<?php
//創(chuàng)建共享內(nèi)存區(qū)域
$shm_key = ftok(__FILE__, 'a');
$shm_id = shm_attach($shm_key, 1024, 0755);

//var_dump($shm_id);die(); resource(4) of type (sysvshm)
const SHARE_KEY = 1;
$child_list = [];

//加入信號(hào)量
$sem_id = ftok(__FILE__, 'b');
$signal = sem_get($sem_id);

//$signal resource(5) of type (sysvsem)


for ($i = 0; $i < 3; $i++) {
  $pid = pcntl_fork();
  if ($pid == -1) {
    exit("Fork fail!".PHP_EOL);
  } elseif ($pid == 0) {
    //獲取信號(hào)量
    sem_acquire($signal);
    if (shm_has_var($shm_id,SHARE_KEY)) {
      $count = shm_get_var($shm_id, SHARE_KEY);
      $count++;
      //模擬業(yè)務(wù)處理
      $sec = rand(1, 3);
      sleep($sec);
      shm_put_var($shm_id, SHARE_KEY, $count);
    } else {
      $count = 0;
      $sec = rand(1, 3);
      sleep($sec);
      shm_put_var($shm_id, SHARE_KEY, $count);
    }

    echo "child process: ".getmypid()." is writing! now count is: $count ".PHP_EOL;

    //釋放信號(hào)量
    sem_release($signal);
    exit("child process".getmypid()."end".PHP_EOL);
  } else {
    $child_list[] = $pid;
  }
}

while (count($child_list) > 0) {
  foreach ($child_list as $key => $pid) {
    $status = pcntl_waitpid($pid, $status);
    if ($status > 0 || $status == -1) {
      unset($child_list[$key]);
    }
  }
  sleep(1);
}

$count = shm_get_var($shm_id, SHARE_KEY);
echo " $count  ".PHP_EOL;

//銷毀信號(hào)量
sem_remove($signal);

shm_remove($shm_id);
shm_detach($shm_id);