time_sleep_until

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

time_sleep_untilLässt das Skript bis zur angegebenen Zeit schlafen

Beschreibung

time_sleep_until(float $timestamp): bool

Lässt das Skript bis zum angegebenen timestamp schlafen.

Parameter-Liste

timestamp

Der Unix-Timestamp, zu dem die Ausführung des Skripts wieder aufgenommen werden soll.

Rückgabewerte

Gibt bei Erfolg true zurück. Bei einem Fehler wird false zurückgegeben.

Fehler/Exceptions

Die Funktion generiert eine E_WARNING-Meldung, wenn der angegebene timestamp in der Vergangenheit liegt.

Beispiele

Beispiel #1 Ein time_sleep_until()-Beispiel

<?php

// Gibt false zurück und generiert eine Warnung
var_dump(time_sleep_until(time()-1));

// funktioniert evtl. nur auf schnellen Rechnern, schläft für bis zu 0.2 Sekunden
var_dump(time_sleep_until(microtime(true)+0.2));

?>

Anmerkungen

Hinweis: Alle eingetroffenen Signale werden erst ausgeliefert, wenn die Ausführung fortgesetzt wird.

Siehe auch

  • sleep() - Verzögert die Programmausführung
  • usleep() - Verzögert die Programmausführung (in Mikrosekunden)
  • time_nanosleep() - Verzögert die Ausführung um die gegebene Anzahl Sekunden und Nanosekunden
  • set_time_limit() - Beschränkt die maximale Ausführungszeit

add a note add a note

User Contributed Notes 3 notes

up
1
rowan dot collins at cwtdigital dot com
11 years ago
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 );
        }
    }
?>
up
0
divinity76 at gmail dot com
4 years ago
if you for some reason need a constant-time implementation of realpath(), try

<?php

function 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):

<?php
realpath_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.
up
0
purdue at nc dot rr dot com
12 years ago
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.
To Top