time_nanosleep
Remember when using usleep() as a replacement for time_sleep_until() that usleep() can be interrupted by signals, time_sleep_until() not.
time_sleep_until
(PHP 5 >= 5.1.0)
time_sleep_until — Make the script sleep until the specified time
Description
bool time_sleep_until
( float
$timestamp
)
Makes the script sleep until the specified
timestamp.
Parameters
-
timestamp -
The timestamp when the script should wake.
Return Values
Returns TRUE on success or FALSE on failure.
Changelog
| Version | Description |
|---|---|
| 5.3.0 | This function is now available on Windows platforms. |
Errors/Exceptions
If the specified timestamp is in the past, this
function will generate a E_WARNING.
Examples
Example #1 A time_sleep_until() example
<?php
//returns false and generates a warning
var_dump(time_sleep_until(time()-1));
// may only work on faster computers, will sleep up to 0.2 seconds
var_dump(time_sleep_until(microtime(true)+0.2));
?>
Notes
Note: All signals will be delivered after the script wakes up.
See Also
- sleep() - Delay execution
- usleep() - Delay execution in microseconds
- time_nanosleep() - Delay for a number of seconds and nanoseconds
- set_time_limit() - Limits the maximum execution time
add a note
User Contributed Notes
time_sleep_until - [6 notes]
f dot schima at ccgmbh dot de ¶
3 years ago
rowan dot collins at cwtdigital dot com ¶
11 months 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 );
}
}
?>
purdue at nc dot rr dot com ¶
1 year 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.
roberto at spadim dot com dot br ¶
6 years ago
better implementation
<?php
if (!function_exists('time_sleep_until')) {
function time_sleep_until($future) {
if ($future < time()) {
trigger_error("Time in past", E_USER_WARNING);
return false;
}
usleep(($future - microtime(1))*1000000);
return true;
}
}
?>
pasha ¶
3 years ago
To ensure that usleep() is called with the same argument as the one being tested - a positive number:
<?php
if (!function_exists('time_sleep_until')) {
function time_sleep_until($future) {
$sleep = ($future - microtime(1))*1000000;
if ($sleep<=0) {
trigger_error("Time in past", E_USER_WARNING);
return false;
}
usleep($sleep);
return true;
}
}
?>
ssnoyes at hotmail dot com ¶
7 years ago
Implementation for < 5.1 or Windows users
<?php
if (!function_exists('time_sleep_until')) {
function time_sleep_until($future) {
if ($future < time()) {
trigger_error("Time in past", E_USER_WARNING);
return false;
}
sleep($future - time());
return true;
}
}
?>