PHP Version
8.2
CodeIgniter4 Version
4.7.5-dev
CodeIgniter4 Installation Method
Git
Which operating systems have you tested for this bug?
macOS
Which server did you use?
cli-server (PHP built-in webserver)
Environment
development
Database
No response
What happened?
Description
MemcachedHandler::decrement() behaves inconsistently with the other cache
handlers (File, Redis, Predis) when the key being decremented does not
yet exist. This is already flagged in the code with a // FIXME comment,
but not resolved:
https://github.com/codeigniter4/CodeIgniter4/blob/develop/system/Cache/Handlers/MemcachedHandler.php#L179
public function decrement(string $key, int $offset = 1): false|int
{
if (! $this->config['raw']) {
return false;
}
$key = static::validateKey($key, $this->prefix);
// FIXME: third parameter isn't other handler actions.
return $this->memcached->decrement($key, $offset, $offset, 60);
}How to see it
$cache = \Config\Services::cache(); // memcached handler, 'raw' => true
$cache->decrement('brand_new_key', 5);
// -> 5 (positive!)Now try the same thing with File, Redis, or Predis instead — they all give:
$cache->decrement('brand_new_key', 5);
// -> -5What I'd expect
If I decrement a key by 5, I'd expect a negative number back when it starts from nothing — like every other handler does. Memcached gives the opposite sign, which feels like a bug you could easily not notice until you switch cache drivers between dev and prod and your numbers suddenly flip.
Why this happens
I checked the PHP docs for Memcached::decrement() — the 3rd argument (initial_value) is used as-is if the key doesn't exist yet, it's not something the offset gets subtracted from. So passing $offset there just plants the key at +$offset instead of decrementing from zero.
(increment() doesn't have this problem, by the way — it's just a lucky coincidence that 0 + $offset and passing $offset as the initial value land on the same number.)
PHP Version
8.2
CodeIgniter4 Version
4.7.5-dev
CodeIgniter4 Installation Method
Git
Which operating systems have you tested for this bug?
macOS
Which server did you use?
cli-server (PHP built-in webserver)
Environment
development
Database
No response
What happened?
Description
MemcachedHandler::decrement()behaves inconsistently with the other cachehandlers (
File,Redis,Predis) when the key being decremented does notyet exist. This is already flagged in the code with a
// FIXMEcomment,but not resolved:
https://github.com/codeigniter4/CodeIgniter4/blob/develop/system/Cache/Handlers/MemcachedHandler.php#L179
How to see it
Now try the same thing with File, Redis, or Predis instead — they all give:
What I'd expect
If I decrement a key by 5, I'd expect a negative number back when it starts from nothing — like every other handler does. Memcached gives the opposite sign, which feels like a bug you could easily not notice until you switch cache drivers between dev and prod and your numbers suddenly flip.
Why this happens
I checked the PHP docs for
Memcached::decrement()— the 3rd argument (initial_value) is used as-is if the key doesn't exist yet, it's not something the offset gets subtracted from. So passing$offsetthere just plants the key at+$offsetinstead of decrementing from zero.(
increment()doesn't have this problem, by the way — it's just a lucky coincidence that0 + $offsetand passing$offsetas the initial value land on the same number.)