Add LimboDBFactory to support multiple LimboDB in single process

bindings/java/src/main/java/org/github/tursodatabase/LimboConnection.java

@@ -1,7 +1,7 @@
 package org.github.tursodatabase;
 
 import org.github.tursodatabase.core.AbstractDB;
-import org.github.tursodatabase.core.LimboDB;
+import org.github.tursodatabase.core.LimboDBFactory;
 
 import java.sql.Connection;
 import java.sql.ResultSet;
@@ -47,20 +47,7 @@ public abstract class LimboConnection implements Connection {
     }
 
     private static AbstractDB open(String url, String fileName, Properties properties) throws SQLException {
-        if (fileName.isEmpty()) {
-            throw new IllegalArgumentException("fileName should not be empty");
-        }
-
-        final AbstractDB database;
-        try {
-            LimboDB.load();
-            database = LimboDB.create(url, fileName);
-        } catch (Exception e) {
-            throw new SQLException("Error opening connection", e);
-        }
-
-        database.open(0);
-        return database;
+        return LimboDBFactory.open(url, fileName, properties);
     }
 
     protected void checkOpen() throws SQLException {

bindings/java/src/main/java/org/github/tursodatabase/core/LimboDBFactory.java

@@ -0,0 +1,47 @@
+package org.github.tursodatabase.core;
+
+import java.sql.SQLException;
+import java.util.Properties;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Factory class for managing and creating instances of {@link LimboDB}.
+ * This class ensures that multiple instances of {@link LimboDB} with the same URL are not created.
+ */
+public class LimboDBFactory {
+
+    private static final ConcurrentHashMap<String, LimboDB> databaseHolder = new ConcurrentHashMap<>();
+
+    /**
+     * If a database with the same URL already exists, it returns the existing instance.
+     * Otherwise, it creates a new instance and stores it in the database holder.
+     *
+     * @param url        the URL of the database
+     * @param fileName   the path to the database file
+     * @param properties additional properties for the database connection
+     * @return an instance of {@link LimboDB}
+     * @throws SQLException             if there is an error opening the connection
+     * @throws IllegalArgumentException if the fileName is empty
+     */
+    public static LimboDB open(String url, String fileName, Properties properties) throws SQLException {
+        if (databaseHolder.containsKey(url)) {
+            return databaseHolder.get(url);
+        }
+
+        if (fileName.isEmpty()) {
+            throw new IllegalArgumentException("fileName should not be empty");
+        }
+
+        final LimboDB database;
+        try {
+            LimboDB.load();
+            database = LimboDB.create(url, fileName);
+        } catch (Exception e) {
+            throw new SQLException("Error opening connection", e);
+        }
+
+        database.open(0);
+        databaseHolder.put(url, database);
+        return database;
+    }
+}

bindings/java/src/test/java/org/github/tursodatabase/core/LimboDBFactoryTest.java

@@ -0,0 +1,32 @@
+package org.github.tursodatabase.core;
+
+import org.github.tursodatabase.TestUtils;
+import org.junit.jupiter.api.Test;
+
+import java.util.Properties;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+
+class LimboDBFactoryTest {
+
+    @Test
+    void single_database_should_be_created_when_urls_are_same() throws Exception {
+        String filePath = TestUtils.createTempFile();
+        String url = "jdbc:sqlite:" + filePath;
+        LimboDB db1 = LimboDBFactory.open(url, filePath, new Properties());
+        LimboDB db2 = LimboDBFactory.open(url, filePath, new Properties());
+        assertEquals(db1, db2);
+    }
+
+    @Test
+    void multiple_databases_should_be_created_when_urls_differ() throws Exception {
+        String filePath1 = TestUtils.createTempFile();
+        String filePath2 = TestUtils.createTempFile();
+        String url1 = "jdbc:sqlite:" + filePath1;
+        String url2 = "jdbc:sqlite:" + filePath2;
+        LimboDB db1 = LimboDBFactory.open(url1, filePath1, new Properties());
+        LimboDB db2 = LimboDBFactory.open(url2, filePath2, new Properties());
+        assertNotEquals(db1, db2);
+    }
+}