This code should do exactly what you want:

<?php

function wincache_session_count( )
{
    $ucache_info = wincache_ucache_info();
    $count = 0;
    foreach ( $ucache_info['ucache_entries'] as $entry ) {
        if ( $entry['is_session'] )
            $count++;
    }
    return $count;
}

?>

You can use the above function till we decide on this feature request. If you can provide some context behind usefulness of the API you are asking for, it will be a good data point in our triage meeting.

This bug has been fixed in SVN.

In case this was a documentation problem, the fix will show up at the
end of next Sunday (CET) on pecl.php.net.

In case this was a pecl.php.net website problem, the change will show
up on the website in short time.
 
Thank you for the report, and for helping us make PECL better.

We have separated user cache and session cache. We have added a function (wincache_scache_info) to get session cache properties. count in the return value will be the session count. wincache_scache_info also accepts an optional boolean (summaryonly) which when set to true will not return individual entries.