Simple PHP daemon using double fork

daemon_sample

#!/usr/bin/php
<?php

// ##### definitions #####
define("DAEMON_NAME", "daemon-sample");
define("DAEMON_ROOT", "/tmp/daemon-sample");
define("DAEMON_PID", "/run/daemon-sample.pid");
define("DAEMON_LOG", "/tmp/daemon-sample/logfile");

// uid and gid from http|www-data user
define("DAEMON_UID", 33);
define("DAEMON_GID", 33);

// ##### helper functions #####
function isCli()
{
    return PHP_SAPI == 'cli';
}

function logger($code, $msg, $var = null)
{
    $codeMap = [
        E_ERROR   => "Error",
        E_WARNING => "Warning",
        E_NOTICE  => "Notice"
    ];

    $now = new DateTime("now");
    $msg = $now->format('c') . " {$codeMap[$code]} : $msg";

    if (!is_null($var)) {
        $msg .= "\n";
        $msg .= var_export($var, true);
        $msg .= "\n";
        $msg .= "\n";

    }

    file_put_contents(
        DAEMON_LOG,
        $msg . "\n",
        FILE_APPEND
    );
}

function handleError($errno, $errstr, $errfile, $errline, $errctx)
{
    if (error_reporting() == 0) {
        return;
    }

    $msg = "$errstr ($errfile:$errline) -> " . var_export($errctx, true);
    logger($errno, $msg);

    return true;
}

function stopDaemon()
{
    if (is_callable('stop')) {
        call_user_func('stop');
    }
}

function handleSignal($signo)
{
    switch ($signo) {
    case SIGTERM:
        logger(E_NOTICE, 'SIGTERM received, dying gracefully!');
        stopDaemon();
        return;
    case SIGINT:
        logger(E_NOTICE, 'SIGINT received, dying gracefully!');
        stopDaemon();
        return;
    case SIGHUP:
        logger(E_NOTICE, 'SIGHUP received, dying gracefully!');
        stopDaemon();
        return;
    default:
        logger(E_WARNING, "Unknown Signal ($signo) received, dying gracefully");
        stopDaemon();
        return;
    }
}

function registerSignalHandler()
{
    pcntl_signal(SIGTERM, 'handleSignal');
    pcntl_signal(SIGHUP, 'handleSignal');
    pcntl_signal(SIGINT, 'handleSignal');
}

function registerEnv()
{
    file_put_contents(DAEMON_PID, getmypid());

    posix_setuid(DAEMON_UID);
    posix_setgid(DAEMON_GID);

    fclose(STDIN);
    fclose(STDOUT);
    fclose(STDERR);
}

// ##### daemon #####
ini_set("display_errors", 0);
set_error_handler("handleError");

if (!isCli()) {
    logger(E_NOTICE, "This script must be run in CLI");
    exit;
}

umask(0);

$pid = pcntl_fork();
if ($pid == -1) {
    logger(E_WARNING, "Failed to fork");
    exit(1);
} else if ($pid) {
    exit(0);
}

if (posix_setsid() < 0) {
    logger(E_WARNING, "Failed to make the process a session leader");
    exit(1);
}

// fix ticks for signal handling
declare(ticks = 1);
registerSignalHandler();

$pid = pcntl_fork();
if ($pid == -1) {
    logger(E_WARNING, "Failed to double fork");
    exit(1);
} else if ($pid) {
    exit(0);
}

chdir(DAEMON_ROOT);

registerEnv();

if (!cli_set_process_title(DAEMON_NAME)) {
    logger(E_WARNING, "Failed to set process title for $pid");
    exit(1);
}

// I'm thinking in a better approach for this
$run = true;

function stop()
{
    global $run;
    $run = false;
}

function loop()
{
    global $run;

    $sleepTime = 250000;

    $i = 0;
    while ($run) {
        logger(E_NOTICE, "($i) Running...");

        if ($i > 99) {
            break;
        }

        $i++;
        usleep($sleepTime);
    }
}

loop();

Reference:
How to write a PHP Daemon
Run php script as daemon process