PHP SQLite Object Cache

PHP Object Caching system with a SQLite backend store and automatic content expiration. Cache is stored using a SQLite database and persists on disk.

Requirements

• PHP 8.0+
• PDO functions in PHP
• SQLite functions in PHP
• JSON functions in PHP
• Ability to write to /dev/shm

Optional components

• igbinary
• msgpack

If either igbinary or msgpack modules are available we will automatically use them as the serialization storage method in the database. If neither are available we fall back to JSON.

Usage

require("/path/to/dir/cache.class.php");

$opts = ["db_file" => "/var/tmp/mycache.sqlite"];
$cache = new \Scottchiefbaker\Cache\Sqlite($opts);

// Store an item
$key     = "cust:123";
$data    = ['name' => 'Jason Doolis', 'age' => 13, 'animal' => 'kitten'];
$expires = time() + 3600;

$ok = $cache->set($key, $data, $expires);

// Fetch an item
$data = $cache->get($key);

Methods

get($key)

Returns stored object.

set($key, $object, $expire_time)

Store an object in cache. Returns status of storage.

delete($key)

Remove an item from cache. Returns status of deletion.

cached_item_count()

Return the number of active items in the cache.

cached_item_keys()

Return array of all the active items in the cache.

remove_expired_entries($vacuum_db)

Remove all expired items from cache. If $vacuum_db is set, the DB will be vacuumed after removal.

empty_cache()

Remove all items from the cache.

Cleanup

Over time objects will be added and deleted to the cache. This may create fragmentation in the database so it might be a good idea to VACUUM it every so often. We have provided a method to do this:

// Remove all expired entries and defragment the database
$vacuum = true;
$ok     = $cache->remove_expired_entries($vacuum);

Real World Example

function get_slow_data($id) {
	global $cache;

	$ckey = "item:$id";
	$data = $cache->get($ckey);

	if ($data) { return $data; }

	// Not found in cache go get the data the slow way
	$data = my_slow_data_function($id);

	// Store the data in the cache for two hours
	$ok = $cache->set($ckey, $data, time() + 7200);

	return $ret;
}