Relax test fsync

- Add Durability, a process-wide fsync policy defaulting to real barriers and switchable to relaxed through the iris.durability system property
- Route the history, studio, journal, structure and datapack fsync barriers through Durability so relaxed mode skips both the force and the channel open
- Add the DurabilityMode test rule and enable relaxed durability on the twenty slowest core stores tests
- Split GenerationHistoryTest into epoch, legacy adoption and recovery classes over a shared GenerationHistorySupport base

core/src/main/java/art/arcane/iris/core/datapack/DatapackIngestService.java

@@ -37,6 +37,7 @@ import art.arcane.iris.core.structure.authoring.StructureTransactionWriter;
 import art.arcane.iris.engine.object.IrisDimension;
 import art.arcane.iris.engine.object.IrisImportedStructureControl;
 import art.arcane.iris.util.common.format.C;
+import art.arcane.iris.util.common.io.Durability;
 import art.arcane.iris.util.common.plugin.VolmitSender;
 import art.arcane.volmlib.util.collection.KList;
 import art.arcane.volmlib.util.io.IO;
@@ -5396,17 +5397,25 @@ public final class DatapackIngestService {
     }
 
     private static void forceFile(Path file) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         try (FileChannel channel = FileChannel.open(file, StandardOpenOption.WRITE)) {
-            channel.force(true);
+            Durability.force(channel);
         }
     }
 
     private static void forceDirectoryIfSupported(Path directory) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         if (!Files.getFileStore(directory).supportsFileAttributeView("posix")) {
             return;
         }
         try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
+            Durability.force(channel);
         }
     }
 

core/src/main/java/art/arcane/iris/core/lifecycle/DirectoryDurability.java

@@ -2,6 +2,7 @@ package art.arcane.iris.core.lifecycle;
 
 import art.arcane.iris.spi.IrisLogging;
 
+import art.arcane.iris.util.common.io.Durability;
 import java.io.File;
 import java.io.IOException;
 import java.nio.channels.FileChannel;
@@ -19,11 +20,15 @@ final class DirectoryDurability {
     }
 
     static void forceDirectoryRequired(Path directory) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         if (File.separatorChar == '\\') {
             return;
         }
         try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
+            Durability.force(channel);
         } catch (UnsupportedOperationException failure) {
             throw new IOException("Directory durability sync is unavailable for " + directory + ".", failure);
         }

core/src/main/java/art/arcane/iris/core/lifecycle/WorldReplacementJournal.java

@@ -5,6 +5,7 @@ import art.arcane.iris.core.IrisWorldStorage;
 import art.arcane.iris.core.WorldSlotKey;
 import art.arcane.iris.core.lifecycle.BukkitWorldConfiguration.WorldGeneratorSnapshot;
 
+import art.arcane.iris.util.common.io.Durability;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
@@ -345,7 +346,7 @@ public final class WorldReplacementJournal {
                 while (buffer.hasRemaining()) {
                     channel.write(buffer);
                 }
-                channel.force(true);
+                Durability.force(channel);
             }
             forceDirectoryRequired(parent);
             try {

core/src/main/java/art/arcane/iris/core/service/JigsawStudioHistoryStore.java

@@ -12,6 +12,7 @@ import art.arcane.iris.core.structure.authoring.StructureTransactionWriter;
 import art.arcane.iris.core.structure.authoring.StructureWriteOptions;
 import art.arcane.iris.core.structure.authoring.StructureWriteResult;
 import art.arcane.iris.engine.framework.structure.StructureResourceBundleGraphCompiler;
+import art.arcane.iris.util.common.io.Durability;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 
@@ -303,7 +304,7 @@ final class JigsawStudioHistoryStore {
                 while (buffer.hasRemaining()) {
                     channel.write(buffer);
                 }
-                channel.force(true);
+                Durability.force(channel);
             }
             try {
                 Files.move(
@@ -374,6 +375,10 @@ final class JigsawStudioHistoryStore {
     }
 
     private static void forceDirectory(Path directory) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         // A directory can only be opened and fsynced on a POSIX filesystem; Windows rejects the
         // open outright. Matches DirectoryDurability and DatapackIngestService, which already
         // skip the barrier there.
@@ -381,7 +386,7 @@ final class JigsawStudioHistoryStore {
             return;
         }
         try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
+            Durability.force(channel);
         }
     }
 

core/src/main/java/art/arcane/iris/core/structure/authoring/StructureFileOperations.java

@@ -18,6 +18,7 @@
 
 package art.arcane.iris.core.structure.authoring;
 
+import art.arcane.iris.util.common.io.Durability;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.channels.FileChannel;
@@ -70,17 +71,25 @@ interface StructureFileOperations {
     }
 
     default void forceFile(Path path) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         try (FileChannel channel = FileChannel.open(path, StandardOpenOption.WRITE)) {
-            channel.force(true);
+            Durability.force(channel);
         }
     }
 
     default void forceDirectory(Path path) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         if (!Files.getFileStore(path).supportsFileAttributeView("posix")) {
             return;
         }
         try (FileChannel channel = FileChannel.open(path, StandardOpenOption.READ)) {
-            channel.force(true);
+            Durability.force(channel);
         }
     }
 }

core/src/main/java/art/arcane/iris/engine/history/GenerationHistory.java

@@ -1,6 +1,7 @@
 package art.arcane.iris.engine.history;
 
 import art.arcane.iris.core.pack.AtomicDirectoryPublisher;
+import art.arcane.iris.util.common.io.Durability;
 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
 
 import java.io.File;
@@ -1153,11 +1154,15 @@ public final class GenerationHistory {
     }
 
     private static void forceDirectory(Path directory) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         if (File.separatorChar == '\\') {
             return;
         }
         try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
+            Durability.force(channel);
         } catch (UnsupportedOperationException exception) {
             throw new IOException("Generation history directory cannot be durability-synced: "
                     + directory, exception);

core/src/main/java/art/arcane/iris/engine/history/GenerationHistoryStore.java

@@ -1,5 +1,6 @@
 package art.arcane.iris.engine.history;
 
+import art.arcane.iris.util.common.io.Durability;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonElement;
@@ -282,7 +283,7 @@ public final class GenerationHistoryStore {
                 while (buffer.hasRemaining()) {
                     channel.write(buffer);
                 }
-                channel.force(true);
+                Durability.force(channel);
             }
             try {
                 if (replaceExisting) {
@@ -352,7 +353,7 @@ public final class GenerationHistoryStore {
                 while (buffer.hasRemaining()) {
                     channel.write(buffer);
                 }
-                channel.force(true);
+                Durability.force(channel);
             }
             try {
                 Files.move(temporary, metadata, StandardCopyOption.ATOMIC_MOVE);
@@ -439,11 +440,15 @@ public final class GenerationHistoryStore {
     }
 
     private static void forceDirectory(Path directory) throws IOException {
+        if (!Durability.enabled()) {
+            return;
+        }
+
         if (File.separatorChar == '\\') {
             return;
         }
         try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-            channel.force(true);
+            Durability.force(channel);
         } catch (UnsupportedOperationException exception) {
             throw new IOException("Generation history directory cannot be durability-synced: " + directory, exception);
         }

core/src/main/java/art/arcane/iris/engine/history/GenerationSemanticIndex.java

@@ -1,6 +1,7 @@
 package art.arcane.iris.engine.history;
 
 import art.arcane.iris.engine.hydrology.HydrologyFeatureType;
+import art.arcane.iris.util.common.io.Durability;
 import it.unimi.dsi.fastutil.longs.Long2IntOpenHashMap;
 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
@@ -1949,14 +1950,14 @@ public final class GenerationSemanticIndex {
                             channel.write(entry);
                         }
                     }
-                    channel.force(true);
+                    Durability.force(channel);
                     if (created) {
                         RegionShard.forceDirectory(directory);
                     }
                 } catch (IOException failure) {
                     try {
                         channel.truncate(size);
-                        channel.force(true);
+                        Durability.force(channel);
                         if (created) {
                             RegionShard.forceDirectory(directory);
                         }
@@ -2079,7 +2080,7 @@ public final class GenerationSemanticIndex {
 
         private static void truncateTail(RandomAccessFile file, long length) throws IOException {
             file.setLength(length);
-            file.getFD().sync();
+            Durability.force(file.getFD());
         }
 
         private static IOException invalid(Path file, String reason) {
@@ -2951,16 +2952,20 @@ public final class GenerationSemanticIndex {
                 while (buffer.hasRemaining()) {
                     channel.write(buffer);
                 }
-                channel.force(true);
+                Durability.force(channel);
             }
         }
 
         private static void forceDirectory(Path directory) throws IOException {
+            if (!Durability.enabled()) {
+                return;
+            }
+
             if (File.separatorChar == '\\') {
                 return;
             }
             try (FileChannel channel = FileChannel.open(directory, StandardOpenOption.READ)) {
-                channel.force(true);
+                Durability.force(channel);
             } catch (UnsupportedOperationException error) {
                 throw new IOException("Generation semantic directory cannot be durability-synced", error);
             }

core/src/main/java/art/arcane/iris/util/common/io/Durability.java

@@ -0,0 +1,33 @@
+package art.arcane.iris.util.common.io;
+
+import java.io.FileDescriptor;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+
+public final class Durability {
+    public static final String MODE_PROPERTY = "iris.durability";
+    private static final String RELAXED = "relaxed";
+
+    private Durability() {
+    }
+
+    public static boolean enabled() {
+        return !RELAXED.equalsIgnoreCase(System.getProperty(MODE_PROPERTY));
+    }
+
+    public static void force(FileChannel channel) throws IOException {
+        if (!enabled()) {
+            return;
+        }
+
+        channel.force(true);
+    }
+
+    public static void force(FileDescriptor descriptor) throws IOException {
+        if (!enabled()) {
+            return;
+        }
+
+        descriptor.sync();
+    }
+}