[skip changelog] New transaction ordering optimized

Comment added for clarity

Unnecessary parameters removed

Libplanet/Blocks/Block.cs

@@ -647,8 +647,8 @@ internal static IEnumerable<Transaction<T>> OrderTxsForEvaluation(
             BlockHash preEvaluationHash)
         {
             return protocolVersion > 1
-                ? OrderTxsForEvaluationV2(protocolVersion, txs, preEvaluationHash)
-                : OrderTxsForEvaluationV0(protocolVersion, txs, preEvaluationHash);
+                ? OrderTxsForEvaluationV2(txs, preEvaluationHash)
+                : OrderTxsForEvaluationV0(txs, preEvaluationHash);
         }
 
         internal void Validate(DateTimeOffset currentTime)
@@ -723,12 +723,9 @@ internal RawBlock ToRawBlock()
         }
 
         private static IEnumerable<Transaction<T>> OrderTxsForEvaluationV0(
-            int protocolVersion,
             IEnumerable<Transaction<T>> txs,
             BlockHash preEvaluationHash)
         {
-            // As the order of transactions should be unpredictable until a block is mined,
-            // the sorter key should be derived from both a block hash and a txid.
             var maskInteger = new BigInteger(preEvaluationHash.ToByteArray());
 
             // Transactions with the same signers are grouped first and the ordering of the groups
@@ -745,16 +742,20 @@ private static IEnumerable<Transaction<T>> OrderTxsForEvaluationV0(
         }
 
         private static IEnumerable<Transaction<T>> OrderTxsForEvaluationV2(
-            int protocolVersion,
             IEnumerable<Transaction<T>> txs,
             BlockHash preEvaluationHash)
         {
             using SHA256 sha256 = SHA256.Create();
-            var mask = new BigInteger(sha256.ComputeHash(preEvaluationHash.ToByteArray()));
-            var numShiftBits = sizeof(long) * 8;
+            var maskInteger = new BigInteger(sha256.ComputeHash(preEvaluationHash.ToByteArray()));
 
-            return txs.OrderBy(tx =>
-                ((new BigInteger(tx.Signer.ToByteArray()) ^ mask) << numShiftBits) + tx.Nonce);
+            // Transactions with the same signers are grouped first and the ordering of the groups
+            // is determined by the signer's address with XOR bitmask applied using
+            // the pre-evaluation hash provided.  Then within each group, transactions
+            // are ordered by nonce.
+            return txs
+                .GroupBy(tx => tx.Signer)
+                .OrderBy(group => maskInteger ^ new BigInteger(group.Key.ToByteArray()))
+                .SelectMany(group => group.OrderBy(tx => tx.Nonce));
         }
 
         private readonly struct BlockSerializationContext