stake-pool: Rework add / remove validator to not use pool tokens (#1581)

* Rework remove

* Add tests

* Transition to checked math

* Update CLI for new types / instructions

* Cargo fmt

* Rename voter_pubkey -> vote_account_address

* Remove max check

* Update validator balance test

Author: joncinque

stake-pool/cli/src/main.rs

@@ -264,12 +264,7 @@ fn command_vsa_create(
     Ok(())
 }
 
-fn command_vsa_add(
-    config: &Config,
-    stake_pool_address: &Pubkey,
-    stake: &Pubkey,
-    token_receiver: &Option<Pubkey>,
-) -> CommandResult {
+fn command_vsa_add(config: &Config, stake_pool_address: &Pubkey, stake: &Pubkey) -> CommandResult {
     if config.rpc_client.get_stake_activation(*stake, None)?.state != StakeActivationState::Active {
         return Err("Stake account is not active.".into());
     }
@@ -280,26 +275,9 @@ fn command_vsa_add(
 
     let stake_pool = get_stake_pool(&config.rpc_client, stake_pool_address)?;
 
-    let mut total_rent_free_balances: u64 = 0;
-
-    let token_receiver_account = Keypair::new();
-
     let mut instructions: Vec<Instruction> = vec![];
     let mut signers = vec![config.fee_payer.as_ref(), config.staker.as_ref()];
 
-    // Create token account if not specified
-    let token_receiver = unwrap_create_token_account(
-        &config,
-        &token_receiver,
-        &token_receiver_account,
-        &stake_pool.pool_mint,
-        &mut instructions,
-        |balance| {
-            signers.push(&token_receiver_account);
-            total_rent_free_balances += balance;
-        },
-    )?;
-
     // Calculate Deposit and Withdraw stake pool authorities
     let pool_deposit_authority =
         find_deposit_authority_program_address(&spl_stake_pool::id(), stake_pool_address).0;
@@ -331,20 +309,14 @@ fn command_vsa_add(
             &pool_withdraw_authority,
             &stake_pool.validator_list,
             &stake,
-            &token_receiver,
-            &stake_pool.pool_mint,
-            &spl_token::id(),
         )?,
     ]);
 
     let mut transaction =
         Transaction::new_with_payer(&instructions, Some(&config.fee_payer.pubkey()));
 
     let (recent_blockhash, fee_calculator) = config.rpc_client.get_recent_blockhash()?;
-    check_fee_payer_balance(
-        config,
-        total_rent_free_balances + fee_calculator.calculate_fee(&transaction.message()),
-    )?;
+    check_fee_payer_balance(config, fee_calculator.calculate_fee(&transaction.message()))?;
     unique_signers!(signers);
     transaction.sign(&signers, recent_blockhash);
     send_transaction(&config, transaction)?;
@@ -355,7 +327,6 @@ fn command_vsa_remove(
     config: &Config,
     stake_pool_address: &Pubkey,
     stake: &Pubkey,
-    withdraw_from: &Pubkey,
     new_authority: &Option<Pubkey>,
 ) -> CommandResult {
     if !config.no_update {
@@ -369,35 +340,8 @@ fn command_vsa_remove(
     let staker_pubkey = config.staker.pubkey();
     let new_authority = new_authority.as_ref().unwrap_or(&staker_pubkey);
 
-    // Calculate amount of tokens to withdraw
-    let stake_account = config.rpc_client.get_account(&stake)?;
-    let tokens_to_withdraw = stake_pool
-        .calc_pool_tokens_for_withdraw(stake_account.lamports)
-        .unwrap();
-
-    // Check balance and mint
-    let token_account =
-        get_token_account(&config.rpc_client, &withdraw_from, &stake_pool.pool_mint)?;
-
-    if token_account.amount < tokens_to_withdraw {
-        let pool_mint = get_token_mint(&config.rpc_client, &stake_pool.pool_mint)?;
-        return Err(format!(
-            "Not enough balance to burn to remove validator stake account from the pool. {} pool tokens needed.",
-            spl_token::amount_to_ui_amount(tokens_to_withdraw, pool_mint.decimals)
-        ).into());
-    }
-
     let mut transaction = Transaction::new_with_payer(
         &[
-            // Approve spending token
-            spl_token::instruction::approve(
-                &spl_token::id(),
-                &withdraw_from,
-                &pool_withdraw_authority,
-                &config.token_owner.pubkey(),
-                &[],
-                tokens_to_withdraw,
-            )?,
             // Create new validator stake account address
             spl_stake_pool::instruction::remove_validator_from_pool(
                 &spl_stake_pool::id(),
@@ -407,9 +351,6 @@ fn command_vsa_remove(
                 &new_authority,
                 &stake_pool.validator_list,
                 &stake,
-                &withdraw_from,
-                &stake_pool.pool_mint,
-                &spl_token::id(),
             )?,
         ],
         Some(&config.fee_payer.pubkey()),
@@ -589,7 +530,7 @@ fn command_list(config: &Config, stake_pool_address: &Pubkey) -> CommandResult {
     for validator in validator_list.validators {
         println!(
             "Validator Vote Account: {}\tBalance: {}\tLast Update Epoch: {}{}",
-            validator.vote_account,
+            validator.vote_account_address,
             Sol(validator.stake_lamports),
             validator.last_update_epoch,
             if validator.last_update_epoch != epoch_info.epoch {
@@ -669,7 +610,7 @@ fn command_update(config: &Config, stake_pool_address: &Pubkey) -> CommandResult
             } else {
                 let (stake_account, _) = find_stake_program_address(
                     &spl_stake_pool::id(),
-                    &item.vote_account,
+                    &item.vote_account_address,
                     &stake_pool_address,
                 );
                 Some(stake_account)
@@ -1439,26 +1380,13 @@ fn main() {
         ("add-validator", Some(arg_matches)) => {
             let stake_pool_address = pubkey_of(arg_matches, "pool").unwrap();
             let stake_account = pubkey_of(arg_matches, "stake_account").unwrap();
-            let token_receiver: Option<Pubkey> = pubkey_of(arg_matches, "token_receiver");
-            command_vsa_add(
-                &config,
-                &stake_pool_address,
-                &stake_account,
-                &token_receiver,
-            )
+            command_vsa_add(&config, &stake_pool_address, &stake_account)
         }
         ("remove-validator", Some(arg_matches)) => {
             let stake_pool_address = pubkey_of(arg_matches, "pool").unwrap();
             let stake_account = pubkey_of(arg_matches, "stake_account").unwrap();
-            let withdraw_from = pubkey_of(arg_matches, "withdraw_from").unwrap();
             let new_authority: Option<Pubkey> = pubkey_of(arg_matches, "new_authority");
-            command_vsa_remove(
-                &config,
-                &stake_pool_address,
-                &stake_account,
-                &withdraw_from,
-                &new_authority,
-            )
+            command_vsa_remove(&config, &stake_pool_address, &stake_account, &new_authority)
         }
         ("deposit", Some(arg_matches)) => {
             let stake_pool_address = pubkey_of(arg_matches, "pool").unwrap();

stake-pool/program/src/error.rs

@@ -85,6 +85,9 @@ pub enum StakePoolError {
     /// Pool token supply is not zero on initialization
     #[error("NonZeroPoolTokenSupply")]
     NonZeroPoolTokenSupply,
+    /// The lamports in the validator stake account is not equal to the minimum
+    #[error("StakeLamportsNotEqualToMinimum")]
+    StakeLamportsNotEqualToMinimum,
 }
 impl From<StakePoolError> for ProgramError {
     fn from(e: StakePoolError) -> Self {

stake-pool/program/src/instruction.rs

@@ -64,34 +64,40 @@ pub enum StakePoolInstruction {
     CreateValidatorStakeAccount,
 
     ///   (Staker only) Adds stake account delegated to validator to the pool's
-    ///   list of managed validators
+    ///   list of managed validators.
+    ///
+    ///   The stake account must have the rent-exempt amount plus at least 1 SOL,
+    ///   and at most 1.001 SOL.
+    ///
+    ///   Once we delegate even 1 SOL, it will accrue rewards one epoch later,
+    ///   so we'll have more than 1 active SOL at this point.
+    ///   At 10% annualized rewards, 1 epoch of 2 days will accrue
+    ///   0.000547945 SOL, so we check that it is at least 1 SOL, and at most
+    ///   1.001 SOL.
     ///
     ///   0. `[w]` Stake pool
     ///   1. `[s]` Staker
     ///   2. `[]` Stake pool deposit authority
     ///   3. `[]` Stake pool withdraw authority
     ///   4. `[w]` Validator stake list storage account
     ///   5. `[w]` Stake account to add to the pool, its withdraw authority should be set to stake pool deposit
-    ///   6. `[w]` User account to receive pool tokens
-    ///   7. `[w]` Pool token mint account
-    ///   8. `[]` Clock sysvar (required)
-    ///   9. '[]' Sysvar stake history account
-    ///  10. `[]` Pool token program id,
-    ///  11. `[]` Stake program id,
+    ///   6. `[]` Clock sysvar
+    ///   7. '[]' Sysvar stake history account
+    ///   8. `[]` Stake program
     AddValidatorToPool,
 
     ///   (Staker only) Removes validator from the pool
     ///
+    ///   Only succeeds if the validator stake account has the minimum of 1 SOL
+    ///   plus the rent-exempt amount.
+    ///
     ///   0. `[w]` Stake pool
     ///   1. `[s]` Staker
     ///   2. `[]` Stake pool withdraw authority
     ///   3. `[]` New withdraw/staker authority to set in the stake account
     ///   4. `[w]` Validator stake list storage account
     ///   5. `[w]` Stake account to remove from the pool
-    ///   6. `[w]` User account with pool tokens to burn from
-    ///   7. `[w]` Pool token mint account
-    ///   8. '[]' Sysvar clock account (required)
-    ///   9. `[]` Pool token program id
+    ///   8. '[]' Sysvar clock
     ///  10. `[]` Stake program id,
     RemoveValidatorFromPool,
 
@@ -197,7 +203,10 @@ pub enum StakePoolInstruction {
     Deposit,
 
     ///   Withdraw the token from the pool at the current ratio.
-    ///   The amount withdrawn is the MIN(u64, stake size)
+    ///
+    ///   Succeeds if the stake account has enough SOL to cover the desired amount
+    ///   of pool tokens, and if the withdrawal keeps the total staked amount
+    ///   above the minimum of rent-exempt amount + 1 SOL.
     ///
     ///   A validator stake account can be withdrawn from freely, and the reserve
     ///   can only be drawn from if there is no active stake left, where all
@@ -307,9 +316,6 @@ pub fn add_validator_to_pool(
     stake_pool_withdraw: &Pubkey,
     validator_list: &Pubkey,
     stake_account: &Pubkey,
-    pool_token_receiver: &Pubkey,
-    pool_mint: &Pubkey,
-    token_program_id: &Pubkey,
 ) -> Result<Instruction, ProgramError> {
     let accounts = vec![
         AccountMeta::new(*stake_pool, false),
@@ -318,11 +324,8 @@ pub fn add_validator_to_pool(
         AccountMeta::new_readonly(*stake_pool_withdraw, false),
         AccountMeta::new(*validator_list, false),
         AccountMeta::new(*stake_account, false),
-        AccountMeta::new(*pool_token_receiver, false),
-        AccountMeta::new(*pool_mint, false),
         AccountMeta::new_readonly(sysvar::clock::id(), false),
         AccountMeta::new_readonly(sysvar::stake_history::id(), false),
-        AccountMeta::new_readonly(*token_program_id, false),
         AccountMeta::new_readonly(stake_program::id(), false),
     ];
     Ok(Instruction {
@@ -341,9 +344,6 @@ pub fn remove_validator_from_pool(
     new_stake_authority: &Pubkey,
     validator_list: &Pubkey,
     stake_account: &Pubkey,
-    burn_from: &Pubkey,
-    pool_mint: &Pubkey,
-    token_program_id: &Pubkey,
 ) -> Result<Instruction, ProgramError> {
     let accounts = vec![
         AccountMeta::new(*stake_pool, false),
@@ -352,10 +352,7 @@ pub fn remove_validator_from_pool(
         AccountMeta::new_readonly(*new_stake_authority, false),
         AccountMeta::new(*validator_list, false),
         AccountMeta::new(*stake_account, false),
-        AccountMeta::new(*burn_from, false),
-        AccountMeta::new(*pool_mint, false),
         AccountMeta::new_readonly(sysvar::clock::id(), false),
-        AccountMeta::new_readonly(*token_program_id, false),
         AccountMeta::new_readonly(stake_program::id(), false),
     ];
     Ok(Instruction {

stake-pool/program/src/lib.rs

@@ -14,14 +14,28 @@ pub mod entrypoint;
 
 // Export current sdk types for downstream users building with a different sdk version
 pub use solana_program;
-use solana_program::pubkey::Pubkey;
+use {
+    crate::stake_program::Meta,
+    solana_program::{native_token::LAMPORTS_PER_SOL, pubkey::Pubkey},
+};
 
 /// Seed for deposit authority seed
 const AUTHORITY_DEPOSIT: &[u8] = b"deposit";
 
 /// Seed for withdraw authority seed
 const AUTHORITY_WITHDRAW: &[u8] = b"withdraw";
 
+/// Minimum amount of staked SOL required in a validator stake account to allow
+/// for merges without a mismatch on credits observed
+pub const MINIMUM_ACTIVE_STAKE: u64 = LAMPORTS_PER_SOL;
+
+/// Get the stake amount under consideration when calculating pool token
+/// conversions
+pub fn minimum_stake_lamports(meta: &Meta) -> u64 {
+    meta.rent_exempt_reserve
+        .saturating_add(MINIMUM_ACTIVE_STAKE)
+}
+
 /// Generates the deposit authority program address for the stake pool
 pub fn find_deposit_authority_program_address(
     program_id: &Pubkey,