Cursor.close() does not complete if it was already called

See #1410

Signed-off-by: Thomas Segismont <tsegismont@gmail.com>

Author: tsegismont

vertx-mysql-client/src/test/java/io/vertx/mysqlclient/tck/ProxySQLPreparedQueryTest.java

@@ -45,6 +45,13 @@ public void testQueryCloseCursor(TestContext ctx) {
     super.testQueryCloseCursor(ctx);
   }
 
+  @Test
+  @Ignore("Fetch command not supported by ProxySQL")
+  @Override
+  public void testQueryCloseCursorTwice(TestContext ctx) {
+    super.testQueryCloseCursorTwice(ctx);
+  }
+
   @Test
   @Ignore("Fetch command not supported by ProxySQL")
   @Override

vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/CursorImpl.java

@@ -118,6 +118,8 @@ private synchronized void close(Promise<Void> promise) {
         result = null;
         ps.closeCursor(id, promise);
       }
+    } else {
+      promise.complete();
     }
   }
 }

vertx-sql-client/src/test/java/io/vertx/sqlclient/tck/PreparedQueryTestBase.java

@@ -11,6 +11,7 @@
 package io.vertx.sqlclient.tck;
 
 import io.vertx.core.AsyncResult;
+import io.vertx.core.Future;
 import io.vertx.core.Handler;
 import io.vertx.core.Vertx;
 import io.vertx.ext.unit.Async;
@@ -273,6 +274,19 @@ public void testQueryCloseCursor(TestContext ctx) {
     });
   }
 
+  @Test
+  public void testQueryCloseCursorTwice(TestContext ctx) {
+    Async async = ctx.async();
+    testCursor(ctx, conn -> {
+      conn
+        .prepare("SELECT * FROM immutable")
+        .onComplete(ctx.asyncAssertSuccess(ps -> {
+          Cursor cursor = ps.cursor(Tuple.tuple());
+          Future.all(cursor.close(), cursor.close()).onComplete(ctx.asyncAssertSuccess(v -> async.complete()));
+        }));
+    });
+  }
+
   @Test
   public void testQueryStreamCloseCursor(TestContext ctx) {
     Async async = ctx.async();