Disable indexers/Enable Indexers

indexers.php

protected function _getIndexers() 
{
	return Mage::getSingleton('index/indexer')->getProcessesCollection();	
}

protected function _stopReindex()
{
    $this->_getIndexers()->walk('setMode', array(Mage_Index_Model_Process::MODE_MANUAL));
    $this->_getIndexers()->walk('save');
}

protected function _startReindex()
{
    $this->_getIndexers()->walk('reindexAll');
    $this->_getIndexers()->walk('setMode', array(Mage_Index_Model_Process::MODE_REAL_TIME));
    $this->_getIndexers()->walk('save');
}