feat: gerousia (#8942)

Fixes #8138.

l1-contracts/src/governance/Gerousia.sol

@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+import {IRegistry} from "@aztec/governance/interfaces/IRegistry.sol";
+import {IApella} from "@aztec/governance/interfaces/IApella.sol";
+import {IGerousia} from "@aztec/governance/interfaces/IGerousia.sol";
+import {Errors} from "@aztec/governance/libraries/Errors.sol";
+
+import {Slot, SlotLib} from "@aztec/core/libraries/TimeMath.sol";
+import {ILeonidas} from "@aztec/core/interfaces/ILeonidas.sol";
+
+/**
+ * @notice  A Gerousia implementation following the empire model
+ *          Beware that while governance generally do not care about the implementation
+ *          this implementation will since it is dependent on the sequencer selection.
+ *          This also means that the implementation here will need to be "updated" if
+ *          the interfaces of the sequencer selection changes, for exampel going optimistic.
+ */
+contract Gerousia is IGerousia {
+  using SlotLib for Slot;
+
+  struct RoundAccounting {
+    Slot lastVote;
+    address leader;
+    bool executed;
+    mapping(address proposal => uint256 count) yeaCount;
+  }
+
+  uint256 public constant LIFETIME_IN_ROUNDS = 5;
+
+  IApella public immutable APELLA;
+  IRegistry public immutable REGISTRY;
+  uint256 public immutable N;
+  uint256 public immutable M;
+
+  mapping(address instance => mapping(uint256 roundNumber => RoundAccounting)) public rounds;
+
+  constructor(IApella _apella, IRegistry _registry, uint256 _n, uint256 _m) {
+    APELLA = _apella;
+    REGISTRY = _registry;
+    N = _n;
+    M = _m;
+
+    require(N > M / 2, Errors.Gerousia__InvalidNAndMValues(N, M));
+    require(N <= M, Errors.Gerousia__NCannotBeLargerTHanM(N, M));
+  }
+
+  // Note that this one is heavily realying on the fact that this contract
+  // could be updated at the same time as another upgrade is made.
+
+  /**
+   * @notice	Cast a vote on a proposal
+   *					Note that this is assuming that the canonical rollup will cast it as
+   * 					part of block production, we will perform it here
+   *
+   * @param _proposal - The proposal to cast a vote on
+   *
+   * @return True if executed successfully, false otherwise
+   */
+  function vote(address _proposal) external override(IGerousia) returns (bool) {
+    require(_proposal.code.length > 0, Errors.Gerousia__ProposalHaveNoCode(_proposal));
+
+    address instance = REGISTRY.getRollup();
+    require(instance.code.length > 0, Errors.Gerousia__InstanceHaveNoCode(instance));
+
+    ILeonidas selection = ILeonidas(instance);
+    Slot currentSlot = selection.getCurrentSlot();
+
+    uint256 roundNumber = computeRound(currentSlot);
+
+    RoundAccounting storage round = rounds[instance][roundNumber];
+
+    require(currentSlot > round.lastVote, Errors.Gerousia__VoteAlreadyCastForSlot(currentSlot));
+
+    address proposer = selection.getCurrentProposer();
+    require(msg.sender == proposer, Errors.Gerousia__OnlyProposerCanVote(msg.sender, proposer));
+
+    round.yeaCount[_proposal] += 1;
+    round.lastVote = currentSlot;
+
+    // @todo We can optimise here for gas by storing some of it packed with the leader.
+    if (round.leader != _proposal && round.yeaCount[_proposal] > round.yeaCount[round.leader]) {
+      round.leader = _proposal;
+    }
+
+    emit VoteCast(_proposal, roundNumber, msg.sender);
+
+    return true;
+  }
+
+  /**
+   * @notice  Push the proposal to the appela
+   *
+   * @param _roundNumber - The round number to execute
+   *
+   * @return True if executed successfully, false otherwise
+   */
+  function pushProposal(uint256 _roundNumber) external override(IGerousia) returns (bool) {
+    // Need to ensure that the round is not active.
+    address instance = REGISTRY.getRollup();
+    require(instance.code.length > 0, Errors.Gerousia__InstanceHaveNoCode(instance));
+
+    ILeonidas selection = ILeonidas(instance);
+    Slot currentSlot = selection.getCurrentSlot();
+
+    uint256 currentRound = computeRound(currentSlot);
+    require(_roundNumber < currentRound, Errors.Gerousia__CanOnlyPushProposalInPast());
+    require(
+      _roundNumber + LIFETIME_IN_ROUNDS >= currentRound,
+      Errors.Gerousia__ProposalTooOld(_roundNumber)
+    );
+
+    RoundAccounting storage round = rounds[instance][_roundNumber];
+    require(!round.executed, Errors.Gerousia__ProposalAlreadyExecuted(_roundNumber));
+    require(round.leader != address(0), Errors.Gerousia__ProposalCannotBeAddressZero());
+    require(round.yeaCount[round.leader] >= N, Errors.Gerousia__InsufficientVotes());
+
+    round.executed = true;
+
+    emit ProposalPushed(round.leader, _roundNumber);
+
+    require(APELLA.propose(round.leader), Errors.Gerousia__FailedToPropose(round.leader));
+    return true;
+  }
+
+  /**
+   * @notice  Fetch the yea count for a specific proposal in a specific round on a specific instance
+   *
+   * @param _instance - The address of the instance
+   * @param _round - The round to lookup
+   * @param _proposal - The address of the proposal
+   *
+   * @return The number of yea votes
+   */
+  function yeaCount(address _instance, uint256 _round, address _proposal)
+    external
+    view
+    override(IGerousia)
+    returns (uint256)
+  {
+    return rounds[_instance][_round].yeaCount[_proposal];
+  }
+
+  /**
+   * @notice  Computes the round at the given slot
+   *
+   * @param _slot - The slot to compute round for
+   *
+   * @return The round number
+   */
+  function computeRound(Slot _slot) public view override(IGerousia) returns (uint256) {
+    return _slot.unwrap() / M;
+  }
+}

l1-contracts/src/governance/interfaces/IApella.sol

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+interface IApella {
+  function propose(address _proposal) external returns (bool);
+}

l1-contracts/src/governance/interfaces/IGerousia.sol

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+import {Slot} from "@aztec/core/libraries/TimeMath.sol";
+
+interface IGerousia {
+  event VoteCast(address indexed proposal, uint256 indexed round, address indexed voter);
+  event ProposalPushed(address indexed proposal, uint256 indexed round);
+
+  function vote(address _proposa) external returns (bool);
+  function pushProposal(uint256 _roundNumber) external returns (bool);
+  function yeaCount(address _instance, uint256 _round, address _proposal)
+    external
+    view
+    returns (uint256);
+  function computeRound(Slot _slot) external view returns (uint256);
+}

l1-contracts/src/governance/libraries/Errors.sol

@@ -2,6 +2,8 @@
 // Copyright 2023 Aztec Labs.
 pragma solidity >=0.8.27;
 
+import {Slot} from "@aztec/core/libraries/TimeMath.sol";
+
 /**
  * @title Errors Library
  * @author Aztec Labs
@@ -10,7 +12,19 @@ pragma solidity >=0.8.27;
  * when there are multiple contracts that could have thrown the error.
  */
 library Errors {
-  // Registry
+  error Gerousia__CanOnlyPushProposalInPast(); // 0x49fdf611"
+  error Gerousia__FailedToPropose(address proposal); // 0x6ca2a2ed
+  error Gerousia__InstanceHaveNoCode(address instance); // 0x20a3b441
+  error Gerousia__InsufficientVotes(); // 0xba1e05ef
+  error Gerousia__InvalidNAndMValues(uint256 N, uint256 M); // 0x520d9704
+  error Gerousia__NCannotBeLargerTHanM(uint256 N, uint256 M); // 0x2fdfc063
+  error Gerousia__OnlyProposerCanVote(address caller, address proposer); // 0xba27df38
+  error Gerousia__ProposalAlreadyExecuted(uint256 roundNumber); // 0x7aeacb17
+  error Gerousia__ProposalCannotBeAddressZero(); // 0xdb3e4b6e
+  error Gerousia__ProposalHaveNoCode(address proposal); // 0xdce0615b
+  error Gerousia__ProposalTooOld(uint256 roundNumber); //0x02283b1a
+  error Gerousia__VoteAlreadyCastForSlot(Slot slot); //0xc2201452
+
   error Nomismatokopio__InssuficientMintAvailable(uint256 available, uint256 needed); // 0xf268b931
 
   error Registry__RollupAlreadyRegistered(address rollup); // 0x3c34eabf

l1-contracts/test/governance/gerousia/Base.t.sol

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+import {Test} from "forge-std/Test.sol";
+
+import {Registry} from "@aztec/governance/Registry.sol";
+import {Gerousia} from "@aztec/governance/Gerousia.sol";
+
+import {IApella} from "@aztec/governance/interfaces/IApella.sol";
+
+contract FakeApella is IApella {
+  address public gerousia;
+
+  mapping(address => bool) public proposals;
+
+  function setGerousia(address _gerousia) external {
+    gerousia = _gerousia;
+  }
+
+  function propose(address _proposal) external override(IApella) returns (bool) {
+    proposals[_proposal] = true;
+    return true;
+  }
+}
+
+contract GerousiaBase is Test {
+  Registry internal registry;
+  FakeApella internal apella;
+  Gerousia internal gerousia;
+
+  function setUp() public virtual {
+    registry = new Registry(address(this));
+    apella = new FakeApella();
+
+    gerousia = new Gerousia(apella, registry, 667, 1000);
+
+    apella.setGerousia(address(gerousia));
+  }
+}

l1-contracts/test/governance/gerousia/constructor.t.sol

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+import {Test} from "forge-std/Test.sol";
+import {Gerousia} from "@aztec/governance/Gerousia.sol";
+import {Errors} from "@aztec/governance/libraries/Errors.sol";
+import {IRegistry} from "@aztec/governance/interfaces/IRegistry.sol";
+import {IApella} from "@aztec/governance/interfaces/IApella.sol";
+
+contract ConstructorTest is Test {
+  IApella internal constant APELLA = IApella(address(0x01));
+  IRegistry internal constant REGISTRY = IRegistry(address(0x02));
+
+  function test_WhenNIsLessThanOrEqualHalfOfM(uint256 _n, uint256 _m) external {
+    // it revert
+
+    uint256 n = bound(_n, 0, _m / 2);
+
+    vm.expectRevert(abi.encodeWithSelector(Errors.Gerousia__InvalidNAndMValues.selector, n, _m));
+    new Gerousia(APELLA, REGISTRY, n, _m);
+  }
+
+  function test_WhenNLargerThanM(uint256 _n, uint256 _m) external {
+    // it revert
+    uint256 m = bound(_m, 0, type(uint256).max - 1);
+    uint256 n = bound(_n, m + 1, type(uint256).max);
+
+    vm.expectRevert(abi.encodeWithSelector(Errors.Gerousia__NCannotBeLargerTHanM.selector, n, m));
+    new Gerousia(APELLA, REGISTRY, n, m);
+  }
+
+  function test_WhenNIsGreatherThanHalfOfM(uint256 _n, uint256 _m) external {
+    // it deploys
+
+    uint256 m = bound(_m, 1, type(uint256).max);
+    uint256 n = bound(_n, m / 2 + 1, m);
+
+    Gerousia g = new Gerousia(APELLA, REGISTRY, n, m);
+
+    assertEq(address(g.APELLA()), address(APELLA));
+    assertEq(address(g.REGISTRY()), address(REGISTRY));
+    assertEq(g.N(), n);
+    assertEq(g.M(), m);
+  }
+}

l1-contracts/test/governance/gerousia/constructor.tree

@@ -0,0 +1,7 @@
+ConstructorTest
+├── when N is less than or equal half of M
+│   └── it revert
+├── when N larger than M
+│   └── it revert
+└── when N is greather than half of M
+    └── it deploys

l1-contracts/test/governance/gerousia/mocks/FalsyApella.sol

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+import {IApella} from "@aztec/governance/interfaces/IApella.sol";
+
+contract FalsyApella is IApella {
+  function propose(address) external pure override(IApella) returns (bool) {
+    return false;
+  }
+}

l1-contracts/test/governance/gerousia/mocks/FaultyApella.sol

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.27;
+
+import {IApella} from "@aztec/governance/interfaces/IApella.sol";
+
+contract FaultyApella is IApella {
+  error Faulty();
+
+  function propose(address) external pure override(IApella) returns (bool) {
+    require(false, Faulty());
+    return true;
+  }
+}