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solana-program-library
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Code Issues Projects Releases Wiki Activity

Refactor curve.rs (#754) 

* Refactor shared out of curve.rs

* Refactor out flat curve

* Refactor out constant product curve

* Cargo fmt

* More moving

* Fixup

* use::super -> user::create::curve

* cp -> constant_product

* Fix circular dependency

* Docs

* Trigger Build
This commit is contained in:
Michael Huang 2020-11-02 07:29:00 -06:00 committed by GitHub
parent 355fa0a12c
commit 5bf4b76df4
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10 changed files with 903 additions and 850 deletions
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5
token-swap/program/src/constraints.rs
View File

@ -1,7 +1,8 @@
//! Various constraints as required for production environments
use crate::{
curve::{ConstantProductCurve, CurveType, FlatCurve, SwapCurve},
curve::base::{CurveType, SwapCurve},
curve::{constant_product::ConstantProductCurve, flat::FlatCurve},
error::SwapError,
};
@ -101,7 +102,7 @@ pub const FEE_CONSTRAINTS: Option<FeeConstraints> = {
mod tests {
use super::*;
use crate::curve::{ConstantProductCurve, CurveType};
use crate::curve::{base::CurveType, constant_product::ConstantProductCurve};
#[test]
fn validate_fees() {

840
token-swap/program/src/curve.rs
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@ -1,840 +0,0 @@
//! Swap calculations and curve implementations
use solana_program::{
program_error::ProgramError,
program_pack::{IsInitialized, Pack, Sealed},
};
use arrayref::{array_mut_ref, array_ref, array_refs, mut_array_refs};
use std::convert::{TryFrom, TryInto};
use std::fmt::Debug;
/// Initial amount of pool tokens for swap contract, hard-coded to something
/// "sensible" given a maximum of u128.
/// Note that on Ethereum, Uniswap uses the geometric mean of all provided
/// input amounts, and Balancer uses 100 * 10 ^ 18.
pub const INITIAL_SWAP_POOL_AMOUNT: u128 = 1_000_000_000;
/// Curve types supported by the token-swap program.
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum CurveType {
/// Uniswap-style constant product curve, invariant = token_a_amount * token_b_amount
ConstantProduct,
/// Flat line, always providing 1:1 from one token to another
Flat,
}
/// Concrete struct to wrap around the trait object which performs calculation.
#[repr(C)]
#[derive(Debug)]
pub struct SwapCurve {
/// The type of curve contained in the calculator, helpful for outside
/// queries
pub curve_type: CurveType,
/// The actual calculator, represented as a trait object to allow for many
/// different types of curves
pub calculator: Box<dyn CurveCalculator>,
}
/// Default implementation for SwapCurve cannot be derived because of
/// the contained Box.
impl Default for SwapCurve {
fn default() -> Self {
let curve_type: CurveType = Default::default();
let calculator: ConstantProductCurve = Default::default();
Self {
curve_type,
calculator: Box::new(calculator),
}
}
}
/// Clone takes advantage of pack / unpack to get around the difficulty of
/// cloning dynamic objects.
/// Note that this is only to be used for testing.
#[cfg(test)]
impl Clone for SwapCurve {
fn clone(&self) -> Self {
let mut packed_self = [0u8; Self::LEN];
Self::pack_into_slice(self, &mut packed_self);
Self::unpack_from_slice(&packed_self).unwrap()
}
}
/// Simple implementation for PartialEq which assumes that the output of
/// `Pack` is enough to guarantee equality
impl PartialEq for SwapCurve {
fn eq(&self, other: &Self) -> bool {
let mut packed_self = [0u8; Self::LEN];
Self::pack_into_slice(self, &mut packed_self);
let mut packed_other = [0u8; Self::LEN];
Self::pack_into_slice(other, &mut packed_other);
packed_self[..] == packed_other[..]
}
}
impl Sealed for SwapCurve {}
impl Pack for SwapCurve {
/// Size of encoding of all curve parameters, which include fees and any other
/// constants used to calculate swaps, deposits, and withdrawals.
/// This includes 1 byte for the type, and 64 for the calculator to use as
/// it needs. Some calculators may be smaller than 64 bytes.
const LEN: usize = 65;
/// Unpacks a byte buffer into a SwapCurve
fn unpack_from_slice(input: &[u8]) -> Result<Self, ProgramError> {
let input = array_ref![input, 0, 65];
#[allow(clippy::ptr_offset_with_cast)]
let (curve_type, calculator) = array_refs![input, 1, 64];
let curve_type = curve_type[0].try_into()?;
Ok(Self {
curve_type,
calculator: match curve_type {
CurveType::ConstantProduct => {
Box::new(ConstantProductCurve::unpack_from_slice(calculator)?)
}
CurveType::Flat => Box::new(FlatCurve::unpack_from_slice(calculator)?),
},
})
}
/// Pack SwapCurve into a byte buffer
fn pack_into_slice(&self, output: &mut [u8]) {
let output = array_mut_ref![output, 0, 65];
let (curve_type, calculator) = mut_array_refs![output, 1, 64];
curve_type[0] = self.curve_type as u8;
self.calculator.pack_into_slice(&mut calculator[..]);
}
}
/// Sensible default of CurveType to ConstantProduct, the most popular and
/// well-known curve type.
impl Default for CurveType {
fn default() -> Self {
CurveType::ConstantProduct
}
}
impl TryFrom<u8> for CurveType {
type Error = ProgramError;
fn try_from(curve_type: u8) -> Result<Self, Self::Error> {
match curve_type {
0 => Ok(CurveType::ConstantProduct),
1 => Ok(CurveType::Flat),
_ => Err(ProgramError::InvalidAccountData),
}
}
}
/// Trait for packing of trait objects, required because structs that implement
/// `Pack` cannot be used as trait objects (as `dyn Pack`).
pub trait DynPack {
/// Only required function is to pack given a trait object
fn pack_into_slice(&self, dst: &mut [u8]);
}
/// Trait representing operations required on a swap curve
pub trait CurveCalculator: Debug + DynPack {
/// Calculate how much destination token will be provided given an amount
/// of source token.
fn swap(
&self,
source_amount: u128,
swap_source_amount: u128,
swap_destination_amount: u128,
) -> Option<SwapResult>;
/// Calculate the withdraw fee in pool tokens
/// Default implementation assumes no fee
fn owner_withdraw_fee(&self, _pool_tokens: u128) -> Option<u128> {
Some(0)
}
/// Calculate the trading fee in trading tokens
/// Default implementation assumes no fee
fn trading_fee(&self, _trading_tokens: u128) -> Option<u128> {
Some(0)
}
/// Calculate the pool token equivalent of the owner fee on trade
/// See the math at: https://balancer.finance/whitepaper/#single-asset-deposit
/// For the moment, we do an approximation for the square root. For numbers
/// just above 1, simply dividing by 2 brings you very close to the correct
/// value.
fn owner_fee_to_pool_tokens(
&self,
owner_fee: u128,
trading_token_amount: u128,
pool_supply: u128,
tokens_in_pool: u128,
) -> Option<u128> {
// Get the trading fee incurred if the owner fee is swapped for the other side
let trade_fee = self.trading_fee(owner_fee)?;
let owner_fee = owner_fee.checked_sub(trade_fee)?;
pool_supply
.checked_mul(owner_fee)?
.checked_div(trading_token_amount)?
.checked_div(tokens_in_pool)
}
/// Get the supply for a new pool
/// The default implementation is a Balancer-style fixed initial supply
fn new_pool_supply(&self) -> u128 {
INITIAL_SWAP_POOL_AMOUNT
}
/// Get the amount of trading tokens for the given amount of pool tokens,
/// provided the total trading tokens and supply of pool tokens.
/// The default implementation is a simple ratio calculation for how many
/// trading tokens correspond to a certain number of pool tokens
fn pool_tokens_to_trading_tokens(
&self,
pool_tokens: u128,
pool_token_supply: u128,
total_trading_tokens: u128,
) -> Option<u128> {
pool_tokens
.checked_mul(total_trading_tokens)?
.checked_div(pool_token_supply)
.and_then(map_zero_to_none)
}
/// Calculate the host fee based on the owner fee, only used in production
/// situations where a program is hosted by multiple frontends
fn host_fee(&self, _owner_fee: u128) -> Option<u128> {
Some(0)
}
}
/// Encodes all results of swapping from a source token to a destination token
pub struct SwapResult {
/// New amount of source token
pub new_source_amount: u128,
/// New amount of destination token
pub new_destination_amount: u128,
/// Amount of destination token swapped
pub amount_swapped: u128,
/// Amount of source tokens going to pool holders
pub trade_fee: u128,
/// Amount of source tokens going to owner
pub owner_fee: u128,
}
/// Helper function for mapping to SwapError::CalculationFailure
fn map_zero_to_none(x: u128) -> Option<u128> {
if x == 0 {
None
} else {
Some(x)
}
}
/// Simple constant 1:1 swap curve, example of different swap curve implementations
#[derive(Clone, Debug, Default, PartialEq)]
pub struct FlatCurve {
/// Fee numerator
pub trade_fee_numerator: u64,
/// Fee denominator
pub trade_fee_denominator: u64,
/// Owner trade fee numerator
pub owner_trade_fee_numerator: u64,
/// Owner trade fee denominator
pub owner_trade_fee_denominator: u64,
/// Owner withdraw fee numerator
pub owner_withdraw_fee_numerator: u64,
/// Owner withdraw fee denominator
pub owner_withdraw_fee_denominator: u64,
/// Host trading fee numerator
pub host_fee_numerator: u64,
/// Host trading fee denominator
pub host_fee_denominator: u64,
}
fn calculate_fee(token_amount: u128, fee_numerator: u128, fee_denominator: u128) -> Option<u128> {
if fee_numerator == 0 {
Some(0)
} else {
let fee = token_amount
.checked_mul(fee_numerator)?
.checked_div(fee_denominator)?;
if fee == 0 {
Some(1) // minimum fee of one token
} else {
Some(fee)
}
}
}
impl CurveCalculator for FlatCurve {
/// Flat curve swap always returns 1:1 (minus fee)
fn swap(
&self,
source_amount: u128,
swap_source_amount: u128,
swap_destination_amount: u128,
) -> Option<SwapResult> {
// debit the fee to calculate the amount swapped
let trade_fee = calculate_fee(
source_amount,
u128::try_from(self.trade_fee_numerator).ok()?,
u128::try_from(self.trade_fee_denominator).ok()?,
)?;
let owner_fee = calculate_fee(
source_amount,
u128::try_from(self.owner_trade_fee_numerator).ok()?,
u128::try_from(self.owner_trade_fee_denominator).ok()?,
)?;
let amount_swapped = source_amount
.checked_sub(trade_fee)?
.checked_sub(owner_fee)?;
let new_destination_amount = swap_destination_amount.checked_sub(amount_swapped)?;
// actually add the whole amount coming in
let new_source_amount = swap_source_amount.checked_add(source_amount)?;
Some(SwapResult {
new_source_amount,
new_destination_amount,
amount_swapped,
trade_fee,
owner_fee,
})
}
/// Calculate the withdraw fee in pool tokens
fn owner_withdraw_fee(&self, pool_tokens: u128) -> Option<u128> {
calculate_fee(
pool_tokens,
u128::try_from(self.owner_withdraw_fee_numerator).ok()?,
u128::try_from(self.owner_withdraw_fee_denominator).ok()?,
)
}
/// Calculate the host fee based on the owner fee, only used in production
/// situations where a program is hosted by multiple frontends
fn host_fee(&self, owner_fee: u128) -> Option<u128> {
calculate_fee(
owner_fee,
u128::try_from(self.host_fee_numerator).ok()?,
u128::try_from(self.host_fee_denominator).ok()?,
)
}
}
/// IsInitialized is required to use `Pack::pack` and `Pack::unpack`
impl IsInitialized for FlatCurve {
fn is_initialized(&self) -> bool {
true
}
}
impl Sealed for FlatCurve {}
impl Pack for FlatCurve {
const LEN: usize = 64;
fn unpack_from_slice(input: &[u8]) -> Result<FlatCurve, ProgramError> {
let input = array_ref![input, 0, 64];
#[allow(clippy::ptr_offset_with_cast)]
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = array_refs![input, 8, 8, 8, 8, 8, 8, 8, 8];
Ok(Self {
trade_fee_numerator: u64::from_le_bytes(*trade_fee_numerator),
trade_fee_denominator: u64::from_le_bytes(*trade_fee_denominator),
owner_trade_fee_numerator: u64::from_le_bytes(*owner_trade_fee_numerator),
owner_trade_fee_denominator: u64::from_le_bytes(*owner_trade_fee_denominator),
owner_withdraw_fee_numerator: u64::from_le_bytes(*owner_withdraw_fee_numerator),
owner_withdraw_fee_denominator: u64::from_le_bytes(*owner_withdraw_fee_denominator),
host_fee_numerator: u64::from_le_bytes(*host_fee_numerator),
host_fee_denominator: u64::from_le_bytes(*host_fee_denominator),
})
}
fn pack_into_slice(&self, output: &mut [u8]) {
(self as &dyn DynPack).pack_into_slice(output);
}
}
impl DynPack for FlatCurve {
fn pack_into_slice(&self, output: &mut [u8]) {
let output = array_mut_ref![output, 0, 64];
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = mut_array_refs![output, 8, 8, 8, 8, 8, 8, 8, 8];
*trade_fee_numerator = self.trade_fee_numerator.to_le_bytes();
*trade_fee_denominator = self.trade_fee_denominator.to_le_bytes();
*owner_trade_fee_numerator = self.owner_trade_fee_numerator.to_le_bytes();
*owner_trade_fee_denominator = self.owner_trade_fee_denominator.to_le_bytes();
*owner_withdraw_fee_numerator = self.owner_withdraw_fee_numerator.to_le_bytes();
*owner_withdraw_fee_denominator = self.owner_withdraw_fee_denominator.to_le_bytes();
*host_fee_numerator = self.host_fee_numerator.to_le_bytes();
*host_fee_denominator = self.host_fee_denominator.to_le_bytes();
}
}
/// The Uniswap invariant calculator.
#[derive(Clone, Debug, Default, PartialEq)]
pub struct ConstantProductCurve {
/// Trade fee numerator
pub trade_fee_numerator: u64,
/// Trade fee denominator
pub trade_fee_denominator: u64,
/// Owner trade fee numerator
pub owner_trade_fee_numerator: u64,
/// Owner trade fee denominator
pub owner_trade_fee_denominator: u64,
/// Owner withdraw fee numerator
pub owner_withdraw_fee_numerator: u64,
/// Owner withdraw fee denominator
pub owner_withdraw_fee_denominator: u64,
/// Host trading fee numerator
pub host_fee_numerator: u64,
/// Host trading fee denominator
pub host_fee_denominator: u64,
}
impl CurveCalculator for ConstantProductCurve {
/// Constant product swap ensures x * y = constant
fn swap(
&self,
source_amount: u128,
swap_source_amount: u128,
swap_destination_amount: u128,
) -> Option<SwapResult> {
// debit the fee to calculate the amount swapped
let trade_fee = self.trading_fee(source_amount)?;
let owner_fee = calculate_fee(
source_amount,
u128::try_from(self.owner_trade_fee_numerator).ok()?,
u128::try_from(self.owner_trade_fee_denominator).ok()?,
)?;
let invariant = swap_source_amount.checked_mul(swap_destination_amount)?;
let new_source_amount_less_fee = swap_source_amount
.checked_add(source_amount)?
.checked_sub(trade_fee)?
.checked_sub(owner_fee)?;
let new_destination_amount = invariant.checked_div(new_source_amount_less_fee)?;
let amount_swapped =
map_zero_to_none(swap_destination_amount.checked_sub(new_destination_amount)?)?;
// actually add the whole amount coming in
let new_source_amount = swap_source_amount.checked_add(source_amount)?;
Some(SwapResult {
new_source_amount,
new_destination_amount,
amount_swapped,
trade_fee,
owner_fee,
})
}
/// Calculate the withdraw fee in pool tokens
fn owner_withdraw_fee(&self, pool_tokens: u128) -> Option<u128> {
calculate_fee(
pool_tokens,
u128::try_from(self.owner_withdraw_fee_numerator).ok()?,
u128::try_from(self.owner_withdraw_fee_denominator).ok()?,
)
}
/// Calculate the trading fee in trading tokens
fn trading_fee(&self, trading_tokens: u128) -> Option<u128> {
calculate_fee(
trading_tokens,
u128::try_from(self.trade_fee_numerator).ok()?,
u128::try_from(self.trade_fee_denominator).ok()?,
)
}
/// Calculate the host fee based on the owner fee, only used in production
/// situations where a program is hosted by multiple frontends
fn host_fee(&self, owner_fee: u128) -> Option<u128> {
calculate_fee(
owner_fee,
u128::try_from(self.host_fee_numerator).ok()?,
u128::try_from(self.host_fee_denominator).ok()?,
)
}
}
/// IsInitialized is required to use `Pack::pack` and `Pack::unpack`
impl IsInitialized for ConstantProductCurve {
fn is_initialized(&self) -> bool {
true
}
}
impl Sealed for ConstantProductCurve {}
impl Pack for ConstantProductCurve {
const LEN: usize = 64;
fn unpack_from_slice(input: &[u8]) -> Result<ConstantProductCurve, ProgramError> {
let input = array_ref![input, 0, 64];
#[allow(clippy::ptr_offset_with_cast)]
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = array_refs![input, 8, 8, 8, 8, 8, 8, 8, 8];
Ok(Self {
trade_fee_numerator: u64::from_le_bytes(*trade_fee_numerator),
trade_fee_denominator: u64::from_le_bytes(*trade_fee_denominator),
owner_trade_fee_numerator: u64::from_le_bytes(*owner_trade_fee_numerator),
owner_trade_fee_denominator: u64::from_le_bytes(*owner_trade_fee_denominator),
owner_withdraw_fee_numerator: u64::from_le_bytes(*owner_withdraw_fee_numerator),
owner_withdraw_fee_denominator: u64::from_le_bytes(*owner_withdraw_fee_denominator),
host_fee_numerator: u64::from_le_bytes(*host_fee_numerator),
host_fee_denominator: u64::from_le_bytes(*host_fee_denominator),
})
}
fn pack_into_slice(&self, output: &mut [u8]) {
(self as &dyn DynPack).pack_into_slice(output);
}
}
impl DynPack for ConstantProductCurve {
fn pack_into_slice(&self, output: &mut [u8]) {
let output = array_mut_ref![output, 0, 64];
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = mut_array_refs![output, 8, 8, 8, 8, 8, 8, 8, 8];
*trade_fee_numerator = self.trade_fee_numerator.to_le_bytes();
*trade_fee_denominator = self.trade_fee_denominator.to_le_bytes();
*owner_trade_fee_numerator = self.owner_trade_fee_numerator.to_le_bytes();
*owner_trade_fee_denominator = self.owner_trade_fee_denominator.to_le_bytes();
*owner_withdraw_fee_numerator = self.owner_withdraw_fee_numerator.to_le_bytes();
*owner_withdraw_fee_denominator = self.owner_withdraw_fee_denominator.to_le_bytes();
*host_fee_numerator = self.host_fee_numerator.to_le_bytes();
*host_fee_denominator = self.host_fee_denominator.to_le_bytes();
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn initial_pool_amount() {
let trade_fee_numerator = 0;
let trade_fee_denominator = 1;
let owner_trade_fee_numerator = 0;
let owner_trade_fee_denominator = 1;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 1;
let host_fee_numerator = 0;
let host_fee_denominator = 1;
let calculator = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
assert_eq!(calculator.new_pool_supply(), INITIAL_SWAP_POOL_AMOUNT);
}
fn check_pool_token_rate(token_a: u128, deposit: u128, supply: u128, expected: Option<u128>) {
let trade_fee_numerator = 0;
let trade_fee_denominator = 1;
let owner_trade_fee_numerator = 0;
let owner_trade_fee_denominator = 1;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 1;
let host_fee_numerator = 0;
let host_fee_denominator = 1;
let calculator = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
assert_eq!(
calculator.pool_tokens_to_trading_tokens(deposit, supply, token_a),
expected
);
}
#[test]
fn trading_token_conversion() {
check_pool_token_rate(2, 5, 10, Some(1));
check_pool_token_rate(10, 5, 10, Some(5));
check_pool_token_rate(5, 5, 10, Some(2));
check_pool_token_rate(5, 5, 10, Some(2));
check_pool_token_rate(u128::MAX, 5, 10, None);
}
#[test]
fn constant_product_swap_calculation_trade_fee() {
// calculation on https://github.com/solana-labs/solana-program-library/issues/341
let swap_source_amount = 1000;
let swap_destination_amount = 50000;
let trade_fee_numerator = 1;
let trade_fee_denominator = 100;
let owner_trade_fee_numerator = 0;
let owner_trade_fee_denominator = 0;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 0;
let host_fee_numerator = 0;
let host_fee_denominator = 0;
let source_amount = 100;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, 4505);
assert_eq!(result.new_destination_amount, 45495);
assert_eq!(result.trade_fee, 1);
assert_eq!(result.owner_fee, 0);
}
#[test]
fn constant_product_swap_calculation_owner_fee() {
// calculation on https://github.com/solana-labs/solana-program-library/issues/341
let swap_source_amount = 1000;
let swap_destination_amount = 50000;
let trade_fee_numerator = 0;
let trade_fee_denominator = 0;
let owner_trade_fee_numerator = 1;
let owner_trade_fee_denominator = 100;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 0;
let host_fee_numerator = 0;
let host_fee_denominator = 0;
let source_amount: u128 = 100;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, 4505);
assert_eq!(result.new_destination_amount, 45495);
assert_eq!(result.trade_fee, 0);
assert_eq!(result.owner_fee, 1);
}
#[test]
fn constant_product_swap_no_fee() {
let swap_source_amount: u128 = 1000;
let swap_destination_amount: u128 = 50000;
let source_amount: u128 = 100;
let curve = ConstantProductCurve::default();
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, 4546);
assert_eq!(result.new_destination_amount, 45454);
}
#[test]
fn flat_swap_calculation() {
let swap_source_amount = 1000;
let swap_destination_amount = 50000;
let trade_fee_numerator = 1;
let trade_fee_denominator = 100;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 100;
let owner_withdraw_fee_numerator = 2;
let owner_withdraw_fee_denominator = 100;
let host_fee_numerator = 2;
let host_fee_denominator = 100;
let source_amount: u128 = 100;
let curve = FlatCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
let amount_swapped = 97;
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, amount_swapped);
assert_eq!(result.trade_fee, 1);
assert_eq!(result.owner_fee, 2);
assert_eq!(
result.new_destination_amount,
swap_destination_amount - amount_swapped
);
}
#[test]
fn pack_flat_curve() {
let trade_fee_numerator = 1;
let trade_fee_denominator = 4;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 5;
let owner_withdraw_fee_numerator = 4;
let owner_withdraw_fee_denominator = 10;
let host_fee_numerator = 4;
let host_fee_denominator = 10;
let curve = FlatCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let mut packed = [0u8; FlatCurve::LEN];
Pack::pack_into_slice(&curve, &mut packed[..]);
let unpacked = FlatCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
let mut packed = vec![];
packed.extend_from_slice(&trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_denominator.to_le_bytes());
packed.extend_from_slice(&host_fee_numerator.to_le_bytes());
packed.extend_from_slice(&host_fee_denominator.to_le_bytes());
let unpacked = FlatCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
}
#[test]
fn pack_constant_product_curve() {
let trade_fee_numerator = 1;
let trade_fee_denominator = 4;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 5;
let owner_withdraw_fee_numerator = 4;
let owner_withdraw_fee_denominator = 10;
let host_fee_numerator = 4;
let host_fee_denominator = 10;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let mut packed = [0u8; ConstantProductCurve::LEN];
Pack::pack_into_slice(&curve, &mut packed[..]);
let unpacked = ConstantProductCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
let mut packed = vec![];
packed.extend_from_slice(&trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_denominator.to_le_bytes());
packed.extend_from_slice(&host_fee_numerator.to_le_bytes());
packed.extend_from_slice(&host_fee_denominator.to_le_bytes());
let unpacked = ConstantProductCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
}
#[test]
fn pack_swap_curve() {
let trade_fee_numerator = 1;
let trade_fee_denominator = 4;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 5;
let owner_withdraw_fee_numerator = 4;
let owner_withdraw_fee_denominator = 10;
let host_fee_numerator = 7;
let host_fee_denominator = 100;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let curve_type = CurveType::ConstantProduct;
let swap_curve = SwapCurve {
curve_type,
calculator: Box::new(curve),
};
let mut packed = [0u8; SwapCurve::LEN];
Pack::pack_into_slice(&swap_curve, &mut packed[..]);
let unpacked = SwapCurve::unpack_from_slice(&packed).unwrap();
assert_eq!(swap_curve, unpacked);
let mut packed = vec![];
packed.push(curve_type as u8);
packed.extend_from_slice(&trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_denominator.to_le_bytes());
packed.extend_from_slice(&host_fee_numerator.to_le_bytes());
packed.extend_from_slice(&host_fee_denominator.to_le_bytes());
let unpacked = SwapCurve::unpack_from_slice(&packed).unwrap();
assert_eq!(swap_curve, unpacked);
}
}

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//! Base curve implementation
use solana_program::{
program_error::ProgramError,
program_pack::{Pack, Sealed},
};
use crate::curve::{
calculator::CurveCalculator, constant_product::ConstantProductCurve, flat::FlatCurve,
};
use arrayref::{array_mut_ref, array_ref, array_refs, mut_array_refs};
use std::convert::{TryFrom, TryInto};
use std::fmt::Debug;
/// Curve types supported by the token-swap program.
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum CurveType {
/// Uniswap-style constant product curve, invariant = token_a_amount * token_b_amount
ConstantProduct,
/// Flat line, always providing 1:1 from one token to another
Flat,
}
/// Concrete struct to wrap around the trait object which performs calculation.
#[repr(C)]
#[derive(Debug)]
pub struct SwapCurve {
/// The type of curve contained in the calculator, helpful for outside
/// queries
pub curve_type: CurveType,
/// The actual calculator, represented as a trait object to allow for many
/// different types of curves
pub calculator: Box<dyn CurveCalculator>,
}
/// Default implementation for SwapCurve cannot be derived because of
/// the contained Box.
impl Default for SwapCurve {
fn default() -> Self {
let curve_type: CurveType = Default::default();
let calculator: ConstantProductCurve = Default::default();
Self {
curve_type,
calculator: Box::new(calculator),
}
}
}
/// Clone takes advantage of pack / unpack to get around the difficulty of
/// cloning dynamic objects.
/// Note that this is only to be used for testing.
#[cfg(test)]
impl Clone for SwapCurve {
fn clone(&self) -> Self {
let mut packed_self = [0u8; Self::LEN];
Self::pack_into_slice(self, &mut packed_self);
Self::unpack_from_slice(&packed_self).unwrap()
}
}
/// Simple implementation for PartialEq which assumes that the output of
/// `Pack` is enough to guarantee equality
impl PartialEq for SwapCurve {
fn eq(&self, other: &Self) -> bool {
let mut packed_self = [0u8; Self::LEN];
Self::pack_into_slice(self, &mut packed_self);
let mut packed_other = [0u8; Self::LEN];
Self::pack_into_slice(other, &mut packed_other);
packed_self[..] == packed_other[..]
}
}
impl Sealed for SwapCurve {}
impl Pack for SwapCurve {
/// Size of encoding of all curve parameters, which include fees and any other
/// constants used to calculate swaps, deposits, and withdrawals.
/// This includes 1 byte for the type, and 64 for the calculator to use as
/// it needs. Some calculators may be smaller than 64 bytes.
const LEN: usize = 65;
/// Unpacks a byte buffer into a SwapCurve
fn unpack_from_slice(input: &[u8]) -> Result<Self, ProgramError> {
let input = array_ref![input, 0, 65];
#[allow(clippy::ptr_offset_with_cast)]
let (curve_type, calculator) = array_refs![input, 1, 64];
let curve_type = curve_type[0].try_into()?;
Ok(Self {
curve_type,
calculator: match curve_type {
CurveType::ConstantProduct => {
Box::new(ConstantProductCurve::unpack_from_slice(calculator)?)
}
CurveType::Flat => Box::new(FlatCurve::unpack_from_slice(calculator)?),
},
})
}
/// Pack SwapCurve into a byte buffer
fn pack_into_slice(&self, output: &mut [u8]) {
let output = array_mut_ref![output, 0, 65];
let (curve_type, calculator) = mut_array_refs![output, 1, 64];
curve_type[0] = self.curve_type as u8;
self.calculator.pack_into_slice(&mut calculator[..]);
}
}
/// Sensible default of CurveType to ConstantProduct, the most popular and
/// well-known curve type.
impl Default for CurveType {
fn default() -> Self {
CurveType::ConstantProduct
}
}
impl TryFrom<u8> for CurveType {
type Error = ProgramError;
fn try_from(curve_type: u8) -> Result<Self, Self::Error> {
match curve_type {
0 => Ok(CurveType::ConstantProduct),
1 => Ok(CurveType::Flat),
_ => Err(ProgramError::InvalidAccountData),
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn pack_swap_curve() {
let trade_fee_numerator = 1;
let trade_fee_denominator = 4;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 5;
let owner_withdraw_fee_numerator = 4;
let owner_withdraw_fee_denominator = 10;
let host_fee_numerator = 7;
let host_fee_denominator = 100;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let curve_type = CurveType::ConstantProduct;
let swap_curve = SwapCurve {
curve_type,
calculator: Box::new(curve),
};
let mut packed = [0u8; SwapCurve::LEN];
Pack::pack_into_slice(&swap_curve, &mut packed[..]);
let unpacked = SwapCurve::unpack_from_slice(&packed).unwrap();
assert_eq!(swap_curve, unpacked);
let mut packed = vec![];
packed.push(curve_type as u8);
packed.extend_from_slice(&trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_denominator.to_le_bytes());
packed.extend_from_slice(&host_fee_numerator.to_le_bytes());
packed.extend_from_slice(&host_fee_denominator.to_le_bytes());
let unpacked = SwapCurve::unpack_from_slice(&packed).unwrap();
assert_eq!(swap_curve, unpacked);
}
}

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//! Swap calculations
use std::fmt::Debug;
/// Initial amount of pool tokens for swap contract, hard-coded to something
/// "sensible" given a maximum of u128.
/// Note that on Ethereum, Uniswap uses the geometric mean of all provided
/// input amounts, and Balancer uses 100 * 10 ^ 18.
pub const INITIAL_SWAP_POOL_AMOUNT: u128 = 1_000_000_000;
/// Helper function for calcuating swap fee
pub fn calculate_fee(
token_amount: u128,
fee_numerator: u128,
fee_denominator: u128,
) -> Option<u128> {
if fee_numerator == 0 {
Some(0)
} else {
let fee = token_amount
.checked_mul(fee_numerator)?
.checked_div(fee_denominator)?;
if fee == 0 {
Some(1) // minimum fee of one token
} else {
Some(fee)
}
}
}
/// Helper function for mapping to SwapError::CalculationFailure
pub fn map_zero_to_none(x: u128) -> Option<u128> {
if x == 0 {
None
} else {
Some(x)
}
}
/// Encodes all results of swapping from a source token to a destination token
pub struct SwapResult {
/// New amount of source token
pub new_source_amount: u128,
/// New amount of destination token
pub new_destination_amount: u128,
/// Amount of destination token swapped
pub amount_swapped: u128,
/// Amount of source tokens going to pool holders
pub trade_fee: u128,
/// Amount of source tokens going to owner
pub owner_fee: u128,
}
/// Trait for packing of trait objects, required because structs that implement
/// `Pack` cannot be used as trait objects (as `dyn Pack`).
pub trait DynPack {
/// Only required function is to pack given a trait object
fn pack_into_slice(&self, dst: &mut [u8]);
}
/// Trait representing operations required on a swap curve
pub trait CurveCalculator: Debug + DynPack {
/// Calculate how much destination token will be provided given an amount
/// of source token.
fn swap(
&self,
source_amount: u128,
swap_source_amount: u128,
swap_destination_amount: u128,
) -> Option<SwapResult>;
/// Calculate the withdraw fee in pool tokens
/// Default implementation assumes no fee
fn owner_withdraw_fee(&self, _pool_tokens: u128) -> Option<u128> {
Some(0)
}
/// Calculate the trading fee in trading tokens
/// Default implementation assumes no fee
fn trading_fee(&self, _trading_tokens: u128) -> Option<u128> {
Some(0)
}
/// Calculate the pool token equivalent of the owner fee on trade
/// See the math at: https://balancer.finance/whitepaper/#single-asset-deposit
/// For the moment, we do an approximation for the square root. For numbers
/// just above 1, simply dividing by 2 brings you very close to the correct
/// value.
fn owner_fee_to_pool_tokens(
&self,
owner_fee: u128,
trading_token_amount: u128,
pool_supply: u128,
tokens_in_pool: u128,
) -> Option<u128> {
// Get the trading fee incurred if the owner fee is swapped for the other side
let trade_fee = self.trading_fee(owner_fee)?;
let owner_fee = owner_fee.checked_sub(trade_fee)?;
pool_supply
.checked_mul(owner_fee)?
.checked_div(trading_token_amount)?
.checked_div(tokens_in_pool)
}
/// Get the supply for a new pool
/// The default implementation is a Balancer-style fixed initial supply
fn new_pool_supply(&self) -> u128 {
INITIAL_SWAP_POOL_AMOUNT
}
/// Get the amount of trading tokens for the given amount of pool tokens,
/// provided the total trading tokens and supply of pool tokens.
/// The default implementation is a simple ratio calculation for how many
/// trading tokens correspond to a certain number of pool tokens
fn pool_tokens_to_trading_tokens(
&self,
pool_tokens: u128,
pool_token_supply: u128,
total_trading_tokens: u128,
) -> Option<u128> {
pool_tokens
.checked_mul(total_trading_tokens)?
.checked_div(pool_token_supply)
.and_then(map_zero_to_none)
}
/// Calculate the host fee based on the owner fee, only used in production
/// situations where a program is hosted by multiple frontends
fn host_fee(&self, _owner_fee: u128) -> Option<u128> {
Some(0)
}
}

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//! The Uniswap invariant calculator.
use solana_program::{
program_error::ProgramError,
program_pack::{IsInitialized, Pack, Sealed},
};
use crate::curve::calculator::{
calculate_fee, map_zero_to_none, CurveCalculator, DynPack, SwapResult,
};
use arrayref::{array_mut_ref, array_ref, array_refs, mut_array_refs};
use std::convert::TryFrom;
/// ConstantProductCurve struct implementing CurveCalculator
#[derive(Clone, Debug, Default, PartialEq)]
pub struct ConstantProductCurve {
/// Trade fee numerator
pub trade_fee_numerator: u64,
/// Trade fee denominator
pub trade_fee_denominator: u64,
/// Owner trade fee numerator
pub owner_trade_fee_numerator: u64,
/// Owner trade fee denominator
pub owner_trade_fee_denominator: u64,
/// Owner withdraw fee numerator
pub owner_withdraw_fee_numerator: u64,
/// Owner withdraw fee denominator
pub owner_withdraw_fee_denominator: u64,
/// Host trading fee numerator
pub host_fee_numerator: u64,
/// Host trading fee denominator
pub host_fee_denominator: u64,
}
impl CurveCalculator for ConstantProductCurve {
/// Constant product swap ensures x * y = constant
fn swap(
&self,
source_amount: u128,
swap_source_amount: u128,
swap_destination_amount: u128,
) -> Option<SwapResult> {
// debit the fee to calculate the amount swapped
let trade_fee = self.trading_fee(source_amount)?;
let owner_fee = calculate_fee(
source_amount,
u128::try_from(self.owner_trade_fee_numerator).ok()?,
u128::try_from(self.owner_trade_fee_denominator).ok()?,
)?;
let invariant = swap_source_amount.checked_mul(swap_destination_amount)?;
let new_source_amount_less_fee = swap_source_amount
.checked_add(source_amount)?
.checked_sub(trade_fee)?
.checked_sub(owner_fee)?;
let new_destination_amount = invariant.checked_div(new_source_amount_less_fee)?;
let amount_swapped =
map_zero_to_none(swap_destination_amount.checked_sub(new_destination_amount)?)?;
// actually add the whole amount coming in
let new_source_amount = swap_source_amount.checked_add(source_amount)?;
Some(SwapResult {
new_source_amount,
new_destination_amount,
amount_swapped,
trade_fee,
owner_fee,
})
}
/// Calculate the withdraw fee in pool tokens
fn owner_withdraw_fee(&self, pool_tokens: u128) -> Option<u128> {
calculate_fee(
pool_tokens,
u128::try_from(self.owner_withdraw_fee_numerator).ok()?,
u128::try_from(self.owner_withdraw_fee_denominator).ok()?,
)
}
/// Calculate the trading fee in trading tokens
fn trading_fee(&self, trading_tokens: u128) -> Option<u128> {
calculate_fee(
trading_tokens,
u128::try_from(self.trade_fee_numerator).ok()?,
u128::try_from(self.trade_fee_denominator).ok()?,
)
}
/// Calculate the host fee based on the owner fee, only used in production
/// situations where a program is hosted by multiple frontends
fn host_fee(&self, owner_fee: u128) -> Option<u128> {
calculate_fee(
owner_fee,
u128::try_from(self.host_fee_numerator).ok()?,
u128::try_from(self.host_fee_denominator).ok()?,
)
}
}
/// IsInitialized is required to use `Pack::pack` and `Pack::unpack`
impl IsInitialized for ConstantProductCurve {
fn is_initialized(&self) -> bool {
true
}
}
impl Sealed for ConstantProductCurve {}
impl Pack for ConstantProductCurve {
const LEN: usize = 64;
fn unpack_from_slice(input: &[u8]) -> Result<ConstantProductCurve, ProgramError> {
let input = array_ref![input, 0, 64];
#[allow(clippy::ptr_offset_with_cast)]
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = array_refs![input, 8, 8, 8, 8, 8, 8, 8, 8];
Ok(Self {
trade_fee_numerator: u64::from_le_bytes(*trade_fee_numerator),
trade_fee_denominator: u64::from_le_bytes(*trade_fee_denominator),
owner_trade_fee_numerator: u64::from_le_bytes(*owner_trade_fee_numerator),
owner_trade_fee_denominator: u64::from_le_bytes(*owner_trade_fee_denominator),
owner_withdraw_fee_numerator: u64::from_le_bytes(*owner_withdraw_fee_numerator),
owner_withdraw_fee_denominator: u64::from_le_bytes(*owner_withdraw_fee_denominator),
host_fee_numerator: u64::from_le_bytes(*host_fee_numerator),
host_fee_denominator: u64::from_le_bytes(*host_fee_denominator),
})
}
fn pack_into_slice(&self, output: &mut [u8]) {
(self as &dyn DynPack).pack_into_slice(output);
}
}
impl DynPack for ConstantProductCurve {
fn pack_into_slice(&self, output: &mut [u8]) {
let output = array_mut_ref![output, 0, 64];
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = mut_array_refs![output, 8, 8, 8, 8, 8, 8, 8, 8];
*trade_fee_numerator = self.trade_fee_numerator.to_le_bytes();
*trade_fee_denominator = self.trade_fee_denominator.to_le_bytes();
*owner_trade_fee_numerator = self.owner_trade_fee_numerator.to_le_bytes();
*owner_trade_fee_denominator = self.owner_trade_fee_denominator.to_le_bytes();
*owner_withdraw_fee_numerator = self.owner_withdraw_fee_numerator.to_le_bytes();
*owner_withdraw_fee_denominator = self.owner_withdraw_fee_denominator.to_le_bytes();
*host_fee_numerator = self.host_fee_numerator.to_le_bytes();
*host_fee_denominator = self.host_fee_denominator.to_le_bytes();
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::curve::calculator::INITIAL_SWAP_POOL_AMOUNT;
#[test]
fn initial_pool_amount() {
let trade_fee_numerator = 0;
let trade_fee_denominator = 1;
let owner_trade_fee_numerator = 0;
let owner_trade_fee_denominator = 1;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 1;
let host_fee_numerator = 0;
let host_fee_denominator = 1;
let calculator = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
assert_eq!(calculator.new_pool_supply(), INITIAL_SWAP_POOL_AMOUNT);
}
fn check_pool_token_rate(token_a: u128, deposit: u128, supply: u128, expected: Option<u128>) {
let trade_fee_numerator = 0;
let trade_fee_denominator = 1;
let owner_trade_fee_numerator = 0;
let owner_trade_fee_denominator = 1;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 1;
let host_fee_numerator = 0;
let host_fee_denominator = 1;
let calculator = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
assert_eq!(
calculator.pool_tokens_to_trading_tokens(deposit, supply, token_a),
expected
);
}
#[test]
fn trading_token_conversion() {
check_pool_token_rate(2, 5, 10, Some(1));
check_pool_token_rate(10, 5, 10, Some(5));
check_pool_token_rate(5, 5, 10, Some(2));
check_pool_token_rate(5, 5, 10, Some(2));
check_pool_token_rate(u128::MAX, 5, 10, None);
}
#[test]
fn constant_product_swap_calculation_trade_fee() {
// calculation on https://github.com/solana-labs/solana-program-library/issues/341
let swap_source_amount = 1000;
let swap_destination_amount = 50000;
let trade_fee_numerator = 1;
let trade_fee_denominator = 100;
let owner_trade_fee_numerator = 0;
let owner_trade_fee_denominator = 0;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 0;
let host_fee_numerator = 0;
let host_fee_denominator = 0;
let source_amount = 100;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, 4505);
assert_eq!(result.new_destination_amount, 45495);
assert_eq!(result.trade_fee, 1);
assert_eq!(result.owner_fee, 0);
}
#[test]
fn constant_product_swap_calculation_owner_fee() {
// calculation on https://github.com/solana-labs/solana-program-library/issues/341
let swap_source_amount = 1000;
let swap_destination_amount = 50000;
let trade_fee_numerator = 0;
let trade_fee_denominator = 0;
let owner_trade_fee_numerator = 1;
let owner_trade_fee_denominator = 100;
let owner_withdraw_fee_numerator = 0;
let owner_withdraw_fee_denominator = 0;
let host_fee_numerator = 0;
let host_fee_denominator = 0;
let source_amount: u128 = 100;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, 4505);
assert_eq!(result.new_destination_amount, 45495);
assert_eq!(result.trade_fee, 0);
assert_eq!(result.owner_fee, 1);
}
#[test]
fn constant_product_swap_no_fee() {
let swap_source_amount: u128 = 1000;
let swap_destination_amount: u128 = 50000;
let source_amount: u128 = 100;
let curve = ConstantProductCurve::default();
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, 4546);
assert_eq!(result.new_destination_amount, 45454);
}
#[test]
fn pack_constant_product_curve() {
let trade_fee_numerator = 1;
let trade_fee_denominator = 4;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 5;
let owner_withdraw_fee_numerator = 4;
let owner_withdraw_fee_denominator = 10;
let host_fee_numerator = 4;
let host_fee_denominator = 10;
let curve = ConstantProductCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let mut packed = [0u8; ConstantProductCurve::LEN];
Pack::pack_into_slice(&curve, &mut packed[..]);
let unpacked = ConstantProductCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
let mut packed = vec![];
packed.extend_from_slice(&trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_denominator.to_le_bytes());
packed.extend_from_slice(&host_fee_numerator.to_le_bytes());
packed.extend_from_slice(&host_fee_denominator.to_le_bytes());
let unpacked = ConstantProductCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
}
}

231
token-swap/program/src/curve/flat.rs Normal file
View File

@ -0,0 +1,231 @@
//! Simple constant 1:1 swap curve
use solana_program::{
program_error::ProgramError,
program_pack::{IsInitialized, Pack, Sealed},
};
use crate::curve::calculator::{calculate_fee, CurveCalculator, DynPack, SwapResult};
use arrayref::{array_mut_ref, array_ref, array_refs, mut_array_refs};
use std::convert::TryFrom;
/// FlatCurve struct implementing CurveCalculator
#[derive(Clone, Debug, Default, PartialEq)]
pub struct FlatCurve {
/// Fee numerator
pub trade_fee_numerator: u64,
/// Fee denominator
pub trade_fee_denominator: u64,
/// Owner trade fee numerator
pub owner_trade_fee_numerator: u64,
/// Owner trade fee denominator
pub owner_trade_fee_denominator: u64,
/// Owner withdraw fee numerator
pub owner_withdraw_fee_numerator: u64,
/// Owner withdraw fee denominator
pub owner_withdraw_fee_denominator: u64,
/// Host trading fee numerator
pub host_fee_numerator: u64,
/// Host trading fee denominator
pub host_fee_denominator: u64,
}
impl CurveCalculator for FlatCurve {
/// Flat curve swap always returns 1:1 (minus fee)
fn swap(
&self,
source_amount: u128,
swap_source_amount: u128,
swap_destination_amount: u128,
) -> Option<SwapResult> {
// debit the fee to calculate the amount swapped
let trade_fee = calculate_fee(
source_amount,
u128::try_from(self.trade_fee_numerator).ok()?,
u128::try_from(self.trade_fee_denominator).ok()?,
)?;
let owner_fee = calculate_fee(
source_amount,
u128::try_from(self.owner_trade_fee_numerator).ok()?,
u128::try_from(self.owner_trade_fee_denominator).ok()?,
)?;
let amount_swapped = source_amount
.checked_sub(trade_fee)?
.checked_sub(owner_fee)?;
let new_destination_amount = swap_destination_amount.checked_sub(amount_swapped)?;
// actually add the whole amount coming in
let new_source_amount = swap_source_amount.checked_add(source_amount)?;
Some(SwapResult {
new_source_amount,
new_destination_amount,
amount_swapped,
trade_fee,
owner_fee,
})
}
/// Calculate the withdraw fee in pool tokens
fn owner_withdraw_fee(&self, pool_tokens: u128) -> Option<u128> {
calculate_fee(
pool_tokens,
u128::try_from(self.owner_withdraw_fee_numerator).ok()?,
u128::try_from(self.owner_withdraw_fee_denominator).ok()?,
)
}
/// Calculate the host fee based on the owner fee, only used in production
/// situations where a program is hosted by multiple frontends
fn host_fee(&self, owner_fee: u128) -> Option<u128> {
calculate_fee(
owner_fee,
u128::try_from(self.host_fee_numerator).ok()?,
u128::try_from(self.host_fee_denominator).ok()?,
)
}
}
/// IsInitialized is required to use `Pack::pack` and `Pack::unpack`
impl IsInitialized for FlatCurve {
fn is_initialized(&self) -> bool {
true
}
}
impl Sealed for FlatCurve {}
impl Pack for FlatCurve {
const LEN: usize = 64;
fn unpack_from_slice(input: &[u8]) -> Result<FlatCurve, ProgramError> {
let input = array_ref![input, 0, 64];
#[allow(clippy::ptr_offset_with_cast)]
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = array_refs![input, 8, 8, 8, 8, 8, 8, 8, 8];
Ok(Self {
trade_fee_numerator: u64::from_le_bytes(*trade_fee_numerator),
trade_fee_denominator: u64::from_le_bytes(*trade_fee_denominator),
owner_trade_fee_numerator: u64::from_le_bytes(*owner_trade_fee_numerator),
owner_trade_fee_denominator: u64::from_le_bytes(*owner_trade_fee_denominator),
owner_withdraw_fee_numerator: u64::from_le_bytes(*owner_withdraw_fee_numerator),
owner_withdraw_fee_denominator: u64::from_le_bytes(*owner_withdraw_fee_denominator),
host_fee_numerator: u64::from_le_bytes(*host_fee_numerator),
host_fee_denominator: u64::from_le_bytes(*host_fee_denominator),
})
}
fn pack_into_slice(&self, output: &mut [u8]) {
(self as &dyn DynPack).pack_into_slice(output);
}
}
impl DynPack for FlatCurve {
fn pack_into_slice(&self, output: &mut [u8]) {
let output = array_mut_ref![output, 0, 64];
let (
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
) = mut_array_refs![output, 8, 8, 8, 8, 8, 8, 8, 8];
*trade_fee_numerator = self.trade_fee_numerator.to_le_bytes();
*trade_fee_denominator = self.trade_fee_denominator.to_le_bytes();
*owner_trade_fee_numerator = self.owner_trade_fee_numerator.to_le_bytes();
*owner_trade_fee_denominator = self.owner_trade_fee_denominator.to_le_bytes();
*owner_withdraw_fee_numerator = self.owner_withdraw_fee_numerator.to_le_bytes();
*owner_withdraw_fee_denominator = self.owner_withdraw_fee_denominator.to_le_bytes();
*host_fee_numerator = self.host_fee_numerator.to_le_bytes();
*host_fee_denominator = self.host_fee_denominator.to_le_bytes();
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn flat_swap_calculation() {
let swap_source_amount = 1000;
let swap_destination_amount = 50000;
let trade_fee_numerator = 1;
let trade_fee_denominator = 100;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 100;
let owner_withdraw_fee_numerator = 2;
let owner_withdraw_fee_denominator = 100;
let host_fee_numerator = 2;
let host_fee_denominator = 100;
let source_amount: u128 = 100;
let curve = FlatCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let result = curve
.swap(source_amount, swap_source_amount, swap_destination_amount)
.unwrap();
let amount_swapped = 97;
assert_eq!(result.new_source_amount, 1100);
assert_eq!(result.amount_swapped, amount_swapped);
assert_eq!(result.trade_fee, 1);
assert_eq!(result.owner_fee, 2);
assert_eq!(
result.new_destination_amount,
swap_destination_amount - amount_swapped
);
}
#[test]
fn pack_flat_curve() {
let trade_fee_numerator = 1;
let trade_fee_denominator = 4;
let owner_trade_fee_numerator = 2;
let owner_trade_fee_denominator = 5;
let owner_withdraw_fee_numerator = 4;
let owner_withdraw_fee_denominator = 10;
let host_fee_numerator = 4;
let host_fee_denominator = 10;
let curve = FlatCurve {
trade_fee_numerator,
trade_fee_denominator,
owner_trade_fee_numerator,
owner_trade_fee_denominator,
owner_withdraw_fee_numerator,
owner_withdraw_fee_denominator,
host_fee_numerator,
host_fee_denominator,
};
let mut packed = [0u8; FlatCurve::LEN];
Pack::pack_into_slice(&curve, &mut packed[..]);
let unpacked = FlatCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
let mut packed = vec![];
packed.extend_from_slice(&trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_trade_fee_denominator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_numerator.to_le_bytes());
packed.extend_from_slice(&owner_withdraw_fee_denominator.to_le_bytes());
packed.extend_from_slice(&host_fee_numerator.to_le_bytes());
packed.extend_from_slice(&host_fee_denominator.to_le_bytes());
let unpacked = FlatCurve::unpack(&packed).unwrap();
assert_eq!(curve, unpacked);
}
}

6
token-swap/program/src/curve/mod.rs Normal file
View File

@ -0,0 +1,6 @@
//! Curve invariant implementations
pub mod base;
pub mod calculator;
pub mod constant_product;
pub mod flat;

4
token-swap/program/src/instruction.rs
View File

@ -2,7 +2,7 @@
#![allow(clippy::too_many_arguments)]
use crate::curve::SwapCurve;
use crate::curve::base::SwapCurve;
use crate::error::SwapError;
use solana_program::{
instruction::{AccountMeta, Instruction},
@ -381,7 +381,7 @@ pub fn unpack<T>(input: &[u8]) -> Result<&T, ProgramError> {
mod tests {
use super::*;
use crate::curve::{CurveType, FlatCurve};
use crate::curve::{base::CurveType, flat::FlatCurve};
#[test]
fn test_instruction_packing() {

10
token-swap/program/src/processor.rs
View File

@ -1,7 +1,9 @@
//! Program state processor
use crate::constraints::{FeeConstraints, FEE_CONSTRAINTS};
use crate::{curve::SwapCurve, error::SwapError, instruction::SwapInstruction, state::SwapInfo};
use crate::{
curve::base::SwapCurve, error::SwapError, instruction::SwapInstruction, state::SwapInfo,
};
use num_traits::FromPrimitive;
use solana_program::{
account_info::{next_account_info, AccountInfo},
@ -731,9 +733,9 @@ fn to_u64(val: u128) -> Result<u64, SwapError> {
mod tests {
use super::*;
use crate::{
curve::{
ConstantProductCurve, CurveCalculator, CurveType, FlatCurve, INITIAL_SWAP_POOL_AMOUNT,
},
curve::base::CurveType,
curve::calculator::{CurveCalculator, INITIAL_SWAP_POOL_AMOUNT},
curve::{constant_product::ConstantProductCurve, flat::FlatCurve},
instruction::{deposit, initialize, swap, withdraw},
};
use solana_program::{instruction::Instruction, program_stubs, rent::Rent};

4
token-swap/program/src/state.rs
View File

@ -1,6 +1,6 @@
//! State transition types
use crate::curve::SwapCurve;
use crate::curve::base::SwapCurve;
use arrayref::{array_mut_ref, array_ref, array_refs, mut_array_refs};
use solana_program::{
program_error::ProgramError,
@ -120,7 +120,7 @@ impl Pack for SwapInfo {
#[cfg(test)]
mod tests {
use super::*;
use crate::curve::FlatCurve;
use crate::curve::flat::FlatCurve;
use std::convert::TryInto;