rsync dir indefinitely whenever it changes.. syncer

rsync_forever.php

#!/usr/bin/env php
<?php
declare (strict_types = 1);
global $argc, $argv;
if ($argc < 3) {
    echo ("Usage: {$argv[0]} 'FOLDER' rsync FOLDER foo@bar:server_folder arg1 arg2 arg3 etc\n");
    exit(1);
}

/**
 * returns a plain string array of path to all files in a directory, including subdirectories,
 * but does not return directories themselves. (meaning if a directory is empty, it will not be included at all)
 *
 * @param string $dir
 * @param bool $realpath
 * @throws UnexpectedValueException if $dir is not readable/does not exists
 * @return string[] files
 */
function get_file_list_recursively(string $dir, bool $realpath = false): array
{
    if (!is_readable($dir)) {
        throw new UnexpectedValueException("Directory is not readable: {$dir}");
    }
    if(!is_dir($dir)){
        return $realpath ? array(realpath($dir)) : array($dir);
    }
    $files = array();
    $files = [];
    foreach ((new RecursiveIteratorIterator(new RecursiveDirectoryIterator($dir, RecursiveDirectoryIterator::SKIP_DOTS))) as $file) {
        /** @var SplFileInfo $file */
        if ($realpath) {
            $files[] = $file->getRealPath();
        } else {
            $files[] = $file->getPathname();
        }
    }
    return $files;
}
function hasDirChanged(string $dir): bool
{
    static $old_scans = array();
    $files = get_file_list_recursively($dir, true);
    $files = array_filter($files, function ($file) {
        return true;
        $ext = pathinfo($file, PATHINFO_EXTENSION);
        $basename = pathinfo($file, PATHINFO_BASENAME);
        if ($basename === "html.html") {
            return false;
        }
        return in_array(strtolower($ext), array(
            "php",
            "js",
            "css",
            "html",
            "htm",
            //"txt",
        ), true); //
    });
    $files = array_values($files);
    $scan = array();
    foreach ($files as $file) {
        // fnv164 is a very fast non-crypto hash
        $hash = hash_file("fnv164", $file, true);
        $scan[$file] = $hash;
    }
    if (isset($old_scans[$dir]) && $old_scans[$dir] === $scan) {
        return false;
    }
    $old_scans[$dir] = $scan;
    return true;
}

$single_instance = fopen(__FILE__, "rb");
if (!flock($single_instance, LOCK_EX | LOCK_NB)) {
    fwrite(STDERR, "Another instance is already running.\n");
    exit(1);
}
$scan_dir = $argv[1];
$rsync_command = '';
for ($i = 2; $i < $argc; ++$i) {
    $rsync_command .= escapeshellarg($argv[$i]) . ' ';
}
echo "scan_dir: {$scan_dir} rsync_command: {$rsync_command}\n";
$sleep_time = 5;
echo "sleep time: {$sleep_time}\n";
for (;;) {
    sleep($sleep_time);
    if (!hasDirChanged($scan_dir)) {
        continue;
    }
    echo "syncing!";
    if (0) {
        $cmd = implode(" ", array(
            "rsync",
            escapeshellarg(__DIR__),
            escapeshellarg("solomeme") . "@" . escapeshellarg("solomeme.ratma.net") . ":" . escapeshellarg("/home/solomeme/websites/solomeme.ratma.net/www"),
            "-aPz", // fsck it
            "--exclude '*.sqlite3'",
            "--exclude '*.txt'",
            "--exclude '*.json'",
            "--exclude 'html.html'",
        ));
    } else {
        $cmd = $rsync_command;
    }
    passthru($cmd, $ret);
    if ($ret !== 0) {
        echo "rsync failed with code {$ret}\n";
        continue;
    }
    echo "SYNCED!\n";
}
//