php - PHP 唤醒后重复进度

Question

每次 php 从 sleep() 唤醒时，我都想重复检查一个变量。此外，如果 3 分钟后仍未找到特定变量，则该函数应停止检查。我该怎么办？这是我到目前为止的代码：

<?php
  $file = file_get_contents("file.txt");
  if($file == 0){
    sleep(3);// then go back to $file
  } else {
    //stuff i want
  }
?>

Answer 1

如果您想继续做某事直到发生其他事情，您需要一个循环。您有两件事要检查是否应该退出循环：文件变量和时间长度。您需要添加一个变量来跟踪时间，或者您需要在每次循环时检查时间并将其与开始时间进行比较。

<?php

     $file = file_get_contents("file.txt");
     $timesChecked = 0;
     while($file == 0 and $timesChecked < 60)
     {
         sleep(3);
         $timesChecked++;
         $file = file_get_contents("file.txt");
     } 
     if($file != 0)
     {
          // stuff i want
     } else {
          // 3 minutes elapsed
     }
 ?>

Answer 2

<?php
  //This function returns false if the time elapses without finding the variable.
  //Otherwise it executes what you want to do. It could instead return true if that makes sense.
  function waitForContent($filename) {
    $timeElapsed = 0;
    $lastTry = 0;//the time the file was last checked for contents

    $filehandler = file_get_contents($filename);
    while ($filehandler == 0) {
      $currentTime = microtime();//current time in microseconds
      $timeElapsed = $currentTime - $lastTry;//Note this may not be three seconds, due to how sleep works.
      $lastTry = currentTime;//update the time of the last trye
      if ($timeElapsed > (180 * 1000)) {//if three minutes has passed, quit.
        return false;
      }
      sleep(3);
      $filehandler = file_get_contents($filename);//update file handler
    }

    stuffIWantToDo();//stuff you want to do function.
  }