, pubkey, &account);
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::rent_collector::RentCollector;
    use solana_sdk::{
        account::{AccountSharedData, WritableAccount},
        epoch_schedule::EpochSchedule,
        genesis_config::ClusterType,
        hash::Hash,
        instruction::{CompiledInstruction, InstructionError},
        message::Message,
        nonce, nonce_account,
        rent::Rent,
        signature::{keypair_from_seed, signers::Signers, Keypair, Signer},
        system_instruction, system_program,
        transaction::Transaction,
    };
    use std::{
        convert::TryFrom,
        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 load_accounts_with_fee_and_rent(
        tx: Transaction,
        ka: &[(Pubkey, AccountSharedData)],
        lamports_per_signature: u64,
        rent_collector: &RentCollector,
        error_counters: &mut ErrorCounters,
    ) -> Vec<TransactionLoadResult> {
        let mut hash_queue = BlockhashQueue::new(100);
        hash_queue.register_hash(&tx.message().recent_blockhash, lamports_per_signature);
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        for ka in ka.iter() {
            accounts.store_slow_uncached(0, &ka.0, &ka.1);
        }

        let ancestors = vec![(0, 0)].into_iter().collect();
        let sanitized_tx = SanitizedTransaction::from_transaction_for_tests(tx);
        accounts.load_accounts(
            &ancestors,
            &[sanitized_tx],
            vec![(Ok(()), None)],
            &hash_queue,
            error_counters,
            rent_collector,
            &FeatureSet::all_enabled(),
        )
    }

    fn load_accounts_with_fee(
        tx: Transaction,
        ka: &[(Pubkey, AccountSharedData)],
        lamports_per_signature: u64,
        error_counters: &mut ErrorCounters,
    ) -> Vec<TransactionLoadResult> {
        load_accounts_with_fee_and_rent(
            tx,
            ka,
            lamports_per_signature,
            &RentCollector::default(),
            error_counters,
        )
    }

    fn load_accounts(
        tx: Transaction,
        ka: &[(Pubkey, AccountSharedData)],
        error_counters: &mut ErrorCounters,
    ) -> Vec<TransactionLoadResult> {
        load_accounts_with_fee(tx, ka, 0, error_counters)
    }

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

    #[test]
    fn test_hold_range_in_memory2() {
        let accts = Accounts::default_for_tests();
        let range = Pubkey::new(&[0; 32])..=Pubkey::new(&[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);
        idx.account_maps.iter().enumerate().for_each(|(_bin, map)| {
            let map = map.read().unwrap();
            assert_eq!(
                map.cache_ranges_held.read().unwrap().to_vec(),
                vec![Some(range.clone())]
            );
        });
        accts.hold_range_in_memory(&range2, true);
        idx.account_maps.iter().enumerate().for_each(|(bin, map)| {
            let map = map.read().unwrap();
            let expected = if bin == 0 {
                vec![Some(range.clone()), Some(range2_inclusive.clone())]
            } else {
                vec![Some(range.clone())]
            };
            assert_eq!(
                map.cache_ranges_held.read().unwrap().to_vec(),
                expected,
                "bin: {}",
                bin
            );
        });
        accts.hold_range_in_memory(&range, false);
        accts.hold_range_in_memory(&range2, false);
    }

    #[test]
    fn test_load_accounts_no_account_0_exists() {
        let accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::AccountNotFound), None,),
        );
    }

    #[test]
    fn test_load_accounts_unknown_program_id() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = AccountSharedData::new(1, 0, &Pubkey::default());
        accounts.push((key0, account));

        let account = AccountSharedData::new(2, 1, &Pubkey::default());
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![Pubkey::default()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::ProgramAccountNotFound), None,)
        );
    }

    #[test]
    fn test_load_accounts_insufficient_funds() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();

        let account = AccountSharedData::new(1, 0, &Pubkey::default());
        accounts.push((key0, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let fee = Bank::calculate_fee(
            &SanitizedMessage::try_from(tx.message().clone()).unwrap(),
            10,
        );
        assert_eq!(fee, 10);

        let loaded_accounts = load_accounts_with_fee(tx, &accounts, 10, &mut error_counters);

        assert_eq!(error_counters.insufficient_funds, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0].clone(),
            (Err(TransactionError::InsufficientFundsForFee), None,),
        );
    }

    #[test]
    fn test_load_accounts_invalid_account_for_fee() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();

        let account = AccountSharedData::new(1, 1, &solana_sdk::pubkey::new_rand()); // <-- owner is not the system program
        accounts.push((key0, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_account_for_fee, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::InvalidAccountForFee), None,),
        );
    }

    #[test]
    fn test_load_accounts_fee_payer_is_nonce() {
        let mut error_counters = ErrorCounters::default();
        let rent_collector = RentCollector::new(
            0,
            &EpochSchedule::default(),
            500_000.0,
            &Rent {
                lamports_per_byte_year: 42,
                ..Rent::default()
            },
        );
        let min_balance = rent_collector.rent.minimum_balance(NonceState::size());
        let nonce = Keypair::new();
        let mut accounts = vec![(
            nonce.pubkey(),
            AccountSharedData::new_data(
                min_balance * 2,
                &NonceVersions::new_current(NonceState::Initialized(nonce::state::Data::default())),
                &system_program::id(),
            )
            .unwrap(),
        )];
        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&nonce],
            &[],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        // Fee leaves min_balance balance succeeds
        let loaded_accounts = load_accounts_with_fee_and_rent(
            tx.clone(),
            &accounts,
            min_balance,
            &rent_collector,
            &mut error_counters,
        );
        assert_eq!(loaded_accounts.len(), 1);
        let (load_res, _nonce) = &loaded_accounts[0];
        let loaded_transaction = load_res.as_ref().unwrap();
        assert_eq!(loaded_transaction.accounts[0].1.lamports(), min_balance);

        // Fee leaves zero balance fails
        accounts[0].1.set_lamports(min_balance);
        let loaded_accounts = load_accounts_with_fee_and_rent(
            tx.clone(),
            &accounts,
            min_balance,
            &rent_collector,
            &mut error_counters,
        );
        assert_eq!(loaded_accounts.len(), 1);
        let (load_res, _nonce) = &loaded_accounts[0];
        assert_eq!(*load_res, Err(TransactionError::InsufficientFundsForFee));

        // Fee leaves non-zero, but sub-min_balance balance fails
        accounts[0].1.set_lamports(3 * min_balance / 2);
        let loaded_accounts = load_accounts_with_fee_and_rent(
            tx,
            &accounts,
            min_balance,
            &rent_collector,
            &mut error_counters,
        );
        assert_eq!(loaded_accounts.len(), 1);
        let (load_res, _nonce) = &loaded_accounts[0];
        assert_eq!(*load_res, Err(TransactionError::InsufficientFundsForFee));
    }

    #[test]
    fn test_load_accounts_no_loaders() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let mut account = AccountSharedData::new(1, 0, &Pubkey::default());
        account.set_rent_epoch(1);
        accounts.push((key0, account));

        let mut account = AccountSharedData::new(2, 1, &Pubkey::default());
        account.set_rent_epoch(1);
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[key1],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 0);
        assert_eq!(loaded_accounts.len(), 1);
        match &loaded_accounts[0] {
            (Ok(loaded_transaction), _nonce) => {
                assert_eq!(loaded_transaction.accounts.len(), 3);
                assert_eq!(loaded_transaction.accounts[0].1, accounts[0].1);
                assert_eq!(loaded_transaction.program_indices.len(), 1);
                assert_eq!(loaded_transaction.program_indices[0].len(), 0);
            }
            (Err(e), _nonce) => Err(e).unwrap(),
        }
    }

    #[test]
    fn test_load_accounts_max_call_depth() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);
        let key3 = Pubkey::new(&[7u8; 32]);
        let key4 = Pubkey::new(&[8u8; 32]);
        let key5 = Pubkey::new(&[9u8; 32]);
        let key6 = Pubkey::new(&[10u8; 32]);

        let account = AccountSharedData::new(1, 0, &Pubkey::default());
        accounts.push((key0, account));

        let mut account = AccountSharedData::new(40, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_owner(native_loader::id());
        accounts.push((key1, account));

        let mut account = AccountSharedData::new(41, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_owner(key1);
        accounts.push((key2, account));

        let mut account = AccountSharedData::new(42, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_owner(key2);
        accounts.push((key3, account));

        let mut account = AccountSharedData::new(43, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_owner(key3);
        accounts.push((key4, account));

        let mut account = AccountSharedData::new(44, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_owner(key4);
        accounts.push((key5, account));

        let mut account = AccountSharedData::new(45, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_owner(key5);
        accounts.push((key6, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key6],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.call_chain_too_deep, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::CallChainTooDeep), None,)
        );
    }

    #[test]
    fn test_load_accounts_bad_owner() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = AccountSharedData::new(1, 0, &Pubkey::default());
        accounts.push((key0, account));

        let mut account = AccountSharedData::new(40, 1, &Pubkey::default());
        account.set_executable(true);
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key1],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::ProgramAccountNotFound), None,)
        );
    }

    #[test]
    fn test_load_accounts_not_executable() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);

        let account = AccountSharedData::new(1, 0, &Pubkey::default());
        accounts.push((key0, account));

        let account = AccountSharedData::new(40, 1, &native_loader::id());
        accounts.push((key1, account));

        let instructions = vec![CompiledInstruction::new(1, &(), vec![0])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key1],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_program_for_execution, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::InvalidProgramForExecution), None,)
        );
    }

    #[test]
    fn test_load_accounts_multiple_loaders() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);

        let mut account = AccountSharedData::new(1, 0, &Pubkey::default());
        account.set_rent_epoch(1);
        accounts.push((key0, account));

        let mut account = AccountSharedData::new(40, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_rent_epoch(1);
        account.set_owner(native_loader::id());
        accounts.push((key1, account));

        let mut account = AccountSharedData::new(41, 1, &Pubkey::default());
        account.set_executable(true);
        account.set_rent_epoch(1);
        account.set_owner(key1);
        accounts.push((key2, account));

        let instructions = vec![
            CompiledInstruction::new(1, &(), vec![0]),
            CompiledInstruction::new(2, &(), vec![0]),
        ];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[],
            Hash::default(),
            vec![key1, key2],
            instructions,
        );

        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.account_not_found, 0);
        assert_eq!(loaded_accounts.len(), 1);
        match &loaded_accounts[0] {
            (Ok(loaded_transaction), _nonce) => {
                assert_eq!(loaded_transaction.accounts.len(), 6);
                assert_eq!(loaded_transaction.accounts[0].1, accounts[0].1);
                assert_eq!(loaded_transaction.program_indices.len(), 2);
                assert_eq!(loaded_transaction.program_indices[0].len(), 1);
                assert_eq!(loaded_transaction.program_indices[1].len(), 2);
                for program_indices in loaded_transaction.program_indices.iter() {
                    for (i, program_index) in program_indices.iter().enumerate() {
                        // +1 to skip first not loader account
                        assert_eq!(
                            loaded_transaction.accounts[*program_index].0,
                            accounts[i + 1].0
                        );
                        assert_eq!(
                            loaded_transaction.accounts[*program_index].1,
                            accounts[i + 1].1
                        );
                    }
                }
            }
            (Err(e), _nonce) => Err(e).unwrap(),
        }
    }

    #[test]
    fn test_load_by_program_slot() {
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );

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

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

    #[test]
    fn test_load_accounts_executable_with_write_lock() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);

        let mut account = AccountSharedData::new(1, 0, &Pubkey::default());
        account.set_rent_epoch(1);
        accounts.push((key0, account));

        let mut account = AccountSharedData::new(40, 1, &native_loader::id());
        account.set_executable(true);
        account.set_rent_epoch(1);
        accounts.push((key1, account));

        let mut account = AccountSharedData::new(40, 1, &native_loader::id());
        account.set_executable(true);
        account.set_rent_epoch(1);
        accounts.push((key2, account));

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let mut message = Message::new_with_compiled_instructions(
            1,
            0,
            1, // only one executable marked as readonly
            vec![key0, key1, key2],
            Hash::default(),
            instructions,
        );
        let tx = Transaction::new(&[&keypair], message.clone(), Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::InvalidWritableAccount), None)
        );

        // Mark executables as readonly
        message.account_keys = vec![key0, key1, key2]; // revert key change
        message.header.num_readonly_unsigned_accounts = 2; // mark both executables as readonly
        let tx = Transaction::new(&[&keypair], message, Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        let result = loaded_accounts[0].0.as_ref().unwrap();
        assert_eq!(result.accounts[..2], accounts[..2]);
        assert_eq!(result.accounts[result.program_indices[0][0]], accounts[2]);
    }

    #[test]
    fn test_load_accounts_upgradeable_with_write_lock() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);
        let programdata_key1 = Pubkey::new(&[7u8; 32]);
        let programdata_key2 = Pubkey::new(&[8u8; 32]);

        let mut account = AccountSharedData::new(1, 0, &Pubkey::default());
        account.set_rent_epoch(1);
        accounts.push((key0, account));

        let program_data = UpgradeableLoaderState::ProgramData {
            slot: 42,
            upgrade_authority_address: None,
        };

        let program = UpgradeableLoaderState::Program {
            programdata_address: programdata_key1,
        };
        let mut account =
            AccountSharedData::new_data(40, &program, &bpf_loader_upgradeable::id()).unwrap();
        account.set_executable(true);
        account.set_rent_epoch(1);
        accounts.push((key1, account));
        let mut account =
            AccountSharedData::new_data(40, &program_data, &bpf_loader_upgradeable::id()).unwrap();
        account.set_rent_epoch(1);
        accounts.push((programdata_key1, account));

        let program = UpgradeableLoaderState::Program {
            programdata_address: programdata_key2,
        };
        let mut account =
            AccountSharedData::new_data(40, &program, &bpf_loader_upgradeable::id()).unwrap();
        account.set_executable(true);
        account.set_rent_epoch(1);
        accounts.push((key2, account));
        let mut account =
            AccountSharedData::new_data(40, &program_data, &bpf_loader_upgradeable::id()).unwrap();
        account.set_rent_epoch(1);
        accounts.push((programdata_key2, account));

        let mut account = AccountSharedData::new(40, 1, &native_loader::id()); // create mock bpf_loader_upgradeable
        account.set_executable(true);
        account.set_rent_epoch(1);
        accounts.push((bpf_loader_upgradeable::id(), account));

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let mut message = Message::new_with_compiled_instructions(
            1,
            0,
            1, // only one executable marked as readonly
            vec![key0, key1, key2],
            Hash::default(),
            instructions,
        );
        let tx = Transaction::new(&[&keypair], message.clone(), Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::InvalidWritableAccount), None)
        );

        // Solution 1: include bpf_loader_upgradeable account
        message.account_keys = vec![key0, key1, bpf_loader_upgradeable::id()];
        let tx = Transaction::new(&[&keypair], message.clone(), Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        let result = loaded_accounts[0].0.as_ref().unwrap();
        assert_eq!(result.accounts[..2], accounts[..2]);
        assert_eq!(result.accounts[result.program_indices[0][0]], accounts[5]);

        // Solution 2: mark programdata as readonly
        message.account_keys = vec![key0, key1, key2]; // revert key change
        message.header.num_readonly_unsigned_accounts = 2; // mark both executables as readonly
        let tx = Transaction::new(&[&keypair], message, Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        let result = loaded_accounts[0].0.as_ref().unwrap();
        assert_eq!(result.accounts[..2], accounts[..2]);
        assert_eq!(result.accounts[result.program_indices[0][0]], accounts[5]);
        assert_eq!(result.accounts[result.program_indices[0][1]], accounts[4]);
        assert_eq!(result.accounts[result.program_indices[0][2]], accounts[3]);
    }

    #[test]
    fn test_load_accounts_programdata_with_write_lock() {
        let mut accounts: Vec<(Pubkey, AccountSharedData)> = Vec::new();
        let mut error_counters = ErrorCounters::default();

        let keypair = Keypair::new();
        let key0 = keypair.pubkey();
        let key1 = Pubkey::new(&[5u8; 32]);
        let key2 = Pubkey::new(&[6u8; 32]);

        let mut account = AccountSharedData::new(1, 0, &Pubkey::default());
        account.set_rent_epoch(1);
        accounts.push((key0, account));

        let program_data = UpgradeableLoaderState::ProgramData {
            slot: 42,
            upgrade_authority_address: None,
        };
        let mut account =
            AccountSharedData::new_data(40, &program_data, &bpf_loader_upgradeable::id()).unwrap();
        account.set_rent_epoch(1);
        accounts.push((key1, account));

        let mut account = AccountSharedData::new(40, 1, &native_loader::id());
        account.set_executable(true);
        account.set_rent_epoch(1);
        accounts.push((key2, account));

        let instructions = vec![CompiledInstruction::new(2, &(), vec![0, 1])];
        let mut message = Message::new_with_compiled_instructions(
            1,
            0,
            1, // only the program marked as readonly
            vec![key0, key1, key2],
            Hash::default(),
            instructions,
        );
        let tx = Transaction::new(&[&keypair], message.clone(), Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        assert_eq!(
            loaded_accounts[0],
            (Err(TransactionError::InvalidWritableAccount), None)
        );

        // Solution 1: include bpf_loader_upgradeable account
        let mut account = AccountSharedData::new(40, 1, &native_loader::id()); // create mock bpf_loader_upgradeable
        account.set_executable(true);
        account.set_rent_epoch(1);
        let accounts_with_upgradeable_loader = vec![
            accounts[0].clone(),
            accounts[1].clone(),
            (bpf_loader_upgradeable::id(), account),
        ];
        message.account_keys = vec![key0, key1, bpf_loader_upgradeable::id()];
        let tx = Transaction::new(&[&keypair], message.clone(), Hash::default());
        let loaded_accounts =
            load_accounts(tx, &accounts_with_upgradeable_loader, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        let result = loaded_accounts[0].0.as_ref().unwrap();
        assert_eq!(result.accounts[..2], accounts_with_upgradeable_loader[..2]);
        assert_eq!(
            result.accounts[result.program_indices[0][0]],
            accounts_with_upgradeable_loader[2]
        );

        // Solution 2: mark programdata as readonly
        message.account_keys = vec![key0, key1, key2]; // revert key change
        message.header.num_readonly_unsigned_accounts = 2; // extend readonly set to include programdata
        let tx = Transaction::new(&[&keypair], message, Hash::default());
        let loaded_accounts = load_accounts(tx, &accounts, &mut error_counters);

        assert_eq!(error_counters.invalid_writable_account, 1);
        assert_eq!(loaded_accounts.len(), 1);
        let result = loaded_accounts[0].0.as_ref().unwrap();
        assert_eq!(result.accounts[..2], accounts[..2]);
        assert_eq!(result.accounts[result.program_indices[0][0]], accounts[2]);
    }

    #[test]
    fn test_accounts_account_not_found() {
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        let mut error_counters = ErrorCounters::default();
        let ancestors = vec![(0, 0)].into_iter().collect();

        let keypair = Keypair::new();
        let mut account = AccountSharedData::new(1, 0, &Pubkey::default());
        account.set_executable(true);
        accounts.store_slow_uncached(0, &keypair.pubkey(), &account);

        assert_eq!(
            accounts.load_executable_accounts(
                &ancestors,
                &mut vec![(keypair.pubkey(), account)],
                0,
                &mut error_counters,
            ),
            Err(TransactionError::ProgramAccountNotFound)
        );
        assert_eq!(error_counters.account_not_found, 1);
    }

    #[test]
    #[should_panic]
    fn test_accounts_empty_bank_hash() {
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        accounts.bank_hash_at(1);
    }

    #[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 = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        accounts.store_slow_uncached(0, &keypair0.pubkey(), &account0);
        accounts.store_slow_uncached(0, &keypair1.pubkey(), &account1);
        accounts.store_slow_uncached(0, &keypair2.pubkey(), &account2);
        accounts.store_slow_uncached(0, &keypair3.pubkey(), &account3);

        let demote_program_write_locks = true;

        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(), demote_program_write_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(), demote_program_write_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, demote_program_write_locks);
        accounts.unlock_accounts(txs.iter(), &results1, demote_program_write_locks);
        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(), demote_program_write_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 = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        accounts.store_slow_uncached(0, &keypair0.pubkey(), &account0);
        accounts.store_slow_uncached(0, &keypair1.pubkey(), &account1);
        accounts.store_slow_uncached(0, &keypair2.pubkey(), &account2);

        let demote_program_write_locks = true;

        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 || {
            let counter_clone = counter_clone.clone();
            let exit_clone = exit_clone.clone();
            loop {
                let txs = vec![writable_tx.clone()];
                let results = accounts_clone
                    .clone()
                    .lock_accounts(txs.iter(), demote_program_write_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, demote_program_write_locks);
                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(), demote_program_write_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, demote_program_write_locks);
            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 = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        accounts.store_slow_uncached(0, &keypair0.pubkey(), &account0);
        accounts.store_slow_uncached(0, &keypair1.pubkey(), &account1);
        accounts.store_slow_uncached(0, &keypair2.pubkey(), &account2);
        accounts.store_slow_uncached(0, &keypair3.pubkey(), &account3);

        let demote_program_write_locks = true;

        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(), demote_program_write_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()));
    }

    #[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 = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        {
            accounts
                .account_locks
                .lock()
                .unwrap()
                .insert_new_readonly(&pubkey);
        }
        let txs = vec![tx0, tx1];
        let programs = vec![(Ok(()), None), (Ok(()), None)];
        let collected_accounts = accounts.collect_accounts_to_store(
            &txs,
            &programs,
            loaded.as_mut_slice(),
            &rent_collector,
            &Hash::default(),
            0,
            true,
            true, // merge_nonce_error_into_system_error
            true, // demote_program_write_locks
        );
        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()));

        // 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 = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        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) as u64, 0, AccountSharedData::default().owner());
            accounts.store_slow_uncached(i, &pubkey, &account);
            accounts.store_slow_uncached(i, &old_pubkey, &zero_account);
            old_pubkey = pubkey;
            accounts.add_root(i);
            if i % 1_000 == 0 {
                info!("  store {}", i);
            }
        }
        info!("done..cleaning..");
        accounts.accounts_db.clean_accounts(None, false, None);
    }

    fn load_accounts_no_store(accounts: &Accounts, tx: Transaction) -> Vec<TransactionLoadResult> {
        let tx = SanitizedTransaction::from_transaction_for_tests(tx);
        let rent_collector = RentCollector::default();
        let mut hash_queue = BlockhashQueue::new(100);
        hash_queue.register_hash(tx.message().recent_blockhash(), 10);

        let ancestors = vec![(0, 0)].into_iter().collect();
        let mut error_counters = ErrorCounters::default();
        accounts.load_accounts(
            &ancestors,
            &[tx],
            vec![(Ok(()), None)],
            &hash_queue,
            &mut error_counters,
            &rent_collector,
            &FeatureSet::all_enabled(),
        )
    }

    #[test]
    fn test_instructions() {
        solana_logger::setup();
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );

        let instructions_key = solana_sdk::sysvar::instructions::id();
        let keypair = Keypair::new();
        let instructions = vec![CompiledInstruction::new(1, &(), vec![0, 1])];
        let tx = Transaction::new_with_compiled_instructions(
            &[&keypair],
            &[solana_sdk::pubkey::new_rand(), instructions_key],
            Hash::default(),
            vec![native_loader::id()],
            instructions,
        );

        let loaded_accounts = load_accounts_no_store(&accounts, tx);
        assert_eq!(loaded_accounts.len(), 1);
        assert!(loaded_accounts[0].0.is_err());
    }

    fn create_accounts_prepare_if_nonce_account() -> (
        Pubkey,
        AccountSharedData,
        AccountSharedData,
        Hash,
        u64,
        Option<AccountSharedData>,
    ) {
        let data =
            NonceVersions::new_current(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);
        (
            Pubkey::default(),
            pre_account,
            account,
            Hash::new(&[1u8; 32]),
            1234,
            None,
        )
    }

    fn run_prepare_if_nonce_account_test(
        account_address: &Pubkey,
        account: &mut AccountSharedData,
        tx_result: &Result<()>,
        maybe_nonce: Option<(
            &Pubkey,
            &AccountSharedData,
            Option<&AccountSharedData>,
            bool,
        )>,
        blockhash: &Hash,
        lamports_per_signature: u64,
        expect_account: &AccountSharedData,
    ) -> bool {
        // Verify expect_account's relationship
        match maybe_nonce {
            Some((nonce_address, _nonce_account, _maybe_fee_payer_account, _))
                if nonce_address == account_address && tx_result.is_ok() =>
            {
                assert_eq!(expect_account, account) // Account update occurs in system_instruction_processor
            }
            Some((nonce_address, nonce_account, _maybe_fee_payer_account, _))
                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,
            maybe_nonce,
            blockhash,
            lamports_per_signature,
        );
        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 mut expect_account = post_account.clone();
        let data =
            NonceVersions::new_current(NonceState::Initialized(nonce::state::Data::default()));
        expect_account.set_state(&data).unwrap();

        assert!(run_prepare_if_nonce_account_test(
            &post_account_address,
            &mut post_account,
            &Ok(()),
            Some((
                &pre_account_address,
                &pre_account,
                maybe_fee_payer_account.as_ref(),
                false,
            )),
            &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(()),
            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 expect_account = post_account.clone();
        // Wrong key
        assert!(run_prepare_if_nonce_account_test(
            &Pubkey::new(&[1u8; 32]),
            &mut post_account,
            &Ok(()),
            Some((
                &pre_account_address,
                &pre_account,
                maybe_fee_payer_account.as_ref(),
                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();
        expect_account
            .set_state(&NonceVersions::new_current(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,
            )),
            Some((
                &pre_account_address,
                &pre_account,
                maybe_fee_payer_account.as_ref(),
                true,
            )),
            &blockhash,
            lamports_per_signature,
            &expect_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 nonce_state = NonceVersions::new_current(NonceState::Initialized(
            nonce::state::Data::new(nonce_authority.pubkey(), Hash::new_unique(), 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 nonce_state = NonceVersions::new_current(NonceState::Initialized(
            nonce::state::Data::new(nonce_authority.pubkey(), Hash::new_unique(), 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 next_blockhash = Hash::new_unique();
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        let txs = vec![tx];
        let programs = vec![(
            Err(TransactionError::InstructionError(
                1,
                InstructionError::InvalidArgument,
            )),
            nonce,
        )];
        let collected_accounts = accounts.collect_accounts_to_store(
            &txs,
            &programs,
            loaded.as_mut_slice(),
            &rent_collector,
            &next_blockhash,
            0,
            true,
            true, // merge_nonce_error_into_system_error
            true, // demote_program_write_locks
        );
        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!(nonce_account::verify_nonce_account(
            &collected_nonce_account,
            &next_blockhash
        ));
    }

    #[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 nonce_state = NonceVersions::new_current(NonceState::Initialized(
            nonce::state::Data::new(nonce_authority.pubkey(), Hash::new_unique(), 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 nonce_state = NonceVersions::new_current(NonceState::Initialized(
            nonce::state::Data::new(nonce_authority.pubkey(), Hash::new_unique(), 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 next_blockhash = Hash::new_unique();
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );
        let txs = vec![tx];
        let programs = vec![(
            Err(TransactionError::InstructionError(
                1,
                InstructionError::InvalidArgument,
            )),
            nonce,
        )];
        let collected_accounts = accounts.collect_accounts_to_store(
            &txs,
            &programs,
            loaded.as_mut_slice(),
            &rent_collector,
            &next_blockhash,
            0,
            true,
            true, // merge_nonce_error_into_system_error
            true, // demote_program_write_locks
        );
        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!(nonce_account::verify_nonce_account(
            &collected_nonce_account,
            &next_blockhash
        ));
    }

    #[test]
    fn test_load_largest_accounts() {
        let accounts = Accounts::new_with_config_for_tests(
            Vec::new(),
            &ClusterType::Development,
            AccountSecondaryIndexes::default(),
            false,
            AccountShrinkThreshold::default(),
        );

        let pubkey0 = Pubkey::new_unique();
        let account0 = AccountSharedData::new(42, 0, &Pubkey::default());
        accounts.store_slow_uncached(0, &pubkey0, &account0);
        let pubkey1 = Pubkey::new_unique();
        let account1 = AccountSharedData::new(42, 0, &Pubkey::default());
        accounts.store_slow_uncached(0, &pubkey1, &account1);
        let pubkey2 = Pubkey::new_unique();
        let account2 = AccountSharedData::new(41, 0, &Pubkey::default());
        accounts.store_slow_uncached(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)]
        );
    }
}