fix(spanner): prevent leaked emulator transactions

Author: cy-yun

Spanner/src/Database.php

@@ -964,6 +964,17 @@ public function runTransaction(callable $operation, array $options = []): mixed
             $this->isRunningTransaction = true;
             try {
                 $res = call_user_func($operation, $transaction);
+            } catch (\Throwable $e) {
+                $active = $transaction->state() === Transaction::STATE_ACTIVE;
+                $singleUse = $transaction->type() === Transaction::TYPE_SINGLE_USE;
+                if ($active && !$singleUse) {
+                    try {
+                        $transaction->rollback($options);
+                    } catch (\Throwable $rollbackException) {
+                        // ignore rollback failure and bubble up the original exception
+                    }
+                }
+                throw $e;
             } finally {
                 $this->isRunningTransaction = false;
             }

Spanner/tests/System/ReadTest.php

@@ -262,6 +262,8 @@ public function testLockHintReadWriteTransaction()
         $rows = iterator_to_array($res->rows());
         $this->assertNotEmpty($rows);
         $this->assertEquals($limit, count($rows));
+
+        $res->transaction()->rollback();
     }
 
     public function testLockHintOnReadOnlyThrowsAnError()