Added FailToExecute event which will be dispatched when executing crontab failed. (#4344)

* Update crontab.md

Co-authored-by: 李铭昕 <715557344@qq.com>

CHANGELOG-2.2.md

@@ -4,6 +4,10 @@
 
 - [#4347](https://github.com/hyperf/hyperf/pull/4347) Fixed bug that amqp io has been bound to more than one coroutine when out of buffer.
 
+## Added
+
+- [#4344](https://github.com/hyperf/hyperf/pull/4344) Added `Hyperf\Crontab\Event\FailToExecute` event which will be dispatched when executing crontab failed.
+
 # v2.2.20 - 2021-12-13
 
 ## Fixed

docs/zh-cn/crontab.md

@@ -253,3 +253,40 @@ return [
 
 当您完成上述的配置后，以及定义了定时任务后，只需要直接启动 `Server`，定时任务便会一同启动。   
 在您启动后，即便您定义了足够短周期的定时任务，定时任务也不会马上开始执行，所有定时任务都会等到下一个分钟周期时才会开始执行，比如您启动的时候是 `10 时 11 分 12 秒`，那么定时任务会在 `10 时 12 分 00 秒` 才会正式开始执行。
+
+### FailToExecute 事件
+
+当定时任务执行失败时，会触发 `FailToExecute` 事件，所以我们可以编写以下监听器，拿到对应的 `Crontab` 和 `Throwable`。
+
+```php
+<?php
+
+declare(strict_types=1);
+
+namespace App\Listener;
+
+use Hyperf\Crontab\Event\FailToExecute;
+use Hyperf\Event\Annotation\Listener;
+use Hyperf\Event\Contract\ListenerInterface;
+use Psr\Container\ContainerInterface;
+
+#[Listener]
+class FailToExecuteCrontabListener implements ListenerInterface
+{
+    public function listen(): array
+    {
+        return [
+            FailToExecute::class,
+        ];
+    }
+
+    /**
+     * @param FailToExecute $event
+     */
+    public function process(object $event)
+    {
+        var_dump($event->crontab->getName());
+        var_dump($event->throwable->getMessage());
+    }
+}
+```

src/crontab/src/Event/FailToExecute.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * This file is part of Hyperf.
+ *
+ * @link     https://www.hyperf.io
+ * @document https://hyperf.wiki
+ * @contact  group@hyperf.io
+ * @license  https://github.com/hyperf/hyperf/blob/master/LICENSE
+ */
+namespace Hyperf\Crontab\Event;
+
+use Hyperf\Crontab\Crontab;
+use Throwable;
+
+class FailToExecute
+{
+    /**
+     * @var Crontab
+     */
+    public $crontab;
+
+    /**
+     * @var Throwable
+     */
+    public $throwable;
+
+    public function __construct(Crontab $crontab, Throwable $throwable)
+    {
+        $this->crontab = $crontab;
+        $this->throwable = $throwable;
+    }
+}

src/crontab/src/Strategy/Executor.php

@@ -16,6 +16,7 @@ use Closure;
 use Hyperf\Contract\ApplicationInterface;
 use Hyperf\Contract\StdoutLoggerInterface;
 use Hyperf\Crontab\Crontab;
+use Hyperf\Crontab\Event\FailToExecute;
 use Hyperf\Crontab\LoggerInterface;
 use Hyperf\Crontab\Mutex\RedisServerMutex;
 use Hyperf\Crontab\Mutex\RedisTaskMutex;
@@ -23,6 +24,7 @@ use Hyperf\Crontab\Mutex\ServerMutex;
 use Hyperf\Crontab\Mutex\TaskMutex;
 use Hyperf\Utils\Coroutine;
 use Psr\Container\ContainerInterface;
+use Psr\EventDispatcher\EventDispatcherInterface;
 use Swoole\Timer;
 use Symfony\Component\Console\Input\ArrayInput;
 use Symfony\Component\Console\Output\NullOutput;
@@ -49,6 +51,11 @@ class Executor
      */
     protected $serverMutex;
 
+    /**
+     * @var null|EventDispatcherInterface
+     */
+    protected $dispatcher;
+
     public function __construct(ContainerInterface $container)
     {
         $this->container = $container;
@@ -57,6 +64,9 @@ class Executor
         } elseif ($container->has(StdoutLoggerInterface::class)) {
             $this->logger = $container->get(StdoutLoggerInterface::class);
         }
+        if ($container->has(EventDispatcherInterface::class)) {
+            $this->dispatcher = $container->get(EventDispatcherInterface::class);
+        }
     }
 
     public function execute(Crontab $crontab)
@@ -83,6 +93,7 @@ class Executor
                                 }
                             } catch (\Throwable $throwable) {
                                 $result = false;
+                                $this->dispatcher && $this->dispatcher->dispatch(new FailToExecute($crontab, $throwable));
                             } finally {
                                 $this->logResult($crontab, $result);
                             }
@@ -139,8 +150,8 @@ class Executor
     {
         if (! $this->taskMutex) {
             $this->taskMutex = $this->container->has(TaskMutex::class)
-            ? $this->container->get(TaskMutex::class)
-            : $this->container->get(RedisTaskMutex::class);
+                ? $this->container->get(TaskMutex::class)
+                : $this->container->get(RedisTaskMutex::class);
         }
         return $this->taskMutex;
     }
@@ -163,8 +174,8 @@ class Executor
     {
         if (! $this->serverMutex) {
             $this->serverMutex = $this->container->has(ServerMutex::class)
-            ? $this->container->get(ServerMutex::class)
-            : $this->container->get(RedisServerMutex::class);
+                ? $this->container->get(ServerMutex::class)
+                : $this->container->get(RedisServerMutex::class);
         }
         return $this->serverMutex;
     }