I've run into a bewildering problem in our CodeIgniter-powered website. One PHP class - TChild - will intermittently start throwing "cannot redeclare class" errors and breaking every page that uses it. The lengths I've gone to to ensure that the declaring code runs only once have gotten frankly ridiculous, but to no avail. The top of tchild.php currently looks like this:
(!( isset( $GLOBALS['tchild_counter'] ) ))
? $GLOBALS['tchild_counter'] = 1
: $GLOBALS['tchild_counter']++ ;
log_message("info", "tchild has been included " . $GLOBALS['tchild_counter'] . " times");
if($GLOBALS['tchild_counter'] != 1) {
log_message("info", "STOP RUNNING TWICE");
} else {
if ( ! defined('BASEPATH')) {
log_message("error", "BASEPATH not set; no direct script access allowed");
exit('No direct script access allowed');
}
log_message("info", "Basepath is fine, checking if tchild exists (proc".getmypid().")");
log_message("info", "why does that last line seem to run twice?");
if ( ! class_exists('TChild')) {
log_message("info", "TChild does not exist, creating it");
if(class_exists('tchild')) {
log_message("info", "tchild apparently exists?");
} else {
log_message("info","okay, I'm extra-sure that tchild doesn't exist");
}
class TChild extends ActiveRecord\Model {
It's a gigantic pile of... something, but at least it should ensure that TChild is only defined once, right? Well, no. Mostly, it works fine, but occasionally the server will get into some strange state where it decides, despite all evidence to the contrary, that TChild is being declared twice. From the extensive logging statements I've added, I'm fairly certain that tchild.php is only included by a single require_once to begin with, and it definitely doesn't get to the class definition more than once. (It does, however, spit out two "STOP RUNNING TWICE" log entries, even when things are running fine. I don't know why, but at least that doesn't break anything.)
Once it starts failing, it will continue to break everything for (usually) a few minutes, then fix itself for reasons as mysterious as the initial failure.
I have no idea what's going on here. Googling around led me to try adding apc.enabled = 0 to my php.ini, but it hasn't made a difference in the crash or in performance. (I don't think it was enabled to begin with, but it was worth a shot.)
Update:
Aha, there was a require statement in a third-party library that was including the file more than once. I still don't know why the class was being redeclared despite all the if/else blocks I had the declaration wrapped inside, but at least things seem to be working now.
