pcntl_alarm

(PHP 4 >= 4.3.0, PHP 5)

pcntl_alarm — 为进程设置一个alarm闹钟信号

说明

int pcntl_alarm ( int $seconds )

创建一个计时器，在指定的秒数后向进程发送一个SIGALRM信号。每次对 pcntl_alarm()的调用都会取消之前设置的alarm信号。

参数

seconds: 等待的秒数。如果seconds设置为0,将不会创建alarm信号。

返回值

返回上次alarm调度（离alarm信号发送）剩余的秒数，或者之前没有alarm调度（译注：或者之前调度已完成）时返回0。

add a note User Contributed Notes pcntl_alarm

thessoro at gmail dot com 20-Apr-2011 03:05


If your process uses SIGALRM and sleep() at the same time, the alarm set could make sleep() to return prematurely. 



To avoid this and ensure your process waits a number of seconds you could use a function or class similar to this one:



<?php

class SleepWorkaroundForSIGALRM {

    private $time;

    function __construct($seconds) {

        $this->time = time() + $seconds;

        while ($this->time >= time()) {

            sleep(1);

        }

    }    

?>

j at ukr-info dot net 19-Oct-2005 10:51


<?php

    declare(ticks = 1);



    function signal_handler($signal) {

        print "Caught SIGALRM\n";

        pcntl_alarm(5);

    }



    pcntl_signal(SIGALRM, "signal_handler", true);

    pcntl_alarm(5);



    for(;;) {

    }



?>

add a note