Implementation method of PHP multi-task second-level timer

Description

When I was deploying crontab in the company recently, I suddenly wondered whether I could use PHP to implement a timer with a granularity of seconds, because crontab can only be up to minutes. At the same time, I also researched that there are not many timers implemented in PHP. Swoole has been extended to implement a millisecond-level timer, which is very efficient, but after all, it is not written in pure PHP code, so in the end I still considered using PHP. To implement a timer class for learning reference.

Implementation

When implementing the timer code, two extensions that come with the PHP system are used

Pcntl - multi-process extension:

The main purpose is to allow PHP to open many sub-processes at the same time and process some tasks in parallel.

Spl - SplMinHeap - Small top heap

A small top heap data structure. When implementing a timer, using this structure is very efficient. The time complexity of insertion and deletion is very low. It is O(logN). Timers like libevent also used rbtree before adopting this data structure after version 1.4. If a linked list or fixed array is used, each insertion or deletion may need to be traversed or sorted again. There are still some performance issues.

Process

Explanation

1. Define the timer structure, what is there Parameters and the like.

2. Then register them all into our timer class Timer.

3. Call the monitor method of the timer class and start monitoring.

4. The monitoring process is an endless while loop, constantly checking whether the top of the time heap has expired. I originally considered looping to check once every second, but then I thought it would still be a problem to loop to check once every second. If it happens to be during our sleep( 1) When the timer expires, we cannot execute it accurately immediately, and there may be a risk of delay, so we still use usleep(1000) to see it in milliseconds and suspend the process to reduce the CPU Load.

Code

/***
* Class Timer
*/
class Timer extends SplMinHeap
{
  /**
  * 比较根节点和新插入节点大小
  * @param mixed $value1
  * @param mixed $value2
  * @return int
  */
  protected function compare($value1, $value2)
  {
    if ($value1['timeout'] > $value2['timeout']) {
      return -1;
    }
    if ($value1[&#39;timeout&#39;] < $value2[&#39;timeout&#39;]) {
      return 1;
    }
    return 0;
  }
  /**
  * 插入节点
  * @param mixed $value
  */
  public function insert($value)
  {
    $value[&#39;timeout&#39;] = time() + $value[&#39;expire&#39;];
    parent::insert($value);
  }
  /**
  * 监听
  * @param bool $debug
  */
  public function monitor($debug = false)
  {
    while (!$this->isEmpty()) {
      $this->exec($debug);
      usleep(1000);
    }
  }
  /**
  * 执行
  * @param $debug
  */
  private function exec($debug)
  {
    $hit = 0;
    $t1  = microtime(true);
    while (!$this->isEmpty()) {
      $node = $this->top();
      if ($node[&#39;timeout&#39;] <= time()) {
        //出堆或入堆
        $node[&#39;repeat&#39;] ? $this->insert($this->extract()) : $this->extract();
        $hit = 1;
        //开启子进程
        if (pcntl_fork() == 0) {
          empty($node[&#39;action&#39;]) ? &#39;&#39; : call_user_func($node[&#39;action&#39;]);
          exit(0);
        }
        //忽略子进程,子进程退出由系统回收
        pcntl_signal(SIGCLD, SIG_IGN);
      } else {
        break;
      }
    }
    $t2 = microtime(true);
    echo ($debug && $hit) ? &#39;时间堆 - 调整耗时: &#39; . round($t2 - $t1, 3) . "秒\r\n" : &#39;&#39;;
  }
}

Instance

$timer = new Timer();
//注册 - 3s - 重复触发
$timer->insert(array('expire' => 3, 'repeat' => true, 'action' => function(){
  echo '3秒 - 重复 - hello world' . "\r\n";
}));
//注册 - 3s - 重复触发
$timer->insert(array('expire' => 3, 'repeat' => true, 'action' => function(){
  echo '3秒 - 重复 - gogo' . "\r\n";
}));
//注册 - 6s - 触发一次
$timer->insert(array('expire' => 6, 'repeat' => false, 'action' => function(){
  echo '6秒 - 一次 - hello xxxx' . "\r\n";
}));
//监听
$timer->monitor(false);

Execution result

I have also tested an extreme situation. At the same time, all 1000 timers expire in 1s, and it only takes 0.126s to adjust all the time stacks. This is no problem, but every time a timer is adjusted, a child process needs to be started. , this may be time-consuming, and it is possible that the 1,000 cannot be processed in 1 second, which will affect the continued triggering of the next monitoring, but without starting the child process, such as direct execution, it should still be able to complete the processing. . . . Of course there must be a better way, but this is the only thing I can think of at the moment.

The above is the detailed content of Implementation method of PHP multi-task second-level timer. For more information, please follow other related articles on the PHP Chinese website!