Openzeppelin PaymentSplitter contract implementation
Article Directory
foreword
PaymentSplitter is used to realize payment to a certain group, and realizes the overload of payment function for ether and erc20. Payees (that is, all objects to be paid) and shares (that is, the payment share of each payee) need to be specified when the contract is constructed. The payment is in the form of pull, that is, the payee address needs to call the release function to obtain the payment.
1. Interface
FUNCTIONS
constructor(payees, shares_)
receive()
totalShares()
totalReleased()
totalReleased(token)
shares(account)
released(account)
released(token, account)
payee(index)
releasable(account)
releasable(token, account)
release(account)
release(token, account)
EVENTS
PayeeAdded(account, shares)
PaymentReleased(to, amount)
ERC20PaymentReleased(token, to, amount)
PaymentReceived(from, amount)
2. Implementation of Openzeppelin
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (finance/PaymentSplitter.sol)
pragma solidity ^0.8.0;
import "../token/ERC20/utils/SafeERC20.sol";
import "../utils/Address.sol";
import "../utils/Context.sol";
/**合约只存储了一个shares来存储支付地址和对应份额，因此只能用于一种代币的发放（eth或某一erc20代币）
* @title PaymentSplitter
* @dev This contract allows to split Ether payments among a group of accounts. The sender does not need to be aware
* that the Ether will be split in this way, since it is handled transparently by the contract.
*
* The split can be in equal parts or in any other arbitrary proportion. The way this is specified is by assigning each
* account to a number of shares. Of all the Ether that this contract receives, each account will then be able to claim
* an amount proportional to the percentage of total shares they were assigned. The distribution of shares is set at the
* time of contract deployment and can't be updated thereafter.
*
* `PaymentSplitter` follows a _pull payment_ model. This means that payments are not automatically forwarded to the
* accounts but kept in this contract, and the actual transfer is triggered as a separate step by calling the {release}
* function.
*
* NOTE: This contract assumes that ERC20 tokens will behave similarly to native tokens (Ether). Rebasing tokens, and
* tokens that apply fees during transfers, are likely to not be supported as expected. If in doubt, we encourage you
* to run tests before sending real value to this contract.
*/
contract PaymentSplitter is Context {
event PayeeAdded(address account, uint256 shares);
event PaymentReleased(address to, uint256 amount);
event ERC20PaymentReleased(IERC20 indexed token, address to, uint256 amount);
event PaymentReceived(address from, uint256 amount);
uint256 private _totalShares;//总份额
uint256 private _totalReleased;//已发放的所有份额（用于eth）
mapping(address => uint256) private _shares;//每个地址的份额
mapping(address => uint256) private _released;//每个地址已发放的份额（用于eth）
address[] private _payees;//所有将支付的地址
mapping(IERC20 => uint256) private _erc20TotalReleased;//已发放的所有份额（用于erc20）
mapping(IERC20 => mapping(address => uint256)) private _erc20Released;//每个地址已发放的份额（用于erc20）
/**构造合约时，必须定义将支付的地址和每个地址的份额，这里不区分eth和erc20
* @dev Creates an instance of `PaymentSplitter` where each account in `payees` is assigned the number of shares at
* the matching position in the `shares` array.
*
* All addresses in `payees` must be non-zero. Both arrays must have the same non-zero length, and there must be no
* duplicates in `payees`.
*/
constructor(address[] memory payees, uint256[] memory shares_) payable {
require(payees.length == shares_.length, "PaymentSplitter: payees and shares length mismatch");
require(payees.length > 0, "PaymentSplitter: no payees");
for (uint256 i = 0; i < payees.length; i++) {
_addPayee(payees[i], shares_[i]);
}
}
/**
* @dev The Ether received will be logged with {PaymentReceived} events. Note that these events are not fully
* reliable: it's possible for a contract to receive Ether without triggering this function. This only affects the
* reliability of the events, and not the actual splitting of Ether.
*
* To learn more about this see the Solidity documentation for
* https://solidity.readthedocs.io/en/latest/contracts.html#fallback-function[fallback
* functions].
*/
receive() external payable virtual {
emit PaymentReceived(_msgSender(), msg.value);
}
/**
* @dev Getter for the total shares held by payees.
*/
function totalShares() public view returns (uint256) {
return _totalShares;
}
/**
* @dev Getter for the total amount of Ether already released.
*/
function totalReleased() public view returns (uint256) {
return _totalReleased;
}
/**
* @dev Getter for the total amount of `token` already released. `token` should be the address of an IERC20
* contract.
*/
function totalReleased(IERC20 token) public view returns (uint256) {
return _erc20TotalReleased[token];
}
/**
* @dev Getter for the amount of shares held by an account.
*/
function shares(address account) public view returns (uint256) {
return _shares[account];
}
/**
* @dev Getter for the amount of Ether already released to a payee.
*/
function released(address account) public view returns (uint256) {
return _released[account];
}
/**
* @dev Getter for the amount of `token` tokens already released to a payee. `token` should be the address of an
* IERC20 contract.
*/
function released(IERC20 token, address account) public view returns (uint256) {
return _erc20Released[token][account];
}
/**
* @dev Getter for the address of the payee number `index`.
*/
function payee(uint256 index) public view returns (address) {
return _payees[index];
}
/**获得某支付地址剩余需支付的eth
* @dev Getter for the amount of payee's releasable Ether.
*/
function releasable(address account) public view returns (uint256) {
uint256 totalReceived = address(this).balance + totalReleased();
return _pendingPayment(account, totalReceived, released(account));
}
/**获得某支付地址剩余需支付的erc20代币
* @dev Getter for the amount of payee's releasable `token` tokens. `token` should be the address of an
* IERC20 contract.
*/
function releasable(IERC20 token, address account) public view returns (uint256) {
uint256 totalReceived = token.balanceOf(address(this)) + totalReleased(token);
return _pendingPayment(account, totalReceived, released(token, account));
}
/**读取地址的剩余待支付eth，并转给该地址
* @dev Triggers a transfer to `account` of the amount of Ether they are owed, according to their percentage of the
* total shares and their previous withdrawals.
*/
function release(address payable account) public virtual {
require(_shares[account] > 0, "PaymentSplitter: account has no shares");
uint256 payment = releasable(account);
require(payment != 0, "PaymentSplitter: account is not due payment");
// _totalReleased is the sum of all values in _released.
// If "_totalReleased += payment" does not overflow, then "_released[account] += payment" cannot overflow.
_totalReleased += payment;
unchecked {
_released[account] += payment;
}
Address.sendValue(account, payment);
emit PaymentReleased(account, payment);
}
/**读取地址的剩余待支付erc20，并转给该地址
* @dev Triggers a transfer to `account` of the amount of `token` tokens they are owed, according to their
* percentage of the total shares and their previous withdrawals. `token` must be the address of an IERC20
* contract.
*/
function release(IERC20 token, address account) public virtual {
require(_shares[account] > 0, "PaymentSplitter: account has no shares");
uint256 payment = releasable(token, account);
require(payment != 0, "PaymentSplitter: account is not due payment");
// _erc20TotalReleased[token] is the sum of all values in _erc20Released[token].
// If "_erc20TotalReleased[token] += payment" does not overflow, then "_erc20Released[token][account] += payment"
// cannot overflow.
_erc20TotalReleased[token] += payment;
unchecked {
_erc20Released[token][account] += payment;
}
SafeERC20.safeTransfer(token, account, payment);
emit ERC20PaymentReleased(token, account, payment);
}
/**合约中实际初始存储的token数量totalReceived可能大于或小于计划发放份额_totalShares，计算实际发放份额时使用合约实际存储或接收的代币数量去计算
* @dev internal logic for computing the pending payment of an `account` given the token historical balances and
* already released amounts.
*/
function _pendingPayment(
address account,
uint256 totalReceived,
uint256 alreadyReleased
) private view returns (uint256) {
return (totalReceived * _shares[account]) / _totalShares - alreadyReleased;
}
/**添加支付地址和份额
* @dev Add a new payee to the contract.
* @param account The address of the payee to add.
* @param shares_ The number of shares owned by the payee.
*/
function _addPayee(address account, uint256 shares_) private {
require(account != address(0), "PaymentSplitter: account is the zero address");
require(shares_ > 0, "PaymentSplitter: shares are 0");
require(_shares[account] == 0, "PaymentSplitter: account already has shares");
_payees.push(account);
_shares[account] = shares_;
_totalShares = _totalShares + shares_;
emit PayeeAdded(account, shares_);
}
}