function ReadLatestUpdate()
{
    global $tweet_file;
    global $cache_time;
    if (!file_exists($tweet_file)) {
        UpdateTimeline();
        return;
    }
    $handle = fopen($tweet_file, 'r');
    $strUpdateDate = fgets($handle);
    fclose($handle);
    if (empty($strUpdateDate)) {
        //file is empty
        UpdateTimeline();
    } else {
        $updateDate = new DateTime($strUpdateDate);
        $now = new DateTime("now");
        $since = $updateDate->diff($now);
        $minutes = $since->days * 24 * 60 + $since->h * 60 + $since->i;
        if ($minutes > $cache_time) {
            //reload feed
            UpdateTimeline();
        } else {
            //read cache
            ReadFromCache();
        }
    }
}
<?php

$pageTitle = "Planet Money Refinance Timeline";
require_once 'header.php';
$datenow = date('m/d/Y');
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    $error = UpdateTimeline();
}
?>


<form id="timeline" class="submitform" action="updatetimeline.php" method="post">
<table>
<tr><td>Event Date</td><td><input type="text" name="eventdate" value="<?php 
echo $datenow;
?>
"/></td></tr>
<tr><td>Title</td><td><input type="text" name="title" /></td></tr>
<tr><td>Description</td><td><textarea rows=5 name="description"></textarea></td></tr>
<tr><td></td><td><input type="submit" name="submit" value="Save" style="float:right;"/></td></tr>
</table>
</form>


<?php 
require "footer.php";
?>

<?php 
function UpdateTimeline()
{