Merge 'bindings/java: Implement LimboConnection close() ' from Kim Seon Woo

## Purpose of thie PR
- Implement `close()` method for `LimboConnection` and `JDBC4Connection`
## Changes
- Instead of closing the database when closing connections, close the
connection instead
## References
- https://github.com/tursodatabase/limbo/issues/615

Closes #797

bindings/java/rs_src/limbo_connection.rs

@@ -12,7 +12,6 @@ use std::rc::Rc;
 use std::sync::Arc;
 
 #[derive(Clone)]
-#[allow(dead_code)]
 pub struct LimboConnection {
     // Because java's LimboConnection is 1:1 mapped to limbo connection, we can use Rc
     pub(crate) conn: Rc<Connection>,
@@ -29,7 +28,6 @@ impl LimboConnection {
         Box::into_raw(Box::new(self)) as jlong
     }
 
-    #[allow(dead_code)]
     pub fn drop(ptr: jlong) {
         let _boxed = unsafe { Box::from_raw(ptr as *mut LimboConnection) };
     }
@@ -43,6 +41,15 @@ pub fn to_limbo_connection(ptr: jlong) -> Result<&'static mut LimboConnection> {
     }
 }
 
+#[no_mangle]
+pub extern "system" fn Java_org_github_tursodatabase_core_LimboConnection__1close<'local>(
+    _env: JNIEnv<'local>,
+    _obj: JObject<'local>,
+    connection_ptr: jlong,
+) {
+    LimboConnection::drop(connection_ptr);
+}
+
 #[no_mangle]
 pub extern "system" fn Java_org_github_tursodatabase_core_LimboConnection_prepareUtf8<'local>(
     mut env: JNIEnv<'local>,

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

@@ -16,6 +16,7 @@ public abstract class LimboConnection implements Connection {
 
   private final long connectionPtr;
   private final AbstractDB database;
+  private boolean closed;
 
   public LimboConnection(String url, String filePath) throws SQLException {
     this(url, filePath, new Properties());
@@ -28,24 +29,8 @@ public abstract class LimboConnection implements Connection {
    * @param filePath path to file
    */
   public LimboConnection(String url, String filePath, Properties properties) throws SQLException {
-    AbstractDB db = null;
-
-    try {
-      db = open(url, filePath, properties);
-    } catch (Throwable t) {
-      try {
-        if (db != null) {
-          db.close();
-        }
-      } catch (Throwable t2) {
-        t.addSuppressed(t2);
-      }
-
-      throw t;
-    }
-
-    this.database = db;
-    this.connectionPtr = db.connect();
+    this.database = open(url, filePath, properties);
+    this.connectionPtr = this.database.connect();
   }
 
   private static AbstractDB open(String url, String filePath, Properties properties)
@@ -59,13 +44,18 @@ public abstract class LimboConnection implements Connection {
 
   @Override
   public void close() throws SQLException {
-    if (isClosed()) return;
-    database.close();
+    if (isClosed()) {
+      return;
+    }
+    this._close(this.connectionPtr);
+    this.closed = true;
   }
 
+  private native void _close(long connectionPtr);
+
   @Override
   public boolean isClosed() throws SQLException {
-    return database.isClosed();
+    return closed;
   }
 
   public AbstractDB getDatabase() {
@@ -114,12 +104,15 @@ public abstract class LimboConnection implements Connection {
    */
   protected void checkCursor(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
       throws SQLException {
-    if (resultSetType != ResultSet.TYPE_FORWARD_ONLY)
+    if (resultSetType != ResultSet.TYPE_FORWARD_ONLY) {
       throw new SQLException("SQLite only supports TYPE_FORWARD_ONLY cursors");
-    if (resultSetConcurrency != ResultSet.CONCUR_READ_ONLY)
+    }
+    if (resultSetConcurrency != ResultSet.CONCUR_READ_ONLY) {
       throw new SQLException("SQLite only supports CONCUR_READ_ONLY cursors");
-    if (resultSetHoldability != ResultSet.CLOSE_CURSORS_AT_COMMIT)
+    }
+    if (resultSetHoldability != ResultSet.CLOSE_CURSORS_AT_COMMIT) {
       throw new SQLException("SQLite only supports closing cursors at commit");
+    }
   }
 
   public void setBusyTimeout(int busyTimeout) {

bindings/java/src/main/java/org/github/tursodatabase/jdbc4/JDBC4Connection.java

@@ -83,13 +83,12 @@ public class JDBC4Connection extends LimboConnection {
 
   @Override
   public void close() throws SQLException {
-    // TODO
+    super.close();
   }
 
   @Override
   public boolean isClosed() throws SQLException {
-    // TODO
-    return false;
+    return super.isClosed();
   }
 
   @Override

bindings/java/src/test/java/org/github/tursodatabase/jdbc4/JDBC4ConnectionTest.java

@@ -65,4 +65,23 @@ class JDBC4ConnectionTest {
   void prepare_simple_create_table() throws Exception {
     connection.prepare("CREATE TABLE users (id INT PRIMARY KEY, username TEXT)");
   }
+
+  @Test
+  void calling_close_multiple_times_throws_no_exception() throws Exception {
+    assertFalse(connection.isClosed());
+    connection.close();
+    assertTrue(connection.isClosed());
+    connection.close();
+  }
+
+  @Test
+  void calling_methods_on_closed_connection_should_throw_exception() throws Exception {
+    connection.close();
+    assertTrue(connection.isClosed());
+    assertThrows(
+        SQLException.class,
+        () ->
+            connection.createStatement(
+                ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY, -1));
+  }
 }