time_sleep_until

At least on my Windows machine, the time_sleep_until function appears to calculate the number of microseconds between now and the sleep-until timestamp, and it appears to use unsigned 32-bit math in this calculation.  This roundoff leads to a maximum sleep time of just under 4295 seconds (1 hour, 11 minutes, 35 seconds).  To get longer sleep times, while still using time_sleep_until to minimize processor overhead, the following loop may be some help to you:<?php$sleepuntil = strtotime("tuesday 3pm");while (time() < $sleepuntil)   time_sleep_until($sleepuntil);// proceed with dated processing?>Of course, one could use something like "cron" instead, to avoid the script doing the extended sleep.  Also note that time_nanosleep appears to do similar math, but it is somewhat more intuitive that the seconds parameter has an upper limit on what it can be.  Still, both functions might report a warning when waking up prematurely due to roundoff.

Not realising that this function existed, I wrote something similar, but it has the additional facility to specify a minimum pause even if the target time has already been reached, for instance in a processor-intensive loop.It's in seconds rather than microseconds (it's intended for heavy-duty CLI scripts), but that could easily be changed by using microtime(true) and usleep if greater granularity was required.<?php    /**     * Pause processing until the specified time, to avoid hammering a DB or service     *     * @param int $target_time Timestamp     * @param int $min_sleep Always sleep for a minimum number of seconds,     *    even if the target timestamp has already passed.     *     Default 0, meaning only sleep until the target timestamp is reached.     *     * @example <code>         while ( ! $finished )         {             $minimum_start_of_next_loop = time() + $min_secs_per_loop;                          # DO STUFF THAT MAY OR MAY NOT TAKE VERY LONG                          sleep_until( $minimum_start_of_next_loop, $min_pause_between_loops );         }     </code>     */    function sleep_until($target_time, $min_sleep = 0)    {        $time_now = time();                $time_to_target = $target_time - $time_now;                // If we've already reached the target time, that's fine        if ( $time_to_target <= $min_sleep )        {            // If required, sleep for a bit anyway            sleep( $min_sleep );        }        else        {            // Sleep for the number of seconds until the target time            sleep( $time_to_target );        }    }?>

if you for some reason need a constant-time implementation of realpath(), try<?phpfunction realpath_constant_time(string $path, float $target_seconds, bool &$constant_time_success = null){    $start_time=microtime(true);    $ret=realpath($path);    $constant_time_success = @time_sleep_until($start_time+$target_seconds);    return $ret;}?>for example, a realtime that always uses exactly 1 millisecond (should be more than enough for SSD-based servers, perhaps rotating harddrive based servers may need something closer to 10 milliseconds, i don't know):<?phprealpath_constant_time("/path/to/../to/file.txt",0.001,$constant_time_success);?>and you can use $constant_time_success to see if you needed more time (and thus failed to do realpath() in constant-time), or if you succeeded.