raspisms/daemons/AbstractDaemon.php

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<?php
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/*
* This file is part of RaspiSMS.
*
* (c) Pierre-Lin Bonnemaison <plebwebsas@gmail.com>
*
* This source file is subject to the GPL-3.0 license that is bundled
* with this source code in the file LICENSE.
*/
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namespace daemons;
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/**
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* Class defining the global structur of a Linux Daemon.
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*/
abstract class AbstractDaemon
{
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protected $name;
protected $uniq;
protected $logger;
protected $no_parent;
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protected $pid_dir;
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private $is_running = true;
private $signals = [
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SIGTERM,
SIGINT,
SIGCHLD,
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SIGHUP,
];
/**
* Class used to handle POSIX signals and fork from the current process.
*
* @param string $name : The name of the class
* @param object $logger : A PSR3 logger instance
* @param string $pid_dir : Directory for the pid files
* @param bool $no_parent : Should the daemon be disconnected from his parent process
* @param array $signals :An array containing additional POSIX signals to handle [optionel]
* @param bool $uniq : Must the process be uniq ?
*/
protected function __construct(string $name, object $logger, string $pid_dir = '/var/run', $no_parent = false, array $signals = [], bool $uniq = false)
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{
$this->name = $name;
$this->logger = $logger;
$this->no_parent = $no_parent;
$this->pid_dir = $pid_dir;
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$this->signals = array_merge($this->signals, $signals);
$this->uniq = $uniq;
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//Allow script to run indefinitly
set_time_limit(0);
//Register signals
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$this->register_signals();
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}
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/**
* True if the daemon is running.
*/
public function is_running()
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{
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return $this->is_running;
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}
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/**
* Used to handle properly SIGINT, SIGTERM, SIGCHLD and SIGHUP.
*
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* @param mixed $signinfo
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*/
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protected function handle_signal(int $signal, $signinfo)
{
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if (SIGTERM === $signal || SIGINT === $signal)
{ //Stop the daemon
$this->is_running = false;
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}
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elseif (SIGHUP === $signal)
{ //Restart the daemon
$this->on_stop();
$this->on_start();
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}
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elseif (SIGCHLD === $signal)
{ //On daemon child stopping
pcntl_waitpid(-1, $status, WNOHANG);
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}
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else
{ //All the other signals
$this->handle_other_signals($signal);
}
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}
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/**
* Launch the infinite loop executing the "run" abstract method.
*/
protected function start()
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{
//If process must be uniq and a process with the same pid file is already running
if (file_exists($this->pid_dir . '/' . $this->name . '.pid') && $this->uniq)
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{
$this->logger->info('Another process named ' . $this->name . ' is already running.');
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return false;
}
//If we must make the daemon independant from any parent, we do a fork and die operation
if ($this->no_parent)
{
$pid = pcntl_fork(); //Fork current process into a child, so we can kill current process and keep only the child with parent PID = 1
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if (-1 === $pid)
{ //Impossible to run script
$this->logger->critical('Impossible to create a subprocess.');
return false;
}
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if ($pid)
{ //Current script
return true;
}
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$this->logger->info("Process {$this->name} started as a child with pid " . getmypid() . '.');
//Child script
$sid = posix_setsid(); //Try to make the child process a main process
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if (-1 === $sid)
{ //Error
$this->logger->critical("Cannot make the child process with pid {$pid} independent.");
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exit(1);
}
$this->logger->info('The child process with pid ' . getmypid() . ' is now independent.');
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}
//Create pid dir if not exists
if (!file_exists($this->pid_dir))
{
$success = mkdir($this->pid_dir, 0777, true);
if (!$success)
{
$this->logger->critical('Cannot create PID directory : ' . $this->pid_dir);
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exit(2);
}
}
//Set process name
cli_set_process_title($this->name);
//Write the pid of the process into a file
file_put_contents($this->pid_dir . '/' . $this->name . '.pid', getmypid());
//Really start the daemon
$this->on_start();
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try
{
while ($this->is_running)
{
pcntl_signal_dispatch(); //Call dispatcher for signals
$this->run();
}
}
catch (\Throwable $t)
{
$this->logger->critical('Exception : ' . $t->getMessage() . ' in ' . $t->getFile() . ' line ' . $t->getLine());
}
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//Stop the daemon
$this->on_stop();
//Delete pid file
if (file_exists($this->pid_dir . '/' . $this->name . '.pid'))
{
unlink($this->pid_dir . '/' . $this->name . '.pid');
}
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}
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/**
* Override to implement the code that run infinetly (actually, it run one time but repeat the operation infinetly.
*/
abstract protected function run();
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/**
* Override to execute code before the ''run'' method on daemon start.
*/
abstract protected function on_start();
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/**
* Override to execute code after the ''run'' method on daemon shutdown.
*/
abstract protected function on_stop();
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/**
* Override to handle additional POSIX signals.
*
* @param int $signal : Signal sent by interrupt
*/
abstract protected function handle_other_signals(int $signal);
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/**
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* Used to register POSIX signals.
*/
private function register_signals()
{
//Enable a tick at every 1 instruction, allowing us to run a function frequently, for exemple looking at signal status
declare(ticks=1);
foreach ($this->signals as $signal)
{
//For each signal define the method handle_signal of the current class as the way to handle it
@pcntl_signal($signal, [
'self',
'handle_signal',
]);
}
}
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}