Native PHP Pub/Sub server (BETA)

PubSubServer.php

<?php

/*
 * PubSubServer.php
 * native PHP Pub/Sub server
 * Author: Gydo194
 * Version: 1.0
 * Date: 2210171714
 */


/*
Usage: 

Initialize:
$server = new PubSubServer("your cache file");
publish message:

$server->Publish("your channel","your message");

listen for messages and dump to client:

$server->blocking_subscribe_to_http("your channel");
This will listen for messages and send them to the client instantly.


*/

class PubSubServer {
    private $cache_file_path;
    private $lastModifiedTime;
    private $currentModifiedTime;
    private $loop_delay = 15000;
    
    
    
    public function __construct($file = null) {
        if($file == null) {
            $this->cache_file_path = __DIR__ . "PubSubServerCache.db";
        } else {
            $this->cache_file_path = $file;
        }
        
        if(!file_exists($this->cache_file_path)) {
            error_log("ERROR: PubSubServer::__construct(): cannot stat {$this->cache_file_path}.");
            return false;
        }
        
        
        $this->lastModifiedTime = filemtime($this->cache_file_path);
        $this->currentModifiedTime = $this->lastModifiedTime;
        
    }
    
    
    
    public function Publish($channel,$message) {
        $data_array = array(
            "channel" => $channel,
            "message" => $message
        );
        
        $data = json_encode($data_array,true);
        
       if(file_put_contents($this->cache_file_path, $data) == FALSE) {
           error_log("ERROR: PubSubServer::Publish(): cannot write file.");
       }
    }
    
    
    public function blocking_subscribe_to_http($channel) {
        set_time_limit(0);
        while(true) {
            ob_flush();
            flush();
            clearstatcache();
            $this->currentModifiedTime = filemtime($this->cache_file_path);
            if($this->currentModifiedTime > $this->lastModifiedTime) {
                $this->lastModifiedTime = $this->currentModifiedTime;
                $raw = file_get_contents($this->cache_file_path);
                if($raw) {
                    
                    $data = json_decode($raw,true);
                    if(array_key_exists("channel", $data) && array_key_exists("message", $data)) {
                        //var_dump($data);
                        if($data["channel"] === $channel) {
                           print($data["message"]);
                        }
                    }
                    
                } else {
                    error_log("ERROR: PubSubServer::blocking_subscribe_to_http(): Cannot read file.");
                }
            }
           usleep($this->loop_delay); 
        }
    }
    
    
}