1 files changed, 90 insertions, 0 deletions
diff --git a/classes/PluginHost.php b/classes/PluginHost.php
index bfc02318b..484364f26 100644
--- a/classes/PluginHost.php
+++ b/classes/PluginHost.php
@@ -32,6 +32,9 @@ class PluginHost {
 	/** @var array<string, array<int, array{'action': string, 'description': string, 'sender': Plugin}>> */
 	private array $plugin_actions = [];
 
+	/** @var array<string, mixed> */
+	private array $scheduled_tasks = [];
+
 	private ?int $owner_uid = null;
 
 	private bool $data_loaded = false;
@@ -906,4 +909,91 @@ class PluginHost {
 		$ref = new ReflectionClass(get_class($plugin));
 		return basename(dirname(dirname($ref->getFileName()))) == "plugins.local";
 	}
+
+	/**
+	 * Adds a backend scheduled task which will be executed by updater (if due) when idle during
+	 * RSSUtils::housekeeping_common().
+	 *
+	 * The granularity is not strictly guaranteed, housekeeping is invoked several times per hour
+	 * depending on how fast feed batch was processed, but no more than once per minute.
+	 *
+	 * Tasks are not run in user context and are available to system plugins only. Task names may not
+	 * overlap.
+	 *
+	 * Tasks should return an integer value (return code) which is stored in the database, a value of
+	 * 0 is considered successful.
+	 *
+	 * @param string $task_name unique name for this task, plugins should prefix this with plugin name
+	 * @param string $cron_expression schedule for this task in cron format
+	 * @param Closure $callback task code that gets executed
+	*/
+	function add_scheduled_task(string $task_name, string $cron_expression, Closure $callback) : bool {
+		$task_name = strtolower($task_name);
+
+		if (isset($this->scheduled_tasks[$task_name])) {
+			user_error("Attempted to override already registered scheduled task $task_name", E_USER_WARNING);
+			return false;
+		} else {
+			$cron = new Cron\CronExpression($cron_expression);
+
+			$this->scheduled_tasks[$task_name] = [
+				"cron" => $cron,
+				"callback" => $callback,
+			];
+			return true;
+		}
+	}
+
+	/**
+	 * Execute scheduled tasks which are due to run and record last run timestamps.
+	 * @return void
+	 */
+	function run_due_tasks() {
+		Debug::log('Processing all scheduled tasks...');
+
+		$tasks_run = 0;
+
+		foreach ($this->scheduled_tasks as $task_name => $task) {
+			$last_run = '1970-01-01 00:00';
+
+			$task_record = ORM::for_table('ttrss_scheduled_tasks')
+				->where('task_name', $task_name)
+				->find_one();
+
+			if ($task_record)
+				$last_run = $task_record->last_run;
+
+			Debug::log("Checking scheduled task: $task_name, last run: $last_run");
+
+			if ($task['cron']->isDue($last_run)) {
+				Debug::log("Task $task_name is due, executing...");
+
+				$rc = (int) $task['callback']();
+
+				Debug::log("Task $task_name has finished with RC=$rc, recording timestamp...");
+
+				if ($task_record) {
+					$task_record->last_run = time();
+					$task_record->last_rc = $rc;
+
+					$task_record->save();
+				} else {
+					$task_record = ORM::for_table('ttrss_scheduled_tasks')->create();
+
+					$task_record->set([
+						'task_name' => $task_name,
+						'last_rc' => $rc,
+						'last_run' => Db::NOW(),
+					]);
+
+					$task_record->save();
+				}
+			}
+		}
+
+		Debug::log("Finished with $tasks_run tasks executed.");
+	}
+
+	// TODO implement some sort of automatic cleanup for orphan task execution records
+
 }