From cec69f63a41c3ce331ac0f16a318007da2062dbc Mon Sep 17 00:00:00 2001
From: Johannes Meyer <johannes.meyer@icinga.com>
Date: Tue, 17 May 2022 12:26:16 +0200
Subject: [PATCH] Introduce class `Icinga\Application\Daemon`

---
 library/Icinga/Application/Daemon.php         | 113 ++++++++++++++++++
 .../Icinga/Application/Daemon/DaemonJob.php   |  27 +++++
 2 files changed, 140 insertions(+)
 create mode 100644 library/Icinga/Application/Daemon.php
 create mode 100644 library/Icinga/Application/Daemon/DaemonJob.php

diff --git a/library/Icinga/Application/Daemon.php b/library/Icinga/Application/Daemon.php
new file mode 100644
index 000000000..b02c004e5
--- /dev/null
+++ b/library/Icinga/Application/Daemon.php
@@ -0,0 +1,113 @@
+<?php
+/* Icinga Web 2 | (c) 2022 Icinga GmbH | GPLv2+ */
+
+namespace Icinga\Application;
+
+use Icinga\Application\Daemon\DaemonJob;
+use LogicException;
+use React\EventLoop\Loop;
+use React\EventLoop\LoopInterface;
+
+class Daemon
+{
+    /** @var LoopInterface */
+    protected $loop;
+
+    /** @var bool */
+    protected $shuttingDown = false;
+
+    /** @var DaemonJob[] */
+    protected $jobs = [];
+
+    /**
+     * Create a new Daemon
+     *
+     * @param LoopInterface|null $loop If not given, the default loop is used
+     */
+    public function __construct(LoopInterface $loop = null)
+    {
+        $this->loop = $loop ?? Loop::get();
+    }
+
+    /**
+     * Initialize the daemon
+     *
+     * @return void
+     */
+    protected function initialize(): void
+    {
+        $this->registerSignals();
+    }
+
+    /**
+     * Register signals
+     *
+     * @return void
+     */
+    protected function registerSignals(): void
+    {
+        $this->loop->addSignal(SIGTERM, [$this, 'shutdown']);
+        $this->loop->addSignal(SIGINT, [$this, 'shutdown']);
+    }
+
+    /**
+     * Deregister signals
+     *
+     * @return void
+     */
+    protected function deregisterSignals(): void
+    {
+        $this->loop->removeSignal(SIGTERM, [$this, 'shutdown']);
+        $this->loop->removeSignal(SIGINT, [$this, 'shutdown']);
+    }
+
+    /**
+     * Launch the daemon
+     *
+     * @return void
+     */
+    public function run(): void
+    {
+        if (empty($this->jobs)) {
+            throw new LogicException('No jobs added');
+        }
+
+        $this->loop->futureTick(function () {
+            $this->initialize();
+        });
+    }
+
+    /**
+     * Stop the daemon
+     *
+     * @return void
+     */
+    public function shutdown(): void
+    {
+        if ($this->shuttingDown) {
+            return;
+        }
+
+        $this->shuttingDown = true;
+        $this->deregisterSignals();
+
+        foreach ($this->jobs as $job) {
+            $job->cancel();
+        }
+    }
+
+    /**
+     * Add a job to this daemon
+     *
+     * @param DaemonJob $job
+     *
+     * @return $this
+     */
+    public function addJob(DaemonJob $job): self
+    {
+        $this->jobs[] = $job;
+        $job->attach($this->loop);
+
+        return $this;
+    }
+}
diff --git a/library/Icinga/Application/Daemon/DaemonJob.php b/library/Icinga/Application/Daemon/DaemonJob.php
new file mode 100644
index 000000000..b94336cd9
--- /dev/null
+++ b/library/Icinga/Application/Daemon/DaemonJob.php
@@ -0,0 +1,27 @@
+<?php
+/* Icinga Web 2 | (c) 2022 Icinga GmbH | GPLv2+ */
+
+namespace Icinga\Application\Daemon;
+
+use React\EventLoop\LoopInterface;
+
+interface DaemonJob
+{
+    /**
+     * Attach this job to the given event loop
+     *
+     * @param LoopInterface $loop
+     *
+     * @return void
+     */
+    public function attach(LoopInterface $loop): void;
+
+    /**
+     * Stop processing of this job
+     *
+     * Cancelling pending runs of the job is optional.
+     *
+     * @return void
+     */
+    public function cancel(): void;
+}