Add event for when supervisor process died

src/Events/SupervisorProcessDied.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Laravel\Horizon\Events;
+
+use Laravel\Horizon\SupervisorProcess;
+
+class SupervisorProcessDied
+{
+    /**
+     * The supervisor process.
+     *
+     * @var \Laravel\Horizon\SupervisorProcess
+     */
+    public $supervisorProcess;
+
+    /**
+     * The code with which the process exited.
+     *
+     * @var int|null
+     */
+    public $exitCode;
+
+    /**
+     * Create a new event instance.
+     *
+     * @param  \Laravel\Horizon\SupervisorProcess  $supervisorProcess
+     * @param  int|null  $exitCode
+     * @return void
+     */
+    public function __construct(SupervisorProcess $supervisorProcess, ?int $exitCode)
+    {
+        $this->supervisorProcess = $supervisorProcess;
+        $this->exitCode = $exitCode;
+    }
+}

src/SupervisorProcess.php

@@ -4,6 +4,7 @@
 
 use Closure;
 use Laravel\Horizon\Contracts\HorizonCommandQueue;
+use Laravel\Horizon\Events\SupervisorProcessDied;
 use Laravel\Horizon\MasterSupervisorCommands\AddSupervisor;
 use Laravel\Horizon\SupervisorCommands\Terminate;
 
@@ -77,6 +78,8 @@ public function monitor()
         // other checks run because we do not care if this is cooling down here.
         if (! $this->process->isRunning() &&
             $this->process->getExitCode() === 13) {
+            event(new SupervisorProcessDied($this, $this->process->getExitCode()));
+
             return $this->markAsDead();
         }
 
@@ -92,6 +95,7 @@ public function monitor()
         // should be marked as dead and not be restarted. Typically, this could be
         // an indication that the supervisor was simply purposefully terminated.
         $exitCode = $this->process->getExitCode();
+        event(new SupervisorProcessDied($this, $exitCode));
 
         $this->markAsDead();