Optimize TransactionAttribute

src/neo/Network/P2P/Payloads/Cosigner.cs

@@ -17,11 +17,7 @@ public class Cosigner : TransactionAttribute
         public ECPoint[] AllowedGroups;
 
         public override TransactionAttributeType Type => TransactionAttributeType.Cosigner;
-
-        public Cosigner()
-        {
-            this.Scopes = WitnessScope.Global;
-        }
+        public override bool AllowMultiple => true;
 
         public override int Size => base.Size +
             /*Account*/             UInt160.Length +

src/neo/Network/P2P/Payloads/Transaction.cs

@@ -50,8 +50,8 @@ public TransactionAttribute[] Attributes
             set { attributes = value; _cosigners = null; _hash = null; _size = 0; }
         }
 
-        private Cosigner[] _cosigners;
-        public Cosigner[] Cosigners => _cosigners ??= attributes.OfType<Cosigner>().ToArray();
+        private Dictionary<UInt160, Cosigner> _cosigners;
+        public IReadOnlyDictionary<UInt160, Cosigner> Cosigners => _cosigners ??= attributes.OfType<Cosigner>().ToDictionary(p => p.Account);
 
         /// <summary>
         /// The <c>NetworkFee</c> for the transaction divided by its <c>Size</c>.
@@ -155,6 +155,19 @@ void ISerializable.Deserialize(BinaryReader reader)
                 _size = (int)reader.BaseStream.Position - startPosition;
         }
 
+        private static IEnumerable<TransactionAttribute> DeserializeAttributes(BinaryReader reader)
+        {
+            int count = (int)reader.ReadVarInt(MaxTransactionAttributes);
+            HashSet<TransactionAttributeType> hashset = new HashSet<TransactionAttributeType>();
+            while (count-- > 0)
+            {
+                TransactionAttribute attribute = TransactionAttribute.DeserializeFrom(reader);
+                if (!attribute.AllowMultiple && !hashset.Add(attribute.Type))
+                    throw new FormatException();
+                yield return attribute;
+            }
+        }
+
         public void DeserializeUnsigned(BinaryReader reader)
         {
             Version = reader.ReadByte();
@@ -167,10 +180,15 @@ public void DeserializeUnsigned(BinaryReader reader)
             if (NetworkFee < 0) throw new FormatException();
             if (SystemFee + NetworkFee < SystemFee) throw new FormatException();
             ValidUntilBlock = reader.ReadUInt32();
-            Attributes = new TransactionAttribute[reader.ReadVarInt(MaxTransactionAttributes)];
-            for (int i = 0; i < Attributes.Length; i++)
-                Attributes[i] = TransactionAttribute.DeserializeFrom(reader);
-            if (Cosigners.Select(u => u.Account).Distinct().Count() != Cosigners.Length) throw new FormatException();
+            Attributes = DeserializeAttributes(reader).ToArray();
+            try
+            {
+                _ = Cosigners;
+            }
+            catch (ArgumentException)
+            {
+                throw new FormatException();
+            }
             Script = reader.ReadVarBytes(ushort.MaxValue);
             if (Script.Length == 0) throw new FormatException();
         }
@@ -199,8 +217,7 @@ public override int GetHashCode()
 
         public UInt160[] GetScriptHashesForVerifying(StoreView snapshot)
         {
-            var hashes = new HashSet<UInt160> { Sender };
-            hashes.UnionWith(Cosigners.Select(p => p.Account));
+            var hashes = new HashSet<UInt160>(Cosigners.Keys) { Sender };
             return hashes.OrderBy(p => p).ToArray();
         }
 

src/neo/Network/P2P/Payloads/TransactionAttribute.cs

@@ -9,6 +9,7 @@ namespace Neo.Network.P2P.Payloads
     public abstract class TransactionAttribute : ISerializable
     {
         public abstract TransactionAttributeType Type { get; }
+        public abstract bool AllowMultiple { get; }
         public virtual int Size => sizeof(TransactionAttributeType);
 
         public void Deserialize(BinaryReader reader)

src/neo/SmartContract/InteropService.Runtime.cs

@@ -81,8 +81,7 @@ internal static bool CheckWitnessInternal(ApplicationEngine engine, UInt160 hash
             {
                 if (engine.ScriptContainer is Transaction tx)
                 {
-                    Cosigner cosigner = tx.Cosigners.FirstOrDefault(p => p.Account.Equals(hash));
-                    if (cosigner is null) return false;
+                    if (!tx.Cosigners.TryGetValue(hash, out Cosigner cosigner)) return false;
                     if (cosigner.Scopes == WitnessScope.Global) return true;
                     if (cosigner.Scopes.HasFlag(WitnessScope.CalledByEntry))
                     {

tests/neo.UnitTests/Ledger/UT_PoolItem.cs

@@ -132,7 +132,7 @@ public static Transaction GenerateTx(long networkFee, int size, byte[] overrideS
             };
 
             tx.Attributes.Length.Should().Be(0);
-            tx.Cosigners.Length.Should().Be(0);
+            tx.Cosigners.Count.Should().Be(0);
 
             int diff = size - tx.Size;
             if (diff < 0) throw new ArgumentException();

tests/neo.UnitTests/Network/P2P/Payloads/UT_Transaction.cs

@@ -11,6 +11,7 @@
 using Neo.VM;
 using Neo.Wallets;
 using System;
+using System.Linq;
 using System.Numerics;
 
 namespace Neo.UnitTests.Network.P2P.Payloads
@@ -250,10 +251,10 @@ public void FeeIsSignatureContractDetailed()
                 // Part II
                 Assert.AreEqual(23, tx.Attributes.GetVarSize());
                 Assert.AreEqual(1, tx.Attributes.Length);
-                Assert.AreEqual(1, tx.Cosigners.Length);
-                Assert.AreEqual(23, tx.Cosigners.GetVarSize());
+                Assert.AreEqual(1, tx.Cosigners.Count);
+                Assert.AreEqual(23, tx.Cosigners.Values.ToArray().GetVarSize());
                 // Note that Data size and Usage size are different (because of first byte on GetVarSize())
-                Assert.AreEqual(22, tx.Cosigners[0].Size);
+                Assert.AreEqual(22, tx.Cosigners.Values.First().Size);
                 // Part III
                 Assert.AreEqual(86, tx.Script.GetVarSize());
                 // Part IV
@@ -649,7 +650,7 @@ public void FeeIsSignatureContract_TestScope_CurrentHash_NEO_GAS()
                 // no attributes must exist
                 tx.Attributes.Length.Should().Be(1);
                 // one cosigner must exist
-                tx.Cosigners.Length.Should().Be(1);
+                tx.Cosigners.Count.Should().Be(1);
 
                 // Fast check
                 Assert.IsTrue(tx.VerifyWitnesses(snapshot, tx.NetworkFee));