From 14f4db7c19c16e5499fb277c3f90971550bc90b8 Mon Sep 17 00:00:00 2001
From: Anca Zamfir <ancazamfir@users.noreply.github.com>
Date: Thu, 9 Dec 2021 05:01:27 +0100
Subject: [PATCH] Remove MedianTime, set block time to Now() (#7382)

* Remove MedianTime, set block time to Now()

* Fix goimports

* Fix import ordering
---
 internal/state/state.go           | 25 +------------------------
 internal/state/validation.go      |  7 -------
 internal/state/validation_test.go |  1 -
 3 files changed, 1 insertion(+), 32 deletions(-)

diff --git a/internal/state/state.go b/internal/state/state.go
index 8b69e6f0c..876c87fe8 100644
--- a/internal/state/state.go
+++ b/internal/state/state.go
@@ -268,7 +268,7 @@ func (state State) MakeBlock(
 	if height == state.InitialHeight {
 		timestamp = state.LastBlockTime // genesis time
 	} else {
-		timestamp = MedianTime(commit, state.LastValidators)
+		timestamp = time.Now()
 	}
 
 	// Fill rest of header with state data.
@@ -288,29 +288,6 @@ func (state State) MakeBlock(
 	return block, bps, nil
 }
 
-// MedianTime computes a median time for a given Commit (based on Timestamp field of votes messages) and the
-// corresponding validator set. The computed time is always between timestamps of
-// the votes sent by honest processes, i.e., a faulty processes can not arbitrarily increase or decrease the
-// computed value.
-func MedianTime(commit *types.Commit, validators *types.ValidatorSet) time.Time {
-	weightedTimes := make([]*weightedTime, len(commit.Signatures))
-	totalVotingPower := int64(0)
-
-	for i, commitSig := range commit.Signatures {
-		if commitSig.Absent() {
-			continue
-		}
-		_, validator := validators.GetByAddress(commitSig.ValidatorAddress)
-		// If there's no condition, TestValidateBlockCommit panics; not needed normally.
-		if validator != nil {
-			totalVotingPower += validator.VotingPower
-			weightedTimes[i] = newWeightedTime(commitSig.Timestamp, validator.VotingPower)
-		}
-	}
-
-	return weightedMedian(weightedTimes, totalVotingPower)
-}
-
 //------------------------------------------------------------------------
 // Genesis
 
diff --git a/internal/state/validation.go b/internal/state/validation.go
index fbd285f8a..8bec8f119 100644
--- a/internal/state/validation.go
+++ b/internal/state/validation.go
@@ -114,13 +114,6 @@ func validateBlock(state State, block *types.Block) error {
 				state.LastBlockTime,
 			)
 		}
-		medianTime := MedianTime(block.LastCommit, state.LastValidators)
-		if !block.Time.Equal(medianTime) {
-			return fmt.Errorf("invalid block time. Expected %v, got %v",
-				medianTime,
-				block.Time,
-			)
-		}
 
 	case block.Height == state.InitialHeight:
 		genesisTime := state.LastBlockTime
diff --git a/internal/state/validation_test.go b/internal/state/validation_test.go
index 411740c37..3fb723a27 100644
--- a/internal/state/validation_test.go
+++ b/internal/state/validation_test.go
@@ -64,7 +64,6 @@ func TestValidateBlockHeader(t *testing.T) {
 		{"ChainID wrong", func(block *types.Block) { block.ChainID = "not-the-real-one" }},
 		{"Height wrong", func(block *types.Block) { block.Height += 10 }},
 		{"Time wrong", func(block *types.Block) { block.Time = block.Time.Add(-time.Second * 1) }},
-		{"Time wrong 2", func(block *types.Block) { block.Time = block.Time.Add(time.Second * 1) }},
 
 		{"LastBlockID wrong", func(block *types.Block) { block.LastBlockID.PartSetHeader.Total += 10 }},
 		{"LastCommitHash wrong", func(block *types.Block) { block.LastCommitHash = wrongHash }},