types: VerifyCommitX return when +2/3 sigs are verified (#4445)

Closes #4417

CHANGELOG_PENDING.md

@@ -19,6 +19,8 @@ program](https://hackerone.com/tendermint).
 
 ### IMPROVEMENTS:
 
+- [types] [\#4417](https://github.com/tendermint/tendermint/issues/4417) VerifyCommitX() functions should return as soon as +2/3 threashold is reached.
+
 ### BUG FIXES:
 
 - [rpc] [\#4437](https://github.com/tendermint/tendermint/pull/4437) Fix tx_search pagination with ordered results (@erikgrinaker)

types/validator_set.go

@@ -636,6 +636,7 @@ func (vals *ValidatorSet) VerifyCommit(chainID string, blockID BlockID,
 	}
 
 	talliedVotingPower := int64(0)
+	votingPowerNeeded := vals.TotalVotingPower() * 2 / 3
 	for idx, commitSig := range commit.Signatures {
 		if commitSig.Absent() {
 			continue // OK, some signatures can be absent.
@@ -658,13 +659,15 @@ func (vals *ValidatorSet) VerifyCommit(chainID string, blockID BlockID,
 		// It's OK that the BlockID doesn't match.  We include stray
 		// signatures (~votes for nil) to measure validator availability.
 		// }
+
+		// return as soon as +2/3 of the signatures are verified
+		if talliedVotingPower > votingPowerNeeded {
+			return nil
+		}
 	}
 
-	if got, needed := talliedVotingPower, vals.TotalVotingPower()*2/3; got <= needed {
-		return ErrNotEnoughVotingPowerSigned{Got: got, Needed: needed}
-	}
-
-	return nil
+	// talliedVotingPower <= needed, thus return error
+	return ErrNotEnoughVotingPowerSigned{Got: talliedVotingPower, Needed: votingPowerNeeded}
 }
 
 // VerifyFutureCommit will check to see if the set would be valid with a different
@@ -762,6 +765,7 @@ func (vals *ValidatorSet) VerifyCommitTrusting(chainID string, blockID BlockID,
 	var (
 		talliedVotingPower int64
 		seenVals           = make(map[int]int, len(commit.Signatures)) // validator index -> commit index
+		votingPowerNeeded  = (vals.TotalVotingPower() * trustLevel.Numerator) / trustLevel.Denominator
 	)
 
 	for idx, commitSig := range commit.Signatures {
@@ -795,16 +799,14 @@ func (vals *ValidatorSet) VerifyCommitTrusting(chainID string, blockID BlockID,
 			// It's OK that the BlockID doesn't match.  We include stray
 			// signatures (~votes for nil) to measure validator availability.
 			// }
+
+			if talliedVotingPower > votingPowerNeeded {
+				return nil
+			}
 		}
 	}
 
-	got := talliedVotingPower
-	needed := (vals.TotalVotingPower() * trustLevel.Numerator) / trustLevel.Denominator
-	if got <= needed {
-		return ErrNotEnoughVotingPowerSigned{Got: got, Needed: needed}
-	}
-
-	return nil
+	return ErrNotEnoughVotingPowerSigned{Got: talliedVotingPower, Needed: votingPowerNeeded}
 }
 
 func verifyCommitBasic(commit *Commit, height int64, blockID BlockID) error {