Introduce caching in the options rebuilding, rather than relying on what Core might provide

Since we often query directly, it was foolish of me to omit this both because Core's caching is often bypassed, and because it won't be reliable.

includes/class-cron-options-cpt.php

@@ -16,6 +16,8 @@ class Cron_Options_CPT extends Singleton {
 	const POST_STATUS_PENDING   = 'inherit';
 	const POST_STATUS_COMPLETED = 'trash';
 
+	const CACHE_KEY             = 'a8c_cron_ctrl_option';
+
 	private $posts_to_clean = array();
 
 	private $option_before_unscheduling = null;
@@ -64,6 +66,14 @@ class Cron_Options_CPT extends Singleton {
 	 * Override cron option requests with data from CPT
 	 */
 	public function get_option() {
+		// Use cached value for reads, except when we're unscheduling and state is important
+		$cached_option = wp_cache_get( self::CACHE_KEY, null, true );
+
+		if ( ! $this->is_unscheduling() && false !== $cached_option ) {
+			return $cached_option;
+		}
+
+		// Start building a new cron option
 		$cron_array = array(
 			'version' => 2, // Core versions the cron array; without this, events will continually requeue
 		);
@@ -133,6 +143,9 @@ class Cron_Options_CPT extends Singleton {
 			$this->option_before_unscheduling = null;
 		}
 
+		// Cache the results, bearing in mind that they won't be used during unscheduling events
+		wp_cache_set( self::CACHE_KEY, $cron_array, null, 1 * \HOUR_IN_SECONDS );
+
 		return $cron_array;
 	}
 
@@ -287,6 +300,9 @@ class Cron_Options_CPT extends Singleton {
 			}
 		}
 
+		// Delete internal cache
+		wp_cache_delete( self::CACHE_KEY );
+
 		// Allow more events to be created
 		Lock::free_lock( self::LOCK );
 	}
@@ -329,6 +345,9 @@ class Cron_Options_CPT extends Singleton {
 			$this->posts_to_clean[] = $job_post_id;
 		}
 
+		// Delete internal cache
+		wp_cache_delete( self::CACHE_KEY );
+
 		return true;
 	}