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Merge pull request #13 from WordPress/sqlite-translator/use-transacti…
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…ons-for-real

Wrap every SQLite query in a transaction
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@aristath
aristath authored Feb 28, 2023
2 parents 22d4481 + eee4638 commit 0ee1770
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Showing 2 changed files with 117 additions and 31 deletions.
65 changes: 62 additions & 3 deletions tests/WP_SQLite_Translator_Tests.php
View file
Original file line number Diff line number Diff line change
Expand Up @@ -851,21 +851,80 @@ public function testStartTransactionCommand() {
$this->assertCount( 0, $this->engine->get_query_results() );
}

public function testNestedTransactionHasNoEffect() {
public function testNestedTransactionWork() {
$this->engine->query( 'BEGIN' );
$this->engine->query( "INSERT INTO _options (option_name) VALUES ('first');" );
$this->engine->query( 'START TRANSACTION' );
$this->engine->query( "INSERT INTO _options (option_name) VALUES ('second');" );
$this->engine->query( 'START TRANSACTION' );
$this->engine->query( "INSERT INTO _options (option_name) VALUES ('third');" );
$this->engine->query( 'SELECT * FROM _options;' );
$this->assertCount( 3, $this->engine->get_query_results() );

$this->engine->query( 'ROLLBACK' );
$this->engine->query( 'SELECT * FROM _options;' );
$this->assertCount( 2, $this->engine->get_query_results() );

$this->engine->query( 'ROLLBACK' );
$this->engine->query( 'SELECT * FROM _options;' );
$this->assertCount( 0, $this->engine->get_query_results() );
$this->assertCount( 1, $this->engine->get_query_results() );

$this->engine->query( 'COMMIT' );
$this->engine->query( 'SELECT * FROM _options;' );
$this->assertCount( 0, $this->engine->get_query_results() );
$this->assertCount( 1, $this->engine->get_query_results() );
}

public function testNestedTransactionWorkComplexModify() {
$this->engine->query( 'BEGIN' );
// Create a complex ALTER Table query where the first
// column is added successfully, but the second fails.
// Behind the scenes, this single MySQL query is split
// into multiple SQLite queries – some of them will
// succeed, some will fail.
$success = $this->engine->query( "
ALTER TABLE _options
ADD COLUMN test varchar(20),
ADD COLUMN test varchar(20)
" );
$this->assertFalse($success);
// Commit the transaction.
$this->engine->query( 'COMMIT' );

// Confirm the entire query failed atomically and no column was
// added to the table.
$this->engine->query( 'DESCRIBE _options;' );
$fields = $this->engine->get_query_results();

$this->assertEquals(
$fields,
array(
(object) array(
'Field' => 'ID',
'Type' => 'integer',
'Null' => 'NO',
'Key' => 'PRI',
'Default' => null,
'Extra' => '',
),
(object) array(
'Field' => 'option_name',
'Type' => 'text',
'Null' => 'NO',
'Key' => '',
'Default' => '',
'Extra' => '',
),
(object) array(
'Field' => 'option_value',
'Type' => 'text',
'Null' => 'NO',
'Key' => '',
'Default' => '',
'Extra' => '',
)
)
);

}

public function testCount() {
Expand Down
83 changes: 55 additions & 28 deletions wp-includes/sqlite/class-wp-sqlite-translator.php
View file
Original file line number Diff line number Diff line change
Expand Up @@ -289,12 +289,12 @@ class WP_SQLite_Translator {
private $return_value;

/**
* Variable to check if there is an active transaction.
* Variable to keep track of nested transactions level.
*
* @var boolean
* @var number
* @access protected
*/
protected $has_active_transaction = false;
protected $transaction_level = 0;

/**
* Constructor.
Expand Down Expand Up @@ -341,7 +341,7 @@ public function __construct( $pdo = null ) {
return false;
}
}

new WP_SQLite_PDO_User_Defined_Functions( $pdo );

// MySQL data comes across stringified by default.
Expand Down Expand Up @@ -523,19 +523,22 @@ private function prepare_directory() {
*/
public function query( $statement, $mode = PDO::FETCH_OBJ, ...$fetch_mode_args ) { // phpcs:ignore WordPress.DB.RestrictedClasses
$this->flush();
if (
preg_match( '/^\s*START TRANSACTION/i', $statement )
|| preg_match( '/^\s*BEGIN/i', $statement )
) {
return $this->beginTransaction();
}
if ( preg_match( '/^\s*COMMIT/i', $statement ) ) {
return $this->commit();
}
if ( preg_match( '/^\s*ROLLBACK/i', $statement ) ) {
return $this->rollBack();
}

try {
if (
preg_match( '/^START TRANSACTION/i', $statement )
|| preg_match( '/^BEGIN/i', $statement )
) {
return $this->beginTransaction();
}
if ( preg_match( '/^COMMIT/i', $statement ) ) {
return $this->commit();
}
if ( preg_match( '/^ROLLBACK/i', $statement ) ) {
return $this->rollBack();
}
// Perform all the queries in a nested transaction.
$this->beginTransaction();

do {
$error = null;
Expand Down Expand Up @@ -629,8 +632,12 @@ public function query( $statement, $mode = PDO::FETCH_OBJ, ...$fetch_mode_args )
break;
}

// Commit the nested transaction.
$this->commit();
return $this->return_value;
} catch ( Exception $err ) {
// Rollback the nested transaction.
$this->rollBack();
if ( defined( 'PDO_DEBUG' ) && PDO_DEBUG === true ) {
throw $err;
}
Expand Down Expand Up @@ -2999,24 +3006,38 @@ private function flush() {
* @return boolean
*/
public function beginTransaction() {
if ( $this->has_active_transaction ) {
return false;
$success = false;
try {
if (0 === $this->transaction_level) {
$success = $this->pdo->beginTransaction();
} else {
$success = $this->pdo->query('SAVEPOINT LEVEL' . $this->transaction_level);
}
} finally {
if ($success) {
++$this->transaction_level;
}
}
$this->has_active_transaction = $this->pdo->beginTransaction();
return $this->has_active_transaction;
return $success;
}

/**
* Method to call PDO::commit().
*
* @see PDO::commit()
*
* @return void
* @return boolean True on success, false on failure.
*/
public function commit() {
if ( $this->has_active_transaction ) {
$this->pdo->commit();
$this->has_active_transaction = false;
if ( $this->transaction_level === 0 ) {
return false;
}

--$this->transaction_level;
if ( 0 === $this->transaction_level ) {
return $this->pdo->commit();
} else {
return (bool) $this->pdo->query( 'RELEASE SAVEPOINT LEVEL' . $this->transaction_level );
}
}

Expand All @@ -3025,12 +3046,18 @@ public function commit() {
*
* @see PDO::rollBack()
*
* @return void
* @return boolean True on success, false on failure.
*/
public function rollBack() {
if ( $this->has_active_transaction ) {
$this->pdo->rollBack();
$this->has_active_transaction = false;
if ( $this->transaction_level === 0 ) {
return false;
}

--$this->transaction_level;
if ( 0 === $this->transaction_level ) {
return $this->pdo->rollBack();
} else {
return (bool) $this->pdo->query( 'ROLLBACK TO SAVEPOINT LEVEL' . $this->transaction_level );
}
}
}

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