From b15c3a8e46cbc8a1f99c59474c3bd624bdd2409e Mon Sep 17 00:00:00 2001
From: ReinforceZwei <39955851+ReinforceZwei@users.noreply.github.com>
Date: Wed, 12 May 2021 22:31:06 +0800
Subject: [PATCH] Fix calling schedule task cause deadlock (#1586)

---
 MinecraftClient/McClient.cs                   | 35 ++++++++++++++++---
 .../Protocol/Handlers/Protocol16.cs           |  9 +++++
 .../Protocol/Handlers/Protocol18.cs           | 11 +++++-
 MinecraftClient/Protocol/IMinecraftCom.cs     |  6 ++++
 4 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/MinecraftClient/McClient.cs b/MinecraftClient/McClient.cs
index f55b5c65..27ed6346 100644
--- a/MinecraftClient/McClient.cs
+++ b/MinecraftClient/McClient.cs
@@ -701,13 +701,38 @@ namespace MinecraftClient
         /// <param name="task">Task to run</param>
         public object ScheduleTask(Delegate task)
         {
-            var taskAndResult = new TaskWithResult(task);
-            lock (threadTasksLock)
+            if (!InvokeRequired())
             {
-                threadTasks.Enqueue(taskAndResult);
+                return task.DynamicInvoke();
+            }
+            else
+            {
+                var taskAndResult = new TaskWithResult(task);
+                lock (threadTasksLock)
+                {
+                    threadTasks.Enqueue(taskAndResult);
+                }
+                taskAndResult.Block();
+                return taskAndResult.Result;
+            }
+        }
+
+        /// <summary>
+        /// Check if calling thread is main thread or other thread
+        /// </summary>
+        /// <returns>True if calling thread is other thread</returns>
+        public bool InvokeRequired()
+        {
+            int callingThreadId = Thread.CurrentThread.ManagedThreadId;
+            if (handler != null)
+            {
+                return handler.GetNetReadThreadId() != callingThreadId;
+            }
+            else
+            {
+                // net read thread (main thread) not yet ready
+                return false;
             }
-            taskAndResult.Block();
-            return taskAndResult.Result;
         }
 
         #region Management: Load/Unload ChatBots and Enable/Disable settings
diff --git a/MinecraftClient/Protocol/Handlers/Protocol16.cs b/MinecraftClient/Protocol/Handlers/Protocol16.cs
index 1ce4730d..aaf5affd 100644
--- a/MinecraftClient/Protocol/Handlers/Protocol16.cs
+++ b/MinecraftClient/Protocol/Handlers/Protocol16.cs
@@ -201,6 +201,15 @@ namespace MinecraftClient.Protocol.Handlers
             netRead.Start();
         }
 
+        /// <summary>
+        /// Get net read thread (main thread) ID
+        /// </summary>
+        /// <returns>Net read thread ID</returns>
+        public int GetNetReadThreadId()
+        {
+            return netRead != null ? netRead.ManagedThreadId : -1;
+        }
+
         public void Dispose()
         {
             try
diff --git a/MinecraftClient/Protocol/Handlers/Protocol18.cs b/MinecraftClient/Protocol/Handlers/Protocol18.cs
index cb6081bb..99424d88 100644
--- a/MinecraftClient/Protocol/Handlers/Protocol18.cs
+++ b/MinecraftClient/Protocol/Handlers/Protocol18.cs
@@ -67,7 +67,7 @@ namespace MinecraftClient.Protocol.Handlers
         PacketTypePalette packetPalette;
         SocketWrapper socketWrapper;
         DataTypes dataTypes;
-        Thread netRead;
+        Thread netRead; // main thread
         ILogger log;
 
         public Protocol18Handler(TcpClient Client, int protocolVersion, IMinecraftComHandler handler, ForgeInfo forgeInfo)
@@ -1112,6 +1112,15 @@ namespace MinecraftClient.Protocol.Handlers
             netRead.Start();
         }
 
+        /// <summary>
+        /// Get net read thread (main thread) ID
+        /// </summary>
+        /// <returns>Net read thread ID</returns>
+        public int GetNetReadThreadId()
+        {
+            return netRead != null ? netRead.ManagedThreadId : -1;
+        }
+
         /// <summary>
         /// Disconnect from the server, cancel network reading.
         /// </summary>
diff --git a/MinecraftClient/Protocol/IMinecraftCom.cs b/MinecraftClient/Protocol/IMinecraftCom.cs
index 4770a098..42d66fcd 100644
--- a/MinecraftClient/Protocol/IMinecraftCom.cs
+++ b/MinecraftClient/Protocol/IMinecraftCom.cs
@@ -235,5 +235,11 @@ namespace MinecraftClient.Protocol
         /// </summary>
         /// <param name="selectedSlot">The slot of the trade, starts at 0.</param>
         bool SelectTrade(int selectedSlot);
+
+        /// <summary>
+        /// Get net read thread (main thread) ID
+        /// </summary>
+        /// <returns>Net read thread ID</returns>
+        int GetNetReadThreadId();
     }
 }