Drop TransactionalMutex class (#73)

Author: mvorisek

README.md

@@ -167,7 +167,6 @@ implementations or create/extend your own implementation.
 - [`MemcachedMutex`](#memcachedmutex)
 - [`RedisMutex`](#redismutex)
 - [`SemaphoreMutex`](#semaphoremutex)
-- [`TransactionalMutex`](#transactionalmutex)
 - [`MySQLMutex`](#mysqlmutex)
 - [`PostgreSQLMutex`](#PostgreSQLMutex)
 
@@ -261,36 +260,6 @@ $mutex->synchronized(function () use ($bankAccount, $amount) {
 });
 ```
 
-#### TransactionalMutex
-
-The **TransactionalMutex**
-delegates the serialization to the database. The exclusive code is executed within
-a transaction. It's up to you to set the correct transaction isolation level.
-However if the transaction fails (i.e. a `PDOException` was thrown), the code
-will be executed again in a new transaction. Therefore the code must not have
-any side effects besides SQL statements. Also the isolation level should be
-conserved for the repeated transaction. If the code throws an exception,
-the transaction is rolled back and not replayed again.
-
-Example:
-```php
-$mutex = new TransactionalMutex($pdo);
-$mutex->synchronized(function () use ($pdo, $accountId, $amount) {
-    $select = $pdo->prepare(
-        'SELECT balance FROM account WHERE id = ? FOR UPDATE'
-    );
-    $select->execute([$accountId]);
-    $balance = $select->fetchColumn();
-
-    $balance -= $amount;
-    if ($balance < 0) {
-        throw new \DomainException('You have no credit');
-    }
-    $pdo->prepare('UPDATE account SET balance = ? WHERE id = ?')
-        ->execute([$balance, $accountId]);
-});
-```
-
 #### MySQLMutex
 
 The **MySQLMutex** uses MySQL's

phpstan.neon.dist

@@ -16,11 +16,6 @@ parameters:
             identifier: if.condNotBoolean
             message: '~^Only booleans are allowed in an if condition, mixed given\.$~'
             count: 1
-        -
-            path: 'src/Mutex/TransactionalMutex.php'
-            identifier: if.condNotBoolean
-            message: '~^Only booleans are allowed in an if condition, mixed given\.$~'
-            count: 1
         -
             path: 'tests/Mutex/*Test.php'
             identifier: empty.notAllowed

src/Mutex/TransactionalMutex.php

@@ -12,7 +12,6 @@
 use Malkusch\Lock\Mutex\PostgreSQLMutex;
 use Malkusch\Lock\Mutex\RedisMutex;
 use Malkusch\Lock\Mutex\SemaphoreMutex;
-use Malkusch\Lock\Mutex\TransactionalMutex;
 use Malkusch\Lock\Util\LockUtil;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Constraint\IsType;
@@ -32,8 +31,6 @@ class MutexConcurrencyTest extends TestCase
 {
     /** @var list<string> */
     protected static $temporaryFiles = [];
-    /** @var \PDO|null */
-    private static $pdo;
 
     #[\Override]
     public static function tearDownAfterClass(): void
@@ -43,24 +40,9 @@ public static function tearDownAfterClass(): void
         }
         self::$temporaryFiles = [];
 
-        self::$pdo = null;
-
         parent::tearDownAfterClass();
     }
 
-    /**
-     * Gets a PDO instance.
-     */
-    private static function getPDO(string $dsn, string $user, string $password): \PDO
-    {
-        if (self::$pdo === null) {
-            self::$pdo = new \PDO($dsn, $user, $password);
-            self::$pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
-        }
-
-        return self::$pdo;
-    }
-
     /**
      * Forks, runs code in the children and wait until all finished.
      *
@@ -135,63 +117,6 @@ static function () use ($filename): void {
                 },
             ];
         }
-
-        $makePDOCase = static function (string $dsn, string $user, string $password, string $vendor) {
-            $pdo = self::getPDO($dsn, $user, $password);
-
-            $options = ['mysql' => 'engine=InnoDB'];
-            $option = $options[$vendor] ?? '';
-            $pdo->exec('CREATE TABLE IF NOT EXISTS counter(id INT PRIMARY KEY, counter INT) ' . $option);
-
-            self::$pdo = null;
-
-            return [
-                static function (int $increment) use ($dsn, $user, $password) {
-                    // This prevents using a closed connection from a child.
-                    if ($increment === 0) {
-                        self::$pdo = null;
-                    }
-                    $pdo = self::getPDO($dsn, $user, $password);
-                    $id = 1;
-                    $select = $pdo->prepare('SELECT counter FROM counter WHERE id = ? FOR UPDATE');
-                    $select->execute([$id]);
-                    $counter = $select->fetchColumn();
-
-                    $counter += $increment;
-
-                    $pdo->prepare('UPDATE counter SET counter = ? WHERE id = ?')
-                        ->execute([$counter, $id]);
-
-                    return $counter;
-                },
-                static function ($timeout) use ($dsn, $user, $password) {
-                    self::$pdo = null;
-                    $pdo = self::getPDO($dsn, $user, $password);
-
-                    return new TransactionalMutex($pdo, $timeout);
-                },
-                static function () use ($pdo): void {
-                    $pdo->beginTransaction();
-                    $pdo->exec('DELETE FROM counter');
-                    $pdo->exec('INSERT INTO counter VALUES (1, 0)');
-                    $pdo->commit();
-                },
-            ];
-        };
-
-        if (getenv('MYSQL_DSN')) {
-            $dsn = getenv('MYSQL_DSN');
-            $user = getenv('MYSQL_USER');
-            $password = getenv('MYSQL_PASSWORD');
-            yield 'mysql' => $makePDOCase($dsn, $user, $password, 'mysql');
-        }
-
-        if (getenv('PGSQL_DSN')) {
-            $dsn = getenv('PGSQL_DSN');
-            $user = getenv('PGSQL_USER');
-            $password = getenv('PGSQL_PASSWORD');
-            yield 'postgres' => $makePDOCase($dsn, $user, $password, 'postgres');
-        }
     }
 
     /**

tests/Mutex/MutexConcurrencyTest.php

@@ -15,7 +15,6 @@
 use Malkusch\Lock\Mutex\PostgreSQLMutex;
 use Malkusch\Lock\Mutex\RedisMutex;
 use Malkusch\Lock\Mutex\SemaphoreMutex;
-use Malkusch\Lock\Mutex\TransactionalMutex;
 use org\bovigo\vfs\vfsStream;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\DoesNotPerformAssertions;
@@ -51,13 +50,6 @@ public static function provideMutexFactoriesCases(): iterable
             return new NoMutex();
         }];
 
-        yield 'TransactionalMutex' => [static function (): Mutex {
-            $pdo = new \PDO('sqlite::memory:');
-            $pdo->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);
-
-            return new TransactionalMutex($pdo, self::TIMEOUT);
-        }];
-
         yield 'FlockMutex' => [static function (): Mutex {
             $file = fopen(vfsStream::url('test/lock'), 'w');