// 采用异常捕获的方式判断是否需要重连
protected function run($query, $bindings, Closure $callback)
{
    $this->reconnectIfMissingConnection();

    $start = microtime(true);

    // Here we will run this query. If an exception occurs we'll determine if it was
    // caused by a connection that has been lost. If that is the cause, we'll try
    // to re-establish connection and re-run the query with a fresh connection.
    try {
        $result = $this->runQueryCallback($query, $bindings, $callback);
    } catch (QueryException $e) {
        $result = $this->handleQueryException(
            $e, $query, $bindings, $callback
        );
    }

    // Once we have run the query we will calculate the time that it took to run and
    // then log the query, bindings, and execution time so we will report them on
    // the event that the developer needs them. We'll log time in milliseconds.
    $this->logQuery(
        $query, $bindings, $this->getElapsedTime($start)
    );

    return $result;
}
// 判断传入的数据库连接是否有效
protected function reconnectIfMissingConnection()
{
    if (is_null($this->pdo)) {
        $this->reconnect();
    }
}
// 重连
public function reconnect()
{
    if (is_callable($this->reconnector)) {
        return call_user_func($this->reconnector, $this);
    }

    throw new LogicException('Lost connection and no reconnector available.');
}

// 判断是连接断开导致的异常
// vendor\Illuminate\Database\DetectsLostConnections.php

protected function causedByLostConnection(Throwable $e)
{
    $message = $e->getMessage();

    return Str::contains($message, [
        'server has gone away',
        'no connection to the server',
        'Lost connection',
        'is dead or not enabled',
        'Error while sending',
        'decryption failed or bad record mac',
        'server closed the connection unexpectedly',
        'SSL connection has been closed unexpectedly',
        'Error writing data to the connection',
        'Resource deadlock avoided',
        'Transaction() on null',
        'child connection forced to terminate due to client_idle_limit',
        'query_wait_timeout',
        'reset by peer',
        'Physical connection is not usable',
        'TCP Provider: Error code 0x68',
        'Name or service not known',
        'ORA-03114',
    ]);
}