pool_swaps_spec.md

[WIP] Pool Swaps Specification

Metadata

Authors	Jack McPherson <[email protected]>
Version	0.1

Contents

[TODO]

Overview

TODO

Conventions

Scope

This document specifies the minimum required interface for the Tracer Pool Swaps protocol. Compliant implementations may implement a superset of the functionality specified in this document, but not a subset.

Requirements Language

This document makes uses of the requirements language specified in RFC2119[1]. This document typesets such keywords in both boldface and italics.

Definitions

Were domain-specific terminology is used, this document defines relevant terms and typesets them in boldface.

Miscellaneous

Where a function returns multiple types, this indicates that the function returns a tuple of these types. Additionally, where returned values are unnamed, they are free to be either anonymous or named.

Definitions

Term	Definition
Pair	TODO
Pool	Smart contract containing two pairs – one long and one short – that tracks changes in the price of an underlying asset. A pool has a fixed leverage.
Market	Collection of pools, all tracking the same underlying asset, but each having unique leverage.
Price update	When funds are moved between the two pairs of a pool
Update interval	Minimum amount of time (in seconds) between price updates
Frontrunning interval	TODO
Price execution	See price update
Shadow pool	Sum of all unexecuted commitments of a given type
Minting	Act of depositing into a pair
Burning	Act of withdrawing from a pair
Commitment	TODO
Commit	See commitment

Smart Contracts

IPoolFactory

Library?	No
Interface?	Yes
Abstract?	No
Implements	N/A

Types

None.

Views

None.

Mutative Functions

deployPool

Visibility	external
Restricted?	Yes

Deploys a new pool with the specified parameters.

Parameters

Name	Type	Description
_owner	address	Address of the owner of the deployed pool
_poolCode	string	Ticker for the deployed pool
_frontRunningInterval	uint32	Front running interval for the deployed pool
_fee	bytes16	Rebalancing fee for the deployed pool
_mintBurnFee	bytes16	Total fee charged to minters/burners
_burnFeePercent	uint16	Percentage mint/burn fee charged to burners
_leverageAmount	uint16	Leverage for the deployed pool
_feeAddress	address	Address of rebalancing fee recipient for the deployed pool
_quoteToken	address	Address of the ERC20 token that the deployed pool uses as the quote asset

Returns

Name	Type	Description
	address	Address of the deployed pool

Events

DeployPool

Parameters

Name	Type	Indexed?	Description
pool	address	Yes	Address of the deployed pool
poolCode	string	No	Ticker of the deployed pool

IPoolKeeper

Types

Upkeep

TODO

Fields

Name	Type	Description
cumulativePrice	int256	Sum of all sample prices for the current interval
lastSamplePrice	int256	Most recent sample price for the current interval
executionPrice	int256	Price for the current execution
lastExecutionPrice	int256	Most recent price an execution occurred at (i.e., preceding executionPrice above)
count	uint32	Number of samples for the current interval
updateInterval	uint32	TODO
roundStart	uint40	TODO

Views

None.

Mutative Functions

updateOracleWrapper

Visibility	external
Restricted?	Yes

Changes the oracle address of the pool keeper

Parameters

Name	Type	Description
oracle	address	Address of the new oracle

Returns

None.

createMarket

Visibility	external
Restricted?	No

Creates a new market. This is where both the market ticker and the price oracle are defined.

Parameters

Name	Type	Description
marketCode	string	Ticker for new market
oracle	address	Address of price oracle for new market

Returns

None.

createPool

Visibility	external
Restricted?	No

Creates a new pool in the market specified by marketCode.

Parameters

Name	Type	Description
marketCode	string	Ticker of the market the new pool belongs to
poolCode	string	Ticker for the new pool
updateInterval	uint32	Minimum amount of time between price updates
frontRunningInterval	uint32	Front running interval for the deployed pool
fee	bytes16	Rebalancing fee for the deployed pool
mintBurnFee	bytes16	Total fee charged to minters/burners
burnFeePercent	uint16	Percentage mint/burn fee charged to burners
leverageAmount	uint16	Leverage for the deployed pool
feeAddress	address	Address of rebalancing fee recipient for the deployed pool
quoteToken	address	Address of the ERC20 token that the deployed pool uses as the quote asset

Returns

None.

Events

CreatePool

Indicates successful creation of a new pool.

Name	Type	Indexed?	Description
poolAddress	address	Yes	Address of the newly-created pool
firstPrice	int256	Yes	Price reported by the price oracle upon pool creation
updateInterval	uint32	Yes	Minimum amount of time between price updates for this pool. See TODO
market	string	No	Ticker of the market to which the newly-created pool belongs

CreateMarket

Indicates successful creation of a new market.

Name	Type	Indexed?	Description
marketCode	string	No	Ticker for this market
oracle	address	No	Address of the price oracle for this market

NewRound

Indicates that a new round has occurred.

Name	Type	Indexed?	Description
oldPrice	int256	Yes	Price before this round
newPrice	int256	Yes	Price after this round began
updateInterval	uint32	Yes	Minimum amount of time between price updates. See TODO
market	string	No	Ticker for this market

PriceSample

Indicates a successful price sample.

Name	Type	Indexed?	Description
cumulativePrice	int256	Yes	Sum of all price samples for the current round
count	int256	Yes	Number of price samples for the current round. See TODO
updateInterval	uint32	Yes	Minimum amount of time between price updates. See TODO
market	string	No	Ticker for this market

ExecutePriceChange

Indicates successful price execution.

Name	Type	Indexed?	Description
oldPrice	int256	Yes	TODO
newPrice	int256	Yes	TODO
updateInterval	uint32	Yes	Minimum amount of time between price updates. See TODO
market	string	No	Ticker for this market
pool	string	No	Ticker for this pool

PoolUpdateError

Indicates a failed pool update.

Name	Type	Indexed?	Description
poolCode	string	Yes	The ticker of the pool
reason	string	No	The reason the pool failed to update

IOracleWrapper

Library?	No
Interface?	Yes
Abstract?	No
Implements

Types

None.

Views

getPrice

Parameters

Name	Type	Description
marketCode	string	Ticker of the market in question

Returns

Name	Type	Description
	int256	Price

assetOracles

Parameters

Name	Type	Description
marketCode	string	Ticker of the market in question

Returns

Name	Type	Description
	address	Address of the asset oracle for the specified market

Mutative Functions

setOracle

Visibility	external
Restricted?	Yes

Parameters

Name	Type	Description
marketCode	string	Ticker of the market
oracle	address	Address of the new price oracle

Returns

None.

Events

None.

ILeveragedPool

Library?	No
Interface?	Yes
Abstract?	No
Implements

Types

CommitType

An eumerated type describing the type of a commitment.

• ShortMint

• ShortBurn

• LongMint

• LongBurn

Commit

Describes a commitment.

Fields

Name	Type	Description
maxImbalance	bytes16	TODO
amount	uint112	Amount being committed to
commitType	CommitType	Type of this commitment
created	uint40	TODO
owner	address	Address of the owner of the commitment

Mutative Functions

initialize

Visibility	external
Restricted?	No

Initialises a pool.

Required for EIP1167[TODO] compliance.

Note: this function SHOULD only be able to be called once per pool. This is due to the nature of EIP1167.

Parameters

Name	Type	Description
_updater	address	TODO
_longToken	address	Address of the long token for this pool
_shortToken	address	Address of the short token for this pool
_poolCode	string	Ticker for this pool
_frontRunningInteral	uint32	Minimum amount of time before a commitment can be executed
_fee	bytes16	Fee for moving funds
_mintBurnFee	bytes16	Total fee charged to minters/burners
_burnFeePercent	uint16	Percentage mint/burn fee charged to burners
_leverageAmount	uint16	How leveraged the pool is
_feeAddress	address	Address of the fee recipient
_quoteToken	address	Address of the quote token for this pool

Returns

None.

commit

Visibility	external
Restricted?	No

Submits a commitment.

Parameters

Name	Type	Description
commitType	CommitType	Type of commitment being submitted
maxImbalance	bytes16	TODO
amount	uint112	Amount to commit to

Returns

None.

uncommit

Visibility	external
Restricted?	No

Cancels an existing commitment, specified by commitID.

Parameters

Name	Type	Description
commitID	uint256	Unique identifier of the commitment

Returns

None.

executeCommitment

Visibility	external
Restricted?	No

Executes a set of commitments, specified by commitIDs.

Parameters

Name	Type	Description
_commitIDs	uint128[]	List of unique identifiers of each commitment to be executed

Returns

None.

executePriceChange

Visibility	external
Restricted?	Yes

Parameters

Name	Type	Description
oldPrice	int256	Price of the previous price change
newPrice	int256	New price

Returns

None.

updateFeeAddress

Visibility	external
Restricted?	Yes

Modifies the address of the fee receiver, setting it to account.

Parameters

Name	Type	Description
account	address	Address of the new fee recipient

Returns

None.

Events

PoolInitialized

Name	Type	Indexed?	Description
longToken	address	Yes	Address of this pool’s long position token
shortToken	address	Yes	Address of this pool’s short position token
quoteToken	address	No	Address of this pool’s quote token
poolCode	string	No	Ticker of this pool

CreateCommit

Indicates successful creation of a commitment.

Name	Type	Indexed?	Description
commitID	uint128	Yes	Unique identifier of the commitment
amount	uint128	Yes	Amount being committed to
maxImbalance	bytes16	Yes	TODO
commitType	CommitType	No	Type of this commitment

RemoveCommit

Indicates successful cancellation of a commitment.

Name	Type	Indexed?	Description
commitID	uint128	Yes	Unique identifier of the removed commit
amount	uint128	Yes	Amount removed from the shadow pool
commitType	CommitType	Yes	Type of the removed commit

ExecuteCommit

Indicates successful execution of a commitment.

Name	Type	Indexed?	Description
commitID	uint128	No	Unique identifier of the commit in question

PriceChange

Indicates successful price change.

Name	Type	Indexed?	Description
startPrice	int256	Yes	Price of last execution
endPrice	int256	Yes	Price for this execution
transferAmount	uint112	Yes	Amount moved between pools

PoolFactory

Library?	No
Interface?	No
Abstract?	No
Implements	IPoolFactory

State

Name	Type	Visibility	Immutable?	Description
pairTokenBase	PoolToken	public	No	Base token of this pool
poolBase	LeveragedPool	public	No	Base pool

Views

None.

Mutative Functions

constructor

Parameters

None

Test Cases

TODO

deployPool

See IPoolFactory.deployPool.

Test Cases

TODO

deployPairToken

Visibility?	internal
Restricted?	No

Deploys a new ERC20-compliant pair token for a pool.

Parameters

Name	Type	Description
owner	address	Address of the owner for the ERC20 pair token
name	string	Name of the ERC20 pair token
symbol	string	Ticker of the ERC20 pair token

Returns

Name	Type	Description
	address	Address of the ERC20 pair token

Test Cases

TODO

PoolKeeper

Library?	No
Interface?	No
Abstract?	No
Implements	IPoolKeeper

State

Name	Type	Visibility	Immutable?	Description
pools	mapping(string => address)	public	No	Maps pool tickers to addresses
poolMarkets	mapping(string => mapping(uint32 => string))	public	No	Maps pool tickers to mappings which in turn, map update intervals to market tickers
upkeep	mapping(string => mapping(uint32 => Upkeep))	public	No	Maps market tickers to mappings which in turn, map update intervals to Upkeeps
lastExecutionTime	mapping(string => uint40)	public	No	Maps pool tickers to timestamps
oracleWrapper	address	public	No	Address of the IOracleWrapper for this contract
factory	PoolFactory	public	Yes	Instance of PoolFactory for this contract

Constants

Name	Type	Value	Description
fixedPoint	bytes16	0x403abc16d674ec800000000000000000	TODO
ADMIN	bytes32	TODO	Role definition for OpenZeppelin Contracts' access control implementation

Views

checkUpkeep

Determines whether upkeep needs to be performed and produces call data in order to do so.

Parameters

Name	Type	Description
checkData	bytes	TODO

Returns

Name	Type	Description
upkeepNeeded	bool	Flag indicating whether upkeep needs to be performed
performData	bytes	Data suitable for passing to TODO

Mutative Functions

constructor

TODO

Parameters

Name	Type	Description

Test Cases

TODO

updateOracleWrapper

See IPoolKeeper.updateOracleWrapper.

createMarket

See IPoolKeeper.createMarket.

createPool

See IPoolKeeper.createPool.

peformUpkeep

See IPoolKeeper.performUpkeep.

LeveragedPool

Library?	No
Interface?	No
Abstract?	No
Implements	ILeveragedPool, AccessControl, Initializable

State

Name	Type	Visibility	Immutable?	Description
shortBalance	uint112	public	No
longBalance	uint112	public	No
frontRunningInterval	uint32	public	No
fee	bytes16	public	No
leverageAmount	bytes16	public	No
tokens	address[2]	public	No
feeAddress	address	public	No
quoteToken	address	public	No
lastPriceTimestasmp	uint40	public	No
commitIDCounter	uint128	public	No
commits	mapping(uint128 => Commit)	public	No
shadowPools	mapping(CommitType => uint112)	public	No
poolCode	string	public	No

Constants

Name	Type	Value	Description
UPDATER	bytes32	TODO	Role definition for OpenZepellin Contracts' access control implementation
ADMIN	bytes32	TODO	Role definition for OpenZepellin Contracts' access control implementation
FEE_HOLDER	bytes32	TODO	Role definition for OpenZepellin Contracts' access control implementation

Views

None.

Mutative Functions

initialize

See ILeveragedPool.initialize.

commit

See ILeveragedPool.commit.

uncommit

See ILeveragedPool.uncommit.

executeCommitment

See ILeveragedPool.executeCommitment.

executePriceChange

See ILeveragedPool.executePriceChange.

updateFeeAddress

See ILeveragedPool.updateFeeAddress.

Events

None.

OracleWrapper

Library?	No
Interface?	No
Abstract?	No
Implements	IOracleWrapper, AccessControl

State

Name	Type	Visibility	Immutable?	Description
assetOracles	mapping(string => address)	public	No	Maps pool tickers to addresses of price oracles.

Constants

Name	Type	Value	Description
OPERATOR	bytes32	TODO	Role definition for OpenZeppelin Contracts' access control implementation
ADMIN	bytes32	TODO	Role definition for OpenZeppelin Contracts' access control implementation

Views

getPrice

See TODO

Mutative Functions

constructor

TODO

setOracle

TODO

Events

None.

Example Flows

Minting

1. Users can commit to mint short or long.
2. If users don't uncommit, this commit is then executed [this is true if a keeper does this - But we might not be getting a keeper to do commits to mint/burn anymore].
3. At this time, the configurable mint/burn fee mintBurnFee is applied to the minting. It's multiplied out by the configurable burnFeePercent, such that if the mintBurnFee is 0.05 and the burnFeePercent is 0.4 then 0.05*(1-0.4)=0.03.
4. This fee is deducted from the amount of tokens to be minted, so that the user is awarded with 1-0.03=0.97
5. The proceeds of the fees are placed in the pool to which the tokens are being minted.

Burning

1. Users can commit to burn short or long.
2. If users don't uncommit, this commit is then executed [this is true if a keeper does this - But we might not be getting a keeper to do commits to mint/burn anymore].
3. At this time, the configurable mint/burn fee mintBurnFee is applied to the burning. It's multiplied out by the configurable burnFeePercent, such that if the mintBurnFee is 0.05 and the burnFeePercent is 0.4 then 0.05*0.4=0.02.
4. This fee is added from the amount of tokens to be burned, so that the user is now burning more tokens than they would have been for the value with 1+0.02=1.02
5. The proceeds of the fees are placed in the pool to which the tokens are being burned.

Updating

TODO

Security Considerations

Privileged Operations

TODO

Unconventional Integer Widths

In an effort to reduce the storage footprint (and thus gas usage) of the Pool Swaps protocol, integers of widths that are not powers of two are used in several places throughout the system.

While this is not a security hazard a priori, great care should be taken to ensure that operations involving these types are correct – especially arithmetic.

References

1. TODO

2. TODO