The Vault



returns (IAuthorizer)
Returns the Vault's Authorizer (Balancer governance contract). Implemented in VaultAuthorization


setAuthorizer(IAuthorizer newAuthorizer)
emits AuthorizerSet(IAuthorizer indexed newAuthorizer)
Sets a new Authorizer for the Vault. The caller must be allowed by the current Authorizer to do this. Implemented in VaultAuthorization


address user,
address relayer)
Returns true if user has allowed relayer to act as a relayer for them. Implemented in VaultAuthorization


address sender,
address relayer,
bool approved)
emits RelayerApprovalChanged(address indexed relayer,
address indexed sender,
bool approved)
Grants or revokes approval for the given relayer to call Authorizer-approved functions on behalf of user. Implemented in VaultAuthorization

Internal Balances


address user,
IERC20[] tokens)
returns (uint256[])
Get a user's internal balances. This is called UserBalance in external interfaces, and "internal balance" in the internal functions. Implemented in UserBalance.


For a more in-depth explanation check out Internal User Balances in the Resources.
manageUserBalance(UserBalanceOp[] ops)
emits one of:
InternalBalanceChanged(address indexed user,
IERC20 indexed token,
int256 delta)
ExternalBalanceTransfer(IERC20 indexed token,
address indexed sender,
address recipient,
uint256 amount)
There are four possible operations in manageUserBalance: each designates a sender/receiver, asset, and amount. The asset is either a token address or the zero address (meaning ETH). The Vault does not store ETH, but you can use ETH when interacting with internal balances; the Vault will do any necessary wrapping/unwrapping.



registerPool(PoolSpecialization specialization)
emits PoolRegistered(bytes32 indexed poolId,
address indexed poolAddress,
PoolSpecialization specialization)
Called from the pool contract to generate a Pool ID, and enter it in the Vault's pool data structures. Implemented in PoolRegistry.


getPool(bytes32 poolId)
returns (address,
Returns a Pool's contract address and specialization setting. Implemented in PoolRegistry.


bytes32 poolId,
IERC20[] tokens,
address[] assetManagers)
emits TokensRegistered(indexed bytes32 poolId,
IERC20[] tokens,
address[] assetManagers)
Called from the pool contract to tell the Vault which tokens are valid for this pool (i.e., which can be used to swap, join, or exit). An asset manager can also be assigned to each token at this step, which is thereafter immutable (unless you deregister and register again). Implemented in PoolTokens.


bytes32 poolId,
IERC20[] tokens)
emits TokensDeregistered(indexed bytes32 poolId, IERC20[] tokens)
Remove tokens from the pool (must have zero balance). Implemented in PoolTokens.


getPoolTokenInfo(bytes32 poolId,
IERC20 token)
returns (uint256 cash,
uint256 managed,
uint256 blockNumber,
address assetManager)
Return details of a particular token. While getPoolTokens gives the total balance, getPoolTokenInfo returns each component of the balance, as well as the time (block) it was last modified, and the asset manager. Implemented in PoolTokens.


getPoolTokens(bytes32 poolId)
returns (IERC20[] tokens,
uint256[] balances,
uint256 lastChangeBlock)
Returns a Pool's registered tokens, the total balance for each, and the most recent block in which any of the tokens were updated. Implemented by PoolAssets. Implemented in PoolTokens.

Joins and Exits

For a more in-depth explanation check out Joins and Exits in the Resources.
Note that any functions that take a token array always expect input "parallel" to the pool tokens. If you are joining a 7-token pool with one token, you must pass an array of 7 amounts, with the rest set to 0.


bytes32 poolId,
address sender,
address recipient,
JoinPoolRequest request)


bytes32 poolId,
address sender,
address recipient,
ExitPoolRequest request)
JoinPoolRequest and ExitPoolRequest takes a userData argument, which specifies exactly how the pool should be joined/exited (e.g., the token addresses and balances transferred to/from the Vault, and expected number of pool tokens to be burned). Implemented by PoolBalances.
Both joins and exits emit the PoolBalanceChanged event.
emits PoolBalanceChanged(
bytes32 indexed poolId,
address indexed liquidityProvider,
IERC20[] tokens,
int256[] deltas,
uint256[] protocolFeeAmounts)

Single Swaps

For a more in-depth explanation check out the Single Swaps page in Guides.
The vault supports "single swaps," a way to perform exactly one trade directly and gas-efficiently with a particular pool (e.g., for token sale GUIs). You can still use the internal balance.


SingleSwap request,
FundManagement funds,
uint256 limit,
uint256 deadline)
returns (uint256 assetDelta)
Implemented in Swaps.

Batch Swaps

For a more in-depth explanation check out the Batch Swaps page in Guides.
Batch swap "steps" specify the assets involved, "many-to-many" sources and destinations, and min/max token limits to guard against slippage. There is also an optional deadline, after which the swap will timeout and revert. These return the token "deltas" - the net result of executing each swap sequentially.


SwapKind kind,
BatchSwapStep[] swaps,
IAsset[] assets,
FundManagement funds,
int256[] limits,
uint256 deadline)
returns (int256[] assetDeltas)
Implemented in Swaps.Both single and batch swaps emit a Swap event for each swap.
event Swap(
bytes32 indexed poolId,
IERC20 indexed tokenIn,
IERC20 indexed tokenOut,
uint256 amountIn,
uint256 amountOut)


SwapKind kind,
BatchSwapStep[] swaps,
IAsset[] assets,
FundManagement funds)
returns (int256[] assetDeltas)
The queryBatchSwap method executes the exact same code as batchSwap - but reverts at the end. This is for GUIs or scripts to calculate a "dry run" of a sequence of swaps. Implemented in Swaps.
queryBatchSwap is not defined as a view function even though that is a common use case. To use it as such, you need to use eth_call instead of eth_sendTransaction.
For example in ethers.js, the command would look something like: const quote = await vault.callStatic.queryBatchSwap(0, [swap0, swap1], assets, funds);

Flash Loans


IFlashLoanRecipient recipient,
IERC20[] tokens,
uint256[] amounts,
bytes userData)
emits FlashLoan(IFlashLoanRecipient indexed recipient,
IERC20 indexed token,
uint256 amount,
uint256 feeAmount)
Execute a flash loan. This sends the given token amounts to the flash loan receiver contract; all borrowed funds - plus the protocol flash loan fee - must be returned to the vault in the same transaction, or it will revert. Implemented by a FlashLoans subclass. Implemented in FlashLoans.

Asset Management

This can only be called by the asset manager of a token in a pool.


PoolBalanceOp[] ops)
emits PoolBalanceManaged(
bytes32 indexed poolId,
address indexed assetManager,
IERC20 indexed token,
int256 cashDelta,
int256 managedDelta)
Deposit or withdraw funds from the pool (i.e., move funds between cash and managed balances), or update the total balance (i.e., reporting a gain or loss from management activities). Implemented in AssetManagers. Each PoolBalanceOp describes the type of operation (deposit/withdraw/update), the pool ID, the token, and the amount.



returns (ProtocolFeesCollector)
The external contract authorized to collect protocol fees. Implemented by Fees.


setPaused(bool paused)
emits PausedStateChanged(bool paused)
Safety mechanism to halt most Vault operations in the event of an emergency. The only functions allowed involve withdrawing funds (e.g., from internal balances, or proportional pool exits). Implemented by Vault.


returns (IWETH)
The Vault's address for WETH. Implemented by Vault.
Last modified 8mo ago