Add incinerator sysvar (#9815)

runtime/src/accounts.rs

@@ -162,7 +162,7 @@ impl Accounts {
                 let (account, rent) = AccountsDB::load(storage, ancestors, accounts_index, key)
                     .and_then(|(mut account, _)| {
                         if message.is_writable(i) && !account.executable {
-                            let rent_due = rent_collector.update(&mut account);
+                            let rent_due = rent_collector.update(&key, &mut account);
                             Some((account, rent_due))
                         } else {
                             Some((account, 0))
@@ -664,7 +664,7 @@ impl Accounts {
                 if message.is_writable(i) {
                     if account.rent_epoch == 0 {
                         account.rent_epoch = rent_collector.epoch;
-                        acc.2 += rent_collector.update(account);
+                        acc.2 += rent_collector.update(&key, account);
                     }
                     accounts.push((key, &*account));
                 }

runtime/src/bank.rs

@@ -42,6 +42,7 @@ use solana_sdk::{
     genesis_config::GenesisConfig,
     hard_forks::HardForks,
     hash::{extend_and_hash, hashv, Hash},
+    incinerator,
     inflation::Inflation,
     native_loader, nonce,
     pubkey::Pubkey,
@@ -795,6 +796,7 @@ impl Bank {
             self.collect_fees();
             self.distribute_rent();
             self.update_slot_history();
+            self.run_incinerator();
 
             // freeze is a one-way trip, idempotent
             *hash = self.hash_internal_state();
@@ -1639,6 +1641,14 @@ impl Bank {
             .fetch_add(collected_rent, Ordering::Relaxed);
     }
 
+    fn run_incinerator(&self) {
+        if let Some((account, _)) = self.get_account_modified_since_parent(&incinerator::id()) {
+            self.capitalization
+                .fetch_sub(account.lamports, Ordering::Relaxed);
+            self.store_account(&incinerator::id(), &Account::default());
+        }
+    }
+
     /// Process a batch of transactions.
     #[must_use]
     pub fn load_execute_and_commit_transactions(
@@ -1751,8 +1761,10 @@ impl Bank {
 
     pub fn deposit(&self, pubkey: &Pubkey, lamports: u64) {
         let mut account = self.get_account(pubkey).unwrap_or_default();
-        self.collected_rent
-            .fetch_add(self.rent_collector.update(&mut account), Ordering::Relaxed);
+        self.collected_rent.fetch_add(
+            self.rent_collector.update(pubkey, &mut account),
+            Ordering::Relaxed,
+        );
         account.lamports += lamports;
         self.store_account(pubkey, &account);
     }
@@ -5843,4 +5855,32 @@ mod tests {
         info!("account: {:?}", account);
         assert!(account.executable);
     }
+
+    #[test]
+    fn test_incinerator() {
+        let (genesis_config, mint_keypair) = create_genesis_config(1_000_000_000_000);
+        let bank0 = Arc::new(Bank::new(&genesis_config));
+
+        // Move to the first normal slot so normal rent behaviour applies
+        let bank = Bank::new_from_parent(
+            &bank0,
+            &Pubkey::default(),
+            genesis_config.epoch_schedule.first_normal_slot,
+        );
+        let pre_capitalization = bank.capitalization();
+
+        // Burn a non-rent exempt amount
+        let burn_amount = bank.get_minimum_balance_for_rent_exemption(0) - 1;
+
+        assert_eq!(bank.get_balance(&incinerator::id()), 0);
+        bank.transfer(burn_amount, &mint_keypair, &incinerator::id())
+            .unwrap();
+        assert_eq!(bank.get_balance(&incinerator::id()), burn_amount);
+        bank.freeze();
+        assert_eq!(bank.get_balance(&incinerator::id()), 0);
+
+        // Ensure that no rent was collected, and the entire burn amount was removed from bank
+        // capitalization
+        assert_eq!(bank.capitalization(), pre_capitalization - burn_amount);
+    }
 }

runtime/src/rent_collector.rs

@@ -1,6 +1,7 @@
 //! calculate and collect rent from Accounts
 use solana_sdk::{
-    account::Account, clock::Epoch, epoch_schedule::EpochSchedule, rent::Rent, sysvar,
+    account::Account, clock::Epoch, epoch_schedule::EpochSchedule, incinerator, pubkey::Pubkey,
+    rent::Rent, sysvar,
 };
 
 #[derive(Default, Serialize, Deserialize, Clone)]
@@ -35,8 +36,11 @@ impl RentCollector {
     // updates this account's lamports and status and returns
     //  the account rent collected, if any
     //
-    pub fn update(&self, account: &mut Account) -> u64 {
-        if account.executable || account.rent_epoch > self.epoch || sysvar::check_id(&account.owner)
+    pub fn update(&self, address: &Pubkey, account: &mut Account) -> u64 {
+        if account.executable
+            || account.rent_epoch > self.epoch
+            || sysvar::check_id(&account.owner)
+            || *address == incinerator::id()
         {
             0
         } else {

sdk/macro/src/lib.rs

@@ -21,8 +21,12 @@ impl Parse for Id {
             let id_vec = bs58::decode(id_literal.value())
                 .into_vec()
                 .map_err(|_| syn::Error::new_spanned(&id_literal, "failed to decode base58 id"))?;
-            let id_array = <[u8; 32]>::try_from(<&[u8]>::clone(&&id_vec[..]))
-                .map_err(|_| syn::Error::new_spanned(&id_literal, "id is not 32 bytes long"))?;
+            let id_array = <[u8; 32]>::try_from(<&[u8]>::clone(&&id_vec[..])).map_err(|_| {
+                syn::Error::new_spanned(
+                    &id_literal,
+                    format!("id is not 32 bytes long: len={}", id_vec.len()),
+                )
+            })?;
             let bytes = id_array.iter().map(|b| LitByte::new(*b, Span::call_site()));
             quote! {
                 ::solana_sdk::pubkey::Pubkey::new_from_array(

sdk/src/incinerator.rs

@@ -0,0 +1,4 @@
+//! Lamports credited to this address will be removed from the total supply (burned) at the end of
+//! the current block.
+
+crate::declare_id!("1nc1nerator11111111111111111111111111111111");

sdk/src/lib.rs

@@ -10,6 +10,7 @@ pub mod entrypoint_native;
 pub mod epoch_schedule;
 pub mod fee_calculator;
 pub mod hash;
+pub mod incinerator;
 pub mod inflation;
 pub mod instruction;
 pub mod loader_instruction;