Exploring wp_cache_* functions in WordPress

In our previous post, we explored the concept of object caching in WordPress, discussing how WordPress caches data and the benefits of using object caching. In this post, we’ll dive deeper into the wp_cache_* functions, which provide developers with a powerful toolset for working with object caching in WordPress.

What are wp_cache_* functions?

The wp_cache_* functions are a set of functions provided by WordPress for working with object caching. These functions provide a simple and consistent way for developers to cache and retrieve data from the cache.

Main cache functions

wp_cache_get()

The wp_cache_get() function is used to retrieve an item from the cache. Here’s an example:

// Try to retrieve the item from the cache
$item = wp_cache_get( 'my_item' );

// If the item is not in the cache, generate it
if ( false === $item ) {
    $item = generate_item();
    wp_cache_set( 'my_item', $item, '', 3600 );
}

For more information on wp_cache_get(), see the WordPress Developer reference.

wp_cache_set()

The wp_cache_set() function is used to store an item in the cache. Here’s an example:

// Generate the item to cache
$item = generate_item();

// Cache the item for 1 hour
wp_cache_set( 'my_item', $item, '', 3600 );

For more information on wp_cache_set(), see the WordPress Developer reference.

wp_cache_add()

The wp_cache_add() function is used to add an item to the cache only if it doesn’t already exist. Here’s an example:

// Generate the item to cache
$item = generate_item();

// Cache the item for 1 hour, but only if it doesn't already exist
wp_cache_add( 'my_item', $item, '', 3600 );

For more information on wp_cache_add(), see the WordPress Developer reference.

wp_cache_delete()

The wp_cache_delete() function is used to remove an item from the cache. Here’s an example:

// Remove the item from the cache
wp_cache_delete( 'my_item' );

For more information on wp_cache_delete(), see the WordPress Developer reference.

wp_cache_flush()

The wp_cache_flush() function is used to clear the entire cache. Here’s an example:

// Clear the entire cache
wp_cache_flush();

For more information on wp_cache_flush(), see the WordPress Developer reference.

Lesser-known cache functions

Aside from the main cache functions mentioned earlier, WordPress also provides several lesser-known cache functions that can be useful in certain situations. Here are some of them:

wp_cache_get_multiple()

The wp_cache_get_multiple() function is used to retrieve multiple items from the cache in a single function call. Here’s an example:

$keys = array( 'key1', 'key2', 'key3' );
$results = wp_cache_get_multiple( $keys );

// $results is an array containing the cached values for 'key1', 'key2', and 'key3'

wp_cache_set_multiple()

Similar to wp_cache_get_multiple(), this function is used to set multiple cache items at once. It accepts an associative array of cache keys and values as its parameter. For example:

$data = array(
    'key1' => 'value1',
    'key2' => 'value2',
    'key3' => 'value3'
);
wp_cache_set_multiple( $data );

wp_cache_incr() and wp_cache_decr()

These functions are used to increment or decrement a cached integer value by a given amount. They accept the cache key as their first parameter, and the amount to increment or decrement as their second parameter. For example:

// Increment the cached value for 'my_key' by 1
wp_cache_incr( 'my_key', 1 );

// Decrement the cached value for 'my_key' by 2
wp_cache_decr( 'my_key', 2 );

Functions controlling cache behavior

In addition to the cache functions themselves, WordPress also provides several functions that can be used to control the behavior of the cache:

wp_suspend_cache_addition()

This function is used to temporarily suspend adding new items to the cache. This can be useful in situations where you want to prevent the cache from being polluted with new data while you’re doing some other processing. To resume cache additions, simply call wp_suspend_cache_addition() again with a false parameter. For example:

// Suspend cache additions
wp_suspend_cache_addition( true );

// Do some processing that shouldn't affect the cache

// Resume cache additions
wp_suspend_cache_addition( false );

wp_suspend_cache_invalidation()

Similar to wp_suspend_cache_addition(), this function is used to temporarily suspend cache invalidation. This can be useful in situations where you want to prevent the cache from being cleared while you’re doing some other processing. To resume cache invalidation, simply call wp_suspend_cache_invalidation() again with a false parameter.

Conclusion

Caching is an important tool for improving website performance, and WordPress provides a set of functions known as wp_cache_* functions that make it easy to implement caching in your WordPress website. By using these functions and following best practices, you can ensure that your website is fast and responsive for your visitors.

If you’re new to object caching in WordPress, you may want to check out our previous introductory post on the topic. Additionally, by exploring advanced caching techniques, such as fragment and transient caching, you can further optimize your website for even better performance.

By taking advantage of caching and other performance optimization techniques, you can provide a better user experience for your website visitors and improve your website’s search engine ranking.