Mongo connection script example for replicaset connection and reconnect on failure (without having to restart server).

mongo_connect.php

<?php

$retry = 0;
$m = false;

// Repeat while no connection and haven't tried 3 times
while (!$m and $retry < 3) {
	try {
		// Connect to replica set
		$m = new MongoClient("mongodb://10.0.1.100,10.0.1.101,10.0.5.1", [
				'replicaSet' => 'rpset',
				'readPreference' => MongoClient::RP_SECONDARY_PREFERRED,
				'connect' => true,
				'w' => 0
				]);

		// Check for a primary connection
		$has_primary = false;
		$conns = $m->getConnections();
		foreach ($conns as $con) {
			if ($con['connection']['connection_type_desc'] == 'PRIMARY') {
				$has_primary = true;
			}
		}

		// If no primary connection
		if (!$has_primary) {
			// Close all connections, and try again
			foreach ($conns as $con) {
				$m->close($con['hash']);
			}
			$m = false;
		}
	}
	catch (Exception $mex) {
	}

	if (!$m and $retry > 0) {
		usleep($retry * 500000);
	}
	$retry++;
}

if (!$m) {
	$error = "We're currently experiencing some database connection issues, please try later!";
	include_once(dirname(dirname(__FILE__))."/header.php");
	include_once(dirname(dirname(__FILE__))."/error.php");
}