Version: 0.3.1

Vault.vy

Yearn Token Vault

Yearn Token Vault. Holds an underlying token, and allows users to interact with the Yearn ecosystem through Strategies connected to the Vault. Vaults are not limited to a single Strategy, they can have as many Strategies as can be designed (however the withdrawal queue is capped at 20.) Deposited funds are moved into the most impactful strategy that has not already reached its limit for assets under management, regardless of which Strategy a user's funds end up in, they receive their portion of yields generated across all Strategies. When a user withdraws, if there are no funds sitting undeployed in the Vault, the Vault withdraws funds from Strategies in the order of least impact. (Funds are taken from the Strategy that will disturb everyone's gains the least, then the next least, etc.) In order to achieve this, the withdrawal queue's order must be properly set and managed by the community (through governance). Vault Strategies are parameterized to pursue the highest risk-adjusted yield. There is an "Emergency Shutdown" mode. When the Vault is put into emergency shutdown, assets will be recalled from the Strategies as quickly as is practical (given on-chain conditions), minimizing loss. Deposits are halted, new Strategies may not be added, and each Strategy exits with the minimum possible damage to position, while opening up deposits to be withdrawn by users. There are no restrictions on withdrawals above what is expected under Normal Operation. For further details, please refer to the specification: https://github.com/iearn-finance/yearn-vaults/blob/master/SPECIFICATION.md

Functions

initialize

function initialize(address,address,address,string,string)

Initializes the Vault, this is called only once, when the contract is deployed. The performance fee is set to 10% of yield, per Strategy. The management fee is set to 2%, per year. The initial deposit limit is set to 0 (deposits disabled); it must be updated after initialization.

If nameOverride is not specified, the name will be 'yearn' combined with the name of token. If symbolOverride is not specified, the symbol will be 'y' combined with the symbol of token.

Parameters:

Name	Type	Description
token	* *	The token that may be deposited into this Vault.
governance	* *	The address authorized for governance interactions.
rewards	* *	The address to distribute rewards to.
nameOverride	* *	Specify a custom Vault name. Leave empty for default choice.
symbolOverride	* *	Specify a custom Vault symbol name. Leave empty for default choice.
guardian	* *	The address authorized for guardian interactions. Defaults to caller.

initialize

function initialize(address,address,address,string,string,address)

If nameOverride is not specified, the name will be 'yearn' combined with the name of token. If symbolOverride is not specified, the symbol will be 'y' combined with the symbol of token.

Parameters:

Name	Type	Description
token	* *	The token that may be deposited into this Vault.
governance	* *	The address authorized for governance interactions.
rewards	* *	The address to distribute rewards to.
nameOverride	* *	Specify a custom Vault name. Leave empty for default choice.
symbolOverride	* *	Specify a custom Vault symbol name. Leave empty for default choice.
guardian	* *	The address authorized for guardian interactions. Defaults to caller.

apiVersion

function apiVersion()

Used to track the deployed version of this contract. In practice you can use this version number to compare with Yearn's GitHub and determine which version of the source matches this deployed contract.

All strategies must have an apiVersion() that matches the Vault's API_VERSION.

Return Values:

Description
API_VERSION which holds the current version of this contract.

setName

function setName(string)

Used to change the value of name. This may only be called by governance.

Parameters:

Name	Type	Description
name	* *	The new name to use.

setSymbol

function setSymbol(string)

Used to change the value of symbol. This may only be called by governance.

Parameters:

Name	Type	Description
symbol	* *	The new symbol to use.

setGovernance

function setGovernance(address)

Nominate a new address to use as governance. The change does not go into effect immediately. This function sets a pending change, and the governance address is not updated until the proposed governance address has accepted the responsibility. This may only be called by the current governance address.

Parameters:

Name	Type	Description
governance	* *	The address requested to take over Vault governance.

acceptGovernance

function acceptGovernance()

Once a new governance address has been proposed using setGovernance(), this function may be called by the proposed address to accept the responsibility of taking over governance for this contract. This may only be called by the proposed governance address.

setGovernance() should be called by the existing governance address, prior to calling this function.

setManagement

function setManagement(address)

Changes the management address. Management is able to make some investment decisions adjusting parameters. This may only be called by governance.

Parameters:

Name	Type	Description
management	* *	The address to use for managing.

setGuestList

function setGuestList(address)

Used to set or change guestList. A guest list is another contract that dictates who is allowed to participate in a Vault (and transfer shares). This may only be called by governance.

Parameters:

Name	Type	Description
guestList	* *	The address of the `GuestList` contract to use.

setRewards

function setRewards(address)

Changes the rewards address. Any distributed rewards will cease flowing to the old address and begin flowing to this address once the change is in effect. This will not change any Strategy reports in progress, only new reports made after this change goes into effect. This may only be called by governance.

Parameters:

Name	Type	Description
rewards	* *	The address to use for collecting rewards.

setDepositLimit

function setDepositLimit(uint256)

Changes the maximum amount of tokens that can be deposited in this Vault. Note, this is not how much may be deposited by a single depositor, but the maximum amount that may be deposited across all depositors. This may only be called by governance.

Parameters:

Name	Type	Description
limit	* *	The new deposit limit to use.

setPerformanceFee

function setPerformanceFee(uint256)

Used to change the value of performanceFee. Should set this value below the maximum strategist performance fee. This may only be called by governance.

Parameters:

Name	Type	Description
fee	* *	The new performance fee to use.

setManagementFee

function setManagementFee(uint256)

Used to change the value of managementFee. This may only be called by governance.

Parameters:

Name	Type	Description
fee	* *	The new management fee to use.

setGuardian

function setGuardian(address)

Used to change the address of guardian. This may only be called by governance or the existing guardian.

Parameters:

Name	Type	Description
guardian	* *	The new guardian address to use.

setEmergencyShutdown

function setEmergencyShutdown(bool)

Activates or deactivates Vault mode where all Strategies go into full withdrawal. During Emergency Shutdown: 1. No Users may deposit into the Vault (but may withdraw as usual.) 2. Governance may not add new Strategies. 3. Each Strategy must pay back their debt as quickly as reasonable to minimally affect their position. 4. Only Governance may undo Emergency Shutdown. See contract level note for further details. This may only be called by governance or the guardian.

Parameters:

Name	Type	Description
active	* *	If true, the Vault goes into Emergency Shutdown. If false, the Vault goes back into Normal Operation.

setWithdrawalQueue

function setWithdrawalQueue(address[20])

Updates the withdrawalQueue to match the addresses and order specified by queue. There can be fewer strategies than the maximum, as well as fewer than the total number of strategies active in the vault. withdrawalQueue will be updated in a gas-efficient manner, assuming the input is well- ordered with 0x0 only at the end. This may only be called by governance or management.

This is order sensitive, specify the addresses in the order in which funds should be withdrawn (so queue[0] is the first Strategy withdrawn from, queue[1] is the second, etc.) This means that the least impactful Strategy (the Strategy that will have its core positions impacted the least by having funds removed) should be at queue[0], then the next least impactful at queue[1], and so on.

Parameters:

Name	Type	Description
queue	* *	The array of addresses to use as the new withdrawal queue. This is order sensitive.

transfer

function transfer(address,uint256)

Transfers shares from the caller's address to receiver. This function will always return true, unless the user is attempting to transfer shares to this contract's address, or to 0x0.

Parameters:

Name	Type	Description
receiver	* *	The address shares are being transferred to. Must not be this contract's address, must not be 0x0.
amount	* *	The quantity of shares to transfer.

Return Values:

Description
True if transfer is sent to an address other than this contract's or 0x0, otherwise the transaction will fail.

transferFrom

function transferFrom(address,address,uint256)

Transfers amount shares from sender to receiver. This operation will always return true, unless the user is attempting to transfer shares to this contract's address, or to 0x0. Unless the caller has given this contract unlimited approval, transfering shares will decrement the caller's allowance by amount.

Parameters:

Name	Type	Description
sender	* *	The address shares are being transferred from.
receiver	* *	The address shares are being transferred to. Must not be this contract's address, must not be 0x0.
amount	* *	The quantity of shares to transfer.

Return Values:

Description
True if transfer is sent to an address other than this contract's or 0x0, otherwise the transaction will fail.

approve

function approve(address,uint256)

Approve the passed address to spend the specified amount of tokens on behalf of msg.sender. Beware that changing an allowance with this method brings the risk that someone may use both the old and the new allowance by unfortunate transaction ordering. See https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729

Parameters:

Name	Type	Description
spender	* *	The address which will spend the funds.
amount	* *	The amount of tokens to be spent.

increaseAllowance

function increaseAllowance(address,uint256)

Increase the allowance of the passed address to spend the total amount of tokens on behalf of msg.sender. This method mitigates the risk that someone may use both the old and the new allowance by unfortunate transaction ordering. See https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729

Parameters:

Name	Type	Description
spender	* *	The address which will spend the funds.
amount	* *	The amount of tokens to increase the allowance by.

decreaseAllowance

function decreaseAllowance(address,uint256)

Decrease the allowance of the passed address to spend the total amount of tokens on behalf of msg.sender. This method mitigates the risk that someone may use both the old and the new allowance by unfortunate transaction ordering. See https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729

Parameters:

Name	Type	Description
spender	* *	The address which will spend the funds.
amount	* *	The amount of tokens to decrease the allowance by.

permit

function permit(address,address,uint256,uint256,bytes)

Approves spender by owner's signature to expend owner's tokens. See https://eips.ethereum.org/EIPS/eip-2612.

Parameters:

Name	Type	Description
owner	* *	The address which is a source of funds and has signed the Permit.
spender	* *	The address which is allowed to spend the funds.
amount	* *	The amount of tokens to be spent.
expiry	* *	The timestamp after which the Permit is no longer valid.
signature	* *	A valid secp256k1 signature of Permit by owner encoded as r, s, v.

Return Values:

Description
True, if transaction completes successfully

totalAssets

function totalAssets()

Returns the total quantity of all assets under control of this Vault, whether they're loaned out to a Strategy, or currently held in the Vault.

Return Values:

Description
The total assets under control of this Vault.

deposit

function deposit()

Deposits _amount token, issuing shares to recipient. If the Vault is in Emergency Shutdown, deposits will not be accepted and this call will fail.

Measuring quantity of shares to issues is based on the total outstanding debt that this contract has ("expected value") instead of the total balance sheet it has ("estimated value") has important security considerations, and is done intentionally. If this value were measured against external systems, it could be purposely manipulated by an attacker to withdraw more assets than they otherwise should be able to claim by redeeming their shares. On deposit, this means that shares are issued against the total amount that the deposited capital can be given in service of the debt that Strategies assume. If that number were to be lower than the "expected value" at some future point, depositing shares via this method could entitle the depositor to less than the deposited value once the "realized value" is updated from further reports by the Strategies to the Vaults. Care should be taken by integrators to account for this discrepancy, by using the view-only methods of this contract (both off-chain and on-chain) to determine if depositing into the Vault is a "good idea".

Parameters:

Name	Type	Description
_amount	* *	The quantity of tokens to deposit, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.

Return Values:

Description
The issued Vault shares.

deposit

function deposit(uint256)

Parameters:

Name	Type	Description
_amount	* *	The quantity of tokens to deposit, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.

Return Values:

Description
The issued Vault shares.

deposit

function deposit(uint256,address)

Parameters:

Name	Type	Description
_amount	* *	The quantity of tokens to deposit, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.

Return Values:

Description
The issued Vault shares.

maxAvailableShares

function maxAvailableShares()

Determines the maximum quantity of shares this Vault can facilitate a withdrawal for, factoring in assets currently residing in the Vault, as well as those deployed to strategies on the Vault's balance sheet.

Regarding how shares are calculated, see dev note on deposit. If you want to calculated the maximum a user could withdraw up to, you want to use this function. Note that the amount provided by this function is the theoretical maximum possible from withdrawing, the real amount depends on the realized losses incurred during withdrawal.

Return Values:

Description
The total quantity of shares this Vault can provide.

withdraw

function withdraw()

Withdraws the calling account's tokens from this Vault, redeeming amount _shares for an appropriate amount of tokens. See note on setWithdrawalQueue for further details of withdrawal ordering and behavior.

Measuring the value of shares is based on the total outstanding debt that this contract has ("expected value") instead of the total balance sheet it has ("estimated value") has important security considerations, and is done intentionally. If this value were measured against external systems, it could be purposely manipulated by an attacker to withdraw more assets than they otherwise should be able to claim by redeeming their shares. On withdrawal, this means that shares are redeemed against the total amount that the deposited capital had "realized" since the point it was deposited, up until the point it was withdrawn. If that number were to be higher than the "expected value" at some future point, withdrawing shares via this method could entitle the depositor to more than the expected value once the "realized value" is updated from further reports by the Strategies to the Vaults. Under exceptional scenarios, this could cause earlier withdrawals to earn "more" of the underlying assets than Users might otherwise be entitled to, if the Vault's estimated value were otherwise measured through external means, accounting for whatever exceptional scenarios exist for the Vault (that aren't covered by the Vault's own design.)

Parameters:

Name	Type	Description
maxShares	* *	How many shares to try and redeem for tokens, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.
maxLoss	* *	The maximum acceptable loss to sustain on withdrawal. Defaults to 0.01%.

Return Values:

Description
The quantity of tokens redeemed for `_shares`.

withdraw

function withdraw(uint256)

Parameters:

Name	Type	Description
maxShares	* *	How many shares to try and redeem for tokens, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.
maxLoss	* *	The maximum acceptable loss to sustain on withdrawal. Defaults to 0.01%.

Return Values:

Description
The quantity of tokens redeemed for `_shares`.

withdraw

function withdraw(uint256,address)

Parameters:

Name	Type	Description
maxShares	* *	How many shares to try and redeem for tokens, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.
maxLoss	* *	The maximum acceptable loss to sustain on withdrawal. Defaults to 0.01%.

Return Values:

Description
The quantity of tokens redeemed for `_shares`.

withdraw

function withdraw(uint256,address,uint256)

Parameters:

Name	Type	Description
maxShares	* *	How many shares to try and redeem for tokens, defaults to all.
recipient	* *	The address to issue the shares in this Vault to. Defaults to the caller's address.
maxLoss	* *	The maximum acceptable loss to sustain on withdrawal. Defaults to 0.01%.

Return Values:

Description
The quantity of tokens redeemed for `_shares`.

pricePerShare

function pricePerShare()

Gives the price for a single Vault share.

See dev note on withdraw.

Return Values:

Description
The value of a single share.

addStrategy

function addStrategy(address,uint256,uint256,uint256)

Add a Strategy to the Vault. This may only be called by governance.

The Strategy will be appended to withdrawalQueue, call setWithdrawalQueue to change the order.

Parameters:

Name	Type	Description
strategy	* *	The address of the Strategy to add.
debtRatio	* *	The share of the total assets in the `vault that the` strategy` has access to.
rateLimit	* *	Limit on the increase of debt per unit time since last harvest
performanceFee	* *	The fee the strategist will receive based on this Vault's performance.

updateStrategyDebtRatio

function updateStrategyDebtRatio(address,uint256)

Change the quantity of assets strategy may manage. This may be called by governance or management.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to update.
debtRatio	* *	The quantity of assets `strategy` may now manage.

updateStrategyRateLimit

function updateStrategyRateLimit(address,uint256)

Change the quantity assets per block this Vault may deposit to or withdraw from strategy. This may only be called by governance or management.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to update.
rateLimit	* *	Limit on the increase of debt per unit time since last harvest

updateStrategyPerformanceFee

function updateStrategyPerformanceFee(address,uint256)

Change the fee the strategist will receive based on this Vault's performance. This may only be called by governance.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to update.
performanceFee	* *	The new fee the strategist will receive.

migrateStrategy

function migrateStrategy(address,address)

Migrates a Strategy, including all assets from oldVersion to newVersion. This may only be called by governance.

Strategy must successfully migrate all capital and positions to new Strategy, or else this will upset the balance of the Vault. The new Strategy should be "empty" e.g. have no prior commitments to this Vault, otherwise it could have issues.

Parameters:

Name	Type	Description
oldVersion	* *	The existing Strategy to migrate from.
newVersion	* *	The new Strategy to migrate to.

revokeStrategy

function revokeStrategy()

Revoke a Strategy, setting its debt limit to 0 and preventing any future deposits. This function should only be used in the scenario where the Strategy is being retired but no migration of the positions are possible, or in the extreme scenario that the Strategy needs to be put into "Emergency Exit" mode in order for it to exit as quickly as possible. The latter scenario could be for any reason that is considered "critical" that the Strategy exits its position as fast as possible, such as a sudden change in market conditions leading to losses, or an imminent failure in an external dependency. This may only be called by governance, the guardian, or the Strategy itself. Note that a Strategy will only revoke itself during emergency shutdown.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to revoke.

revokeStrategy

function revokeStrategy(address)

Parameters:

Name	Type	Description
strategy	* *	The Strategy to revoke.

addStrategyToQueue

function addStrategyToQueue(address)

Adds strategy to withdrawalQueue. This may only be called by governance or management.

The Strategy will be appended to withdrawalQueue, call setWithdrawalQueue to change the order.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to add.

removeStrategyFromQueue

function removeStrategyFromQueue(address)

Remove strategy from withdrawalQueue. This may only be called by governance or management.

We don't do this with revokeStrategy because it should still be possible to withdraw from the Strategy if it's unwinding.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to remove.

debtOutstanding

function debtOutstanding()

Determines if strategy is past its debt limit and if any tokens should be withdrawn to the Vault.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to check. Defaults to the caller.

Return Values:

Description
The quantity of tokens to withdraw.

debtOutstanding

function debtOutstanding(address)

Parameters:

Name	Type	Description
strategy	* *	The Strategy to check. Defaults to the caller.

Return Values:

Description
The quantity of tokens to withdraw.

creditAvailable

function creditAvailable()

Amount of tokens in Vault a Strategy has access to as a credit line. This will check the Strategy's debt limit, as well as the tokens available in the Vault, and determine the maximum amount of tokens (if any) the Strategy may draw on. In the rare case the Vault is in emergency shutdown this will return 0.

Parameters:

Name	Type	Description
strategy	* *	The Strategy to check. Defaults to caller.

Return Values:

Description
The quantity of tokens available for the Strategy to draw on.

creditAvailable

function creditAvailable(address)

Parameters:

Name	Type	Description
strategy	* *	The Strategy to check. Defaults to caller.

Return Values:

Description
The quantity of tokens available for the Strategy to draw on.

expectedReturn

function expectedReturn()

Provide an accurate expected value for the return this strategy would provide to the Vault the next time report() is called (since the last time it was called).

Parameters:

Name	Type	Description
strategy	* *	The Strategy to determine the expected return for. Defaults to caller.

Return Values:

Description
The anticipated amount `strategy` should make on its investment since its last report.

expectedReturn

function expectedReturn(address)

Parameters:

Name	Type	Description
strategy	* *	The Strategy to determine the expected return for. Defaults to caller.

Return Values:

Description
The anticipated amount `strategy` should make on its investment since its last report.

report

function report(uint256,uint256,uint256)

Reports the amount of assets the calling Strategy has free (usually in terms of ROI). The performance fee is determined here, off of the strategy's profits (if any), and sent to governance. The strategist's fee is also determined here (off of profits), to be handled according to the strategist on the next harvest. This may only be called by a Strategy managed by this Vault.

For approved strategies, this is the most efficient behavior. The Strategy reports back what it has free, then Vault "decides" whether to take some back or give it more. Note that the most it can take is gain + _debtPayment, and the most it can give is all of the remaining reserves. Anything outside of those bounds is abnormal behavior. All approved strategies must have increased diligence around calling this function, as abnormal behavior could become catastrophic.

Parameters:

Name	Type	Description
gain	* *	Amount Strategy has realized as a gain on it's investment since its last report, and is free to be given back to Vault as earnings
loss	* *	Amount Strategy has realized as a loss on it's investment since its last report, and should be accounted for on the Vault's balance sheet
_debtPayment	* *	Amount Strategy has made available to cover outstanding debt

Return Values:

Description
Amount of debt outstanding (if totalDebt > debtLimit or emergency shutdown).

sweep

function sweep(address)

Removes tokens from this Vault that are not the type of token managed by this Vault. This may be used in case of accidentally sending the wrong kind of token to this Vault. Tokens will be sent to governance. This will fail if an attempt is made to sweep the tokens that this Vault manages. This may only be called by governance.

Parameters:

Name	Type	Description
token	* *	The token to transfer out of this vault.
amount	* *	The quantity or tokenId to transfer out.

sweep

function sweep(address,uint256)

Parameters:

Name	Type	Description
token	* *	The token to transfer out of this vault.
amount	* *	The quantity or tokenId to transfer out.

Events

Transfer

sender : address, indexed
receiver : address, indexed
value : uint256, notIndexed

Approval

owner : address, indexed
spender : address, indexed
value : uint256, notIndexed

StrategyAdded

strategy : address, indexed
debtRatio : uint256, notIndexed
rateLimit : uint256, notIndexed
performanceFee : uint256, notIndexed

StrategyReported

strategy : address, indexed
gain : uint256, notIndexed
loss : uint256, notIndexed
debtPaid : uint256, notIndexed
totalGain : uint256, notIndexed
totalLoss : uint256, notIndexed
totalDebt : uint256, notIndexed
debtAdded : uint256, notIndexed
debtRatio : uint256, notIndexed

UpdateGovernance

governance : address, notIndexed

UpdateManagement

management : address, notIndexed

UpdateGuestList

guestList : address, notIndexed

UpdateRewards

rewards : address, notIndexed

UpdateDepositLimit

depositLimit : uint256, notIndexed

UpdatePerformanceFee

performanceFee : uint256, notIndexed

UpdateManagementFee

managementFee : uint256, notIndexed

UpdateGuardian

guardian : address, notIndexed

EmergencyShutdown

active : bool, notIndexed

UpdateWithdrawalQueue

queue : address[20], notIndexed

StrategyUpdateDebtRatio

strategy : address, indexed
debtRatio : uint256, notIndexed

StrategyUpdateRateLimit

strategy : address, indexed
rateLimit : uint256, notIndexed

StrategyUpdatePerformanceFee

strategy : address, indexed
performanceFee : uint256, notIndexed

StrategyMigrated

oldVersion : address, indexed
newVersion : address, indexed

StrategyRevoked

strategy : address, indexed

StrategyRemovedFromQueue

strategy : address, indexed

StrategyAddedToQueue

strategy : address, indexed