add logs to execution

src/ApplicationLogs/LogReader.cs

@@ -176,8 +176,13 @@ private void OnCommitting(NeoSystem system, Block block, DataCache snapshot, IRe
             foreach (var appExec in applicationExecutedList.Where(p => p.Transaction != null))
             {
                 var txJson = TxLogToJson(appExec);
+                if (RpcServer.LogEvents.TryGetValue(appExec.Transaction.Hash, out var list))
+                {
+                    txJson["logs"] = new JArray(list.Select(q => new JString(q.Message)));
+                }
                 Put(appExec.Transaction.Hash.ToArray(), Neo.Utility.StrictUTF8.GetBytes(txJson.ToString()));
             }
+            RpcServer.LogEvents.Clear();
 
             //processing log for block
             var blockJson = BlockLogToJson(block, applicationExecutedList);

src/RpcServer/RpcServer.SmartContract.cs

@@ -121,6 +121,8 @@ private JObject GetInvokeResult(byte[] script, Signer[] signers = null, Witness[
                 lock (sessions)
                     sessions.Add(id, session);
             }
+            if (session.Engine.ScriptContainer is Transaction tx && LogEvents.ContainsKey(tx.Hash))
+                json["logs"] = new JArray(LogEvents[tx.Hash].Select(p => new JString(p.Message)));
             return json;
         }
 

src/RpcServer/RpcServer.cs

@@ -15,7 +15,6 @@
 using Microsoft.AspNetCore.ResponseCompression;
 using Microsoft.AspNetCore.Server.Kestrel.Https;
 using Microsoft.Extensions.DependencyInjection;
-using Neo.IO;
 using Neo.IO.Json;
 using Neo.Network.P2P;
 using System;
@@ -28,6 +27,9 @@
 using System.Security.Cryptography.X509Certificates;
 using System.Text;
 using System.Threading.Tasks;
+using Neo.Ledger;
+using Neo.Network.P2P.Payloads;
+using Neo.SmartContract;
 
 namespace Neo.Plugins
 {
@@ -39,6 +41,15 @@ public partial class RpcServer : IDisposable
         private RpcServerSettings settings;
         private readonly NeoSystem system;
         private readonly LocalNode localNode;
+        /// <summary>
+        /// Public interface of _logEvents.
+        /// </summary>
+        public static Dictionary<UInt256, Queue<LogEventArgs>> LogEvents { get; } = new();
+
+        /// <summary>
+        /// Maximum number of events to be logged per contract
+        /// </summary>
+        private const int MaxLogEvents = 50;
 
         public RpcServer(NeoSystem system, RpcServerSettings settings)
         {
@@ -47,6 +58,14 @@ public RpcServer(NeoSystem system, RpcServerSettings settings)
             localNode = system.LocalNode.Ask<LocalNode>(new LocalNode.GetInstance()).Result;
             RegisterMethods(this);
             Initialize_SmartContract();
+
+            ApplicationEngine.Log += OnContractLogEvent;
+            Blockchain.Committed += OnCommitted;
+        }
+
+        private void OnCommitted(NeoSystem system, Block block)
+        {
+            LogEvents.Clear();
         }
 
         private bool CheckAuth(HttpContext context)
@@ -92,8 +111,28 @@ private static JObject CreateResponse(JObject id)
             return response;
         }
 
+        // It is potentially possible to have dos attack by sending a lot of transactions and logs.
+        // To prevent this, we limit the number of logs to be logged per contract.
+        // If the number of logs is greater than MAX_LOG_EVENTS, we remove the oldest log.
+        private static void OnContractLogEvent(object _, LogEventArgs e)
+        {
+            if (e.ScriptContainer is not Transaction tx) return;
+            if (!LogEvents.TryGetValue(tx.Hash, out var _logs))
+            {
+                _logs = new Queue<LogEventArgs>();
+                LogEvents.Add(tx.Hash, _logs);
+            }
+            if (LogEvents[tx.Hash].Count >= MaxLogEvents)
+            {
+                _logs.Dequeue();
+            }
+            _logs.Enqueue(e);
+        }
+
         public void Dispose()
         {
+            Blockchain.Committed -= OnCommitted;
+            ApplicationEngine.Log -= OnContractLogEvent;
             Dispose_SmartContract();
             if (host != null)
             {

src/RpcServer/RpcServerPlugin.cs

@@ -36,7 +36,6 @@ public override void Dispose()
                 server.Dispose();
             base.Dispose();
         }
-
         protected override void OnSystemLoaded(NeoSystem system)
         {
             RpcServerSettings s = settings.Servers.FirstOrDefault(p => p.Network == system.Settings.Network);