core, dex: Optimize sender calculation in block transactions. (#22)

* Add Transactions.TouchSenders that calculates sender and update cache

* Use TouchSenders to fill the caches

3 files changed, 40 insertions, 0 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index 3b71cb64b..60730d197 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -347,6 +347,10 @@ func (bc *BlockChain) AddConfirmedBlock(block *coreTypes.Block) error {
 	if err != nil {
 		return err
 	}
+	_, err := transactions.TouchSenders(types.MakeSigner(bc.Config(), new(big.Int)))
+	if err != nil {
+		return err
+	}
 
 	addressMap := map[common.Address]struct{}{}
 	for _, tx := range transactions {
diff --git a/core/types/transaction.go b/core/types/transaction.go
index 857ac2137..46c24bd81 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -21,6 +21,7 @@ import (
 	"errors"
 	"io"
 	"math/big"
+	"sync"
 	"sync/atomic"
 
 	"github.com/dexon-foundation/dexon/common"
@@ -271,6 +272,35 @@ func (s Transactions) GetRlp(i int) []byte {
 	return enc
 }
 
+// TouchSenders calculates the sender of each transaction and update the cache.
+func (s Transactions) TouchSenders(signer Signer) (errorTx *Transaction, err error) {
+	wg := sync.WaitGroup{}
+	wg.Add(len(s))
+	txError := make(chan error, 1)
+	for _, tx := range s {
+		go func(tx *Transaction) {
+			defer wg.Done()
+			if len(txError) > 0 {
+				return
+			}
+			_, err := Sender(signer, tx)
+			if err != nil {
+				select {
+				case txError <- err:
+					errorTx = tx
+				default:
+				}
+			}
+		}(tx)
+	}
+	wg.Wait()
+	select {
+	case err = <-txError:
+	default:
+	}
+	return
+}
+
 // TxDifference returns a new set which is the difference between a and b.
 func TxDifference(a, b Transactions) Transactions {
 	keep := make(Transactions, 0, len(a))
diff --git a/dex/app.go b/dex/app.go
index a90dfae37..7d9c9e13a 100644
--- a/dex/app.go
+++ b/dex/app.go
@@ -362,6 +362,12 @@ func (d *DexconApp) VerifyBlock(block *coreTypes.Block) coreTypes.BlockVerifySta
 		return coreTypes.VerifyInvalidBlock
 	}
 
+	_, err := transactions.TouchSenders(types.MakeSigner(d.blockchain.Config(), new(big.Int)))
+	if err != nil {
+		log.Error("Failed to calculate sender", "error", err)
+		return coreTypes.VerifyInvalidBlock
+	}
+
 	addressNonce, err := d.validateNonce(transactions)
 	if err != nil {
 		log.Error("Validate nonce failed", "error", err)