PHP - Manual: time_sleep_until

2024-11-14

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time_sleep_until

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

time_sleep_until — 使脚本睡眠到指定的时间为止。

说明

time_sleep_until(float $timestamp): bool

使脚本睡眠到指定的 timestamp。

参数

timestamp: 将脚本唤醒的时间戳。

返回值

成功时返回 true，或者在失败时返回 false。

更新日志

版本	说明
5.3.0	自此，函数在Windows平台可用。

错误／异常

如果设定的 timestamp 为过去的时间，脚本将会产生一个 E_WARNING 级别的错误。

范例

示例 #1 time_sleep_until() 的一个例子


<?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));

?>

注释

注意: 所有的信号会被延迟至脚本唤醒以后。

参见

sleep() - 延缓执行
usleep() - 以指定的微秒数延迟执行
time_nanosleep() - 延缓执行若干秒和纳秒
set_time_limit() - 设置脚本最大执行时间

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User Contributed Notes 3 notes

down

purdue at nc dot rr dot com ¶

11 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.

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-1

rowan dot collins at cwtdigital dot com ¶

10 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 );
        }
    }
?>

down

-2

divinity76 at gmail dot com ¶

2 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.

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官方地址：https://www.php.net/manual/en/function.time-sleep-until.php

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time_sleep_until

说明

参数

返回值

更新日志

错误／异常

范例

注释

参见

User Contributed Notes 3 notes