Fix write buffer manager null

src/main/java/it/cavallium/dbengine/database/disk/LLLocalKeyValueDatabase.java

@@ -1024,8 +1024,6 @@ public class LLLocalKeyValueDatabase implements LLKeyValueDatabase {
 			var writeBufferManager = new WriteBufferManager(writeBufferManagerSize, blockCache, false);
 			refs.track(writeBufferManager);
 			options.setWriteBufferManager(writeBufferManager);
-		} else {
-			options.setWriteBufferManager(null);
 		}
 
 		if (useDirectIO) {

src/main/java/it/cavallium/dbengine/database/disk/RocksLog4jLogger.java

@@ -4,7 +4,7 @@ import org.apache.logging.log4j.Logger;
 import org.rocksdb.DBOptions;
 import org.rocksdb.InfoLogLevel;
 
-class RocksLog4jLogger extends org.rocksdb.Logger {
+public class RocksLog4jLogger extends org.rocksdb.Logger {
 
 	private final Logger logger;
 

src/test/java/it/cavallium/dbengine/TestPersistentCache.java

@@ -0,0 +1,90 @@
+package it.cavallium.dbengine;
+
+import it.cavallium.dbengine.database.disk.RocksLog4jLogger;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+import java.util.concurrent.CompletionException;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.rocksdb.BlockBasedTableConfig;
+import org.rocksdb.ColumnFamilyDescriptor;
+import org.rocksdb.ColumnFamilyHandle;
+import org.rocksdb.ColumnFamilyOptions;
+import org.rocksdb.DBOptions;
+import org.rocksdb.Env;
+import org.rocksdb.FlushOptions;
+import org.rocksdb.PersistentCache;
+import org.rocksdb.ReadOptions;
+import org.rocksdb.RocksDB;
+import org.rocksdb.RocksDBException;
+import org.rocksdb.TableFormatConfig;
+import org.rocksdb.WriteOptions;
+import org.rocksdb.util.SizeUnit;
+
+public class TestPersistentCache {
+
+	public static Logger LOG = LogManager.getLogger(TestPersistentCache.class);
+
+	@Test
+	public void test() throws RocksDBException, IOException {
+		var dbDir = Files.createTempDirectory("test-");
+		var persistentCacheDir = dbDir.resolve("persistent-cache");
+		LOG.info("Persistent cache directory: {}", persistentCacheDir);
+		Files.createDirectories(persistentCacheDir);
+		try (var dbOpts = new DBOptions(); var persistentCache = new PersistentCache(Env.getDefault(),
+				persistentCacheDir.toString(),
+				2 * SizeUnit.GB,
+				new RocksLog4jLogger(dbOpts, LOG),
+				false
+		)) {
+			dbOpts.setCreateIfMissing(true);
+			dbOpts.setCreateMissingColumnFamilies(true);
+			dbOpts.setIncreaseParallelism(Runtime.getRuntime().availableProcessors());
+			var col1Options = new ColumnFamilyOptions();
+			var tableConfig = new BlockBasedTableConfig();
+			tableConfig.setPersistentCache(persistentCache);
+			col1Options.setTableFormatConfig(tableConfig);
+			var col1Descriptor = new ColumnFamilyDescriptor(RocksDB.DEFAULT_COLUMN_FAMILY, col1Options);
+			var col2Options = new ColumnFamilyOptions();
+			col2Options.setTableFormatConfig(tableConfig);
+			var col2Descriptor = new ColumnFamilyDescriptor("col2".getBytes(StandardCharsets.UTF_8), col2Options);
+			var handles = new ArrayList<ColumnFamilyHandle>(2);
+			try (var db = RocksDB.open(dbOpts, dbDir.toString(), List.of(col1Descriptor, col2Descriptor), handles)) {
+				var cfh1 = handles.get(0);
+				var cfh2 = handles.get(1);
+				try (var writeOptions = new WriteOptions()) {
+					writeOptions.setDisableWAL(true);
+					db.put(cfh1, writeOptions, "col1-key1".getBytes(), "col1-key1-value".getBytes());
+					for (int i = 0; i < (2 << 16); i++) {
+						db.put(cfh2, writeOptions, ("col2-key" + i).getBytes(), ("col2-key" + i  + "-value").getBytes());
+					}
+				}
+				try (var flushOptions = new FlushOptions().setWaitForFlush(true).setAllowWriteStall(true)) {
+					db.flush(flushOptions);
+				}
+				try (var readOptions = new ReadOptions()) {
+					var col1Key1Value = new String(db.get(cfh1, readOptions, "col1-key1".getBytes()), StandardCharsets.UTF_8);
+					var col2Key1Value = new String(db.get(cfh2, readOptions, "col2-key1".getBytes()), StandardCharsets.UTF_8);
+					Assertions.assertEquals("col1-key1-value", col1Key1Value);
+					Assertions.assertEquals("col2-key1-value", col2Key1Value);
+				}
+			}
+		} finally {
+			try (var fileWalker = Files.walk(dbDir)) {
+				fileWalker.sorted(Comparator.reverseOrder()).forEach(file -> {
+					try {
+						Files.delete(file);
+					} catch (IOException ex) {
+						throw new CompletionException(ex);
+					}
+				});
+			}
+		}
+	}
+}