Fix race-condition-induced dead lock on replay restart in 1.14+

MC clears it scheduled tasks on disconnect. If we don't wait for
that to have happened on the async sender, then we might loose
some of the initial handshake packets (resulting in a dead lock in
fabric's registry syncing code).

src/main/java/com/replaymod/core/ReplayMod.java

@@ -42,6 +42,8 @@ import net.minecraft.util.NonBlockingThreadExecutor;
 //$$ import com.google.common.util.concurrent.ListenableFutureTask;
 //$$ import net.minecraft.resources.FolderPack;
 //$$ import net.minecraftforge.eventbus.api.SubscribeEvent;
+//$$ import java.util.Queue;
+//$$ import java.util.concurrent.FutureTask;
 //$$
 //#if MC>=11300
 //$$ import com.replaymod.core.versions.LangResourcePack;
@@ -89,8 +91,9 @@ import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
-import java.util.Queue;
+import java.util.concurrent.ExecutionException;
-import java.util.concurrent.FutureTask;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 
 import static com.replaymod.core.versions.MCVer.*;
 
@@ -385,16 +388,28 @@ public class ReplayMod implements
         });
     }
 
-    public void runSync(Runnable runnable) {
+    /**
+     * Execute the given runnable on the main client thread, returning only after it has been run (or after 30 seconds).
+     */
+    public void runSync(Runnable runnable) throws InterruptedException, ExecutionException, TimeoutException {
         //#if MC>=11400
         if (mc.isOnThread()) {
-        //#else
-        //$$ if (mc.isCallingFromMinecraftThread()) {
-        //#endif
             runnable.run();
         } else {
-            runLater(runnable);
+            executor.executeFuture(() -> {
+                runnable.run();
+                return null;
+            }).get(30, TimeUnit.SECONDS);
         }
+        //#else
+        //$$ if (mc.isCallingFromMinecraftThread()) {
+        //$$     runnable.run();
+        //$$ } else {
+        //$$     FutureTask<Void> future = new FutureTask<>(runnable, null);
+        //$$     runLater(future);
+        //$$     future.get(30, TimeUnit.SECONDS);
+        //$$ }
+        //#endif
     }
 
     /**

src/main/java/com/replaymod/replay/ReplayHandler.java

@@ -35,6 +35,8 @@ import net.minecraft.network.ClientConnection;
 
 import java.io.IOException;
 import java.util.*;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeoutException;
 
 //#if MC>=11300
 import com.replaymod.replay.mixin.EntityLivingBaseAccessor;
@@ -162,18 +164,22 @@ public class ReplayHandler {
         channel.close();
 
         // Force re-creation of camera entity by unloading the previous world
-        ReplayMod.instance.runSync(() -> {
+        try {
-            //#if MC>=11300
+            ReplayMod.instance.runSync(() -> {
-            mc.mouse.unlockCursor();
+                //#if MC>=11300
-            //#else
+                mc.mouse.unlockCursor();
-            //$$ mc.setIngameNotInFocus();
+                //#else
-            //#endif
+                //$$ mc.setIngameNotInFocus();
-            //#if MC>=11400
+                //#endif
-            mc.disconnect();
+                //#if MC>=11400
-            //#else
+                mc.disconnect();
-            //$$ mc.loadWorld(null);
+                //#else
-            //#endif
+                //$$ mc.loadWorld(null);
-        });
+                //#endif
+            });
+        } catch (InterruptedException | ExecutionException | TimeoutException e) {
+            LOGGER.error("Failed to properly restart (shutdown) replay:", e);
+        }
 
         restrictions = new Restrictions();