# Mining Contract

By [Untitled](https://paragraph.com/@0x5100a4c7ed5e75649931e14df0755f29f2f6bc2f) · 2022-03-23

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[https://github.com/sushiswap/sushiswap/blob/canary/contracts/MasterChef.sol](https://github.com/sushiswap/sushiswap/blob/canary/contracts/MasterChef.sol)

System Functions
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Add: add new LP token for Mining.

Set: set reward allocPoint, which can be used to calculate reward per block for specific pool.

massUpdatePools: Update all accSushiPerShare for all pools

updatePool: Mainly used to update single accSushiPerShare for specific pool, also mint sushi for a period.

Deposit
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a. updatePool

b. calculate pending reward = user current LP number \* accSushiPerShare - debt

c. transfer reward to msg.sender

d. transfer LP token from msg.sender to the contract

e. change User LP, change debt

f. debt = User LP \* accSushiPerShareAtCurrent

actually debt is used to record current accSushiPerShare. User pending reward = (accSushiPerShareAtClaim - accSushiPerShareAtCurrent) \* User LP

User LP will not changed until next user operation.

Withdraw
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The same with deposit operation, beside the User LP is decreased rather than increased.

Other functions
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Always consider to use safeTransfer

[https://github.com/sushiswap/sushiswap/blob/56cedd0e06a6cf665083b3a662f9f77b80303ebe/contracts/MasterChef.sol#L283](https://github.com/sushiswap/sushiswap/blob/56cedd0e06a6cf665083b3a662f9f77b80303ebe/contracts/MasterChef.sol#L283)

Always consider to use a EmergencyWithdraw function

Notice
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1.  Some contract has a function called notifyRewards:
    

check AC’s contract here

[https://github.com/MaiaDAO/hermes-protocol/commit/11bc521f4fb80dc42b6adfa3bcbbe3fe3db35897?diff=split](https://github.com/MaiaDAO/hermes-protocol/commit/11bc521f4fb80dc42b6adfa3bcbbe3fe3db35897?diff=split)

It guarantees all new reward will be fairly distributed in the next duration. Always append DURATIONS after current block.

This will also effect distribution speeds

2\. Also some contract will use another set function to set distribution speeds which is also acceptable.

[https://bscscan.com/address/0x3052a0f6ab15b4ae1df39962d5ddefaca86dab47#code](https://bscscan.com/address/0x3052a0f6ab15b4ae1df39962d5ddefaca86dab47#code)

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*Originally published on [Untitled](https://paragraph.com/@0x5100a4c7ed5e75649931e14df0755f29f2f6bc2f/mining-contract)*