Pool LMDB databases

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

@@ -6,11 +6,10 @@ import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.time.Duration;
 import java.util.Comparator;
-import java.util.concurrent.Phaser;
+import java.util.concurrent.atomic.AtomicInteger;
-import java.util.concurrent.TimeUnit;
+import org.apache.lucene.search.DocIdSetIterator;
-import java.util.concurrent.TimeoutException;
+import org.apache.lucene.util.BitSet;
 import org.lmdbjava.Net5ByteBufProxy;
 import org.lmdbjava.Env;
 import static org.lmdbjava.EnvFlags.*;
@@ -18,19 +17,24 @@ import static org.lmdbjava.EnvFlags.*;
 public class LLTempLMDBEnv implements Closeable {
 
 	private static final long TWENTY_GIBIBYTES = 20L * 1024L * 1024L * 1024L;
-	private static final int MAX_DATABASES = 16777216;
+	public static final int MAX_DATABASES = 1024;
+	private static final AtomicInteger NEXT_LMDB_ENV_ID = new AtomicInteger(0);
+	private final BitSet freeIds;
 
+	private final int envId;
 	private final Path tempDirectory;
 	private final Env<ByteBuf> env;
 	private volatile boolean closed;
 
 	public LLTempLMDBEnv() throws IOException {
+		this.envId = NEXT_LMDB_ENV_ID.getAndIncrement();
 		tempDirectory = Files.createTempDirectory("lmdb");
 		var envBuilder = Env.create(Net5ByteBufProxy.PROXY_NETTY)
 				.setMapSize(TWENTY_GIBIBYTES)
 				.setMaxDbs(MAX_DATABASES);
 		//env = envBuilder.open(tempDirectory.toFile(), MDB_NOLOCK, MDB_NOSYNC, MDB_NOTLS, MDB_NORDAHEAD, MDB_WRITEMAP);
 		env = envBuilder.open(tempDirectory.toFile(), MDB_NOTLS, MDB_NOSYNC, MDB_NORDAHEAD, MDB_NOMETASYNC);
+		freeIds = BitSet.of(DocIdSetIterator.range(0, MAX_DATABASES), MAX_DATABASES);
 	}
 
 	public Env<ByteBuf> getEnv() {
@@ -40,6 +44,28 @@ public class LLTempLMDBEnv implements Closeable {
 		return env;
 	}
 
+	public int allocateDb() {
+		synchronized (freeIds) {
+			var freeBit = freeIds.nextSetBit(0);
+			if (freeBit == DocIdSetIterator.NO_MORE_DOCS) {
+				throw new IllegalStateException("LMDB databases limit has been reached in environment "
+						+ envId + ": " + MAX_DATABASES);
+			}
+			freeIds.clear(freeBit);
+			return freeBit;
+		}
+	}
+
+	public static String stringifyDbId(int bit) {
+		return "$db_" + bit;
+	}
+
+	public void freeDb(int db) {
+		synchronized (freeIds) {
+			freeIds.set(db);
+		}
+	}
+
 	@Override
 	public void close() throws IOException {
 		this.closed = true;

src/main/java/it/cavallium/dbengine/lucene/LMDBArray.java

@@ -10,6 +10,8 @@ import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.longs.Long2ObjectMap;
 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
+import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
+import it.unimi.dsi.fastutil.longs.LongSet;
 import java.io.Closeable;
 import java.io.IOException;
 import java.util.ArrayDeque;
@@ -23,11 +25,12 @@ import org.lmdbjava.Txn;
 
 public class LMDBArray<V> implements IArray<V>, Closeable {
 
-	private static final AtomicLong NEXT_LMDB_ARRAY_ID = new AtomicLong(0);
 
 	private final AtomicBoolean closed = new AtomicBoolean();
 	private final LMDBCodec<V> valueCodec;
+	private final LLTempLMDBEnv tempEnv;
 	private final Env<ByteBuf> env;
+	private final int lmdbDbId;
 	private final Dbi<ByteBuf> lmdb;
 	private final V defaultValue;
 
@@ -43,10 +46,11 @@ public class LMDBArray<V> implements IArray<V>, Closeable {
 	private final long virtualSize;
 
 	public LMDBArray(LLTempLMDBEnv env, LMDBCodec<V> codec, long size, @Nullable V defaultValue) {
-		var name = "$array_" + NEXT_LMDB_ARRAY_ID.getAndIncrement();
 		this.valueCodec = codec;
+		this.tempEnv = env;
 		this.env = env.getEnv();
-		this.lmdb = this.env.openDbi(name, MDB_CREATE);
+		this.lmdbDbId = env.allocateDb();
+		this.lmdb = this.env.openDbi(LLTempLMDBEnv.stringifyDbId(lmdbDbId), MDB_CREATE);
 		this.defaultValue = defaultValue;
 		
 		this.writing = true;
@@ -252,6 +256,7 @@ public class LMDBArray<V> implements IArray<V>, Closeable {
 				txn.commit();
 			}
 			lmdb.close();
+			this.tempEnv.freeDb(lmdbDbId);
 		}
 	}
 

src/main/java/it/cavallium/dbengine/lucene/LMDBPriorityQueue.java

@@ -30,12 +30,13 @@ import reactor.util.function.Tuples;
 
 public class LMDBPriorityQueue<T> implements PriorityQueue<T>, Reversable<ReversableResourceIterable<T>>, ReversableResourceIterable<T> {
 
-	private static final AtomicLong NEXT_LMDB_QUEUE_ID = new AtomicLong(0);
 	private static final AtomicLong NEXT_ITEM_UID = new AtomicLong(0);
 
 	private final AtomicBoolean closed = new AtomicBoolean();
 	private final LMDBSortedCodec<T> codec;
+	private final LLTempLMDBEnv tempEnv;
 	private final Env<ByteBuf> env;
+	private final int lmdbDbId;
 	private final Dbi<ByteBuf> lmdb;
 
 	private boolean writing;
@@ -54,10 +55,11 @@ public class LMDBPriorityQueue<T> implements PriorityQueue<T>, Reversable<Revers
 	private long size = 0;
 
 	public LMDBPriorityQueue(LLTempLMDBEnv env, LMDBSortedCodec<T> codec) {
-		var name = "$queue_" + NEXT_LMDB_QUEUE_ID.getAndIncrement();
 		this.codec = codec;
+		this.tempEnv = env;
 		this.env = env.getEnv();
-		this.lmdb = this.env.openDbi(name, codec::compareDirect, MDB_CREATE, MDB_DUPSORT, MDB_DUPFIXED);
+		this.lmdbDbId = env.allocateDb();
+		this.lmdb = this.env.openDbi(LLTempLMDBEnv.stringifyDbId(lmdbDbId), codec::compareDirect, MDB_CREATE, MDB_DUPSORT, MDB_DUPFIXED);
 		
 		this.writing = true;
 		this.iterating = false;
@@ -520,6 +522,7 @@ public class LMDBPriorityQueue<T> implements PriorityQueue<T>, Reversable<Revers
 				txn.commit();
 			}
 			lmdb.close();
+			this.tempEnv.freeDb(lmdbDbId);
 		}
 	}