ReadStreamTask.php

<?php

class ReadStreamTask extends AsyncTask{
    public function __construct(string $host, CommandSender $sender){ // Step 1
        $this->host = $host;
        parent::__construct($sender);
    }

    public function onRun(){
        $socket = fsockopen($this->host); // Step 2
        $length = Binary::readInt(fread($socket, 4)); // Step 2
        if($length === 0){
            $this->setResult(""); // Step 4
        }
        $buffer = "";
        $this->publishProgress(0.0); // Step 3
        for($read = 0; $read < $length; $read += 1024){
            $buffer .= fread($socket, 1024); // Step 2
            $this->publishProgress($read / $length); // Step 3
        }
        $read -= 1024;
        if($read < $length) $buffer .= fread($socket, $length - $read); // Step 2
        $this->setResult($buffer); // Step 4
    }

    public function onProgressUpdated(Server $server, $data){ // Step 3
        $sender = $this->peekLocal($server); // same as fetchLocal() except that it doesn't delete the data
        if(!($sender instanceof Player and !$sender->isOnline())){
            $sender->sendMessage(sprintf("Downloaded %g%% data", $data * 100));
        }
    }

    public function onCompletion(Server $server){
        $sender = $this->fetchLocal($server); // remove the data finally
        $result = $this->getResult(); // only call this method once, and store the result in a variable. Otherwise, PocketMine unserializes it every time.
        if(!($sender instanceof Player and !$sender->isOnline())){
            $sender->sendMessage(sprintf("Downloaded %g KB data, md5 hash is %s", strlen($result) / 1024, md5($result)));
        }
    }
}