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SupplySchedule

Description

Defines the Oikos inflationary supply schedule, according to which the oikos inflationary supply is released.

Minting is performed in increments of a week whenever recordMintEvent is called from Oikos.mint. Minting can be called weekly after the time elapses for more than 7 days. These accrue so that no tokens are lost even if minting is not performed for several periods; the accrued total is minted at the next invocation. These computations are covered in more detail in the mintableSupply description.

The supply decay follows an exponential decay formula calculated for each week.

supplyForWeek = Initial Weekly Supply * (1 - rate of decay) ^ number of weeks

Schedule

To the initial 100 million tokens, 75 million / 52 weeks tokens were added for 39 weeks in 2019. Supply decay was implemented in week 40 whereby the weekly inflationary supply follows an exponential decay of 1.25% per week for a total of 195 weeks at Week 234.

After Week 235 the OKS supply will grow at 2.5% APR based on the total Supply of OKS each week. Compounded weekly the supply growth APY is 2.53% for the terminal supply growth.

Source: SupplySchedule.sol

Architecture


Inheritance Graph

SupplySchedule inheritance graph



Libraries


Variables


MINT_PERIOD_DURATION

The duration of each minting period. This is constant at one week.

Type: uint public

Value: 1 weeks


lastMintEvent

The timestamp when new supply was last minted - Is set to the number of weeks since inflation start date plus a minting buffer to allow feePeriod to close first.

Type: uint public


synthetixProxy

The address of the main SynthetixProxy contract.

Type: Oikos Proxy


INFLATION_START_DATE

The timestamp at which the inflationary OKS supply began to be minted.

Type: uint public constant

Value: 1551830400 (2019-03-06T00:00:00+00:00)


INITIAL_WEEKLY_SUPPLY

The amount of tokens being issued weekly before exponential decay started. Used to calculate the supply each week once decay starts.

Type: uint public constant

Value: 1442307692307692307692307 - 75e6 / 52


MINT_BUFFER

A buffer added to the lastMintEvent to ensure that oikos rewards are issued after a feePeriod closes.

Type: uint public constant

Value: 1 days


minterReward

Used as the quantity of OKS to reward the caller of Oikos.mint, which incentivises users to continue minting the inflationary supply over time. Initialised to 200 OKS.

Type: uint public


SUPPLY_DECAY_START

Week number when supply decay starts. Used along with weekCounter to determine when decay supply starts.

Type: uint public

Value: 40


SUPPLY_DECAY_END

Week number when supply decay ends. Used along with weekCounter to determine when decay supply should end.

Inflation after this week would become be on the terminal inflation schedule.

Type: uint public

Value: 234


weekCounter

Counter to record the number of weeks inflation has been issued and calculate the applicable supply to add based on the current weekCounter.

Type: uint public


Functions


constructor

Sets up the minting schedule and the inherited Owned instance.

Details

Signature

constructor(address _owner, uint _lastMintEvent, uint _weeksCounter) public

Superconstructors


setSynthetixProxy

Allows the owner to set the oikos address.

Details

Signature

setSynthetix(ISynthetix _synthetixProxy) external

Modifiers


mintableSupply

Returns the number of tokens currently mintable from the inflationary supply.

If isMintable returns false, this is 0. Otherwise, it is the number of tokens accruing per week in the current year, multiplied by the number of whole weeks since the last mint event.

Details

Signature

mintableSupply() public view returns (uint)


weeksSinceLastIssuance

This just returns its argument floor divided by MINT_PERIOD_DURATION. Since this is only used in mintableSupply() it seems as if a variable would have done better than a public function.

Details

Signature

weeksSinceLastIssuance() public view returns (uint)


isMintable

Returns true if minting from the inflationary supply is permitted at the present time.

This means that tokens are only mintable once a week.

Details

Signature

isMintable() public view returns (bool)


recordMintEvent

This is called within Oikos.mint to declare that the outstanding inflationary supply of tokens has been minted before they are actually distributed.

When called, this function adds a quantity of mintableSupply() tokens to the current schedule.totalSupplyMinted entry, and updates the lastMintEvent timestamp.

Although this function has no check that any tokens actually are mintable when it is called, the Oikos contract requires it to be the case, so double calls should not occur. Similarly, the function does not itself enforce that the actual token supply has been increased by Oikos in a manner consistent with the defined schedule and must simply trust that this compact is observed.

The function always returns true if the transaction was not reverted.

Details

Signature

recordMintEvent() external returns (bool)

Modifiers

Emits


setMinterReward

Allows the owner to set the current minter reward.

Details

Signature

setMinterReward(uint _amount) external

Modifiers

Emits


Modifiers


onlySynthetix

Reverts the transaction if msg.sender is not the oikos address. Oikos address is found by lookup to the proxy.target().


Events


SupplyMinted

Records that a quantity of new tokens was minted.

Signature: SupplyMinted(uint supplyMinted, uint numberOfWeeksIssued, uint lastMintEvent, uint timestamp)


MinterRewardUpdated

Records that the minter reward was updated.

Signature: MinterRewardUpdated(uint newRewardAmount)