Merge pull request #939 from graphprotocol/mde/pr939-fix-oz-l-02

fix: clear vote for earlier rounds (OZ L-02)

Author: Maikol

packages/contracts/contracts/rewards/SubgraphAvailabilityManager.sol

@@ -197,11 +197,15 @@ contract SubgraphAvailabilityManager is Governed {
     ) 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;
+        if (_deny) {
+            lastDenyVote[currentNonce][_subgraphDeploymentID][_oracleIndex] = timestamp;
+            // clear opposite vote for a subgraph deployment if it exists
+            lastAllowVote[currentNonce][_subgraphDeploymentID][_oracleIndex] = 0;
+        } else {
+            lastAllowVote[currentNonce][_subgraphDeploymentID][_oracleIndex] = timestamp;
+            // clear opposite vote for a subgraph deployment if it exists
+            lastDenyVote[currentNonce][_subgraphDeploymentID][_oracleIndex] = 0;
+        }
 
         emit OracleVote(_subgraphDeploymentID, _deny, _oracleIndex, timestamp);
 

packages/contracts/test/rewards/subgraphAvailability.test.ts

@@ -329,6 +329,31 @@ describe('SubgraphAvailabilityManager', () => {
       // previous votes are no longer valid
       expect(await rewardsManager.isDenied(subgraphDeploymentID1)).to.be.false
     })
+
+    it('clears opposite vote when voting', async () => {
+      const denied = true
+      await subgraphAvailabilityManager.connect(oracleOne).vote(subgraphDeploymentID1, denied, 0)
+      await subgraphAvailabilityManager.connect(oracleTwo).vote(subgraphDeploymentID1, denied, 1)
+      await subgraphAvailabilityManager.connect(oracleThree).vote(subgraphDeploymentID1, denied, 2)
+
+      // 3/5 oracles vote denied = true so subgraph is denied
+      expect(await rewardsManager.isDenied(subgraphDeploymentID1)).to.be.true
+
+      // oracleOne changes its vote to denied = false
+      await subgraphAvailabilityManager.connect(oracleOne).vote(subgraphDeploymentID1, false, 0)
+
+      // last deny vote should be 0 for oracleOne
+      expect(
+        await subgraphAvailabilityManager.lastDenyVote(0, subgraphDeploymentID1, 0),
+      ).to.be.equal(0)
+
+      // executionThreshold isn't met now since oracleOne changed its vote
+      expect(await subgraphAvailabilityManager.checkVotes(subgraphDeploymentID1, denied)).to.be
+        .false
+
+      // subgraph is still denied in rewards manager because only one oracle changed its vote
+      expect(await rewardsManager.isDenied(subgraphDeploymentID1)).to.be.true
+    })
   })
 
   describe('vote many', async () => {