Simplify awareness state caching by using the Transients API.

Author: mindctrl

src/wp-includes/collaboration/class-wp-sync-post-meta-storage.php

@@ -101,26 +101,12 @@ public function add_update( string $room, $update ): bool {
 	 */
 	public function get_awareness_state( string $room ): array {
 		$room_hash = md5( $room );
-		$cache_key = "sync_awareness_{$room_hash}";
-		$cached    = wp_cache_get( $cache_key, 'sync' );
-
-		if ( is_array( $cached ) ) {
-			return array_values( $cached );
-		}
-
-		$post_id = $this->get_storage_post_id( $room );
-		if ( null === $post_id ) {
-			return array();
-		}
-
-		$awareness = get_post_meta( $post_id, self::AWARENESS_META_KEY, true );
+		$awareness = get_transient( "sync_awareness_{$room_hash}" );
 
 		if ( ! is_array( $awareness ) ) {
 			return array();
 		}
 
-		wp_cache_set( $cache_key, $awareness, 'sync', MINUTE_IN_SECONDS );
-
 		return array_values( $awareness );
 	}
 
@@ -135,33 +121,7 @@ public function get_awareness_state( string $room ): array {
 	 */
 	public function set_awareness_state( string $room, array $awareness ): bool {
 		$room_hash = md5( $room );
-		$cache_key = "sync_awareness_{$room_hash}";
-
-		/**
-		 * Cache the awareness state to reduce post meta reads and writes.
-		 *
-		 * Awareness is inherently ephemeral and is not critical for
-		 * content consistency, so it's acceptable for it to be stale
-		 * or missing for a short period of time.
-		 *
-		 * For sites without object caching, fall back to post meta.
-		 */
-		wp_cache_set( $cache_key, $awareness, 'sync', MINUTE_IN_SECONDS );
-		if ( wp_using_ext_object_cache() ) {
-			return true;
-		}
-
-		$post_id = $this->get_storage_post_id( $room );
-
-		if ( null === $post_id ) {
-			return false;
-		}
-
-		// update_post_meta returns false if the value is the same as the existing value.
-		$this->with_suspended_posts_last_changed_update(
-			fn() => update_post_meta( $post_id, self::AWARENESS_META_KEY, $awareness )
-		);
-		return true;
+		return set_transient( "sync_awareness_{$room_hash}", $awareness, MINUTE_IN_SECONDS );
 	}
 
 	/**