using closure in custom session function - php

Question

I am trying to write a custom SESSION class for PHP to move sessions into the database and away from the file system.
An error is thrown only in the _read() method when the closure $connect2DB is being called. In all other methods calling $connect2DB does not cause any errors.
Also if I instantiate the class as an object myself all methods including the infamous _read() works as expected. Can you find the error?
I have following code:
class sessionDBHandler {
public function __construct() {
session_set_save_handler(
array($this, "_open"),
array($this, "_close"),
array($this, "_read"),
array($this, "_write"),
array($this, "_destroy"),
array($this, "_gc")
);
register_shutdown_function('session_write_close');
}
public function _open() {
global $sessCon;
global $HOST;
global $USER;
global $PW;
global $DATABASE;
$sessCon=new mysqli($HOST,$USER,$PW,$DATABASE); //mysqli connection
}
public function _close() {
global $sessCon;
$sessCon->close();
}
public function _read($id) {
global $sessCon;
global $connect2DB;
global $SESSIONTAB;
$qRes=$connect2DB($sessCon,'select `data` from `'.$SESSIONTAB.'` where `ID`=?',array("s",$id)); //<-- error message here
if(!empty($qRes["res"][0]["data"])) return $qRes["res"][0]["data"];
else return '';
}
public function _write($id,$data) {
global $sessCon;
global $connect2DB;
global $SESSIONTAB;
$qRes=$connect2DB($sessCon,'select `ID` from `'.$SESSIONTAB.'` where `ID`=?',array("s",$id));
$param=array(); //buliding SQL query parameters
$param[0]="sis";
$param[]=$id;
$param[]=time();
$param[]=$data;
if(!empty($qRes["res"][0]["ID"])) {
$param[0].="s";
$param[]=$id;
}
$qRes=$connect2DB($sessCon,(!empty($qRes["res"][0]["ID"]) ? 'update' : 'insert').' `'.$SESSIONTAB.'` set `ID`=?, `access`=?, `data`=?'.(!empty($qRes["res"][0]["ID"]) ? ' where `ID`=?' : ''),$param);
if($qRes["info"]["affectedRows"]>0) return true;
else return '';
}
public function _destroy($id) {
global $sessCon;
global $connect2DB;
global $SESSIONTAB;
$qRes=$connect2DB($sessCon,'delete from `'.$SESSIONTAB.'` where `ID`=?',array("s",$id));
if($qRes["info"]["affectedRows"]>0) return true;
else return '';
}
public function _gc($max) {
global $sessCon;
global $connect2DB;
global $SESSIONTAB;
$qRes=$connect2DB($sessCon,'delete from `'.$SESSIONTAB.'` where `access`<?',array("i",(time()-$max)));
if($qRes["info"]["affectedRows"]>0) return true;
else return '';
}
}
and I tell PHP where it findes those functions (before calling session_start() here:
new sessionDBHandler();
My problem seems to be the closure I am using as my MySQL abstraction layer. The error I get is:
Fatal error: Function name must be a string in /Users/user/Sites/script.php on line 401
which suggests to me that it somehow cannot find the namespace of $connect2DB.
The thing is though if I call those functions without __constructor and its session_set_save_handler directive, it will work just fine:
$test=new sessionDBHandler();
$test->_open();
echo $test->_read("d6e08112ff6fc8a7eb6e76832327bf81");
$test->_close();
the above works without an error.
Now I am using closures here because I have to keep the footprint of this script very low and unset $connect2DB at the bottom of the script among other reasons so I would love to keep the current abstraction layer.
Any ideas what I can do here?
thanks everyone!
perhaps the $connect2DB is not initialized when sessions is being called?
connnect2DB
/**
* Simple MySQLi abstraction layer
*
* #param resource $mysqli The MySQLi connection link
* #param string $query The MySQL query for prepaired statement
* #param array $v The parameters to replace ? in $query. First element must be the type
* #param integer $o Option for more debug infos [0]=no infos(default) [1]=adding debug infos
*
* #return array [for select]=associative array of table result [for everything else]=associative array with affectedRows,info and insertID
*
* #author Dominik Wilkowski
*/
$connect2DB=function($mysqli,$query,$v=array(),$o=0) {
if($mysqli->connect_errno) {
return array('info'=>array('error'=>'Connect failed: '.$mysqli->connect_error)); //error handling here
exit();
}
if($v && (substr_count($query,"?")!=strlen($v[0]) || strlen($v[0])!=((count($v)-1)>=0 ? (count($v)-1) : 0))) {
return array('info'=>array('error'=>'Placeholders are unequal! placeholders:'.substr_count($query,"?").', replacements:'.strlen($v[0]).', param:'.(count($v)-1).' ('.$v[0].')')); //error handling here...
exit();
}
if($res=$mysqli->prepare($query)) {
//dynamically bind all $v
if($v) {
$values=array($v[0]);
for($i=1; $i<count($v); $i++) {
${'bind'.$i}=$v[$i];
$values[]=&${'bind'.$i};
}
call_user_func_array(array($res,'bind_param'),$values);
}
$res->execute();
//bind all table rows to result
if(strtolower(substr($query,0,6))=="select") {
$field=$fields=$tempRow=array();
$meta=$res->result_metadata();
while($field=$meta->fetch_field()) {
$fieldName=$field->name;
$fields[]=&$tempRow[$fieldName];
}
$meta->free_result();
call_user_func_array(array($res,"bind_result"),$fields);
//return associative array
$results=array();
$i=0;
while($res->fetch()) {
$results["res"][$i]=array();
foreach($tempRow as $k=>$v2) $results["res"][$i][$k] = $v2;
$i++;
}
$res->free_result();
}
else { //return infos about the query
if($mysqli->warning_count) {
if($err=$mysqli->query("SHOW WARNINGS")) {
$row=$err->fetch_row();
$results["info"]["error"].=$row[0].' ('.$row[1].'): '.$row[2];
$err->close();
}
}
$results["info"]["affectedRows"]=$mysqli->affected_rows;
$results["info"]["info"]=$mysqli->info;
$results["info"]["insertID"]=$mysqli->insert_id;
}
$res->close();
}
if($o===1) { //adding debug infos
$q=$query;
for($i=1;$i<count($v);$i++) $q=preg_replace("/\?/",(substr($v[0],($i-1),1)=="s" ? '"' : '').$v[$i].(substr($v[0],($i-1),1)=="s" ? '"' : ''),$q,1);
$results["info"]["query"]=$q;
$results["info"]["param"]=json_encode($v);
}
if(strtolower(substr($query,0,6))=="update" || strtolower(substr($query,0,6))=="delete") { //optimize at update and delete
preg_match_all('/((update|delete) `(.*)` )/i',$query,$tables);
foreach($tables[3] as $t) $mysqli->query('OPTIMIZE TABLE '.$t);
}
return $results;
};
Update #2
Our earlier test suggested that namespace indeed does not seem to be initialized at the time when _read() runs so I wrote a small test case for this to double check.
<?php
$LOGIN='login credentials';
//Closure
$nob=function() {
return 'closure running!<br>';
};
//Session handler
class sessionDBHandler {
public function __construct() {
session_set_save_handler(
array($this, "_open"),
array($this, "_close"),
array($this, "_read"),
array($this, "_write"),
array($this, "_destroy"),
array($this, "_gc")
);
register_shutdown_function('session_write_close');
}
public function _open() {
global $sessCon;
global $LOGIN;
echo '_open running with: '.$LOGIN.'<br>';
$sessCon='connection established!<br>';
}
public function _close() {
global $sessCon;
echo $sessCon='connection closed!<br>';
}
public function _read($id) {
global $sessCon;
global $nob;
echo $nob();
echo 'requested id is: '.$id.'<br>';
echo 'sessCon is: '.$sessCon;
}
public function _write($id,$data) {
global $sessCon;
echo 'requested id is: '.$id.' and data: '.$data.'<br>';
echo 'sessCon is: '.$sessCon;
}
public function _destroy($id) {
global $sessCon;
echo 'requested id is: '.$id.'<br>';
echo 'sessCon is: '.$sessCon;
}
public function _gc($max) {
global $sessCon;
echo 'requested max is: '.$max.'<br>';
echo 'sessCon is: '.$sessCon;
}
}
new sessionDBHandler();
session_start();
?>
Interestingly enough this will run without errors and output this:
_open running with: login credentials
closure running!
requested id is: 746b70a979d9ef8c6686e659707b4b38
sessCon is: connection established!
requested id is: 746b70a979d9ef8c6686e659707b4b38 and data:
sessCon is: connection established!
connection closed!
Now that suggests that there seems to be an error in my particular implementation. Whoever wants to have a stab at this is very welcome to join :)
Update #3
I want to unset my closure after I run my application and had therefore unset($connect2DB); on the very bottom of the script. This however seemed to have caused a "premature" unset somehow. Removing this will remove the error.
However
Is there a way to safely unset my closure after the script has run so it doesn't flow into the main script?