feat(protocol): trigger simultaneous recurring TKO snapshots (#16715)

packages/protocol/contracts/L1/TaikoData.sol

@@ -140,7 +140,7 @@ library TaikoData {
         uint64 genesisHeight;
         uint64 genesisTimestamp;
         uint64 lastSyncedBlockId;
-        uint64 lastSynecdAt;
+        uint64 lastSynecdAt; // typo!
     }
 
     struct SlotB {
@@ -149,7 +149,7 @@ library TaikoData {
         bool provingPaused;
         uint8 __reservedB1;
         uint16 __reservedB2;
-        uint32 __reservedB3;
+        uint32 lastSnapshotIdx;
         uint64 lastUnpausedAt;
     }
 
@@ -164,7 +164,6 @@ library TaikoData {
             uint64 blockId_mod_blockRingBufferSize
                 => mapping(uint32 transitionId => TransitionState ts)
             ) transitions;
-        // Ring buffer for Ether deposits
         bytes32 __reserve1;
         SlotA slotA; // slot 5
         SlotB slotB; // slot 6

packages/protocol/contracts/L1/TaikoEvents.sol

@@ -45,6 +45,12 @@ abstract contract TaikoEvents {
     /// @param slotB The SlotB data structure.
     event StateVariablesUpdated(TaikoData.SlotB slotB);
 
+    /// @notice Emitted when the Taiko token snapshot is taken.
+    /// @param tkoAddress The Taiko token address.
+    /// @param snapshotIdx The snapshot index.
+    /// @param snapshotId The snapshot id.
+    event TaikoTokenSnapshot(address tkoAddress, uint256 snapshotIdx, uint256 snapshotId);
+
     /// @dev Emitted when a block transition is proved or re-proved.
     /// @param blockId The ID of the proven block.
     /// @param tran The verified transition.

packages/protocol/contracts/L1/TaikoL1.sol

@@ -59,7 +59,6 @@ contract TaikoL1 is EssentialContract, ITaikoL1, TaikoEvents, TaikoErrors {
         // reset some previously used slots for future reuse
         state.slotB.__reservedB1 = 0;
         state.slotB.__reservedB2 = 0;
-        state.slotB.__reservedB3 = 0;
         state.__reserve1 = 0;
     }
 

packages/protocol/contracts/L1/TaikoToken.sol

@@ -53,7 +53,7 @@ contract TaikoToken is EssentialContract, ERC20SnapshotUpgradeable, ERC20VotesUp
     }
 
     /// @notice Creates a new token snapshot.
-    function snapshot() public onlyFromOwnerOrNamed(LibStrings.B_SNAPSHOOTER) returns (uint256) {
+    function snapshot() public onlyFromNamed(LibStrings.B_TAIKO) returns (uint256) {
         return _snapshot();
     }
 
@@ -84,6 +84,10 @@ contract TaikoToken is EssentialContract, ERC20SnapshotUpgradeable, ERC20VotesUp
         return super.transferFrom(_from, _to, _amount);
     }
 
+    function currentSnapshotId() public view returns (uint256) {
+        return _getCurrentSnapshotId();
+    }
+
     function _beforeTokenTransfer(
         address _from,
         address _to,

packages/protocol/contracts/L1/libs/LibProposing.sol

@@ -4,7 +4,7 @@ pragma solidity 0.8.24;
 import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
 import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "../../common/IAddressResolver.sol";
-import "../../common/LibStrings.sol";
+import "../../common/LibSnapshot.sol";
 import "../../libs/LibAddress.sol";
 import "../../libs/LibNetwork.sol";
 import "../hooks/IHook.sol";
@@ -185,6 +185,8 @@ library LibProposing {
 
         {
             IERC20 tko = IERC20(_resolver.resolve(LibStrings.B_TAIKO_TOKEN, false));
+            _takeTaikoTokenSnapshot(_state, address(tko), b);
+
             uint256 tkoBalance = tko.balanceOf(address(this));
 
             // Run all hooks.
@@ -230,6 +232,19 @@ library LibProposing {
         });
     }
 
+    function _takeTaikoTokenSnapshot(
+        TaikoData.State storage _state,
+        address _taikoToken,
+        TaikoData.SlotB memory _slotB
+    )
+        private
+    {
+        uint32 idx = LibSnapshot.autoSnapshot(_taikoToken, block.number, _slotB.lastSnapshotIdx);
+        if (idx != 0) {
+            _state.slotB.lastSnapshotIdx = idx;
+        }
+    }
+
     function _isProposerPermitted(
         TaikoData.SlotB memory _slotB,
         IAddressResolver _resolver

packages/protocol/contracts/L2/TaikoL2.sol

@@ -5,7 +5,7 @@ import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 
 import "../common/EssentialContract.sol";
-import "../common/LibStrings.sol";
+import "../common/LibSnapshot.sol";
 import "../libs/LibAddress.sol";
 import "../signal/ISignalService.sol";
 import "./Lib1559Math.sol";
@@ -47,15 +47,24 @@ contract TaikoL2 is EssentialContract {
     uint64 private __currentBlockTimestamp;
 
     /// @notice The L1's chain ID.
+    /// @dev Slot 4.
     uint64 public l1ChainId;
 
+    uint32 public lastSnapshotIdx;
+
     uint256[46] private __gap;
 
     /// @notice Emitted when the latest L1 block details are anchored to L2.
     /// @param parentHash The hash of the parent block.
     /// @param gasExcess The gas excess value used to calculate the base fee.
     event Anchored(bytes32 parentHash, uint64 gasExcess);
 
+    /// @notice Emitted when the Taiko token snapshot is taken.
+    /// @param tkoAddress The Taiko token address.
+    /// @param snapshotIdx The snapshot index.
+    /// @param snapshotId The snapshot id.
+    event TaikoTokenSnapshot(address tkoAddress, uint256 snapshotIdx, uint256 snapshotId);
+
     error L2_BASEFEE_MISMATCH();
     error L2_INVALID_L1_CHAIN_ID();
     error L2_INVALID_L2_CHAIN_ID();
@@ -105,6 +114,7 @@ contract TaikoL2 is EssentialContract {
 
     /// @notice Anchors the latest L1 block details to L2 for cross-layer
     /// message verification.
+    /// @dev The gas limit for this transaction is set to 250K in geth and raiko.
     /// @dev This function can be called freely as the golden touch private key is publicly known,
     /// but the Taiko node guarantees the first transaction of each block is always this anchor
     /// transaction, and any subsequent calls will revert with L2_PUBLIC_INPUT_HASH_MISMATCH.
@@ -168,6 +178,12 @@ contract TaikoL2 is EssentialContract {
         __currentBlockTimestamp = uint64(block.timestamp);
         gasExcess = _gasExcess;
 
+        address tko = resolve(LibStrings.B_TAIKO_TOKEN, true);
+        if (tko != address(0)) {
+            uint32 idx = LibSnapshot.autoSnapshot(tko, _l1BlockId, lastSnapshotIdx);
+            if (idx != 0) lastSnapshotIdx = idx;
+        }
+
         emit Anchored(_parentHash, _gasExcess);
     }
 

packages/protocol/contracts/common/LibSnapshot.sol

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.24;
+
+import "./IAddressResolver.sol";
+import "./LibStrings.sol";
+
+/// @title ISnapshot
+/// @custom:security-contact security@taiko.xyz
+interface ISnapshot {
+    function snapshot() external returns (uint256);
+}
+
+/// @title LibSnapshot
+/// @custom:security-contact security@taiko.xyz
+library LibSnapshot {
+    uint256 public constant SNAPSHOT_INTERVAL = 7200; // uint = 1 L1 block
+
+    /// @notice Emitted when the Taiko token snapshot is taken.
+    /// @param tkoAddress The Taiko token address.
+    /// @param snapshotIdx The snapshot index.
+    /// @param snapshotId The snapshot id.
+    event TaikoTokenSnapshot(address tkoAddress, uint256 snapshotIdx, uint256 snapshotId);
+
+    /// @dev Takes a snapshot every 200,000 L1 blocks which is roughly 27 days.
+    /// @param _taikoToken The Taiko token address.
+    /// @param _blockId The L1's block ID.
+    /// @param _lastSnapshotIdx The latest snapshot's index.
+    /// @return The new snapshot's index, 0 if no new snapshot is taken.
+    function autoSnapshot(
+        address _taikoToken,
+        uint256 _blockId,
+        uint64 _lastSnapshotIdx
+    )
+        internal
+        returns (uint32)
+    {
+        if (_blockId % SNAPSHOT_INTERVAL != 0) return 0;
+
+        // if snapshotIdx = type(uint32).max, we can handle L1 block id up to 4e14.
+        uint32 snapshotIdx = uint32(_blockId / SNAPSHOT_INTERVAL + 1);
+        if (snapshotIdx == _lastSnapshotIdx) return 0;
+
+        uint256 snapshotId = ISnapshot(_taikoToken).snapshot();
+        emit TaikoTokenSnapshot(_taikoToken, snapshotIdx, snapshotId);
+        return snapshotIdx;
+    }
+}

packages/protocol/contracts/common/LibStrings.sol

@@ -7,9 +7,6 @@ library LibStrings {
     /// @notice bytes32 representation of the string "chain_pauser".
     bytes32 internal constant B_CHAIN_PAUSER = bytes32("chain_pauser");
 
-    /// @notice bytes32 representation of the string "snapshooter".
-    bytes32 internal constant B_SNAPSHOOTER = bytes32("snapshooter");
-
     /// @notice bytes32 representation of the string "withdrawer".
     bytes32 internal constant B_WITHDRAWER = bytes32("withdrawer");
 

packages/protocol/contracts/tokenvault/BridgedERC20.sol

@@ -33,10 +33,8 @@ contract BridgedERC20 is
     error BTOKEN_CANNOT_RECEIVE();
     error BTOKEN_UNAUTHORIZED();
 
-    modifier onlyOwnerOrSnapshooter() {
-        if (msg.sender != owner() && msg.sender != snapshooter) {
-            revert BTOKEN_UNAUTHORIZED();
-        }
+    modifier onlyAuthorizedForSnapshot() {
+        if (!isAuthorizedForSnapshot(msg.sender)) revert BTOKEN_UNAUTHORIZED();
         _;
     }
 
@@ -81,7 +79,7 @@ contract BridgedERC20 is
     }
 
     /// @notice Creates a new token snapshot.
-    function snapshot() external onlyOwnerOrSnapshooter returns (uint256) {
+    function snapshot() external onlyAuthorizedForSnapshot returns (uint256) {
         return _snapshot();
     }
 
@@ -118,6 +116,28 @@ contract BridgedERC20 is
         return __srcDecimals;
     }
 
+    /// @notice Gets the current snapshot ID.
+    /// @return The current snapshot ID.
+    function currentSnapshotId() public view returns (uint256) {
+        return _getCurrentSnapshotId();
+    }
+
+    /// @notice Checks if an address can take a snapshot.
+    /// @param addr The address.
+    /// @return true if the address can perform a snapshot, false otherwise.
+    function isAuthorizedForSnapshot(address addr) public view returns (bool) {
+        if (addr == address(0)) return false;
+
+        if (
+            addr == resolve(LibStrings.B_TAIKO, true)
+                && address(this) == resolve(LibStrings.B_TAIKO_TOKEN, true)
+        ) return true;
+
+        if (addr == snapshooter) return true;
+
+        return false;
+    }
+
     /// @notice Gets the canonical token's address and chain ID.
     /// @return The canonical token's address.
     /// @return The canonical token's chain ID.

packages/protocol/package.json

@@ -30,7 +30,7 @@
     "eslint-plugin-promise": "^6.1.1",
     "ethers": "^5.7.2",
     "solc": "0.7.3",
-    "solhint": "^4.5.2",
+    "solhint": "^4.5.4",
     "ts-node": "^10.9.2",
     "typescript": "^5.2.2"
   },

packages/protocol/test/L1/TaikoL1.t.sol

@@ -187,7 +187,7 @@ contract TaikoL1Test is TaikoL1TestBase {
     }
 
     function test_snapshot() external {
-        vm.prank(tko.owner(), tko.owner());
+        vm.prank(address(L1));
         tko.snapshot();
 
         uint256 totalSupplyAtSnapshot = tko.totalSupplyAt(1);