[New Operator] - Beefy LP Vault #114

maximebrugel · 2022-05-04T10:26:47Z

Context

On the Beefy app, we can find two types of vaults : LPs and Single Assets

The first Beefy Operator is focused on Single Asset Vaults, see PR : #107.
But now, we need a new operator for the LPs vaults.

How the operator works :

There are two steps :

Zapping
Interacting with Beefy

The protocols takes one of the paired tokens.

For example, in the BTCB-ETH LP vault, we can deposit BTCB or ETH and withdraw BTCB or ETH. The users is not managing Beefy vault tokens or LP Tokens.

Deposit (steps)

Input => Token from the pair
Swap half of the token for the second paired token.
Add liquidity to get the LP Token.
Deposit the token in the Beefy Vault.
Output => Beefy Vault token (shares).

Withdraw (steps)

Input => Beefy Vault token (shares)
Withdraw from beefy and receive the LP.
Remove liquidity (will burn the LP) and receive the paired tokens.
Swap one of the tokens for the chosen one.
Output => Token from the pair

You can get more details in the README.md file for the price calculation (operator folder).

1 Operator = 1 Router Type

Since that the operator is interacting directly with the AMM router to swap and add/remove liquidity, we need to be aware of the router interface. Some AMMs does not have the same interface.
We created an operator for Biswap (where one function needed the fee parameter) and one for the classic UniswapV2 router.

One Operator will list all the supported routers with the same interface. If we need an other router interface, we need an other operator. Supporting Biswap and UniswapV2, will cover a lot of beefy vaults.

Co-authored-by: Leo <[email protected]>

refactor: update function names and comments

adrien-supizet

1st review:

Left to review:

private functions from contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol in details
Unit tests
Optimal amount computation

adrien-supizet · 2022-05-10T13:59:56Z

scripts/operators/addParaswapOperator.ts

    // Deploy ParaswapOperator
    const paraswapOperator = await paraswapOperatorFactory.deploy(tokenTransferProxy, augustusSwapper);
    await paraswapOperator.deployed();
-    console.log
+    console.log;


adrien-supizet · 2022-05-10T14:13:11Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+/// Note: "Zap" means that we are converting an asset for the LP Token by
+///       swapping and adding liquidity.


Who is we?
💅 It's better to phrase comments with impersonal type as the deployed contracts are standalone pieces of code. We just happen to deploy and maintain them.

Suggested change

/// Note: "Zap" means that we are converting an asset for the LP Token by

/// swapping and adding liquidity.

/// Note: "Zapping" means that the asset is converted for the LP Token by

/// swapping and adding liquidity.

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

adrien-supizet · 2022-05-10T14:34:48Z

contracts/operators/Beefy/BeefyVaultStorage.sol

+    /// @param underlying The underlying token address or zapper
+    event VaultAdded(address vault, address underlying);


💅 underlying is not explicit enough imo
I even prefer the explicit namingtokenOrZapper if there's no other way to describe the variable

adrien-supizet · 2022-05-10T14:36:55Z

contracts/operators/Beefy/README.md

+
+To solve the problem of remaining dust after adding liquidity in a uniswap like liquidity pool, we need to perform a calculation to minimize the amount of unused token by the uniswap like router.
+
+> For this exemple, we will use an WBNB-USDT Uniswap luqidity pool, and we have 1 WBNB as a total investment.


Suggested change

> For this exemple, we will use an WBNB-USDT Uniswap luqidity pool, and we have 1 WBNB as a total investment.

> For this example, we will use a WBNB-USDT Uniswap liquidity pool, and we have 1 WBNB as a total investment.

adrien-supizet · 2022-05-10T14:39:09Z

contracts/operators/Beefy/README.md

+
+## Optimal swap amount
+
+To solve the problem of remaining dust after adding liquidity in a uniswap like liquidity pool, we need to perform a calculation to minimize the amount of unused token by the uniswap like router.


Suggested change

To solve the problem of remaining dust after adding liquidity in a uniswap like liquidity pool, we need to perform a calculation to minimize the amount of unused token by the uniswap like router.

To solve the problem of remaining dust after adding liquidity in a Uniswap-like liquidity pool, we need to perform a calculation to minimize the amount of unused tokens by the Uniswap-like router.

adrien-supizet · 2022-05-10T14:42:15Z

contracts/operators/Beefy/README.md

+After the swap, the ratio between **A** and **B** in the liquidity pool is:
+$${A+s \over B-b} = {a-s \over b}$$
+
+From this equation we can solve for s as using [b espression](#find-b) as follow:


Suggested change

From this equation we can solve for s as using [b espression](#find-b) as follow:

From this equation we can solve for s using [b espression](#find-b) as follow:

adrien-supizet · 2022-05-10T14:43:25Z

contracts/operators/Beefy/README.md

+
+b = B(1 - f)s / (A + (1 - f)s)
+
+##### Replace b by his value expressed in terms of s


Suggested change

##### Replace b by his value expressed in terms of s

##### Replace b with the value expressed in terms of s

adrien-supizet · 2022-05-10T15:26:07Z

contracts/interfaces/external/IBiswapRouter02.sol

+
+import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";
+
+interface IBiswapRouter02 is IUniswapV2Router02 {


Since IBiswapRouter02 is IUniswapV2Router02:

I believe that the functions getAmountOut and getAmountIn are overloaded, not overridden. This would allow us to use IBiswapRouter02 instead of IUniswapV2Router02 in the uniswapLPVaultOperator and allow factorization of the two contracts, for better legibility and maintenance

The biswapLPVaultOperator would use the same code as uniswapLpvault but override the only two functions whose implementation is different.

adrien-supizet · 2022-05-11T08:09:57Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+    }
+
+    /// @notice Perform a vault token withdraw (moo) from Beefy, and
+    ///         transfer the rest as one of the paired token.abi


❔ token.abi? Not sure I get what you mean here

Remove the .abi

adrien-supizet · 2022-05-11T08:11:52Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+        uint256 amount,
+        address token
+    ) private {
+        IBiswapRouter02 biswapRouter = IBiswapRouter02(router);


🔧 This can be declared further down in the scope to save gas fees if the execution reverts

adrien-supizet · 2022-05-11T08:40:44Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+        // LP Tokens needs to be sent back to the pair address to be burned
+        IERC20(pair).safeTransfer(pair, IERC20(pair).balanceOf(address(this)));
+
+        // We are removing liquidity by burning the LP Token and not


💅 Same comment: refrain from using "we" which does not translate well in English in this context

adrien-supizet · 2022-05-11T08:41:49Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+        require(token0 == token || token1 == token, "BLVO: INVALID_TOKEN");
+
+        // LP Tokens needs to be sent back to the pair address to be burned
+        IERC20(pair).safeTransfer(pair, IERC20(pair).balanceOf(address(this)));


❔ Not sure I understand why balanceOf is chained after the transfer

We are transferring the received LP Tokens to the LP Token address to burn the LP tokens... This mechanism a little bit weird, but correct. However we must compute the balance before/after withdrawing to send the right amount, i'm fixing this issue.

adrien-supizet · 2022-05-11T08:43:22Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+
+    /// @dev Zap one of the paired tokens for the LP Token, deposit the
+    ///         asset in the Beefy vault and receive the vault token (moo)
+    /// @param router The uniswap v2 router address to use for swaping and adding liquidity


Suggested change

/// @param router The uniswap v2 router address to use for swaping and adding liquidity

/// @param router The Uniswap v2 router address to use for swapping and adding liquidity

adrien-supizet · 2022-05-11T08:48:05Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+            1,
+            path,
+            address(this),
+            block.timestamp


❔ Why is the interface expecting the block timestamp for a swap? Please enlighten me, I am not very familiar with the Biswap router

You can specify the unix timestamp after which the transaction will revert (for e.g I want to execute my transaction and i need my tokens to be swapped in 1 min max).

adrien-supizet · 2022-05-11T08:50:55Z

contracts/operators/Beefy/BeefyZapBiswapLPVaultOperator.sol

+    /// @dev Calculate the optimal amount of tokenA to swap in order
+    ///         to obtain the same market value of tokenB after the trade
+    ///         in order to add as many tokensA and tokensB as possible
+    ///         to the liquidity so that as few as possible remain.


Suggested change

/// @dev Calculate the optimal amount of tokenA to swap in order

/// to obtain the same market value of tokenB after the trade

/// in order to add as many tokensA and tokensB as possible

/// to the liquidity so that as few as possible remain.

/// @dev Calculate the optimal amount of tokenA to swap to obtain

/// the same market value of tokenB after the trade.

/// This allows to add as many tokensA and tokensB as possible

/// to the liquidity to minimize the remaining amount.

maximebrugel and others added 15 commits April 25, 2022 15:52

feat: beefy zap lp operators

89192aa

Co-authored-by: Leo <[email protected]>

test: add beefy lp zap operator to fixtures

eda8d39

Test: Add deposit beefy LP vault tests (WIP)

211fd26

Test: Add withdraw beefy LP vault tests (WIP)

eebcc02

feat: zapper migration deposit

35408ef

feat: zapper migration withdraw

85ea9e9

feat: zapper refactoring

c367e7e

fix: reworked zapper nomenclature

f07045e

fix: remove dust value and fix withdraw

432c4eb

refactor: update function names and comments

feat: add UniswapV2 LP vault operator

4ebce17

refactor: prettier

4e2c026

test: add basic beefy UniV2 LP vault tests

a86cf36

test: fix Uniswap withdraw with unknown vault

c864609

test: add basic beefy Biswap LP vault tests

21e8bf0

feat: remove BeefyZapperHelper library

a7db987

maximebrugel added the To review Let people know this PR is ready for a review label May 4, 2022

maximebrugel requested a review from adrien-supizet May 4, 2022 10:26

adrien-supizet reviewed May 10, 2022

View reviewed changes

adrien-supizet removed the To review Let people know this PR is ready for a review label May 11, 2022

adrien-supizet reviewed May 11, 2022

View reviewed changes

maximebrugel added the Fix and merge Minor changes required label May 12, 2022

fix: code review fixes

11e278c

maximebrugel merged commit 3191665 into master May 18, 2022

maximebrugel deleted the beefy-lp-operator branch May 18, 2022 07:58

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[New Operator] - Beefy LP Vault #114

[New Operator] - Beefy LP Vault #114

maximebrugel commented May 4, 2022

adrien-supizet left a comment

adrien-supizet May 10, 2022

adrien-supizet May 10, 2022

adrien-supizet May 10, 2022

adrien-supizet May 10, 2022

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adrien-supizet May 10, 2022

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maximebrugel May 12, 2022

adrien-supizet May 11, 2022

adrien-supizet May 11, 2022

adrien-supizet May 11, 2022

maximebrugel May 12, 2022 •

edited

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adrien-supizet May 11, 2022

adrien-supizet May 11, 2022

maximebrugel May 12, 2022

maximebrugel May 12, 2022

adrien-supizet May 11, 2022

		/// Note: "Zap" means that we are converting an asset for the LP Token by
		/// swapping and adding liquidity.

		/// @param underlying The underlying token address or zapper
		event VaultAdded(address vault, address underlying);


		To solve the problem of remaining dust after adding liquidity in a uniswap like liquidity pool, we need to perform a calculation to minimize the amount of unused token by the uniswap like router.

		> For this exemple, we will use an WBNB-USDT Uniswap luqidity pool, and we have 1 WBNB as a total investment.

	> For this exemple, we will use an WBNB-USDT Uniswap luqidity pool, and we have 1 WBNB as a total investment.
	> For this example, we will use a WBNB-USDT Uniswap liquidity pool, and we have 1 WBNB as a total investment.


		## Optimal swap amount

		To solve the problem of remaining dust after adding liquidity in a uniswap like liquidity pool, we need to perform a calculation to minimize the amount of unused token by the uniswap like router.

	From this equation we can solve for s as using [b espression](#find-b) as follow:
	From this equation we can solve for s using [b espression](#find-b) as follow:


		b = B(1 - f)s / (A + (1 - f)s)

		##### Replace b by his value expressed in terms of s

	##### Replace b by his value expressed in terms of s
	##### Replace b with the value expressed in terms of s


		import "@uniswap/v2-periphery/contracts/interfaces/IUniswapV2Router02.sol";

		interface IBiswapRouter02 is IUniswapV2Router02 {

	/// @param router The uniswap v2 router address to use for swaping and adding liquidity
	/// @param router The Uniswap v2 router address to use for swapping and adding liquidity

[New Operator] - Beefy LP Vault #114

[New Operator] - Beefy LP Vault #114

Conversation

maximebrugel commented May 4, 2022

Context

How the operator works :

Deposit (steps)

Withdraw (steps)

1 Operator = 1 Router Type

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maximebrugel May 12, 2022 •

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