Fix selecting empty result sets and avoid implicitly executing twice

Trying to fetch a result set row for a query that returns an empty
result set results in the query being executed again. We avoid this by
first checking if there are any columns and avoid fetch result rows
otherwise.

Author: clue

res/sqlite-worker.php

@@ -174,16 +174,21 @@
             }
 
             $rows = array();
-            while (($row = $result->fetchArray(\SQLITE3_ASSOC)) !== false) {
-                // base64-encode any string that is not valid UTF-8 without control characters (BLOB)
-                foreach ($row as &$value) {
-                    if (\is_string($value) && \preg_match('/[\x00-\x08\x11\x12\x14-\x1f\x7f]/u', $value) !== 0) {
-                        $value = ['base64' => \base64_encode($value)];
-                    } elseif (\is_float($value)) {
-                        $value = ['float' => $value];
+            if ($result->numColumns() !== 0) {
+                // Fetch all rows only if this result set has any columns.
+                // INSERT/UPDATE/DELETE etc. do not return any columns, trying
+                // to fetch the results here will issue the same query again.
+                while (($row = $result->fetchArray(\SQLITE3_ASSOC)) !== false) {
+                    // base64-encode any string that is not valid UTF-8 without control characters (BLOB)
+                    foreach ($row as &$value) {
+                        if (\is_string($value) && \preg_match('/[\x00-\x08\x11\x12\x14-\x1f\x7f]/u', $value) !== 0) {
+                            $value = ['base64' => \base64_encode($value)];
+                        } elseif (\is_float($value)) {
+                            $value = ['float' => $value];
+                        }
                     }
+                    $rows[] = $row;
                 }
-                $rows[] = $row;
             }
             $result->finalize();
 

tests/FunctionalDatabaseTest.php

@@ -596,6 +596,36 @@ public function testExecRejectsWhenAlreadyClosed($flag)
         $loop->run();
     }
 
+    /**
+     * @dataProvider provideSocketFlags
+     * @param bool $flag
+     */
+    public function testQueryInsertResolvesWithResultWithLastInsertIdAndRunsUntilQuit($flag)
+    {
+        $loop = React\EventLoop\Factory::create();
+        $factory = new Factory($loop);
+
+        $ref = new ReflectionProperty($factory, 'useSocket');
+        $ref->setAccessible(true);
+        $ref->setValue($factory, $flag);
+
+        $promise = $factory->open(':memory:');
+
+        $data = null;
+        $promise->then(function (DatabaseInterface $db) use (&$data){
+            $db->exec('CREATE TABLE foo (id INTEGER PRIMARY KEY AUTOINCREMENT, bar STRING)');
+            $db->query('INSERT INTO foo (bar) VALUES (?)', ['test'])->then(function (Result $result) use (&$data) {
+                $data = $result->insertId;
+            });
+
+            $db->quit();
+        });
+
+        $loop->run();
+
+        $this->assertSame(1, $data);
+    }
+
     protected function expectCallableNever()
     {
         $mock = $this->createCallableMock();