introduce transaction support (when using PDO adapter)

still basic test coverage, Store implementation checks required.

related to #110

src/ARC2/Store/Adapter/PDOAdapter.php

@@ -16,6 +16,8 @@
  */
 class PDOAdapter extends AbstractAdapter
 {
+    protected $transactionCounter;
+
     public function checkRequirements()
     {
         if (false == \extension_loaded('pdo_mysql')) {
@@ -322,4 +324,46 @@ public function deleteQuery($sql)
         $affectedRows = $this->db->exec($sql);
         return $affectedRows;
     }
+
+    /*
+     * Transaction related
+     *
+     * the following implementation prevents problems, if you have sub-transactions.
+     * thanks to http://php.net/manual/de/pdo.begintransaction.php#109753
+     */
+
+    public function beginTransaction()
+    {
+        // if not already in a transaction
+        if (false === $this->db->inTransaction()) {
+            if (0 == $this->transactionCounter) {
+                return $this->db->beginTransaction();
+            }
+            return $this->transactionCounter >= 0;
+        }
+    }
+
+    public function inTransaction()
+    {
+        return $this->db->inTransaction();
+    }
+
+    public function commit()
+    {
+        if(0 >= --$this->transactionCounter) {
+            return $this->db->commit();
+        }
+        return $this->transactionCounter >= 0;
+    }
+
+    public function rollback()
+    {
+        if($this->transactionCounter >= 0) {
+            $this->transactionCounter = 0;
+            return $this->db->rollback();
+        }
+
+        $this->transactionCounter = 0;
+        return false;
+    }
 }

store/ARC2_Store.php

@@ -883,4 +883,48 @@ public function logQuery($q)
         fwrite($fp, date('Y-m-d\TH:i:s\Z', time()).' : '.$q.''."\n\n");
         fclose($fp);
     }
+
+    /*
+     * Transaction support
+     * FYI: https://github.com/semsol/arc2/issues/110
+     *
+     * Functions only work when using PDO as adapter.
+     * When calling these with mysqli an exception will be thrown.
+     */
+
+    public function beginTransaction()
+    {
+        if ('pdo' !== $this->db->getAdapterName()) {
+            throw new \Exception('Please use the PDO adapter if you want transaction support.');
+        }
+
+        $this->db->beginTransaction();
+    }
+
+    public function inTransaction()
+    {
+        if ('pdo' !== $this->db->getAdapterName()) {
+            throw new \Exception('Please use the PDO adapter if you want transaction support.');
+        }
+
+        return $this->db->inTransaction();
+    }
+
+    public function commit()
+    {
+        if ('pdo' !== $this->db->getAdapterName()) {
+            throw new \Exception('Please use the PDO adapter if you want transaction support.');
+        }
+
+        return $this->db->commit();
+    }
+
+    public function rollback()
+    {
+        if ('pdo' !== $this->db->getAdapterName()) {
+            throw new \Exception('Please use the PDO adapter if you want transaction support.');
+        }
+
+        return $this->db->rollback();
+    }
 }

tests/db_adapter_depended/src/ARC2/Store/Adapter/PDOAdapterTest.php

@@ -0,0 +1,109 @@
+<?php
+
+namespace Tests\db_adapter_depended\src\ARC2\Store\Adapter;
+
+use ARC2\Store\Adapter\PDOAdapter;
+use Tests\ARC2_TestCase;
+
+class PDOAdapterTest extends ARC2_TestCase
+{
+    public function setUp()
+    {
+        parent::setUp();
+
+        if ('pdo' !== $this->dbConfig['db_adapter']) {
+            $this->markTestSkipped('Only runs when DB_ADAPTER=pdo.');
+        }
+
+        $this->fixture = new PDOAdapter($this->dbConfig);
+        $this->fixture->connect();
+
+        // remove all tables
+        $tables = $this->fixture->fetchList('SHOW TABLES');
+        foreach($tables as $table) {
+            $this->fixture->simpleQuery('DROP TABLE '. $table['Tables_in_'.$this->dbConfig['db_name']]);
+        }
+    }
+
+    /*
+     * Transaction related tests
+     */
+
+    public function testSimpleTransactionHandling()
+    {
+        $this->assertFalse($this->fixture->inTransaction());
+
+        $this->fixture->beginTransaction();
+
+        $this->assertTrue($this->fixture->inTransaction());
+
+        $this->fixture->rollback();
+    }
+
+    public function testTransactionCommit()
+    {
+        $this->fixture->simpleQuery('CREATE TABLE transactionTest (
+            id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+            name VARCHAR(30) NOT NULL
+        )');
+
+        $this->fixture->beginTransaction();
+
+        /*
+         * transaction started
+         */
+
+        $this->fixture->simpleQuery('INSERT INTO transactionTest (id, name) VALUES (1, "foo")');
+        $this->fixture->simpleQuery('INSERT INTO transactionTest (id, name) VALUES (2, "bar")');
+
+        $this->assertEquals(1, \count($this->fixture->fetchList('SHOW TABLES LIKE "transactionTest"')));
+
+        $this->assertEquals(2, \count($this->fixture->fetchList('SELECT * FROM transactionTest')));
+
+        /*
+         * end transaction, commit CHANGES
+         */
+
+        $this->fixture->commit();
+
+        $this->assertEquals(1, \count($this->fixture->fetchList('SHOW TABLES LIKE "transactionTest"')));
+        $this->assertEquals(2, \count($this->fixture->fetchList('SELECT * FROM transactionTest')));
+
+        // disconnect, force a commit/rollback by PDO
+        // connect again and ask the DB for our latest changes
+        $this->fixture->disconnect();
+        $this->fixture->connect();
+
+        $this->assertEquals(1, \count($this->fixture->fetchList('SHOW TABLES LIKE "transactionTest"')));
+        $this->assertEquals(2, \count($this->fixture->fetchList('SELECT * FROM transactionTest')));
+    }
+
+    public function testTransactionRollback()
+    {
+        $this->fixture->simpleQuery('CREATE TABLE transactionTest (
+            id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
+            name VARCHAR(30) NOT NULL
+        )');
+
+        $this->fixture->beginTransaction();
+
+        /*
+         * transaction started
+         */
+
+        $this->fixture->simpleQuery('INSERT INTO transactionTest (id, name) VALUES (1, "foo")');
+        $this->fixture->simpleQuery('INSERT INTO transactionTest (id, name) VALUES (2, "bar")');
+
+        $this->assertEquals(1, \count($this->fixture->fetchList('SHOW TABLES LIKE "transactionTest"')));
+
+        $this->assertEquals(2, \count($this->fixture->fetchList('SELECT * FROM transactionTest')));
+
+        /*
+         * end transaction, rollback and REVERT ALL CHANGES
+         */
+
+        $this->fixture->rollback();
+
+        $this->assertEquals(0, \count($this->fixture->fetchList('SELECT * FROM transactionTest')));
+    }
+}