feat: subgraph availability manager contract

packages/contracts/contracts/rewards/SubgraphAvailabilityManager.sol

@@ -2,8 +2,6 @@
 
 pragma solidity ^0.7.6;
 
-import { SafeMathUpgradeable } from "@openzeppelin/contracts-upgradeable/math/SafeMathUpgradeable.sol";
-
 import { Governed } from "../governance/Governed.sol";
 import { IRewardsManager } from "../rewards/IRewardsManager.sol";
 
@@ -17,8 +15,6 @@
  * Governor can transfer ownership to a new governor.
  */
 contract SubgraphAvailabilityManager is Governed {
-    using SafeMathUpgradeable for uint256;
-
     // -- Immutable --
 
     /// @notice Number of oracles
@@ -81,9 +77,9 @@
 
     // -- Modifiers --
 
     modifier onlyOracle(uint256 _oracleIndex) {
         require(_oracleIndex < NUM_ORACLES, "SAM: index out of bounds");
         require(msg.sender == oracles[_oracleIndex], "SAM: caller must be oracle");
         _;
     }
 
@@ -106,14 +102,11 @@
     ) {
         require(_governor != address(0), "SAM: governor must be set");
         require(_rewardsManager != address(0), "SAM: rewardsManager must be set");
-        require(
-            _executionThreshold >= NUM_ORACLES.div(2).add(1),
-            "SAM: executionThreshold too low"
-        );
+        require(_executionThreshold >= (NUM_ORACLES / 2) + 1, "SAM: executionThreshold too low");
         require(_executionThreshold <= NUM_ORACLES, "SAM: executionThreshold too high");
 
         // Oracles should not be address zero
-        for (uint256 i = 0; i < _oracles.length; i++) {
+        for (uint256 i; i < _oracles.length; i++) {
             address oracle = _oracles[i];
             require(oracle != address(0), "SAM: oracle cannot be address zero");
             oracles[i] = oracle;
@@ -133,10 +126,10 @@
      * @dev Set the vote time limit. Refreshes all existing votes by incrementing the current nonce.
      * @param _voteTimeLimit Vote time limit in seconds
      */
     function setVoteTimeLimit(uint256 _voteTimeLimit) external onlyGovernor {
         voteTimeLimit = _voteTimeLimit;
         currentNonce++;
         emit VoteTimeLimitSet(_voteTimeLimit);
     }
 
     /**
@@ -144,15 +137,15 @@
      * @param _index Index of the oracle
      * @param _oracle Address of the oracle
      */
     function setOracle(uint256 _index, address _oracle) external onlyGovernor {
         require(_index < NUM_ORACLES, "SAM: index out of bounds");
         require(_oracle != address(0), "SAM: oracle cannot be address zero");
 
         oracles[_index] = _oracle;
         // Increment the current nonce to refresh all existing votes for subgraph deployment IDs
         currentNonce++;
 
         emit OracleSet(_index, _oracle);
     }
 
     /**
@@ -162,12 +155,12 @@
      * @param _deny True to deny, false to allow
      * @param _oracleIndex Index of the oracle voting
      */
     function vote(
         bytes32 _subgraphDeploymentID,
         bool _deny,
         uint256 _oracleIndex
     ) external onlyOracle(_oracleIndex) {
         _vote(_subgraphDeploymentID, _deny, _oracleIndex);
     }
 
     /**
@@ -177,14 +170,14 @@
      * @param _deny Array of booleans, true to deny, false to allow
      * @param _oracleIndex Index of the oracle voting
      */
     function voteMany(
         bytes32[] calldata _subgraphDeploymentID,
         bool[] calldata _deny,
         uint256 _oracleIndex
     ) external onlyOracle(_oracleIndex) {
         require(_subgraphDeploymentID.length == _deny.length, "!length");
-        for (uint256 i = 0; i < _subgraphDeploymentID.length; i++) {
+        for (uint256 i; i < _subgraphDeploymentID.length; i++) {
             _vote(_subgraphDeploymentID[i], _deny[i], _oracleIndex);
         }
     }
 
@@ -197,24 +190,24 @@
      * @param _deny True to deny, false to allow
      * @param _oracleIndex Index of the oracle voting
      */
     function _vote(
         bytes32 _subgraphDeploymentID,
         bool _deny,
         uint256 _oracleIndex
     ) private {
         uint256 timestamp = block.timestamp;
 
         // corresponding votes based on _deny for a subgraph deployment
         uint256[NUM_ORACLES] storage lastVoteForSubgraph = _deny
             ? lastDenyVote[currentNonce][_subgraphDeploymentID]
             : lastAllowVote[currentNonce][_subgraphDeploymentID];
         lastVoteForSubgraph[_oracleIndex] = timestamp;
 
         emit OracleVote(_subgraphDeploymentID, _deny, _oracleIndex, timestamp);
 
         // check if execution threshold is reached, if it is call the RewardsManager
         if (checkVotes(_subgraphDeploymentID, _deny)) {
             rewardsManager.setDenied(_subgraphDeploymentID, _deny);
         }
     }
 
@@ -225,29 +218,29 @@
      * @param _deny True to deny, false to allow
      * @return True if execution threshold is reached
      */
     function checkVotes(bytes32 _subgraphDeploymentID, bool _deny) public view returns (bool) {
-        uint256 votes = 0;
+        uint256 votes;
 
         // timeframe for a vote to be valid
         uint256 voteTimeValidity = block.timestamp - voteTimeLimit;
 
         // corresponding votes based on _deny for a subgraph deployment
         uint256[NUM_ORACLES] storage lastVoteForSubgraph = _deny
             ? lastDenyVote[currentNonce][_subgraphDeploymentID]
             : lastAllowVote[currentNonce][_subgraphDeploymentID];
 
-        for (uint256 i = 0; i < NUM_ORACLES; i++) {
+        for (uint256 i; i < NUM_ORACLES; i++) {
             // check if vote is within the vote time limit
             if (lastVoteForSubgraph[i] > voteTimeValidity) {
                 votes++;
             }
 
             // check if execution threshold is reached
             if (votes == executionThreshold) {
                 return true;
             }
         }
 
         return false;
     }
 }