Simplify and improve consensus payload serialization and deserializat…

…ion (neo-project#1149)

* Simplify and improve consensus payload serialiation

* Simplyfing read

* Function return instead of out parameter

* Reorganize

* Update UT_IOHelper.cs

neo.UnitTests/IO/UT_IOHelper.cs

@@ -23,6 +23,46 @@ public void TestAsSerializableGeneric()
             Assert.AreEqual(UInt160.Zero, result);
         }
 
+        [TestMethod]
+        public void TestNullableArray()
+        {
+            var caseArray = new UInt160[]
+            {
+                null, UInt160.Zero, new UInt160(
+                new byte[] {
+                    0xAA,0x00,0x00,0x00,0x00,
+                    0xBB,0x00,0x00,0x00,0x00,
+                    0xCC,0x00,0x00,0x00,0x00,
+                    0xDD,0x00,0x00,0x00,0x00
+                })
+            };
+
+            byte[] data;
+            using (var stream = new MemoryStream())
+            using (var writter = new BinaryWriter(stream))
+            {
+                Neo.IO.Helper.WriteNullableArray(writter, caseArray);
+                data = stream.ToArray();
+            }
+
+            // Read Error
+
+            using (var stream = new MemoryStream(data))
+            using (var reader = new BinaryReader(stream))
+            {
+                Assert.ThrowsException<FormatException>(() => Neo.IO.Helper.ReadNullableArray<UInt160>(reader, 2));
+            }
+
+            // Read 100%
+
+            using (var stream = new MemoryStream(data))
+            using (var reader = new BinaryReader(stream))
+            {
+                var read = Neo.IO.Helper.ReadNullableArray<UInt160>(reader);
+                CollectionAssert.AreEqual(caseArray, read);
+            }
+        }
+
         [TestMethod]
         public void TestAsSerializable()
         {
@@ -48,7 +88,7 @@ public void TestAsSerializable()
         [TestMethod]
         public void TestAsSerializableArray()
         {
-            byte[] byteArray = Neo.IO.Helper.ToByteArray<UInt160>(new UInt160[] { UInt160.Zero });
+            byte[] byteArray = Neo.IO.Helper.ToByteArray(new UInt160[] { UInt160.Zero });
             UInt160[] result = Neo.IO.Helper.AsSerializableArray<UInt160>(byteArray);
             Assert.AreEqual(1, result.Length);
             Assert.AreEqual(UInt160.Zero, result[0]);

neo/Consensus/ConsensusContext.cs

@@ -104,18 +104,10 @@ public void Deserialize(BinaryReader reader)
             ViewNumber = reader.ReadByte();
             TransactionHashes = reader.ReadSerializableArray<UInt256>();
             Transaction[] transactions = reader.ReadSerializableArray<Transaction>(Block.MaxTransactionsPerBlock);
-            PreparationPayloads = new ConsensusPayload[reader.ReadVarInt(Blockchain.MaxValidators)];
-            for (int i = 0; i < PreparationPayloads.Length; i++)
-                PreparationPayloads[i] = reader.ReadBoolean() ? reader.ReadSerializable<ConsensusPayload>() : null;
-            CommitPayloads = new ConsensusPayload[reader.ReadVarInt(Blockchain.MaxValidators)];
-            for (int i = 0; i < CommitPayloads.Length; i++)
-                CommitPayloads[i] = reader.ReadBoolean() ? reader.ReadSerializable<ConsensusPayload>() : null;
-            ChangeViewPayloads = new ConsensusPayload[reader.ReadVarInt(Blockchain.MaxValidators)];
-            for (int i = 0; i < ChangeViewPayloads.Length; i++)
-                ChangeViewPayloads[i] = reader.ReadBoolean() ? reader.ReadSerializable<ConsensusPayload>() : null;
-            LastChangeViewPayloads = new ConsensusPayload[reader.ReadVarInt(Blockchain.MaxValidators)];
-            for (int i = 0; i < LastChangeViewPayloads.Length; i++)
-                LastChangeViewPayloads[i] = reader.ReadBoolean() ? reader.ReadSerializable<ConsensusPayload>() : null;
+            PreparationPayloads = reader.ReadNullableArray<ConsensusPayload>(Blockchain.MaxValidators);
+            CommitPayloads = reader.ReadNullableArray<ConsensusPayload>(Blockchain.MaxValidators);
+            ChangeViewPayloads = reader.ReadNullableArray<ConsensusPayload>(Blockchain.MaxValidators);
+            LastChangeViewPayloads = reader.ReadNullableArray<ConsensusPayload>(Blockchain.MaxValidators);
             if (TransactionHashes.Length == 0 && !RequestSentOrReceived)
                 TransactionHashes = null;
             Transactions = transactions.Length == 0 && !RequestSentOrReceived ? null : transactions.ToDictionary(p => p.Hash);
@@ -416,38 +408,10 @@ public void Serialize(BinaryWriter writer)
             writer.Write(ViewNumber);
             writer.Write(TransactionHashes ?? new UInt256[0]);
             writer.Write(Transactions?.Values.ToArray() ?? new Transaction[0]);
-            writer.WriteVarInt(PreparationPayloads.Length);
-            foreach (var payload in PreparationPayloads)
-            {
-                bool hasPayload = !(payload is null);
-                writer.Write(hasPayload);
-                if (!hasPayload) continue;
-                writer.Write(payload);
-            }
-            writer.WriteVarInt(CommitPayloads.Length);
-            foreach (var payload in CommitPayloads)
-            {
-                bool hasPayload = !(payload is null);
-                writer.Write(hasPayload);
-                if (!hasPayload) continue;
-                writer.Write(payload);
-            }
-            writer.WriteVarInt(ChangeViewPayloads.Length);
-            foreach (var payload in ChangeViewPayloads)
-            {
-                bool hasPayload = !(payload is null);
-                writer.Write(hasPayload);
-                if (!hasPayload) continue;
-                writer.Write(payload);
-            }
-            writer.WriteVarInt(LastChangeViewPayloads.Length);
-            foreach (var payload in LastChangeViewPayloads)
-            {
-                bool hasPayload = !(payload is null);
-                writer.Write(hasPayload);
-                if (!hasPayload) continue;
-                writer.Write(payload);
-            }
+            writer.WriteNullableArray(PreparationPayloads);
+            writer.WriteNullableArray(CommitPayloads);
+            writer.WriteNullableArray(ChangeViewPayloads);
+            writer.WriteNullableArray(LastChangeViewPayloads);
         }
     }
 }

neo/IO/Helper.cs

@@ -112,6 +112,14 @@ public static string ReadFixedString(this BinaryReader reader, int length)
             return Encoding.UTF8.GetString(data.TakeWhile(p => p != 0).ToArray());
         }
 
+        public static T[] ReadNullableArray<T>(this BinaryReader reader, int max = 0x1000000) where T : class, ISerializable, new()
+        {
+            T[] array = new T[reader.ReadVarInt((ulong)max)];
+            for (int i = 0; i < array.Length; i++)
+                array[i] = reader.ReadBoolean() ? reader.ReadSerializable<T>() : null;
+            return array;
+        }
+
         public static T ReadSerializable<T>(this BinaryReader reader) where T : ISerializable, new()
         {
             T obj = new T();
@@ -225,6 +233,18 @@ public static void WriteFixedString(this BinaryWriter writer, string value, int
                 writer.Write(new byte[length - bytes.Length]);
         }
 
+        public static void WriteNullableArray<T>(this BinaryWriter writer, T[] value) where T : class, ISerializable
+        {
+            writer.WriteVarInt(value.Length);
+            foreach (var item in value)
+            {
+                bool isNull = item is null;
+                writer.Write(!isNull);
+                if (isNull) continue;
+                item.Serialize(writer);
+            }
+        }
+
         public static void WriteVarBytes(this BinaryWriter writer, byte[] value)
         {
             writer.WriteVarInt(value.Length);