<?php
namespace Doctrine\DBAL\Connections;
use Doctrine\Common\EventManager;
use Doctrine\DBAL\Configuration;
use Doctrine\DBAL\Connection;
use Doctrine\DBAL\Driver;
use Doctrine\DBAL\Driver\Connection as DriverConnection;
use Doctrine\DBAL\Driver\Exception as DriverException;
use Doctrine\DBAL\Event\ConnectionEventArgs;
use Doctrine\DBAL\Events;
use Doctrine\DBAL\Exception;
use Doctrine\DBAL\Statement;
use InvalidArgumentException;
use function array_rand;
use function count;
/**
* Primary-Replica Connection
*
* Connection can be used with primary-replica setups.
*
* Important for the understanding of this connection should be how and when
* it picks the replica or primary.
*
* 1. Replica if primary was never picked before and ONLY if 'getWrappedConnection'
* or 'executeQuery' is used.
* 2. Primary picked when 'executeStatement', 'insert', 'delete', 'update', 'createSavepoint',
* 'releaseSavepoint', 'beginTransaction', 'rollback', 'commit' or 'prepare' is called.
* 3. If Primary was picked once during the lifetime of the connection it will always get picked afterwards.
* 4. One replica connection is randomly picked ONCE during a request.
*
* ATTENTION: You can write to the replica with this connection if you execute a write query without
* opening up a transaction. For example:
*
* $conn = DriverManager::getConnection(...);
* $conn->executeQuery("DELETE FROM table");
*
* Be aware that Connection#executeQuery is a method specifically for READ
* operations only.
*
* Use Connection#executeStatement for any SQL statement that changes/updates
* state in the database (UPDATE, INSERT, DELETE or DDL statements).
*
* This connection is limited to replica operations using the
* Connection#executeQuery operation only, because it wouldn't be compatible
* with the ORM or SchemaManager code otherwise. Both use all the other
* operations in a context where writes could happen to a replica, which makes
* this restricted approach necessary.
*
* You can manually connect to the primary at any time by calling:
*
* $conn->ensureConnectedToPrimary();
*
* Instantiation through the DriverManager looks like:
*
* @psalm-import-type Params from \Doctrine\DBAL\DriverManager
* @example
*
* $conn = DriverManager::getConnection(array(
* 'wrapperClass' => 'Doctrine\DBAL\Connections\PrimaryReadReplicaConnection',
* 'driver' => 'pdo_mysql',
* 'primary' => array('user' => '', 'password' => '', 'host' => '', 'dbname' => ''),
* 'replica' => array(
* array('user' => 'replica1', 'password', 'host' => '', 'dbname' => ''),
* array('user' => 'replica2', 'password', 'host' => '', 'dbname' => ''),
* )
* ));
*
* You can also pass 'driverOptions' and any other documented option to each of this drivers
* to pass additional information.
*/
class PrimaryReadReplicaConnection extends Connection
{
/**
* Primary and Replica connection (one of the randomly picked replicas).
*
* @var DriverConnection[]|null[]
*/
protected $connections = ['primary' => null, 'replica' => null];
/**
* You can keep the replica connection and then switch back to it
* during the request if you know what you are doing.
*
* @var bool
*/
protected $keepReplica = false;
/**
* Creates Primary Replica Connection.
*
* @internal The connection can be only instantiated by the driver manager.
*
* @param array<string,mixed> $params
*
* @throws Exception
* @throws InvalidArgumentException
*
* @phpstan-param array<string,mixed> $params
* @psalm-param Params $params
*/
public function __construct(
array $params,
Driver $driver,
?Configuration $config = null,
?EventManager $eventManager = null
) {
if (! isset($params['replica'], $params['primary'])) {
throw new InvalidArgumentException('primary or replica configuration missing');
}
if (count($params['replica']) === 0) {
throw new InvalidArgumentException('You have to configure at least one replica.');
}
if (isset($params['driver'])) {
$params['primary']['driver'] = $params['driver'];
foreach ($params['replica'] as $replicaKey => $replica) {
$params['replica'][$replicaKey]['driver'] = $params['driver'];
}
}
$this->keepReplica = (bool) ($params['keepReplica'] ?? false);
parent::__construct($params, $driver, $config, $eventManager);
}
/**
* Checks if the connection is currently towards the primary or not.
*/
public function isConnectedToPrimary(): bool
{
return $this->_conn !== null && $this->_conn === $this->connections['primary'];
}
/**
* @param string|null $connectionName
*
* @return bool
*/
public function connect($connectionName = null)
{
if ($connectionName !== null) {
throw new InvalidArgumentException(
'Passing a connection name as first argument is not supported anymore.'
. ' Use ensureConnectedToPrimary()/ensureConnectedToReplica() instead.'
);
}
return $this->performConnect();
}
protected function performConnect(?string $connectionName = null): bool
{
$requestedConnectionChange = ($connectionName !== null);
$connectionName = $connectionName ?? 'replica';
if ($connectionName !== 'replica' && $connectionName !== 'primary') {
throw new InvalidArgumentException('Invalid option to connect(), only primary or replica allowed.');
}
// If we have a connection open, and this is not an explicit connection
// change request, then abort right here, because we are already done.
// This prevents writes to the replica in case of "keepReplica" option enabled.
if ($this->_conn !== null && ! $requestedConnectionChange) {
return false;
}
$forcePrimaryAsReplica = false;
if ($this->getTransactionNestingLevel() > 0) {
$connectionName = 'primary';
$forcePrimaryAsReplica = true;
}
if (isset($this->connections[$connectionName])) {
$this->_conn = $this->connections[$connectionName];
if ($forcePrimaryAsReplica && ! $this->keepReplica) {
$this->connections['replica'] = $this->_conn;
}
return false;
}
if ($connectionName === 'primary') {
$this->connections['primary'] = $this->_conn = $this->connectTo($connectionName);
// Set replica connection to primary to avoid invalid reads
if (! $this->keepReplica) {
$this->connections['replica'] = $this->connections['primary'];
}
} else {
$this->connections['replica'] = $this->_conn = $this->connectTo($connectionName);
}
if ($this->_eventManager->hasListeners(Events::postConnect)) {
$eventArgs = new ConnectionEventArgs($this);
$this->_eventManager->dispatchEvent(Events::postConnect, $eventArgs);
}
return true;
}
/**
* Connects to the primary node of the database cluster.
*
* All following statements after this will be executed against the primary node.
*/
public function ensureConnectedToPrimary(): bool
{
return $this->performConnect('primary');
}
/**
* Connects to a replica node of the database cluster.
*
* All following statements after this will be executed against the replica node,
* unless the keepReplica option is set to false and a primary connection
* was already opened.
*/
public function ensureConnectedToReplica(): bool
{
return $this->performConnect('replica');
}
/**
* Connects to a specific connection.
*
* @param string $connectionName
*
* @return DriverConnection
*
* @throws Exception
*/
protected function connectTo($connectionName)
{
$params = $this->getParams();
$connectionParams = $this->chooseConnectionConfiguration($connectionName, $params);
try {
return $this->_driver->connect($connectionParams);
} catch (DriverException $e) {
throw $this->convertException($e);
}
}
/**
* @param string $connectionName
* @param mixed[] $params
*
* @return mixed
*/
protected function chooseConnectionConfiguration($connectionName, $params)
{
if ($connectionName === 'primary') {
return $params['primary'];
}
$config = $params['replica'][array_rand($params['replica'])];
if (! isset($config['charset']) && isset($params['primary']['charset'])) {
$config['charset'] = $params['primary']['charset'];
}
return $config;
}
/**
* {@inheritDoc}
*/
public function executeStatement($sql, array $params = [], array $types = [])
{
$this->ensureConnectedToPrimary();
return parent::executeStatement($sql, $params, $types);
}
/**
* {@inheritDoc}
*/
public function beginTransaction()
{
$this->ensureConnectedToPrimary();
return parent::beginTransaction();
}
/**
* {@inheritDoc}
*/
public function commit()
{
$this->ensureConnectedToPrimary();
return parent::commit();
}
/**
* {@inheritDoc}
*/
public function rollBack()
{
$this->ensureConnectedToPrimary();
return parent::rollBack();
}
/**
* {@inheritDoc}
*/
public function close()
{
unset($this->connections['primary'], $this->connections['replica']);
parent::close();
$this->_conn = null;
$this->connections = ['primary' => null, 'replica' => null];
}
/**
* {@inheritDoc}
*/
public function createSavepoint($savepoint)
{
$this->ensureConnectedToPrimary();
parent::createSavepoint($savepoint);
}
/**
* {@inheritDoc}
*/
public function releaseSavepoint($savepoint)
{
$this->ensureConnectedToPrimary();
parent::releaseSavepoint($savepoint);
}
/**
* {@inheritDoc}
*/
public function rollbackSavepoint($savepoint)
{
$this->ensureConnectedToPrimary();
parent::rollbackSavepoint($savepoint);
}
public function prepare(string $sql): Statement
{
$this->ensureConnectedToPrimary();
return parent::prepare($sql);
}
}