core: remove useless branching code (#403)

7 files changed, 29 insertions, 80 deletions

diff --git a/core/agreement-state.go b/core/agreement-state.go
index 77f2933..69700b5 100644
--- a/core/agreement-state.go
+++ b/core/agreement-state.go
@@ -43,7 +43,7 @@ const (
 	stateSleep
 )
 
-var nullBlockHash = common.Hash{}
+var nullBlockHash common.Hash
 var skipBlockHash common.Hash
 
 func init() {
diff --git a/core/agreement.go b/core/agreement.go
index eead462..80a09d2 100644
--- a/core/agreement.go
+++ b/core/agreement.go
@@ -280,19 +280,14 @@ func (a *agreement) sanityCheck(vote *types.Vote) error {
 }
 
 func (a *agreement) checkForkVote(vote *types.Vote) error {
-	if err := func() error {
-		a.data.lock.RLock()
-		defer a.data.lock.RUnlock()
-		if votes, exist := a.data.votes[vote.Period]; exist {
-			if oldVote, exist := votes[vote.Type][vote.ProposerID]; exist {
-				if vote.BlockHash != oldVote.BlockHash {
-					return &ErrForkVote{vote.ProposerID, oldVote, vote}
-				}
+	a.data.lock.RLock()
+	defer a.data.lock.RUnlock()
+	if votes, exist := a.data.votes[vote.Period]; exist {
+		if oldVote, exist := votes[vote.Type][vote.ProposerID]; exist {
+			if vote.BlockHash != oldVote.BlockHash {
+				return &ErrForkVote{vote.ProposerID, oldVote, vote}
 			}
 		}
-		return nil
-	}(); err != nil {
-		return err
 	}
 	return nil
 }
diff --git a/core/consensus.go b/core/consensus.go
index 0e5a1fb..7ceac51 100644
--- a/core/consensus.go
+++ b/core/consensus.go
@@ -1086,9 +1086,7 @@ func (con *Consensus) deliverFinalizedBlocksWithoutLock() (err error) {
 	for _, b := range deliveredBlocks {
 		con.deliverBlock(b)
 	}
-	if err = con.lattice.PurgeBlocks(deliveredBlocks); err != nil {
-		return
-	}
+	err = con.lattice.PurgeBlocks(deliveredBlocks)
 	return
 }
 
@@ -1150,9 +1148,7 @@ func (con *Consensus) prepareBlock(b *types.Block,
 		err = ErrCRSNotReady
 		return
 	}
-	if err = con.signer.SignCRS(b, crs); err != nil {
-		return
-	}
+	err = con.signer.SignCRS(b, crs)
 	return
 }
 
diff --git a/core/db/level-db.go b/core/db/level-db.go
index 75c3037..1fe29fa 100644
--- a/core/db/level-db.go
+++ b/core/db/level-db.go
@@ -72,11 +72,7 @@ func (lvl *LevelDBBackedDB) HasBlock(hash common.Hash) bool {
 }
 
 func (lvl *LevelDBBackedDB) internalHasBlock(key []byte) (bool, error) {
-	exists, err := lvl.db.Has(key, nil)
-	if err != nil {
-		return false, err
-	}
-	return exists, nil
+	return lvl.db.Has(key, nil)
 }
 
 // GetBlock implements the Reader.GetBlock method.
@@ -90,9 +86,6 @@ func (lvl *LevelDBBackedDB) GetBlock(
 		return
 	}
 	err = rlp.DecodeBytes(queried, &block)
-	if err != nil {
-		return
-	}
 	return
 }
 
@@ -113,9 +106,7 @@ func (lvl *LevelDBBackedDB) UpdateBlock(block types.Block) (err error) {
 		err = ErrBlockDoesNotExist
 		return
 	}
-	if err = lvl.db.Put(blockKey, marshaled, nil); err != nil {
-		return
-	}
+	err = lvl.db.Put(blockKey, marshaled, nil)
 	return
 }
 
@@ -134,9 +125,7 @@ func (lvl *LevelDBBackedDB) PutBlock(block types.Block) (err error) {
 		err = ErrBlockExists
 		return
 	}
-	if err = lvl.db.Put(blockKey, marshaled, nil); err != nil {
-		return
-	}
+	err = lvl.db.Put(blockKey, marshaled, nil)
 	return
 }
 
@@ -166,10 +155,7 @@ func (lvl *LevelDBBackedDB) PutCompactionChainTipInfo(
 	if info.Height+1 != height {
 		return ErrInvalidCompactionChainTipHeight
 	}
-	if err = lvl.db.Put(compactionChainTipInfoKey, marshaled, nil); err != nil {
-		return err
-	}
-	return nil
+	return lvl.db.Put(compactionChainTipInfoKey, marshaled, nil)
 }
 
 func (lvl *LevelDBBackedDB) internalGetCompactionChainTipInfo() (
@@ -181,9 +167,7 @@ func (lvl *LevelDBBackedDB) internalGetCompactionChainTipInfo() (
 		}
 		return
 	}
-	if err = rlp.DecodeBytes(queried, &info); err != nil {
-		return
-	}
+	err = rlp.DecodeBytes(queried, &info)
 	return
 }
 
@@ -201,11 +185,7 @@ func (lvl *LevelDBBackedDB) GetCompactionChainTipInfo() (
 
 // HasDKGPrivateKey check existence of DKG private key of one round.
 func (lvl *LevelDBBackedDB) HasDKGPrivateKey(round uint64) (bool, error) {
-	exists, err := lvl.db.Has(lvl.getDKGPrivateKeyKey(round), nil)
-	if err != nil {
-		return false, err
-	}
-	return exists, nil
+	return lvl.db.Has(lvl.getDKGPrivateKeyKey(round), nil)
 }
 
 // GetDKGPrivateKey get DKG private key of one round.
@@ -218,9 +198,7 @@ func (lvl *LevelDBBackedDB) GetDKGPrivateKey(round uint64) (
 		}
 		return
 	}
-	if err = rlp.DecodeBytes(queried, &prv); err != nil {
-		return
-	}
+	err = rlp.DecodeBytes(queried, &prv)
 	return
 }
 
@@ -239,11 +217,8 @@ func (lvl *LevelDBBackedDB) PutDKGPrivateKey(
 	if err != nil {
 		return err
 	}
-	if err := lvl.db.Put(
-		lvl.getDKGPrivateKeyKey(round), marshaled, nil); err != nil {
-		return err
-	}
-	return nil
+	return lvl.db.Put(
+		lvl.getDKGPrivateKeyKey(round), marshaled, nil)
 }
 
 func (lvl *LevelDBBackedDB) getBlockKey(hash common.Hash) (ret []byte) {
diff --git a/core/lattice-data.go b/core/lattice-data.go
index e55c0db..998fb1f 100644
--- a/core/lattice-data.go
+++ b/core/lattice-data.go
@@ -257,10 +257,7 @@ func (data *latticeData) sanityCheck(b *types.Block) error {
 			return ErrNotAckParent
 		}
 	}
-	if err := data.checkAckingRelations(b); err != nil {
-		return err
-	}
-	return nil
+	return data.checkAckingRelations(b)
 }
 
 // addBlock processes blocks. It does sanity check, inserts block into lattice
diff --git a/core/lattice.go b/core/lattice.go
index b30306a..4c53352 100644
--- a/core/lattice.go
+++ b/core/lattice.go
@@ -90,9 +90,7 @@ func (l *Lattice) PrepareBlock(
 	if b.Witness, err = l.app.PrepareWitness(b.Witness.Height); err != nil {
 		return
 	}
-	if err = l.signer.SignBlock(b); err != nil {
-		return
-	}
+	err = l.signer.SignBlock(b)
 	return
 }
 
@@ -103,9 +101,7 @@ func (l *Lattice) PrepareEmptyBlock(b *types.Block) (err error) {
 	if err = l.data.prepareEmptyBlock(b); err != nil {
 		return
 	}
-	if b.Hash, err = utils.HashBlock(b); err != nil {
-		return
-	}
+	b.Hash, err = utils.HashBlock(b)
 	return
 }
 
@@ -139,18 +135,13 @@ func (l *Lattice) SanityCheck(b *types.Block) (err error) {
 			return
 		}
 	}
-	if err = func() (err error) {
-		l.lock.RLock()
-		defer l.lock.RUnlock()
-		if err = l.data.sanityCheck(b); err != nil {
-			if _, ok := err.(*ErrAckingBlockNotExists); ok {
-				err = ErrRetrySanityCheckLater
-			}
-			return
+	l.lock.RLock()
+	defer l.lock.RUnlock()
+	if err = l.data.sanityCheck(b); err != nil {
+		if _, ok := err.(*ErrAckingBlockNotExists); ok {
+			err = ErrRetrySanityCheckLater
 		}
 		return
-	}(); err != nil {
-		return
 	}
 	return
 }
@@ -159,10 +150,8 @@ func (l *Lattice) SanityCheck(b *types.Block) (err error) {
 func (l *Lattice) Exist(hash common.Hash) bool {
 	l.lock.RLock()
 	defer l.lock.RUnlock()
-	if _, err := l.data.findBlock(hash); err != nil {
-		return false
-	}
-	return true
+	_, err := l.data.findBlock(hash)
+	return err == nil
 }
 
 // addBlockToLattice adds a block into lattice, and delivers blocks with the
diff --git a/core/leader-selector.go b/core/leader-selector.go
index 94d28fa..bcfa57f 100644
--- a/core/leader-selector.go
+++ b/core/leader-selector.go
@@ -150,10 +150,7 @@ func (l *leaderSelector) processBlock(block *types.Block) error {
 func (l *leaderSelector) potentialLeader(block *types.Block) (bool, *big.Int) {
 	dist := l.distance(block.CRSSignature)
 	cmp := l.minCRSBlock.Cmp(dist)
-	if cmp > 0 || (cmp == 0 && block.Hash.Less(l.minBlockHash)) {
-		return true, dist
-	}
-	return false, dist
+	return (cmp > 0 || (cmp == 0 && block.Hash.Less(l.minBlockHash))), dist
 }
 
 func (l *leaderSelector) updateLeader(block *types.Block, dist *big.Int) {