Implement BackgroundQueueMailer

README.md

@@ -0,0 +1,44 @@
+# BackgroundQueueMailer
+
+Delegates sending emails to [adt/background-queue](https://github.com/AppsDevTeam/BackgroundQueue).
+
+## Installation
+composer:
+```
+composer require adt/background-queue-mailer
+```
+
+If you're not familiar with [adt/background-queue](https://github.com/AppsDevTeam/BackgroundQueue),
+you should head there in the first place.
+
+## Usage
+
+To use BackgroundQueueMailer as buffer between your application and SmtpMailer, register
+it in your `config.neon`:
+
+```neon
+services:
+	smtpMailer:
+		class: \Nette\Mail\SmtpMailer
+		autowired: no # this is important
+
+	nette.mailer: \ADT\Mail\BackgroundQueueMailer(@smtpMailer, 'backgroundMail')
+
+backgroundQueue:
+	callbacks:
+		backgroundMail: @nette.mailer::process
+``` 
+
+where `@smtpMailer` is outgoing mailer, and `backgroundMail` is unique callback name.
+
+Callback name has to be same in both mailer definition and BackgroundQueue callback list. If they
+are not, warning is logged using Tracy. This should get resolved [here](https://github.com/AppsDevTeam/BackgroundQueue/issues/8).
+
+The `autowired: no` option is important because Nette DI container would not know
+which `\Nette\Mail\IMailer` to inject in your application. By setting `autowired: no` on
+SMTP mailer only one instance of `IMailer` interface remains.
+
+You cannot set `autowired: no` on `nette.mailer` because your application
+would not be able to inject it.
+
+It is also important that you autowire `\Nette\Mail\IMailer` throughout your application.

composer.json

@@ -16,6 +16,12 @@
     },
     "minimum-stability": "stable",
     "require": {
-        "adt/background-queue": "^3.1"
+        "adt/background-queue": "^3.1",
+        "tracy/tracy": "^2.3"
+    },
+    "autoload": {
+        "psr-4": {
+            "ADT\\Mail\\BackgroundQueueMailer\\": "src/"
+        }
     }
 }

src/Mailer.php

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+<?php
+
+namespace ADT\Mail\BackgroundQueueMailer;
+
+use ADT\BackgroundQueue;
+use Nette\Mail;
+use Nette\Utils\JSON;
+use Tracy\Debugger;
+
+
+class Mailer extends \Nette\Object implements Mail\IMailer {
+
+	/** @var Mail\IMailer */
+	protected $next;
+
+	/** @var string */
+	protected $callbackName;
+
+	/** @var BackgroundQueue\Service */
+	protected $backgroundQueueService;
+
+	public function __construct(
+		Mail\IMailer $next,
+		$callbackName,
+		BackgroundQueue\Service $backgroundQueueService
+	) {
+		$this->next = $next;
+		$this->callbackName = $callbackName;
+		$this->backgroundQueueService = $backgroundQueueService;
+	}
+
+	public function send(Mail\Message $mail) {
+		$entity = new BackgroundQueue\Entity\QueueEntity;
+		$entity->setCallbackName($this->callbackName);
+		$entity->setParameters([
+			// Parameters are stored as LONGTEXT UTF-8, so they cannot contain binary data.
+			// This should be fine if we encode mail as JSON.
+			'mail' => JSON::encode(serialize($mail)),
+		]);
+
+		$this->backgroundQueueService
+			->publish($entity);
+	}
+
+	public function process(BackgroundQueue\Entity\QueueEntity $entity) {
+		if ($entity->getCallbackName() !== $this->callbackName) {
+			Debugger::log("Callback names do not match, expected: '{$this->callbackName}' but got: '{$entity->getCallbackName()}'; skipping'", Debugger::WARNING);
+			return FALSE; // repeatable error
+		}
+
+		$parameters = $entity->getParameters();
+		$mail = unserialize(JSON::decode($parameters['mail']));
+
+		try {
+			$this->next->send($mail);
+			return TRUE; // done
+		} catch (Mail\SendException $e) {
+			return FALSE; // repeatable error
+		}
+
+		// everything else is unrepeatable error (logged in BackgroundQueue)
+	}
+
+}