FeesDepositor

Table of Contents

Summary
Functions
Events

Summary

A periphery contract on L1 that acts as a recipient of fees sent by the L1Withdrawer contract on L2. Its purpose is to perform a deposit transaction to OP Mainnet with those fees via the OptimismPortal once it has received sufficient funds.

It's a proxied contract with the owner of the ProxyAdmin as the address allowed to call the setter functions.

The following shows how fees flow through the L1Withdrawer and FeesDepositor during the disbursement process once they have been pulled from the vaults on L2:

flowchart LR
    subgraph SourceChain["OP Stack Chain"]
        FS[FeeSplitter]
        L1W[L1Withdrawer]
    end

    subgraph L1["L1 (Ethereum)"]
        OP1["OptimismPortal<br/>(OP Stack Chain)"]
        FD[FeesDepositor]
        OP2["OptimismPortal<br/>(OP Mainnet)"]
    end

    subgraph TargetChain["OP Mainnet"]
        L2R[L2 Recipient]
    end

    FS -->|"1. Send fees"| L1W
    L1W -->|"2. Withdraw to L1<br/>(if threshold is reached)"| OP1
    OP1 -->|"3. Send fees"| FD
    FD -->|"4. Deposit to OP Mainnet<br/>(if threshold is reached)"| OP2
    OP2 -->|"5. Execute on OP Mainnet"| L2R

Functions

`receive`

Initiates the deposit transaction process to OP Mainnet if and only if the contract holds funds equal to or above the minDepositAmount threshold.

receive() external payable

MUST initiate a deposit transaction to the recipient on OP Mainnet via L1CrossDomainMessenger.sendMessage() if the minDepositAmount threshold is reached, with the following parameters:
- _target: the configured l2Recipient address
- _message: empty bytes (hex"") for direct ETH transfer
- _minGasLimit: the configured gasLimit value
- msg.value: the contract's entire balance
MUST emit the FundsReceived event with the sender, amount received, and the current balance of the contract.
MUST emit the FeesDeposited event only if the threshold is reached.

Note: The use of L1CrossDomainMessenger is essential for this flow. In cases where the deposit transaction fails due to resource metering constraints (insufficient gas or exceeding block resource limits), the message can be replayed with higher gas limits, ensuring funds are never permanently locked.

`setMinDepositAmount`

Updates the minimum deposit amount the contract must hold before the deposit process can be initiated.

function setMinDepositAmount(uint96 _newMinDepositAmount) external

MUST only be callable by ProxyAdmin.owner().
MUST emit the MinDepositAmountUpdated event.
MUST update the minDepositAmount storage variable.

`setL2Recipient`

Updates the address that will receive the funds on OP Mainnet during the deposit process.

function setL2Recipient(address _newRecipient) external

MUST only be callable by ProxyAdmin.owner().
MUST emit the RecipientUpdated event.
MUST update the l2Recipient storage variable.

`setGasLimit`

Updates the gas limit used for the deposit transaction during the fees deposit process.

function setGasLimit(uint32 _gasLimit) external

MUST only be callable by ProxyAdmin.owner().
MUST emit the GasLimitUpdated event.
MUST update the gasLimit storage variable.

Events

`FeesDeposited`

Emitted when a deposit to OP Mainnet is initiated.

event FeesDeposited(address indexed recipient, uint256 amount)

`MinDepositAmountUpdated`

Emitted when the minimum deposit amount before the deposit process can be initiated is updated.

event MinDepositAmountUpdated(uint96 oldMinDepositAmount, uint96 newMinDepositAmount)

`L2RecipientUpdated`

Emitted when the recipient of the funds on OP Mainnet is updated.

event L2RecipientUpdated(address oldL2Recipient, address newL2Recipient)

`FundsReceived`

Emitted whenever funds are received.

event FundsReceived(address indexed sender, uint256 amount, uint256 newBalance)

`GasLimitUpdated`

Emitted when the gas limit for the deposit transaction is updated.

event GasLimitUpdated(uint32 oldGasLimit, uint32 newGasLimit)

OP Stack Specification