WIP: Add private message queue post

source/_posts/2018-02-27-queuing-private-messages-in-drupal-8.md

@@ -0,0 +1,42 @@
+---
+title: Queuing Private Messages in Drupal 8
+tags:
+    - drupal
+    - drupal-8
+    - drupal-modules
+    - drupal-planet
+draft: true
+---
+[Private Message][0].
+
+## Queuing a Message
+
+The module provices a `PrivateMessageQueuer` service (`private_message_queue.queuer`) which queues the items via the `queue()` method.
+
+The method accepts an array of `User` objects as the messsage recipients, the message body text and another user as the message owner.
+
+Here is an example:
+
+```php
+$recipients = $this->getRecipients(); // An array of User objects.
+$message = 'Some message text';
+$owner = \Drupal::currentUser();
+
+$queuer = \Drupal::service('private_message_queue.queuer');
+$queuer->queue($recipients, $message, $owner);
+```
+
+These three pieces of data are then saved as part of the queued item.
+
+Add screenshot of queue.
+
+## Processing the Queue
+
+The module also provides a `PrivateMessageQueue` queue worker, which processes the queued items. For each item, it creates a new private message setting the owner and the message body.
+
+It uses the `PrivateMessageThread` class from the Private Message module to find for an existing thread for the specified recipients, or creates a new thread if one isn't found. The new message is then added to the thread.
+
+The queue is processed on each cron run, so I recommend adding a module like [Ultimate Cron][1] so that you can process the queued items frequently (e.g. every 15 minutes) and run the heavier tasks like checking for updates etc less frequently (e.g. once a day).
+
+[0]: https://www.drupal.org/project/private_message
+[1]: https://www.drupal.org/project/ultimate_cron