PHP Simple Profiler

/* BEGIN PROFILER.PHP */
$profiler_start;
$profiler_phases = array();
$profiler_current;
function profiler_start($phase) {
    global $profiler_start, $profiler_current;
    $profiler_current = $phase;
    $profiler_start = microtime();
}
function profiler_next($phase) {
    global $profiler_start, $profiler_current, $profiler_phases;
    $now = microtime();
    $profiler_phases[] = $profiler_current . ": " . (($now - $profiler_start) / 1000) . "ms";
    $profiler_current = $phase;
    $profiler_start = $now;
}
function profiler_end() {
    global $profiler_start, $profiler_current, $profiler_phases;
    $profiler_phases[] = $profiler_current . ": " . ((microtime() - $profiler_start) / 1000) . "ms";
}
function profiler_result() {
    global $profiler_phases;
    return implode("\n", $profiler_phases);
}
/* END PROFILER.PHP */

/* BEGIN EXAMPLE USAGE */
include "profiler.php";
profiler_start("init");
$f = fopen("file.txt", "w");
profiler_next("write");
fwrite($f, "Test String");
profiler_next("close");
fclose($f);
profiler_end();
echo profiler_result();
/* END EXAMPLE USAGE */

/* BEGIN EXAMPLE RESULT
init: 50ms
write: 100ms
close: 30ms
/* END EXAMPLE RESULT */