Put Account's data in an Arc

runtime/src/accounts_cache.rs

@@ -57,6 +57,7 @@ impl SlotCacheInner {
     pub fn get_cloned(&self, pubkey: &Pubkey) -> Option<CachedAccount> {
         self.cache
             .get(pubkey)
+            // Could return AccountNoData here
             // 1) Maybe can eventually use a Cow to avoid a clone on every read
             // 2) Popping is only safe if its guaranteed only replay/banking threads
             // are reading from the AccountsDb
@@ -86,7 +87,7 @@ impl Deref for SlotCacheInner {
 
 #[derive(Debug, Clone)]
 pub struct CachedAccount {
-    pub account: Account,
+    pub account: Account, // would become AccountNoData
     pub hash: Hash,
 }
 

runtime/src/accounts_db.rs

@@ -276,6 +276,7 @@ impl<'a> LoadedAccount<'a> {
         }
     }
 
+    /* would become AccountNoData */
     pub fn account(self) -> Account {
         match self {
             LoadedAccount::Stored(stored_account_meta) => stored_account_meta.clone_account(),
@@ -2195,7 +2196,7 @@ impl AccountsDb {
         bank_hashes.insert(slot, new_hash_info);
     }
 
-    pub fn load(&self, ancestors: &Ancestors, pubkey: &Pubkey) -> Option<(Account, Slot)> {
+    pub fn load(&self, ancestors: &Ancestors, pubkey: &Pubkey) -> Option<(Account /* would become AccountNoData */, Slot)> {
         self.do_load(ancestors, pubkey, None)
     }
 

runtime/src/bank.rs

@@ -111,9 +111,9 @@ impl ExecuteTimings {
 type BankStatusCache = StatusCache<Result<()>>;
 #[frozen_abi(digest = "3ZaEt781qwhfQSE4DZPBHhng2S6MuimchRjkR9ZWzDFs")]
 pub type BankSlotDelta = SlotDelta<Result<()>>;
-type TransactionAccountRefCells = Vec<Rc<RefCell<Account>>>;
-type TransactionAccountDepRefCells = Vec<(Pubkey, RefCell<Account>)>;
-type TransactionLoaderRefCells = Vec<Vec<(Pubkey, RefCell<Account>)>>;
+type TransactionAccountRefCells = Vec<Rc<RefCell<Account>>>;  /* would become AccountNoData */
+type TransactionAccountDepRefCells = Vec<(Pubkey, RefCell<Account>)>;  /* would become AccountNoData */
+type TransactionLoaderRefCells = Vec<Vec<(Pubkey, RefCell<Account>)>>;  /* would become AccountNoData */
 
 // Eager rent collection repeats in cyclic manner.
 // Each cycle is composed of <partiion_count> number of tiny pubkey subranges

runtime/src/message_processor.rs

@@ -58,7 +58,7 @@ impl Executors {
 pub struct PreAccount {
     key: Pubkey,
     is_writable: bool,
-    account: RefCell<Account>,
+    account: RefCell<Account>, /* would become AccountNoData */
 }
 impl PreAccount {
     pub fn new(key: &Pubkey, account: &Account, is_writable: bool) -> Self {

sdk/src/account.rs

@@ -1,6 +1,6 @@
 use crate::{clock::Epoch, pubkey::Pubkey};
 use solana_program::{account_info::AccountInfo, sysvar::Sysvar};
-use std::{cell::RefCell, cmp, fmt, rc::Rc};
+use std::{cell::RefCell, cmp, fmt, rc::Rc, sync::Arc};
 
 /// An Account with data that is stored on chain
 #[repr(C)]
@@ -21,6 +21,36 @@ pub struct Account {
     pub rent_epoch: Epoch,
 }
 
+#[derive(Clone, Default, Debug, PartialEq, Eq, AbiExample)]
+pub struct AccountNoData {
+    /// lamports in the account
+    pub lamports: u64,
+    /// data held in this account
+    pub data: Arc<Vec<u8>>,
+    /// the program that owns this account. If executable, the program that loads this account.
+    pub owner: Pubkey,
+    /// this account's data contains a loaded program (and is now read-only)
+    pub executable: bool,
+    /// the epoch at which this account will next owe rent
+    pub rent_epoch: Epoch,
+}
+
+pub trait AnAccount: Default + Clone + Sized {
+    fn lamports(&self) -> u64;
+    fn set_lamports(&mut self, lamports: u64);
+    fn data(&self) -> &Vec<u8>;
+    fn set_data(&mut self, data: Vec<u8>);
+    fn owner(&self) -> &Pubkey;
+    fn set_owner(&mut self, owner: Pubkey);
+    fn executable(&self) -> bool;
+    fn rent_epoch(&self) -> Epoch;
+    fn set_rent_epoch(&mut self, epoch: Epoch);
+    fn clone_as_account_no_data(&self) -> AccountNoData;
+    fn clone_as_account(&self) -> Account;
+    fn from_account_no_data(item: AccountNoData) -> Self;
+    fn to_account_no_data(&mut self) -> AccountNoData;
+}
+
 impl fmt::Debug for Account {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let data_len = cmp::min(64, self.data.len());

sdk/src/keyed_account.rs

@@ -14,7 +14,7 @@ pub struct KeyedAccount<'a> {
     is_signer: bool, // Transaction was signed by this account's key
     is_writable: bool,
     key: &'a Pubkey,
-    pub account: &'a RefCell<Account>,
+    pub account: &'a RefCell<Account>, /* would become AccountNoData */
 }
 
 impl<'a> KeyedAccount<'a> {