Outputting exec() ping result progressively

问题

I'm trying to write a function that pings a few hundred addresses and returns their values (milliseconds). So far I've achieved the initial idea which is to ping and get the result but the problem arises when using the same code for hundreds of addresses, the PHP page stalls until it either times out or reaches the last ping command.

I would be glad if I could get some suggestions to output the results progressively, here is my current code:

<?php

// "for" loop added according to suggestion for browser compatibility (IE, FF, CHR, OPR, SFR)
for($i = 0; $i < 5000; $i++)
{
    echo ' ';
}

function GetPing($ip = NULL) {
    // Returns the client ping if no address has been passed to the function
    if(empty($ip)) {
        $ip = $_SERVER['REMOTE_ADDR'];
    }

    // Check which OS is being run by the client
    if(getenv('OS') == 'Windows_NT') {
        //echo '<b>Detected local system:</b> Windows NT/2000/XP/2003/2008/Vista/7<p>';
        $exec = exec("ping -n 1 -l 32 -i 128 " . $ip);
        return end(explode(' ', $exec));
    }
    else {
        //echo '<b>Detected local system:</b> Linux/Unix<p>';
        $exec = exec("ping -c 1 -s 32 -t 128 " . $ip);
        $array = explode('/', end(explode('=', $exec )));
        return ceil($array[1]) . 'ms';
    }
    // ob_flush and flush added according to suggestion for buffer output
    ob_flush();
    flush();
}

// Added to test 20 sequential outputs
for($count = 0; $count < 20; $count++)
    echo GetPing('8.8.8.8') . '<div>';

?>

After some feedback, I've added a for loop as well as ob_flush() and flush() to my script and I've also set output_buffering to 0 in php.ini. It seems to work for most browsers that I tested so far (IE8, Firefox 12, Chrome 19, Opera 11, Safari 5). It seems the current code is now working as intended but any suggestion to improve on it is immensely appreciated.

Thank you for your feedback.

回答1:

this is just a guess; I've written years ago a very wobbly chat script that used output buffering as well (and fetching new messages in while(true) loop) ..

While doing this I've encountered the same problems that sometimes the script stalled (blank screen), sometimes it took a while until the characters appeared and additionally this was also browser specific.

Here are the relevant code snippets I've added to the script to have it work with IE6 and FF2 (as I said, years ago ...)

<?php
    // End output buffering
    ob_end_flush(); 

    // IE and Safari Workaround
    // They will only display the webpage if it's completely loaded or
    // at least 5000 bytes have been "printed".
    for($i=0;$i<5000;$i++)
    {
        echo ' ';
    }

    while( ... )
    {
        echo 'Message';
        ob_flush();
        flush();
    }
?>

It worked for me, so maybe you could give it a try as well. (Altough I have no idea how modern browsers and server infrastrucutre will behave to this).