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109 lines
4.4 KiB
Solidity
109 lines
4.4 KiB
Solidity
// SPDX-License-Identifier: MIT
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// OpenZeppelin Contracts (last updated v4.6.0) (governance/extensions/GovernorPreventLateQuorum.sol)
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pragma solidity ^0.8.0;
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import "../Governor.sol";
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import "../../utils/math/Math.sol";
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/**
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* @dev A module that ensures there is a minimum voting period after quorum is reached. This prevents a large voter from
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* swaying a vote and triggering quorum at the last minute, by ensuring there is always time for other voters to react
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* and try to oppose the decision.
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*
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* If a vote causes quorum to be reached, the proposal's voting period may be extended so that it does not end before at
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* least a given number of blocks have passed (the "vote extension" parameter). This parameter can be set by the
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* governance executor (e.g. through a governance proposal).
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*
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* _Available since v4.5._
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*/
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abstract contract GovernorPreventLateQuorum is Governor {
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using SafeCast for uint256;
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using Timers for Timers.BlockNumber;
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uint64 private _voteExtension;
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mapping(uint256 => Timers.BlockNumber) private _extendedDeadlines;
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/// @dev Emitted when a proposal deadline is pushed back due to reaching quorum late in its voting period.
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event ProposalExtended(uint256 indexed proposalId, uint64 extendedDeadline);
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/// @dev Emitted when the {lateQuorumVoteExtension} parameter is changed.
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event LateQuorumVoteExtensionSet(uint64 oldVoteExtension, uint64 newVoteExtension);
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/**
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* @dev Initializes the vote extension parameter: the number of blocks that are required to pass since a proposal
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* reaches quorum until its voting period ends. If necessary the voting period will be extended beyond the one set
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* at proposal creation.
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*/
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constructor(uint64 initialVoteExtension) {
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_setLateQuorumVoteExtension(initialVoteExtension);
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}
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/**
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* @dev Returns the proposal deadline, which may have been extended beyond that set at proposal creation, if the
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* proposal reached quorum late in the voting period. See {Governor-proposalDeadline}.
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*/
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function proposalDeadline(uint256 proposalId) public view virtual override returns (uint256) {
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return Math.max(super.proposalDeadline(proposalId), _extendedDeadlines[proposalId].getDeadline());
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}
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/**
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* @dev Casts a vote and detects if it caused quorum to be reached, potentially extending the voting period. See
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* {Governor-_castVote}.
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*
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* May emit a {ProposalExtended} event.
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*/
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function _castVote(
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uint256 proposalId,
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address account,
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uint8 support,
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string memory reason,
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bytes memory params
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) internal virtual override returns (uint256) {
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uint256 result = super._castVote(proposalId, account, support, reason, params);
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Timers.BlockNumber storage extendedDeadline = _extendedDeadlines[proposalId];
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if (extendedDeadline.isUnset() && _quorumReached(proposalId)) {
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uint64 extendedDeadlineValue = block.number.toUint64() + lateQuorumVoteExtension();
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if (extendedDeadlineValue > proposalDeadline(proposalId)) {
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emit ProposalExtended(proposalId, extendedDeadlineValue);
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}
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extendedDeadline.setDeadline(extendedDeadlineValue);
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}
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return result;
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}
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/**
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* @dev Returns the current value of the vote extension parameter: the number of blocks that are required to pass
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* from the time a proposal reaches quorum until its voting period ends.
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*/
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function lateQuorumVoteExtension() public view virtual returns (uint64) {
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return _voteExtension;
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}
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/**
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* @dev Changes the {lateQuorumVoteExtension}. This operation can only be performed by the governance executor,
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* generally through a governance proposal.
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*
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* Emits a {LateQuorumVoteExtensionSet} event.
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*/
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function setLateQuorumVoteExtension(uint64 newVoteExtension) public virtual onlyGovernance {
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_setLateQuorumVoteExtension(newVoteExtension);
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}
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/**
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* @dev Changes the {lateQuorumVoteExtension}. This is an internal function that can be exposed in a public function
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* like {setLateQuorumVoteExtension} if another access control mechanism is needed.
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*
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* Emits a {LateQuorumVoteExtensionSet} event.
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*/
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function _setLateQuorumVoteExtension(uint64 newVoteExtension) internal virtual {
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emit LateQuorumVoteExtensionSet(_voteExtension, newVoteExtension);
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_voteExtension = newVoteExtension;
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}
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}
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