Fix racing condition when creating snapshot while generating new chunks

Author: SeraphJACK

build.gradle

@@ -15,7 +15,7 @@ tasks.named('wrapper', Wrapper).configure {
 
 jarJar.enable()
 
-var mod_version = "custom-build"
+var mod_version = "0.0.0-custom-build"
 
 var gitTag = System.getProperty("git.tag")
 if (gitTag != null && !gitTag.isEmpty()) {

src/main/java/top/seraphjack/rmc/MinecraftAdapter.java

@@ -1,6 +1,7 @@
 package top.seraphjack.rmc;
 
 import java.util.List;
+import java.util.concurrent.CountDownLatch;
 
 import net.minecraft.network.chat.Component;
 import net.minecraft.server.MinecraftServer;
@@ -31,10 +32,21 @@ private void logAndBroadcastMessage(String message, Object... args) {
 
     @Override
     public void preBackup() {
-        logAndBroadcastMessage("Backup started");
-        server.saveEverything(true, true, true);
-        for (ServerLevel level : server.getAllLevels()) {
-            level.noSave = true;
+        final CountDownLatch latch = new CountDownLatch(1);
+        final Runnable backupAndSetNoSave = () -> {
+            logAndBroadcastMessage("Backup started");
+            server.saveEverything(true, true, true);
+            for (ServerLevel level : server.getAllLevels()) {
+                level.noSave = true;
+            }
+            latch.countDown();
+        };
+        server.executeIfPossible(backupAndSetNoSave);
+
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
         }
     }
 

src/main/java/top/seraphjack/rmc/RMCCommand.java

@@ -30,7 +30,7 @@ public final class RMCCommand {
 
     public static final DynamicCommandExceptionType ERROR_INVALID_INTERVAL =
             new DynamicCommandExceptionType(msg -> new LiteralMessage("Invalid ISO8601 duration: " + msg));
-    private static final DateTimeFormatter DATE_TIME_FORMAT =  DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
+    private static final DateTimeFormatter DATE_TIME_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
     private static final Logger log = LoggerFactory.getLogger(RMCCommand.class);
 
     static void register(CommandDispatcher<CommandSourceStack> dispatcher) {
@@ -90,12 +90,14 @@ private static int listSnapshots(CommandContext<CommandSourceStack> context) {
 
     private static int restore(CommandContext<CommandSourceStack> context) {
         final var snapshot = StringArgumentType.getString(context, "snapshot");
-        try {
-            RMC.backupCore.restore(snapshot);
-        } catch (Exception e) {
-            log.error("Error restoring snapshot", e);
-            throw new RuntimeException(e);
-        }
+        new Thread(() -> {
+            try {
+                RMC.backupCore.restore(snapshot);
+            } catch (Exception e) {
+                log.error("Error restoring snapshot", e);
+                throw new RuntimeException(e);
+            }
+        }, "RMC-Restore-Worker").start();
         return SINGLE_SUCCESS;
     }