Merge pull request #12 from zkLinkProtocol/issue_8

set tx gas price

contracts/ZkLink.sol

@@ -50,6 +50,8 @@ contract ZkLink is IZkLink, IMailbox, IAdmin, OwnableUpgradeable, UUPSUpgradeabl
     event InitGateway(IL2Gateway gateway);
     /// @notice Contract's permit status changed
     event ContractAllowStatusUpdate(address contractAddress, bool isPermit);
+    /// @notice Tx gas price changed
+    event TxGasPriceUpdate(uint256 oldTxGasPrice, uint256 newTxGasPrice);
     /// @notice Validator's status changed
     event ValidatorStatusUpdate(address validatorAddress, bool isActive);
     /// @notice Fee params for L1->L2 transactions changed
@@ -107,6 +109,13 @@ contract ZkLink is IZkLink, IMailbox, IAdmin, OwnableUpgradeable, UUPSUpgradeabl
         emit ContractAllowStatusUpdate(_contractAddress, _permitted);
     }
 
+    /// @dev Update the tx gas price
+    function setTxGasPrice(uint256 _newTxGasPrice) external onlyOwner {
+        uint256 oldTxGasPrice = txGasPrice;
+        txGasPrice = _newTxGasPrice;
+        emit TxGasPriceUpdate(oldTxGasPrice, _newTxGasPrice);
+    }
+
     function setValidator(address _validator, bool _active) external onlyGateway {
         validators[_validator] = _active;
         emit ValidatorStatusUpdate(_validator, _active);