Wp Rocket Cache Invalidation

WP Rocket: cache invalidation from third-party code

For developers shipping a plugin or theme that mutates content WP Rocket has cached — saving a custom CPT, completing a WooCommerce order, importing data, processing a webhook, scheduling a bulk update. WP Rocket caches HTML to disk (NOT to the WP object cache); raw cache invalidation requires going through the plugin's public API, otherwise stale HTML stays served until the cache TTL or the next save.

WP Rocket is a paid plugin, not on Packagist, not in the WordPress.org plugin directory. Many sites have it; many don't. Every code path that touches rocket_clean_* MUST be feature-detected first — otherwise your code fatals on installs without WP Rocket.

Misconception this skill corrects

"I'll call wp_cache_flush() after my plugin saves data — that clears WP Rocket too."

It doesn't. wp_cache_flush() clears the WordPress object cache (transients, options, post meta caches in Redis / Memcached / WP_Cache_Object). WP Rocket is a page cache that writes static HTML files to disk under wp-content/cache/wp-rocket/.... The two are completely independent layers — you can flush the object cache 1000 times and the WP Rocket cached HTML stays untouched.

The right entry point: rocket_clean_post( $post_id ) if a specific post changed, or one of the more granular rocket_clean_* functions for other scenarios. Verified at wp-content/plugins/wp-rocket/inc/common/purge.php:167 and inc/functions/files.php.

Other AI-prone misconceptions:

• "I'll just unlink() the WP Rocket cache files for this URL." Wrong direction — WP Rocket's filename layout is non-trivial: desktop / mobile / tablet variants, language variants (/cache/wp-rocket/example.com-en/...), query-string variants, gzipped variants, webp variants. Manual deletion misses some, leaves stale files, AND skips the before_/after_ action hooks that other plugins (CDN purgers, Varnish, Cloudflare addons) listen for.
• "function_exists('rocket_clean_post') is paranoid; everyone has WP Rocket." No, WP Rocket is paid. ~30% of WP installs use SOME caching plugin; even of those, WP Rocket is one of many. Always feature-detect.
• "is_plugin_active('wp-rocket/wp-rocket.php')" is the right check." Half-true. is_plugin_active() requires wp-admin/includes/plugin.php to be loaded — it's NOT available during early hooks like plugins_loaded. defined('WP_ROCKET_VERSION') and function_exists('rocket_clean_post') work everywhere.

When to use this skill

Trigger when ANY of the following is true:

• The diff calls rocket_clean_*, wp_cache_flush(), rocket_* cache operations, OR raw filesystem operations against wp-content/cache/wp-rocket/.
• A plugin saves data and the user expects the cached page to refresh.
• WooCommerce / membership / LMS plugin invalidation flows (e.g. user enrolls in a course → cached course page shows old "no access" state).
• Reviewing PR code that hooks save_post / transition_post_status / woocommerce_* events and wants to invalidate cache.
• Custom CPT integration where post-save → page invalidation is needed.
• Bulk import / migration scripts that should NOT churn the cache during the import (delay invalidation to the end).

Plugin identity (verified)

Public cache-invalidation API (verified)

All functions live in wp-content/plugins/wp-rocket/inc/functions/files.php except rocket_clean_post which is in inc/common/purge.php.

Workflow

1. Always feature-detect first

if ( ! function_exists( 'rocket_clean_post' ) ) {
    return;   // WP Rocket not active; skip silently
}

rocket_clean_post( $post_id );

OR, with the constant guard:

if ( defined( 'WP_ROCKET_VERSION' ) ) {
    rocket_clean_post( $post_id );
}

Both work; the function_exists form is more defensive (handles the rare case where WP Rocket is partially loaded). Pick one and stay consistent.

For namespaced PHP code, use a full backslash: if ( ! \function_exists( 'rocket_clean_post' ) ) return;.

2. Pick the right granularity

Do not call rocket_clean_domain() from frequent events. It's the heaviest operation; over-using it defeats WP Rocket's whole purpose by constantly re-warming. Reserve it for actually-site-wide changes.

3. Hook into post-save events

// Most common pattern — clear when a CPT entry is saved.
add_action( 'save_post_my_cpt', function ( int $post_id, \WP_Post $post, bool $update ): void {
    if ( wp_is_post_revision( $post_id ) || wp_is_post_autosave( $post_id ) ) {
        return;
    }
    if ( ! \function_exists( 'rocket_clean_post' ) ) {
        return;
    }
    rocket_clean_post( $post_id );
}, 10, 3 );

save_post_<cpt> is preferable to plain save_post (more specific). Skip revisions and autosaves — both fire save_post but neither matters for cache.

4. Hook into WooCommerce events

// Order completion → clear product page cache
add_action( 'woocommerce_order_status_completed', function ( int $order_id ): void {
    if ( ! \function_exists( 'rocket_clean_post' ) ) {
        return;
    }
    $order = wc_get_order( $order_id );
    if ( ! $order ) {
        return;
    }
    foreach ( $order->get_items() as $item ) {
        $product_id = $item->get_product_id();
        if ( $product_id ) {
            rocket_clean_post( $product_id );   // each ordered product's page
        }
    }
}, 20, 1 );

Reason: stock count changes after a sale; cached product pages show stale stock. WP Rocket has its own WC integration but third-party plugins that touch stock or display cached prices need their own invalidation.

5. Bulk imports — defer invalidation

function my_import_posts( array $records ): void {
    // Suppress WP Rocket's automatic purges during the import.
    add_filter( 'rocket_is_importing', '__return_true' );

    foreach ( $records as $record ) {
        wp_insert_post( $record );
    }

    // Restore + nuke once.
    remove_filter( 'rocket_is_importing', '__return_true' );

    if ( \function_exists( 'rocket_clean_domain' ) ) {
        rocket_clean_domain();
    }
}

For a 10K-post import, calling rocket_clean_post() per-row generates 10K cache wipes + 10K filesystem operations. One rocket_clean_domain() at the end is orders of magnitude faster.

6. Lifecycle action hooks for monitoring

Verified in inc/functions/files.php and inc/common/purge.php — the public clean functions fire before_* and after_* actions:

Use these for:

• CDN purges triggered by cache wipes (after_rocket_clean_post → call your CDN API).
• Audit logging — record cache-invalidation events with the post / URL info.
• Custom invalidation chains — when post X changes, also invalidate URL Y.

// Audit log — every invalidation
add_action( 'after_rocket_clean_domain', function ( string $root, string $lang, string $url ): void {
    do_action( 'qm/info', "WP Rocket: domain cache cleared for {$url} (lang: {$lang})" );
}, 10, 3 );

// Trigger Cloudflare purge after WP Rocket clears a post
add_action( 'after_rocket_clean_post', function ( $post, array $purge_urls ): void {
    foreach ( $purge_urls as $url ) {
        my_cloudflare_purge( $url );
    }
}, 10, 2 );

7. Multisite considerations

rocket_clean_domain( $lang ) clears the cache for the current site's domain. On multisite, switching context first:

foreach ( get_sites() as $site ) {
    switch_to_blog( $site->blog_id );
    if ( \function_exists( 'rocket_clean_domain' ) ) {
        rocket_clean_domain();
    }
    restore_current_blog();
}

rocket_clean_cache_dir() clears the entire cache directory on disk — across all blogs at once. Use for "I'm activating WP Rocket-affecting changes globally" (theme switch, network-wide settings rollout).

8. The $run_actions flag in rocket_clean_files

Verified at inc/functions/files.php:547 — rocket_clean_files( $urls, $filesystem = null, $run_actions = true ). The third arg defaults to true — fires the before_/after_ hooks per file. Pass false for silent purge if you're calling it from inside another after_rocket_clean_* hook (avoids infinite recursion).

add_action( 'after_rocket_clean_post', function ( $post, array $purge_urls ) {
    // Don't fire actions on these supplementary cleans (we're already inside an action)
    rocket_clean_files( [ home_url( '/related-feed' ) ], null, $run_actions = false );
}, 10, 2 );

Critical rules

• Always feature-detect with function_exists('rocket_clean_post') or defined('WP_ROCKET_VERSION'). WP Rocket is paid; not every site has it.
• wp_cache_flush() does NOT clear WP Rocket cache. Two different layers — object cache vs file cache.
• is_plugin_active('wp-rocket/wp-rocket.php') requires wp-admin/includes/plugin.php — not available during early hooks. Use defined / function_exists instead.
• Pick the smallest granularity that covers the change. rocket_clean_post over rocket_clean_domain for a single-post change.
• Skip revisions / autosaves when hooking save_post — they fire but don't change visible content.
• Defer invalidation during bulk imports — temporarily return true from rocket_is_importing, insert posts, remove the filter, then call rocket_clean_domain once.
• Don't call rocket_clean_domain from high-frequency events. Defeats WP Rocket's purpose.
• Use $run_actions = false in rocket_clean_files when calling from inside another action handler to avoid recursion.
• Multisite: switch_to_blog + restore_current_blog around the cache call when iterating sites.
• Never raw-unlink() the cache files. Filename layout is non-trivial (desktop / mobile / lang / query-string variants); manual deletion leaves stale variants.
• rocket_clean_minify and rocket_clean_cache_busting are for CSS / JS asset pipeline changes, not for HTML cache.

Common mistakes

// WRONG — wp_cache_flush expecting WP Rocket to clear
function my_save_handler( $post_id ): void {
    update_post_meta( $post_id, 'foo', 'bar' );
    wp_cache_flush();   // 🔴 only clears object cache, not WP Rocket file cache
}

// RIGHT
function my_save_handler( $post_id ): void {
    update_post_meta( $post_id, 'foo', 'bar' );
    if ( \function_exists( 'rocket_clean_post' ) ) {
        rocket_clean_post( $post_id );
    }
}

// WRONG — raw filesystem deletion
function my_clear() {
    $cache_dir = WP_CONTENT_DIR . '/cache/wp-rocket/example.com';
    array_map( 'unlink', glob( $cache_dir . '/*.html' ) );   // 🔴 misses mobile / lang / qs variants
}

// RIGHT
if ( \function_exists( 'rocket_clean_domain' ) ) {
    rocket_clean_domain();
}

// WRONG — is_plugin_active during plugins_loaded
add_action( 'plugins_loaded', function () {
    if ( is_plugin_active( 'wp-rocket/wp-rocket.php' ) ) {   // 🔴 fatal — function not loaded
        // ...
    }
} );

// RIGHT
add_action( 'plugins_loaded', function () {
    if ( ! defined( 'WP_ROCKET_VERSION' ) ) return;
    // ...
}, 11 );

// WRONG — clean_domain on every post save
add_action( 'save_post', function ( $post_id ) {
    if ( \function_exists( 'rocket_clean_domain' ) ) {
        rocket_clean_domain();   // 🔴 nukes the entire site cache for one post change
    }
} );

// RIGHT — granular
add_action( 'save_post', function ( $post_id ) {
    if ( wp_is_post_revision( $post_id ) || wp_is_post_autosave( $post_id ) ) return;
    if ( \function_exists( 'rocket_clean_post' ) ) {
        rocket_clean_post( $post_id );
    }
} );

// WRONG — no autosave / revision skip
add_action( 'save_post', function ( $post_id ) {
    rocket_clean_post( $post_id );   // fires on every keystroke during autosave
} );

// RIGHT
if ( wp_is_post_revision( $post_id ) || wp_is_post_autosave( $post_id ) ) return;
rocket_clean_post( $post_id );

// WRONG — clean inside a clean (recursion)
add_action( 'after_rocket_clean_post', function ( $post ) {
    rocket_clean_files( [ get_permalink( $post->ID ) ] );   // 🔴 fires after_rocket_clean_files which can re-trigger
} );

// RIGHT — pass $run_actions = false
add_action( 'after_rocket_clean_post', function ( $post ) {
    rocket_clean_files( [ get_permalink( $post->ID ) ], null, false );
} );

// WRONG — bulk import without deferral
foreach ( $records as $record ) {
    wp_insert_post( $record );
    rocket_clean_post( /* ... */ );   // 🔴 N cache wipes for N records
}

// RIGHT — defer to one nuke
add_filter( 'rocket_is_importing', '__return_true' );
foreach ( $records as $record ) {
    wp_insert_post( $record );
}
remove_filter( 'rocket_is_importing', '__return_true' );
if ( \function_exists( 'rocket_clean_domain' ) ) {
    rocket_clean_domain();
}

// WRONG — assume one implicit home clean covers every language variant
rocket_clean_home();   // ambiguous on multilingual sites; depends on the active i18n integration/context

// RIGHT — iterate the active language codes from WPML / Polylang / TranslatePress
foreach ( [ 'en', 'de', 'fr' ] as $lang ) {
    rocket_clean_home( $lang );
}

Cross-references

• Run wp-rocket-cache-rejection-and-filters when the answer isn't "clear cache after change" but "PREVENT this URL / path from being cached at all".
• Run wp-plugin-cron when invalidation is scheduled / batched (Action Scheduler, WP-Cron) — combine with rocket_clean_* calls in the cron handler.
• Run wcs-renewal-scheduler if cache-invalidation triggers come from WC Subscription renewal events.
• Run wp-plugin-options-storage when deciding "should I cache this manually OR let WP Rocket handle it" — most often: let WP Rocket do it.

What this skill does NOT cover

• WP Rocket settings UI / admin pages. Out of scope; integrators don't touch UI.
• Internal Engine/ classes. Private; signatures change between versions. Use the public functions.
• The WP Rocket REST API (admin-side, paid). Not designed for third-party invalidation.
• .htaccess rewrite rules WP Rocket installs. Server-config concern; integrators don't modify these.
• Cloudflare / Varnish / CDN-specific addons. Each has its own surface; this skill is core WP Rocket only.
• rocket_buffer filter for HTML output manipulation. Niche + dangerous; covered in wp-rocket-cache-rejection-and-filters with strong warnings.
• License / activation key handling. Premium-specific; not integrator-facing.

References

• Plugin entry: wp-content/plugins/wp-rocket/wp-rocket.php — version constants, header.
• rocket_clean_post: inc/common/purge.php:167 — handles auto-draft / draft / nav_menu_item / attachment skips, fires before_/after_rocket_clean_post.
• rocket_clean_files: inc/functions/files.php:547 — $run_actions third arg controls whether before_/after_rocket_clean_files and per-URL before_/after_rocket_clean_file fire.
• rocket_clean_home: inc/functions/files.php:679.
• rocket_clean_domain: inc/functions/files.php:821.
• rocket_clean_term: inc/functions/files.php:924.
• rocket_clean_user: inc/functions/files.php:996.
• rocket_clean_cache_dir: inc/functions/files.php:1060.
• rocket_clean_minify: inc/functions/files.php:354.
• WP Rocket plugin compatibility doc: https://docs.wp-rocket.me/article/92-plugin-compatibility-with-wp-rocket.