faster computation of transaction ID and length

data/pools/transactionPool.go

@@ -763,7 +763,7 @@ func (pool *TransactionPool) AssembleBlock(round basics.Round, deadline time.Tim
 
 				for i, txib := range payset {
 					fee := txib.Txn.Fee.Raw
-					encodedLen := len(protocol.Encode(&txib))
+					encodedLen := txib.GetEncodedLength()
 
 					stats.IncludedCount++
 					totalFees += fee

data/transactions/signedtxn.go

@@ -70,7 +70,16 @@ func (s SignedTxnInBlock) ID() {
 
 // GetEncodedLength returns the length in bytes of the encoded transaction
 func (s SignedTxn) GetEncodedLength() int {
-	return len(protocol.Encode(&s))
+	enc := s.MarshalMsg(protocol.GetEncodingBuf())
+	defer protocol.PutEncodingBuf(enc)
+	return len(enc)
+}
+
+// GetEncodedLength returns the length in bytes of the encoded transaction
+func (s SignedTxnInBlock) GetEncodedLength() int {
+	enc := s.MarshalMsg(protocol.GetEncodingBuf())
+	defer protocol.PutEncodingBuf(enc)
+	return len(enc)
 }
 
 // Authorizer returns the address against which the signature/msig/lsig should be checked,

data/transactions/transaction.go

@@ -156,7 +156,9 @@ func (tx Transaction) ToBeHashed() (protocol.HashID, []byte) {
 
 // ID returns the Txid (i.e., hash) of the transaction.
 func (tx Transaction) ID() Txid {
-	return Txid(crypto.HashObj(tx))
+	enc := tx.MarshalMsg(append(protocol.GetEncodingBuf(), []byte(protocol.Transaction)...))
+	defer protocol.PutEncodingBuf(enc)
+	return Txid(crypto.Hash(enc))
 }
 
 // Sign signs a transaction using a given Account's secrets.

ledger/eval.go

@@ -733,7 +733,7 @@ func (eval *BlockEvaluator) transactionGroup(txgroup []transactions.SignedTxnWit
 		txibs = append(txibs, txib)
 
 		if eval.validate {
-			groupTxBytes += len(protocol.Encode(&txib))
+			groupTxBytes += txib.GetEncodedLength()
 			if eval.blockTxBytes+groupTxBytes > eval.proto.MaxTxnBytesPerBlock {
 				return ErrNoSpace
 			}

protocol/codec.go

@@ -241,3 +241,25 @@ func NewJSONDecoder(r io.Reader) Decoder {
 func NewDecoderBytes(b []byte) Decoder {
 	return codec.NewDecoderBytes(b, CodecHandle)
 }
+
+// encodingPool holds temporary byte slice buffers used for encoding messages.
+var encodingPool = sync.Pool{
+	New: func() interface{} {
+		return []byte{}
+	},
+}
+
+// GetEncodingBuf returns a byte slice that can be used for encoding a
+// temporary message.  The byte slice has zero length but potentially
+// non-zero capacity.  The caller gets full ownership of the byte slice,
+// but is encouraged to return it using PutEncodingBuf().
+func GetEncodingBuf() []byte {
+	return encodingPool.Get().([]byte)[:0]
+}
+
+// PutEncodingBuf places a byte slice into the pool of temporary buffers
+// for encoding.  The caller gives up ownership of the byte slice when
+// passing it to PutEncodingBuf().
+func PutEncodingBuf(s []byte) {
+	encodingPool.Put(s)
+}