From 191f1d5ee266d32cf08f243f953925718fdb61c1 Mon Sep 17 00:00:00 2001
From: Rongjian Lan <rongjian.lan@gmail.com>
Date: Sun, 5 Apr 2020 21:11:21 -0700
Subject: [PATCH] Final attempt: Don't div by 0; print out debug info (#2746)

* Revert "Revert "fix earned-reward by writing the stats only once, remove from UpdateValdiatorVotingPower (#2737)" (#2742)"

This reverts commit 832b01dfff0b2fec3cc647f507a8d105a8dbf4a7.

* Don't div by 0; print out debug info
---
 core/blockchain.go              | 23 +++++++----------
 core/offchain.go                | 44 +++++++++++++++++----------------
 staking/availability/measure.go |  8 ++++--
 3 files changed, 38 insertions(+), 37 deletions(-)

diff --git a/core/blockchain.go b/core/blockchain.go
index 6d54f2a1c..7def6bed7 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -2287,9 +2287,9 @@ func (bc *BlockChain) UpdateValidatorVotingPower(
 	block *types.Block,
 	newEpochSuperCommittee, currentEpochSuperCommittee *shard.State,
 	state *state.DB,
-) error {
+) (map[common.Address]*staking.ValidatorStats, error) {
 	if newEpochSuperCommittee == nil {
-		return shard.ErrSuperCommitteeNil
+		return nil, shard.ErrSuperCommitteeNil
 	}
 
 	rosters, bootedFromSuperCommittee :=
@@ -2319,7 +2319,7 @@ func (bc *BlockChain) UpdateValidatorVotingPower(
 	for i := range newEpochSuperCommittee.Shards {
 		subCommittee := &newEpochSuperCommittee.Shards[i]
 		if newEpochSuperCommittee.Epoch == nil {
-			return errors.Wrapf(
+			return nil, errors.Wrapf(
 				errNilEpoch,
 				"block epoch %v current-committee-epoch %v",
 				block.Epoch(),
@@ -2328,13 +2328,13 @@ func (bc *BlockChain) UpdateValidatorVotingPower(
 		}
 		roster, err := votepower.Compute(subCommittee, newEpochSuperCommittee.Epoch)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		rosters[i] = roster
 	}
 
+	validatorStats := map[common.Address]*staking.ValidatorStats{}
 	networkWide := votepower.AggregateRosters(rosters)
-
 	for key, value := range networkWide {
 		stats, err := rawdb.ReadValidatorStats(bc.db, key)
 		if err != nil {
@@ -2358,7 +2358,7 @@ func (bc *BlockChain) UpdateValidatorVotingPower(
 		if currentEpochSuperCommittee.Epoch != nil {
 			wrapper, err := state.ValidatorWrapper(key)
 			if err != nil {
-				return err
+				return nil, err
 			}
 
 			aprComputed, err := apr.ComputeForValidator(
@@ -2382,7 +2382,7 @@ func (bc *BlockChain) UpdateValidatorVotingPower(
 			)
 
 			if err != nil {
-				return err
+				return nil, err
 			}
 
 			computed := availability.ComputeCurrentSigning(snapshot, wrapper)
@@ -2399,15 +2399,10 @@ func (bc *BlockChain) UpdateValidatorVotingPower(
 				stats.BootedStatus = effective.BannedForDoubleSigning
 			}
 		}
-
-		if err := rawdb.WriteValidatorStats(
-			batch, key, stats,
-		); err != nil {
-			return err
-		}
+		validatorStats[key] = stats
 	}
 
-	return nil
+	return validatorStats, nil
 }
 
 // deleteValidatorSnapshots deletes the snapshot staking information of given validator address
diff --git a/core/offchain.go b/core/offchain.go
index 9f0355d9c..48bcae675 100644
--- a/core/offchain.go
+++ b/core/offchain.go
@@ -135,26 +135,6 @@ func (bc *BlockChain) CommitOffChainData(
 		}
 	}
 
-	// Update voting power of validators for all shards
-	if isNewEpoch && isBeaconChain {
-		currentSuperCommittee, _ := bc.ReadShardState(bc.CurrentHeader().Epoch())
-		if shardState, err := shard.DecodeWrapper(
-			header.ShardState(),
-		); err == nil {
-			if err := bc.UpdateValidatorVotingPower(
-				batch, block, shardState, currentSuperCommittee, state,
-			); err != nil {
-				utils.Logger().
-					Err(err).
-					Msg("[UpdateValidatorVotingPower] Failed to update voting power")
-			}
-		} else {
-			utils.Logger().
-				Err(err).
-				Msg("[UpdateValidatorVotingPower] Failed to decode shard state")
-		}
-	}
-
 	// Writing beacon chain cross links
 	if isBeaconChain &&
 		bc.chainConfig.IsCrossLink(block.Epoch()) &&
@@ -214,6 +194,29 @@ func (bc *BlockChain) CommitOffChainData(
 		}
 	}
 
+	// Update voting power of validators for all shards
+	tempValidatorStats := map[common.Address]*staking.ValidatorStats{}
+	if isNewEpoch && isBeaconChain {
+		currentSuperCommittee, _ := bc.ReadShardState(bc.CurrentHeader().Epoch())
+		if shardState, err := shard.DecodeWrapper(
+			header.ShardState(),
+		); err == nil {
+			if stats, err := bc.UpdateValidatorVotingPower(
+				batch, block, shardState, currentSuperCommittee, state,
+			); err != nil {
+				utils.Logger().
+					Err(err).
+					Msg("[UpdateValidatorVotingPower] Failed to update voting power")
+			} else {
+				tempValidatorStats = stats
+			}
+		} else {
+			utils.Logger().
+				Err(err).
+				Msg("[UpdateValidatorVotingPower] Failed to decode shard state")
+		}
+	}
+
 	// Update block reward accumulator and slashes
 	if isBeaconChain {
 		if isStaking {
@@ -223,7 +226,6 @@ func (bc *BlockChain) CommitOffChainData(
 			); err != nil {
 				return NonStatTy, err
 			}
-			tempValidatorStats := map[common.Address]*staking.ValidatorStats{}
 			for _, paid := range [...][]reward.Payout{
 				roundResult.BeaconchainAward, roundResult.ShardChainAward,
 			} {
diff --git a/staking/availability/measure.go b/staking/availability/measure.go
index b73bac020..75ad45616 100644
--- a/staking/availability/measure.go
+++ b/staking/availability/measure.go
@@ -184,8 +184,12 @@ func ComputeCurrentSigning(
 		utils.Logger().Error().Msg("negative number of blocks to sign")
 	}
 
-	s1, s2 :=
-		numeric.NewDecFromBigInt(signed), numeric.NewDecFromBigInt(toSign)
+	s1, s2 := numeric.NewDecFromBigInt(signed), numeric.NewDecFromBigInt(toSign)
+	if s2.IsZero() || s2.IsNil() {
+		utils.Logger().Debug().Interface("s2", s2).
+			Msg("s2 is 0 or nil")
+		return computed
+	}
 	computed.Percentage = s1.Quo(s2)
 	computed.IsBelowThreshold = IsBelowSigningThreshold(computed.Percentage)
 	return computed