stake-pool: Add instruction creators that re-use existing seeds

[joncinque]

Problem

The IncreaseAdditionalValidatorStake and DecreaseAdditionalValidatorStake instruction creators helpers that take the vote account require that you pass in the transient_stake_seed:

solana-program-library/stake-pool/program/src/instruction.rs

Lines 1325 to 1334 in c9eb289

	pub fn decrease_additional_validator_stake_with_vote(
	program_id: &Pubkey,
	stake_pool: &StakePool,
	stake_pool_address: &Pubkey,
	vote_account_address: &Pubkey,
	lamports: u64,
	validator_stake_seed: Option<NonZeroU32>,
	transient_stake_seed: u64,
	ephemeral_stake_seed: u64,
	) -> Instruction {

And

solana-program-library/stake-pool/program/src/instruction.rs

Lines 1240 to 1249 in c9eb289

	pub fn increase_additional_validator_stake_with_vote(
	program_id: &Pubkey,
	stake_pool: &StakePool,
	stake_pool_address: &Pubkey,
	vote_account_address: &Pubkey,
	lamports: u64,
	validator_stake_seed: Option<NonZeroU32>,
	transient_stake_seed: u64,
	ephemeral_stake_seed: u64,
	) -> Instruction {

Since these instructions are usually meant to reuse an existing transient stake account, these instruction creators can be confusing.

Solution

Create a new variant of these creators, decrease_additional_validator_stake_with_list and increase_additional_validator_stake_with_list, which takes in the pool's ValidatorList, ie:

pub fn increase_additional_validator_stake_with_list(
    program_id: &Pubkey,
    stake_pool: &StakePool,
    validator_list: &ValidatorList,
    stake_pool_address: &Pubkey,
    vote_account_address: &Pubkey,
    lamports: u64,
    ephemeral_stake_seed: u64,
) -> Instruction {

From the validator list, it can figure out the seeds and be much easier to use.

[lucky-gru]

@joncinque
increase_additional_validator_stake_with_vote uses &stake_pool.validator_list without having the validator list as an argument.
IncreaseValidatorStake instruction requires a transient_stake_seed.
so need to add another instruction that doesn't require a transient_stake_seed. I don't think it's your intent.
Or that instruction can consume lists of transient_stake_seeds?
Then, How can I get a transient_stake_seed from validators lists?

[joncinque]

I'm not sure I totally understand the comment, but the concept is that ValidatorList contains the validator stake seed and the transient stake seed for the given vote account address:

solana-program-library/stake-pool/program/src/state.rs

Lines 708 to 716 in 4d0c646

	/// Transient account seed suffix, used to derive the transient stake
	/// account address
	pub transient_seed_suffix: PodU64,
	/// Unused space, initially meant to specify the end of seed suffixes
	pub unused: PodU32,
	/// Validator account seed suffix
	pub validator_seed_suffix: PodU32, // really `Option<NonZeroU32>` so 0 is `None`

So increase_additional_validator_stake_with_list can just read those values for the given validator and pass them into increase_additional_validator_stake_with_vote

[Hrushi20]

So do we want to iterate through the validator lists and execute the DecreaseAdditionalValidatorStake / IncreaseAdditionalValidatorStake? Do we return an array of instructions?

[joncinque]

@Hrushi20 it's only one instruction in this case, but you'll need to search through the ValidatorList to find the validator and use the transient stake seed stored there