CRM_Queue_TaskRunner - Add background-friendly handler for `CRM_Queue…

…_Task`s

CRM/Queue/BAO/Queue.php

@@ -18,7 +18,7 @@
 /**
  * Track a list of known queues.
  */
-class CRM_Queue_BAO_Queue extends CRM_Queue_DAO_Queue {
+class CRM_Queue_BAO_Queue extends CRM_Queue_DAO_Queue implements \Civi\Test\HookInterface {
 
   /**
    * Get a list of valid queue types.
@@ -33,4 +33,24 @@ public static function getTypes($context = NULL) {
     ];
   }
 
+  /**
+   * Queues which contain `CRM_Queue_Task` records should use the `task` runner to evaluate them.
+   *
+   * @code
+   * $q = Civi::queue('do-stuff', ['type' => 'Sql', 'runner' => 'task']);
+   * $q->createItem(new CRM_Queue_Task('my_callback_func', [1,2,3]));
+   * @endCode
+   *
+   * @param \CRM_Queue_Queue $queue
+   * @param array $items
+   * @param array $outcomes
+   * @throws \API_Exception
+   * @see CRM_Utils_Hook::queueRun()
+   */
+  public static function hook_civicrm_queueRun_task(CRM_Queue_Queue $queue, array $items, array &$outcomes) {
+    foreach ($items as $itemPos => $item) {
+      $outcomes[$itemPos] = (new \CRM_Queue_TaskRunner())->run($queue, $item);
+    }
+  }
+
 }

CRM/Queue/Runner.php

@@ -26,9 +26,9 @@
  *   This is used by some CLI upgrades.
  *
  * This runner is not appropriate for all queues or workloads, so you might choose or create
- * a different runner. For example, `CRM_Queue_Autorunner` is geared toward background task lists.
+ * a different runner. For example, `CRM_Queue_TaskRunner` is geared toward background task lists.
  *
- * @see CRM_Queue_Autorunner
+ * @see CRM_Queue_TaskRunner
  */
 class CRM_Queue_Runner {
 

CRM/Queue/TaskRunner.php

@@ -0,0 +1,108 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ * `CRM_Queue_TaskRunner`  a list tasks from a queue. It is designed to supported background
+ * tasks which run automatically.
+ *
+ * This runner is not appropriate for all queues or workloads, so you might choose or create
+ * a different runner. For example, `CRM_Queue_Runner` is geared toward background task lists.
+ *
+ * @see CRM_Queue_Runner
+ */
+class CRM_Queue_TaskRunner {
+
+  /**
+   * @param \CRM_Queue_Queue $queue
+   * @param $item
+   * @return string
+   *   One of the following:
+   *    - 'ok': Task executed normally. Removed from queue.
+   *    - 'retry': Task encountered an error. Will try again later.
+   *    - 'fail': Task encountered an error. Will not try again later. Removed from queue.
+   * @throws \API_Exception
+   */
+  public function run(CRM_Queue_Queue $queue, $item): string {
+    $this->assertType($item->data, ['CRM_Queue_Task'], 'Cannot run. Invalid task given.');
+
+    /** @var \CRM_Queue_Task $task */
+    $task = $item->data;
+
+    if (is_numeric($queue->getSpec('retry_limit')) && $item->run_count > 1 + $queue->getSpec('retry_limit')) {
+      \Civi::log()->debug("Skipping exhausted task: " . $task->title);
+      $outcome = 'fail';
+      $exception = new \API_Exception(sprintf('Skipping exhausted task after %d tries: %s', $item->run_count, print_r($task, 1)));
+    }
+    else {
+      \Civi::log()->debug("Running task: " . $task->title);
+      try {
+        $runResult = $task->run($this->createContext($queue));
+        $outcome = $runResult ? 'ok' : 'fail';
+        $exception = ($outcome === 'ok') ? NULL : new \API_Exception('Queue task returned false');
+      }
+      catch (\Exception $e) {
+        $outcome = 'fail';
+        $exception = $e;
+      }
+
+      if ($outcome === 'fail' && $this->isRetriable($queue, $item)) {
+        $outcome = 'retry';
+      }
+    }
+
+    if ($outcome !== 'ok') {
+      \CRM_Utils_Hook::queueTaskError($queue, $item, $outcome, $exception);
+    }
+
+    switch ($outcome) {
+      case 'ok':
+        $queue->deleteItem($item);
+        break;
+
+      case 'retry':
+        $queue->releaseItem($item);
+        break;
+
+      case 'fail':
+        $queue->deleteItem($item);
+        break;
+    }
+
+    return $outcome;
+  }
+
+  /**
+   * @param \CRM_Queue_Queue $queue
+   * return CRM_Queue_TaskContext;
+   */
+  private function createContext(\CRM_Queue_Queue $queue): \CRM_Queue_TaskContext {
+    $taskCtx = new \CRM_Queue_TaskContext();
+    $taskCtx->queue = $queue;
+    $taskCtx->log = \CRM_Core_Error::createDebugLogger();
+    return $taskCtx;
+  }
+
+  private function assertType($object, array $types, string $message) {
+    foreach ($types as $type) {
+      if ($object instanceof  $type) {
+        return;
+      }
+    }
+    throw new \Exception($message);
+  }
+
+  private function isRetriable(\CRM_Queue_Queue $queue, $item): bool {
+    return property_exists($item, 'run_count')
+      && is_numeric($queue->getSpec('retry_limit'))
+      && $queue->getSpec('retry_limit') + 1 > $item->run_count;
+  }
+
+}

CRM/Utils/Hook.php

@@ -2701,6 +2701,55 @@ public static function alterEntityRefParams(&$params, $formName) {
     );
   }
 
+  /**
+   * Fire `hook_civicrm_queueRun_{$runner}`.
+   *
+   * This event only fires if these conditions are met:
+   *
+   * 1. The `$queue` has been persisted in `civicrm_queue`.
+   * 2. The `$queue` has a `runner` property.
+   * 3. The `$queue` has some pending tasks.
+   * 4. The system has a queue-running agent.
+   *
+   * @param \CRM_Queue_Queue $queue
+   * @param array $items
+   *   List of claimed items which we may evaluate.
+   * @param array $outcomes
+   *   The outcomes of each task. One of 'ok', 'retry', 'fail'.
+   *   Keys should match the keys in $items.
+   */
+  public static function queueRun(CRM_Queue_Queue $queue, array $items, &$outcomes) {
+    $runner = $queue->getSpec('runner');
+    if (empty($runner) || !preg_match(';^[A-Za-z0-9_]+$;', $runner)) {
+      throw new \CRM_Core_Exception("Cannot autorun queue: " . $queue->getName());
+    }
+    return self::singleton()->invoke(['queue', 'items', 'outcomes'], $queue, $items,
+      $outcomes, $exception, self::$_nullObject, self::$_nullObject,
+      'civicrm_queueRun_' . $runner
+    );
+  }
+
+  /**
+   * This is called if automatic execution of a queue-task fails.
+   *
+   * @param \CRM_Queue_Queue $queue
+   * @param \CRM_Queue_DAO_QueueItem|\stdClass $item
+   *   The enqeued item $item.
+   *   In principle, this is the $item format determined by the queue, which includes `id` and `data`.
+   *   In practice, it is typically an instance of `CRM_Queue_DAO_QueueItem`.
+   * @param string $outcome
+   *   The outcome of the task. One of 'ok', 'retry', 'fail'.
+   *   The outcome may be altered - eg to flip between 'retry' or 'fail'.
+   * @param \Throwable|null $exception
+   *   If the task failed, this is the cause of the failure.
+   */
+  public static function queueTaskError(CRM_Queue_Queue $queue, $item, &$outcome, ?Throwable $exception) {
+    return self::singleton()->invoke(['job', 'params'], $queue, $item,
+      $outcome, $exception, self::$_nullObject, self::$_nullObject,
+      'civicrm_queueTaskError'
+    );
+  }
+
   /**
    * This hook is called before a scheduled job is executed
    *