Does Laminas Filesystem Cache Return Expired Values Without the ExpiredValues Plugin?

Answer

Yes. The Laminas Filesystem cache adapter can return a value whose lifetime has elapsed if the ExpiredValues plugin is not in the plugin stack and no read‑time cleanup callback is defined.

Likely explanation

The Filesystem adapter reports that it does not support the automatic_cleaning capability. Consequently, expired cache files are removed only during write operations (or when a cache_clean_callback is explicitly invoked). On a read‑heavy workload, an expired file may remain on disk until the next write, allowing get() to return stale data.

Confirmed facts

• The adapter’s getCapabilities() output does not include automatic_cleaning.
• Without the ExpiredValues plugin, get() returns the unserialized value from the file, regardless of its expiration metadata.
• The ExpiredValues plugin checks the expiration timestamp on each get and either removes the entry or returns null, guaranteeing that no stale value is served.
• Defining a cache_clean_callback that calls $cache->cleanExpired() triggers cleanup on every read, mimicking automatic cleaning.

Steps to verify or enforce the desired behavior

1. Create a cache instance with the Filesystem adapter and a short lifetime (e.g., 2 seconds).
2. Store a value, wait longer than the lifetime, then call get() without the ExpiredValues plugin. Observe whether the stale value is returned.
3. Repeat the test with the ExpiredValues plugin added to the plugin stack; get() should return null or false.
4. If you prefer not to use the plugin, set a cache_clean_callback on the adapter:

   $adapter->setOptions([
       'cache_clean_callback' => function ($cache) {
           $cache->cleanExpired();
       }
   ]);
   

   Then verify that get() after expiration returns null.
5. Optionally, inspect the adapter’s capabilities:

   $caps = $adapter->getCapabilities();
   var_dump($caps['automatic_cleaning']); // should be bool(false)