PHP Memcached Gets Usage (Detailed Guide w/ Code Examples)

Use Case(s)

The PHP Memcached::get method is used when you need to retrieve an item from memcached by its key. A common use case for this function would be to fetch data that has been previously stored in cache, like user sessions, recently accessed database queries, or other time-intensive computations.

Code Examples

Example 1: Basic Get

This is a simple example of how to use the Memcached::get method.

$memcached = new Memcached();
$memcached->addServer('localhost', 11211);

$key = "sample_key";
$value = $memcached->get($key);

if ($value) {
    echo "Value: " . $value;
} else {
    echo "No value found.";
}

In this example, we create a new Memcached instance and add a server. Then we try to get the value associated with "sample_key". If a value is found, it is printed; otherwise, we print "No value found.".

Example 2: Using the Get Function With a Callback

This example shows how you can pass a callback function to the get method. The callback will be executed if the key is not found in the cache.

$memcached = new Memcached();
$memcached->addServer('localhost', 11211);

$key = "sample_key";
$cacheResult = $memcached->get($key, function($memcached, $key, &$value) {
    $value = "Default value";
    return true;
});

echo "Value: " . $cacheResult;

In this example, if "sample_key" is not found in the cache, the callback function is executed, setting a default value which is then returned.

Best Practices

1. Always check whether the get method returns a value before using it to avoid null reference exceptions.
2. Use the memcached get functionality with a callback for keys that may not be present in the cache, to handle those cases gracefully.
3. Avoid storing large objects in Memcached as it might fill up your cache quickly.

Common Mistakes

1. Forgetting to check if the server is added successfully can lead to errors. Always check if the server is added successfully before proceeding with gets or sets.
2. Not handling cache misses. If a key is not found in the cache, make sure your code is equipped to handle this scenario, either by fetching from a persistent store or providing a default value.

FAQs

Q: What happens if the key is not found in memcache? A: If the key is not found, Memcached::get will return FALSE. You should always check the return value before using it.

Q: Can I use Memcached::get for multiple keys? A: Yes, for getting multiple keys at once, you can use the Memcached::getMulti method.