PHP pthreads v3使用中的一些坑和注意點(diǎn)分析

?php

class Task extends Thread
{
  public $data;

  public function run()
  {
    global $num;
    var_dump($num);
    $this->data = 'abc';

    //這是打印null
    var_dump($GLOBALS);
    $GLOBALS['test'] = 'def';
  }
}

//主線程中的全局變量，子線程中是無(wú)法訪問(wèn)的
//php中創(chuàng)建子線程，它會(huì)有一個(gè)單獨(dú)的堆，運(yùn)行在單獨(dú)的地址空間中
//并不能像有些語(yǔ)言中，子線程是可以訪問(wèn)的到主線程中的變量的。
$num = 666;

$GLOBALS['test'] = 'test';

$t = new Task();
$t->start()  $t->join();

//主線程可以訪問(wèn)子線程的變量
var_dump($t->data);

?php

class Task extends Thread
{
  private $data;

  public function __construct($data)
  {
    $this->data = $data;
  }

  public function run()
  {
    echo "task data : ", $this->data, "\n";
    $this->data = 'def';
    echo "task data : ", $this->data, "\n";
  }
}

$data = 'abc';

//我們這里傳入的是引用
$t = new Task($data);
$t->start()  $t->join();

//但是$data變量數(shù)據(jù)并沒(méi)改變
//這說(shuō)明我們通過(guò)構(gòu)造函數(shù)傳入Task對(duì)象中的$data只是一個(gè)拷貝
//子線程中并不能夠操作主線程中的變量
var_dump($data);

?php

class Task extends Thread
{
  private $call;


  public function __construct()
  {
    //pthreads v3版本好像可以設(shè)置成員為匿名函數(shù)
    //在v2版本中好像是不可以的
    $this->call = function ($param1, $param2) {
      echo "task call param1 : {$param1} param2 : {$param2}\n";
    };
  }

  public function run()
  {
    //直接調(diào)用成員匿名函數(shù)
    ($this->call)("hello", "world");
  }
}

$t = new Task();
$t->start()  $t->join();

?php

class Task extends Thread
{
  private $db;

  public function __construct()
  {
    //注意這里會(huì)報(bào)錯(cuò)，不能對(duì)PDO實(shí)例進(jìn)行序列化或反序列化
    $this->db = new PDO('mysql:dbname=test;host=192.168.33.226', 'root', '');
  }

  public function run()
  {
    $result = $this->db->query("select id,name from tb_user");
    while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
      echo "{$row['id']}\t{$row['name']}\n";
    }
  }
}

$t = new Task();
$t->start()  $t->join();

?php

class Task extends Thread
{
  //我們需要把數(shù)據(jù)庫(kù)連接資源，聲明為靜態(tài)成員，然后調(diào)用靜態(tài)方法進(jìn)行創(chuàng)建
  private static $db;

  //我們直接在__construct()構(gòu)造函數(shù)里對(duì)$db進(jìn)行實(shí)例化，好像會(huì)是null，有興趣的可以試試
  public static function getConn()
  {
    if (!is_resource(self::$db)) {
      self::$db = new PDO('mysql:dbname=test;host=192.168.33.226', 'root', '');
    }
    return self::$db;
  }

  public function run()
  {
    $result = self::getConn()->query("select id,name from tb_user");
    while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
      echo "{$row['id']}\t{$row['name']}\n";
    }
  }
}

$t = new Task();
$t->start()  $t->join();