revenue-distribution: track debt write-offs in state (malbeclabs/doublezero-solana#93)

This change implements [RFC-0002], which outlines adding state variables
to track debt write-offs in the distribution and Solana validator
deposit accounts.

NOTE: This change replaces the forgive-solana-validator-debt instruction
with write-off-solana-validator-debt instruction. This interface change
only affects the debt accountant authority.

Closes #2128.

[RFC-0002]:
https://github.com/doublezerofoundation/doublezero-solana/blob/fc3856f334f24034b34a0df3087e75bf38d240b3/docs/rfc/0002_IMPROVED_DEBT_WRITE_OFF_TRACKING.md

Author: karl-dz

solana/programs/revenue-distribution/CHANGELOG.md

@@ -5,6 +5,7 @@
 - add null rewards root protection ([#86])
 - fix swap balance in journal ([#87])
 - allow same-distribution debt write-offs ([#91])
+- track debt write-offs in state ([#93])
 
 ## [v0.1.0] 
 
@@ -13,4 +14,5 @@
 [#86]: https://github.com/doublezerofoundation/doublezero-solana/pull/86
 [#87]: https://github.com/doublezerofoundation/doublezero-solana/pull/87
 [#91]: https://github.com/doublezerofoundation/doublezero-solana/pull/91
+[#93]: https://github.com/doublezerofoundation/doublezero-solana/pull/93
 [v0.1.0]: https://github.com/doublezerofoundation/doublezero-solana/tree/revenue-distribution/v0.1.0

solana/programs/revenue-distribution/src/instruction/account.rs

@@ -649,42 +649,81 @@ impl From<PaySolanaValidatorDebtAccounts> for Vec<AccountMeta> {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
-pub struct ForgiveSolanaValidatorDebtAccounts {
+pub struct EnableSolanaValidatorDebtWriteOffAccounts {
+    pub program_config_key: Pubkey,
+    pub distribution_key: Pubkey,
+    pub payer_key: Pubkey,
+}
+
+impl EnableSolanaValidatorDebtWriteOffAccounts {
+    pub fn new(dz_epoch: DoubleZeroEpoch, payer_key: &Pubkey) -> Self {
+        Self {
+            program_config_key: ProgramConfig::find_address().0,
+            distribution_key: Distribution::find_address(dz_epoch).0,
+            payer_key: *payer_key,
+        }
+    }
+}
+
+impl From<EnableSolanaValidatorDebtWriteOffAccounts> for Vec<AccountMeta> {
+    fn from(accounts: EnableSolanaValidatorDebtWriteOffAccounts) -> Self {
+        let EnableSolanaValidatorDebtWriteOffAccounts {
+            program_config_key,
+            distribution_key,
+            payer_key,
+        } = accounts;
+
+        vec![
+            AccountMeta::new_readonly(program_config_key, false),
+            AccountMeta::new(distribution_key, false),
+            AccountMeta::new(payer_key, true),
+            AccountMeta::new_readonly(system_program::ID, false),
+        ]
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct WriteOffSolanaValidatorDebtAccounts {
     pub program_config_key: Pubkey,
     pub debt_accountant_key: Pubkey,
     pub distribution_key: Pubkey,
-    pub next_distribution_key: Pubkey,
+    pub solana_validator_deposit_key: Pubkey,
+    pub write_off_distribution_key: Pubkey,
 }
 
-impl ForgiveSolanaValidatorDebtAccounts {
+impl WriteOffSolanaValidatorDebtAccounts {
     pub fn new(
         debt_accountant_key: &Pubkey,
         dz_epoch: DoubleZeroEpoch,
-        next_dz_epoch: DoubleZeroEpoch,
+        node_id: &Pubkey,
+        write_off_dz_epoch: DoubleZeroEpoch,
     ) -> Self {
         Self {
             program_config_key: ProgramConfig::find_address().0,
             debt_accountant_key: *debt_accountant_key,
             distribution_key: Distribution::find_address(dz_epoch).0,
-            next_distribution_key: Distribution::find_address(next_dz_epoch).0,
+            solana_validator_deposit_key: SolanaValidatorDeposit::find_address(node_id).0,
+            write_off_distribution_key: Distribution::find_address(write_off_dz_epoch).0,
         }
     }
 }
 
-impl From<ForgiveSolanaValidatorDebtAccounts> for Vec<AccountMeta> {
-    fn from(accounts: ForgiveSolanaValidatorDebtAccounts) -> Self {
-        let ForgiveSolanaValidatorDebtAccounts {
+impl From<WriteOffSolanaValidatorDebtAccounts> for Vec<AccountMeta> {
+    fn from(accounts: WriteOffSolanaValidatorDebtAccounts) -> Self {
+        let WriteOffSolanaValidatorDebtAccounts {
             program_config_key,
             debt_accountant_key,
             distribution_key,
-            next_distribution_key,
+            solana_validator_deposit_key,
+            write_off_distribution_key,
         } = accounts;
 
         vec![
             AccountMeta::new_readonly(program_config_key, false),
             AccountMeta::new_readonly(debt_accountant_key, true),
             AccountMeta::new(distribution_key, false),
-            AccountMeta::new(next_distribution_key, false),
+            AccountMeta::new(solana_validator_deposit_key, false),
+            AccountMeta::new(write_off_distribution_key, false),
         ]
     }
 }

solana/programs/revenue-distribution/src/instruction/mod.rs

@@ -93,8 +93,9 @@ pub enum RevenueDistributionInstructionData {
         amount: u64,
         proof: MerkleProof,
     },
-    ForgiveSolanaValidatorDebt {
-        debt: SolanaValidatorDebt,
+    EnableSolanaValidatorDebtWriteOff,
+    WriteOffSolanaValidatorDebt {
+        amount: u64,
         proof: MerkleProof,
     },
     InitializeSwapDestination,
@@ -137,8 +138,10 @@ impl RevenueDistributionInstructionData {
         Discriminator::new_sha2(b"dz::ix::initialize_solana_validator_deposit");
     pub const PAY_SOLANA_VALIDATOR_DEBT: Discriminator<DISCRIMINATOR_LEN> =
         Discriminator::new_sha2(b"dz::ix::pay_solana_validator_debt");
-    pub const FORGIVE_SOLANA_VALIDATOR_DEBT: Discriminator<DISCRIMINATOR_LEN> =
-        Discriminator::new_sha2(b"dz::ix::forgive_solana_validator_debt");
+    pub const ENABLE_SOLANA_VALIDATOR_DEBT_WRITE_OFF: Discriminator<DISCRIMINATOR_LEN> =
+        Discriminator::new_sha2(b"dz::ix::enable_solana_validator_debt_write_off");
+    pub const WRITE_OFF_SOLANA_VALIDATOR_DEBT: Discriminator<DISCRIMINATOR_LEN> =
+        Discriminator::new_sha2(b"dz::ix::write_off_solana_validator_debt");
     pub const INITIALIZE_SWAP_DESTINATION: Discriminator<DISCRIMINATOR_LEN> =
         Discriminator::new_sha2(b"dz::ix::initialize_swap_destination");
     pub const WITHDRAW_SOL: Discriminator<DISCRIMINATOR_LEN> =
@@ -222,11 +225,14 @@ impl BorshDeserialize for RevenueDistributionInstructionData {
 
                 Ok(Self::PaySolanaValidatorDebt { amount, proof })
             }
-            Self::FORGIVE_SOLANA_VALIDATOR_DEBT => {
-                let debt = BorshDeserialize::deserialize_reader(reader)?;
+            Self::ENABLE_SOLANA_VALIDATOR_DEBT_WRITE_OFF => {
+                Ok(Self::EnableSolanaValidatorDebtWriteOff)
+            }
+            Self::WRITE_OFF_SOLANA_VALIDATOR_DEBT => {
+                let amount = BorshDeserialize::deserialize_reader(reader)?;
                 let proof = BorshDeserialize::deserialize_reader(reader)?;
 
-                Ok(Self::ForgiveSolanaValidatorDebt { debt, proof })
+                Ok(Self::WriteOffSolanaValidatorDebt { amount, proof })
             }
             Self::INITIALIZE_SWAP_DESTINATION => Ok(Self::InitializeSwapDestination),
             Self::SWEEP_DISTRIBUTION_TOKENS_V1 => Ok(Self::SweepDistributionTokens),
@@ -314,9 +320,12 @@ impl BorshSerialize for RevenueDistributionInstructionData {
                 amount.serialize(writer)?;
                 proof.serialize(writer)
             }
-            Self::ForgiveSolanaValidatorDebt { debt, proof } => {
-                Self::FORGIVE_SOLANA_VALIDATOR_DEBT.serialize(writer)?;
-                debt.serialize(writer)?;
+            Self::EnableSolanaValidatorDebtWriteOff => {
+                Self::ENABLE_SOLANA_VALIDATOR_DEBT_WRITE_OFF.serialize(writer)
+            }
+            Self::WriteOffSolanaValidatorDebt { amount, proof } => {
+                Self::WRITE_OFF_SOLANA_VALIDATOR_DEBT.serialize(writer)?;
+                amount.serialize(writer)?;
                 proof.serialize(writer)
             }
             Self::InitializeSwapDestination => Self::INITIALIZE_SWAP_DESTINATION.serialize(writer),