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Possible fix for the elusive Forge config corruption bug

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Block file watcher from proceeding until config is done saving

Related: https://github.com/MinecraftForge/MinecraftForge/issues/9122
This commit is contained in:
embeddedt 2023-07-18 12:44:11 -04:00
parent c3e3dff805
commit b499a054b9
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GPG Key ID: A69433EC199B5613
2 changed files with 122 additions and 0 deletions
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119
forge/src/main/java/org/embeddedt/modernfix/forge/config/NightConfigFixer.java Normal file
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@ -0,0 +1,119 @@
package org.embeddedt.modernfix.forge.config;
import com.electronwill.nightconfig.core.file.CommentedFileConfig;
import com.electronwill.nightconfig.core.file.FileConfig;
import com.electronwill.nightconfig.core.file.FileWatcher;
import cpw.mods.modlauncher.api.LamdbaExceptionUtils;
import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet;
import net.minecraftforge.fml.common.ObfuscationReflectionHelper;
import org.embeddedt.modernfix.core.ModernFixMixinPlugin;
import org.embeddedt.modernfix.util.CommonModUtil;
import java.lang.reflect.Field;
import java.nio.file.Path;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
/**
* Relatively simple patch to wait for config saving to finish, made complex by Night Config classes being package-private,
* and Forge not allowing mixins into libraries.
*/
public class NightConfigFixer {
public static void monitorFileWatcher() {
CommonModUtil.runWithoutCrash(() -> {
FileWatcher watcher = FileWatcher.defaultInstance();
Field field = FileWatcher.class.getDeclaredField("watchedFiles");
field.setAccessible(true);
ConcurrentHashMap<Path, ?> theMap = (ConcurrentHashMap<Path, ?>)field.get(watcher);
// replace the backing map of watched files with one we control
field.set(watcher, new MonitoringMap(theMap));
ModernFixMixinPlugin.instance.logger.info("Applied Forge config corruption patch");
}, "replacing Night Config watchedFiles map");
}
private static final Class<?> WATCHED_FILE = LamdbaExceptionUtils.uncheck(() -> Class.forName("com.electronwill.nightconfig.core.file.FileWatcher$WatchedFile"));
private static final Class<?> CONFIG_WATCHER = LamdbaExceptionUtils.uncheck(() -> Class.forName("net.minecraftforge.fml.config.ConfigFileTypeHandler$ConfigWatcher"));
private static final Field CHANGE_HANDLER = ObfuscationReflectionHelper.findField(WATCHED_FILE, "changeHandler");
private static final Field COMMENTED_FILE_CONFIG = ObfuscationReflectionHelper.findField(CONFIG_WATCHER, "commentedFileConfig");
private static final Class<?> WRITE_SYNC_CONFIG = LamdbaExceptionUtils.uncheck(() -> Class.forName("com.electronwill.nightconfig.core.file.WriteSyncFileConfig"));
private static final Class<?> AUTOSAVE_CONFIG = LamdbaExceptionUtils.uncheck(() -> Class.forName("com.electronwill.nightconfig.core.file.AutosaveCommentedFileConfig"));
private static final Field AUTOSAVE_FILECONFIG = ObfuscationReflectionHelper.findField(AUTOSAVE_CONFIG, "fileConfig");
private static final Field CURRENTLY_WRITING = ObfuscationReflectionHelper.findField(WRITE_SYNC_CONFIG, "currentlyWriting");
static class MonitoringMap extends ConcurrentHashMap<Path, Object> {
public MonitoringMap(ConcurrentHashMap<Path, ?> oldMap) {
super(oldMap);
}
@Override
public Object computeIfAbsent(Path key, Function<? super Path, ?> mappingFunction) {
return super.computeIfAbsent(key, path -> {
Object watchedFile = mappingFunction.apply(path);
try {
Runnable changeHandler = (Runnable)CHANGE_HANDLER.get(watchedFile);
// replace Forge's config tracker with our own
if(CONFIG_WATCHER.isAssignableFrom(changeHandler.getClass()))
CHANGE_HANDLER.set(watchedFile, new MonitoringConfigTracker(changeHandler));
else
ModernFixMixinPlugin.instance.logger.warn("Unexpected Forge config tracker class: {}", changeHandler.getClass().getName());
} catch(ReflectiveOperationException e) {
e.printStackTrace();
}
return watchedFile;
});
}
}
static class MonitoringConfigTracker implements Runnable {
private final Runnable configTracker;
MonitoringConfigTracker(Runnable r) {
this.configTracker = r;
}
private static final Set<Class<?>> UNKNOWN_FILE_CONFIG_CLASSES = Collections.synchronizedSet(new ReferenceOpenHashSet<>());
private boolean isSaving(FileConfig config) throws ReflectiveOperationException {
if(WRITE_SYNC_CONFIG.isAssignableFrom(config.getClass())) {
return CURRENTLY_WRITING.getBoolean(config);
} else if(AUTOSAVE_CONFIG.isAssignableFrom(config.getClass())) {
FileConfig fc = (FileConfig)AUTOSAVE_FILECONFIG.get(config);
return isSaving(fc);
} else {
if(UNKNOWN_FILE_CONFIG_CLASSES.add(config.getClass()))
ModernFixMixinPlugin.instance.logger.warn("Unexpected FileConfig class: {}", config.getClass().getName());
return false;
}
}
/**
* This entrypoint runs when the file watcher has detected a change on the config file. Before passing
* this through to Forge, use reflection hacks to confirm the config system is not still writing to the file.
* If it is, spin until writing finishes. Immediately returning might result in the event never being observed.
*/
@Override
public void run() {
try {
CommentedFileConfig cfg = (CommentedFileConfig)COMMENTED_FILE_CONFIG.get(this.configTracker);
while(isSaving(cfg)) {
// block until the config is no longer marked as saving
// Forge shouldn't save the config twice in a row under normal conditions so this should fix the
// original bug
try {
Thread.sleep(500);
} catch (InterruptedException e) {
return;
}
}
} catch(ReflectiveOperationException e) {
e.printStackTrace();
}
configTracker.run();
}
}
}

3
forge/src/main/java/org/embeddedt/modernfix/platform/forge/ModernFixPlatformHooksImpl.java
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@ -29,6 +29,7 @@ import org.embeddedt.modernfix.core.ModernFixMixinPlugin;
import org.embeddedt.modernfix.api.constants.IntegrationConstants;
import org.embeddedt.modernfix.forge.classloading.FastAccessTransformerList;
import org.embeddedt.modernfix.forge.classloading.ModernFixResourceFinder;
import org.embeddedt.modernfix.forge.config.NightConfigFixer;
import org.embeddedt.modernfix.forge.packet.PacketHandler;
import org.embeddedt.modernfix.forge.spark.SparkLaunchProfiler;
import org.embeddedt.modernfix.util.CommonModUtil;
@ -180,6 +181,8 @@ public class ModernFixPlatformHooksImpl {
if(ModernFixMixinPlugin.instance.isOptionEnabled("feature.spark_profile_launch.OnForge")) {
CommonModUtil.runWithoutCrash(() -> SparkLaunchProfiler.start("launch"), "Failed to start profiler");
}
NightConfigFixer.monitorFileWatcher();
}
private Method defineClassMethod = null;