set gas price to external contract

contracts/DODOVendorMachine/impl/DVM.sol

@@ -10,6 +10,7 @@ pragma experimental ABIEncoderV2;
 
 import {IFeeRateModel} from "../../intf/IFeeRateModel.sol";
 import {IPermissionManager} from "../../lib/PermissionManager.sol";
+import {IGasPriceSource} from "../../lib/GasPriceSource.sol";
 import {DVMTrader} from "./DVMTrader.sol";
 import {DVMFunding} from "./DVMFunding.sol";
 import {DVMVault} from "./DVMVault.sol";
@@ -22,6 +23,7 @@ contract DVM is DVMTrader, DVMFunding {
         address lpFeeRateModel,
         address mtFeeRateModel,
         address tradePermissionManager,
+        address gasPriceSource,
         uint256 i,
         uint256 k
     ) external {
@@ -32,10 +34,10 @@ contract DVM is DVMTrader, DVMFunding {
         _LP_FEE_RATE_MODEL_ = IFeeRateModel(lpFeeRateModel);
         _MT_FEE_RATE_MODEL_ = IFeeRateModel(mtFeeRateModel);
         _TRADE_PERMISSION_ = IPermissionManager(tradePermissionManager);
+        _GAS_PRICE_LIMIT_ = IGasPriceSource(gasPriceSource);
         _MAINTAINER_ = maintainer;
         _I_ = i;
         _K_ = k;
-        _GAS_PRICE_LIMIT_ = uint256(-1);
     }
 
     // ============ Version Control ============

contracts/DODOVendorMachine/impl/DVMStorage.sol

@@ -14,6 +14,7 @@ import {SafeMath} from "../../lib/SafeMath.sol";
 import {DODOMath} from "../../lib/DODOMath.sol";
 import {DecimalMath} from "../../lib/DecimalMath.sol";
 import {IPermissionManager} from "../../lib/PermissionManager.sol";
+import {IGasPriceSource} from "../../lib/GasPriceSource.sol";
 import {IFeeRateModel} from "../../intf/IFeeRateModel.sol";
 import {DVMVault} from "./DVMVault.sol";
 
@@ -22,7 +23,7 @@ contract DVMStorage is InitializableOwnable, ReentrancyGuard {
 
     // ============ Variables for Control ============
 
-    uint256 public _GAS_PRICE_LIMIT_;
+    IGasPriceSource public _GAS_PRICE_LIMIT_;
 
     // ============ Advanced Controls ============
 
@@ -62,6 +63,11 @@ contract DVMStorage is InitializableOwnable, ReentrancyGuard {
         _;
     }
 
+    modifier limitGasPrice() {
+        require(tx.gasprice <= _GAS_PRICE_LIMIT_.getGasPrice(), "GAS_PRICE_EXCEED");
+        _;
+    }
+
     // ============ Helper Functions ============
 
     function calculateBase0(uint256 baseAmount, uint256 quoteAmount) public view returns (uint256) {
@@ -93,8 +99,8 @@ contract DVMStorage is InitializableOwnable, ReentrancyGuard {
         _MAINTAINER_ = newMaintainer;
     }
 
-    function setGasPriceLimit(uint256 newGasPriceLimit) external onlyOwner {
-        _GAS_PRICE_LIMIT_ = newGasPriceLimit;
+    function setGasPriceSource(address newGasPriceLimitSource) external onlyOwner {
+        _GAS_PRICE_LIMIT_ = IGasPriceSource(newGasPriceLimitSource);
     }
 
     function setBuy(bool open) external onlyOwner {

contracts/DODOVendorMachine/impl/DVMTrader.sol

@@ -20,6 +20,7 @@ contract DVMTrader is DVMStorage {
     function sellBase(address to)
         external
         preventReentrant
+        limitGasPrice
         isSellAllow(to)
         returns (uint256 receiveQuoteAmount)
     {
@@ -37,6 +38,7 @@ contract DVMTrader is DVMStorage {
     function sellQuote(address to)
         external
         preventReentrant
+        limitGasPrice
         isBuyAllow(to)
         returns (uint256 receiveBaseAmount)
     {

contracts/DODOVendorMachine/intf/IDVM.sol

@@ -16,6 +16,7 @@ interface IDVM {
         address lpFeeRateModel,
         address mtFeeRateModel,
         address tradePermissionManager,
+        address gasPriceSource,
         uint256 i,
         uint256 k
     ) external;

contracts/Factory/DVMFactory.sol

@@ -22,6 +22,8 @@ contract DVMFactory is Ownable {
     address public _FEE_RATE_MODEL_TEMPLATE_;
     address public _PERMISSION_MANAGER_TEMPLATE_;
 
+    address public _DEFAULT_GAS_PRICE_SOURCE_;
+
     // base -> quote -> DVM address list
     mapping(address => mapping(address => address[])) _REGISTRY_;
 
@@ -30,13 +32,15 @@ contract DVMFactory is Ownable {
         address vaultTemplate,
         address dvmTemplate,
         address feeRateModelTemplate,
-        address permissionManagerTemplate
+        address permissionManagerTemplate,
+        address defaultGasPriceSource
     ) public {
         _CLONE_FACTORY_ = cloneFactory;
         _VAULT_TEMPLATE_ = vaultTemplate;
         _DVM_TEMPLATE_ = dvmTemplate;
         _FEE_RATE_MODEL_TEMPLATE_ = feeRateModelTemplate;
         _PERMISSION_MANAGER_TEMPLATE_ = permissionManagerTemplate;
+        _DEFAULT_GAS_PRICE_SOURCE_ = defaultGasPriceSource;
     }
 
     function createStandardDODOVendorMachine(
@@ -59,6 +63,7 @@ contract DVMFactory is Ownable {
             createConstFeeRateModel(msg.sender, lpFeeRate),
             createConstFeeRateModel(msg.sender, mtFeeRate),
             createPermissionManager(msg.sender),
+            _DEFAULT_GAS_PRICE_SOURCE_,
             i,
             k
         );

contracts/lib/GasPriceSource.sol

@@ -0,0 +1,29 @@
+/*
+
+    Copyright 2020 DODO ZOO.
+    SPDX-License-Identifier: Apache-2.0
+
+*/
+
+pragma solidity 0.6.9;
+pragma experimental ABIEncoderV2;
+
+import {Ownable} from "./Ownable.sol";
+
+interface IGasPriceSource {
+    function setGasPrice(uint256) external;
+
+    function getGasPrice() external view returns (uint256);
+}
+
+contract GasPriceSource is IGasPriceSource, Ownable {
+    uint256 public _GAS_PRICE_;
+
+    function setGasPrice(uint256 gasPrice) external override {
+        _GAS_PRICE_ = gasPrice;
+    }
+
+    function getGasPrice() external override view returns (uint256) {
+        return _GAS_PRICE_;
+    }
+}