Staking Pool v1

This repository contains the implementation of the staking pool with hourly compounding, hardcap, contribution limits and expiry date.

Implementation details

Lifecycle

Staking pool can be in one of these states during it's lifetime :

Deployed --> Initialized --> Open --> Expired --> Swept

Transitions

Deployed - smart contract deployed to the network or terminate() called when in Initialized state

Initialized - init() function executed

Open - block.timestamp >= start

Expired - block.timestamp >= end

Swept - sweep() function executed

State vs staking pool operations

	Rewards locked	Staking	Unstaking	Compounding
Deployed	No	No	No	No
Initialized	Yes	No	No	No
Open	Yes	Yes	Yes	Yes
Expired	Yes	No	Yes	No
Swept	No	No	Yes	No

Compounding

Our implementation is using linear compounding function

compounded = compounded * (1+ratio)**n

compounded: deposit+compounded rewards
ratio:      hourly compounding ratio
n:          amount of hourly intervals

Power function used in the compounding equation comes from ABDKMath64x64solidity math library.

To keep the smart contract state minimal, Stake struct in the stakes mapping keeps compounded value that is being updated on every additional stake and unstake function calls, in other words in any function that changes the stake.deposit.

mapping(address => Stake) public stakes;

Funding

Our staking pool requires the owner to provide the funds to cover all potential rewards given hardCap, ratio and staking pool time dimension.

The equation for total future rewards is:

maxFutureRewards = hardCap - hardCap * compound(1+ratio)**((end-start)/1 hour)

Sweeping after expiry

Since the funding requires maximum amount of rewards to be provided the sweeping functionality is required for staking pool owner to reclaim unnecessary funds.

Sweep can only be called by owner after reaching staking pool expiry, where compounding has stopped and thus total amount of rewards is fixed.

We define unnecessary funds as the difference between maxFutureRewards and rewards at the staking pool expiry.

remainingRewards = maxFutureRewards - sum(withdrawnRewards)

sweepAmount(t == end) = remainingRewards - sum(stakedRewards)

sweepAmount(t) = maxFutureRewards - sum(withdrawnRewards(t)) - sum(stakedRewards(t))

Building

In order to build after a successful clone:

npm install
npm run compile

Testing

npm run test

Local deployment

npm run deploy:dev

Volta deployment steps

Create a .env file and set the variable

DEPLOYER_PRIV_KEY = <private_key>

Make sure the corresponding address has enough funds on Volta testnet. If needed, get some Volta tokens (VT) on Volta faucet.
run following command

npm deploy:volta

More information to come...

farque65/staking-pool