session_set_start_handler throwing warnings - php

Question

I am writing my own session handler as below to make Aerospike as the session manager. However, it is throwing warnings about session handler.
Warning: session_start(): Cannot find save handler '' - session startup failed in /var/www/session.php on line 165
I have set the values of session.save_path and session.save_handler to "" in php.ini as I want to manage the session data storage and retrieval myself with the below class.
NOTE: I can use the default aerospike session handling but it saves session data as bytes(hexadecimal format), I can't use it as it is as other applications need to read this data as well, so I am trying to save data as a json encoded string.
A weird behavior is that the close method always gets called at script shutdown even though the session_set_save_handler's return value is false!
This works sometimes without error and sometimes throws a warning shown above. Not sure what is missing.
Code:
<?php
ini_set( 'display_errors', 1 );
ini_set( 'error_reporting', E_ALL );
define('SESS_ID', '66ac548234f96b48b42e18b2d3d7b73a3f1aceb01fa4c20647d3dcaa055b5099');
class MySessionHandler implements SessionHandlerInterface {
private $database = null;
private $recordKey = null;
public function __construct(){
$this->init();
}
private function init() {
$this->database = new \Aerospike(
[
"hosts" => [
0 => [
"addr" => "IP_HERE",
"port" => 3000
]
]
], false);
$this->recordKey = $this->database->initKey( 'cache', 'data', SESS_ID);
}
private function isConnected() : bool {
return ( $this->database instanceof \Aerospike ) && $this->database->isConnected();
}
public function open($savepath = '', $id = ''){
// If successful
if( is_null($this->database) ) {
$this->init();
}
$status = $this->database->get($this->recordKey, $data);
if ($status == \Aerospike::OK) {
$data = json_decode($data['bins']['PHP_SESSION'], 1);
if( !is_array($data) ) {
$data = [];
}
} else {
$data = [];
}
return true;
}
public function read($id)
{
if( is_null($this->database) ) {
$this->init();
}
$status = $this->database->get($this->recordKey, $data);
if ($status == \Aerospike::OK) {
$data = json_decode($data['bins']['PHP_SESSION'], 1);
if( !is_array($data) ) {
$data = [];
}
} else {
$data = [];
}
$_SESSION = $data;
return json_encode($data);
}
public function write($id, $dataNode)
{
if( is_null($this->database) ) {
$this->init();
}
$data = false;
if( $this->isConnected() ) {
$bins = [
"PHP_SESSION" => json_encode($_SESSION)
];
$status = $this->database->put( $this->recordKey, $bins );
if ($status == \Aerospike::OK) {
$data = true;
} else {
// error while saving data, log it
}
}
return $data;
}
public function destroy($id)
{
$removeStatus = false;
if( $this->isConnected() ) {
$status = $this->database->remove( $this->recordKey );
if ($status == \Aerospike::OK) {
$removeStatus = true;
} else {
// error while saving data, log it
}
}
return $removeStatus;
}
public function close(){
// Close the database connection
if($this->isConnected() && $this->database->close()){
// Return True
return true;
}
// Return False
return false;
}
public function gc($max)
{
return 0;
}
public function __destruct()
{
$this->close();
}
}
$s = new MySessionHandler();
// Set handler to overide SESSION
$newSession = session_set_save_handler($s, true);
var_dump($newSession); // this returns false sometimes and throws a warning
register_shutdown_function('session_write_close');
session_id(SESS_ID);
session_start();
$_SESSION['dfc'] = 'xdc1';
//unset($_SESSION['dfc']);
pr($_SESSION);
unset($s);
function pr($data) {
if( is_object($data) ) {
// $data = serialize($data);
}
echo '<pre>' . var_export($data, 1) . '</pre>';
}
These warnings are thrown intermittently and I am not sure what might be causing this. Any help would be appreciated.

Answer 1

The PHP client for Aerospike comes with a session handler. Set session.save_handler=aerospike. See the php.ini options of the module.
If you're writing your own session handler
Don't set session.save_handler=''. You want to comment it out in your php.ini instead, because that gets loaded and executed first (before your script) and it's non-sensical. There is no such handler. That should suppress the warning.
Watch out for null bytes. PHP strings can have those in the middle, but Aerospike strings will terminate there, so it'll get truncated at that point. Read the documentation on Handling Unsupported Types, which is why you're provided the \Aerospike\Bytes wrapper class.