Question

我有以下代码：

function failureCallback($host, $port) {
    print "memcache '$host:$port' failed";
}

$this->memcache = new Memcache;

## bool Memcache::addServer  (  string $host  [,  int $port = 11211  [,  bool $persistent  [,  int $weight  [,  int $timeout  [,  int $retry_interval  [,  bool $status  [,  callback $failure_callback  [,  int $timeoutms  ]]]]]]]] )
 $this->memcache->addServer('192.168.1.35', '11211', FALSE, 50, 10, 10, TRUE, 'failureCallback' );

服务器在线并正在运行（已验证！），但在每个连接上都会调用Failure回调函数。那是为什么？

参考：

PHP documentation: Memcache :: addServer - ＆gt; failure_callback

允许用户指定回调在遇到一个人时运行的功能错误。之前运行回调尝试进行故障转移。功能有两个参数，主机名和故障服务器的端口

编辑：在回调函数之前使用正确数量的参数更新了帖子，但没有任何运气：（

Answer 1

您的代码不起作用的原因是您实际上没有传递回调。您只是调用该函数并传递返回值。 PHP中的回调通常是带有函数名的字符串或对象方法的数组。

$this->memcache->addServer('192.168.1.35', '11211', 0, 50, 10, TRUE, array($this, '_call_memecache_failure');

参数应该由函数传递。您可以在PHP in the documentation

中详细了解回调的工作原理

示例（来自文档）：

<?php 

// An example callback function
function my_callback_function() {
    echo 'hello world!';
}

// An example callback method
class MyClass {
    static function myCallbackMethod() {
        echo 'Hello World!';
    }
}

// Type 1: Simple callback
call_user_func('my_callback_function'); 

// Type 2: Static class method call
call_user_func(array('MyClass', 'myCallbackMethod')); 

// Type 3: Object method call
$obj = new MyClass();
call_user_func(array($obj, 'myCallbackMethod'));

// Type 4: Static class method call (As of PHP 5.2.3)
call_user_func('MyClass::myCallbackMethod');

// Type 5: Relative static class method call (As of PHP 5.3.0)
class A {
    public static function who() {
        echo "A\n";
    }
}

class B extends A {
    public static function who() {
        echo "B\n";
    }
}

call_user_func(array('B', 'parent::who')); // A
?>

Answer 2

http://docs.php.net/memcache.addserver说：

内存缓存:: addServer
[...]
使用此方法时（与Memcache :: connect（）和Memcache :: pconnect（）相反），在实际需要之前不会建立网络连接。

class Foo {
  protected $memcache;

  public function __construct() {
    echo "Foo::construct\n";
    $this->memcache = new Memcache;
    echo "  adding server\n";
    $this->memcache->addServer('127.0.0.1', 11211, false, 50, 5, 5, true, array($this, 'failureCallback'));
    echo "  constructor done\n";
  }

  public function bar($value) {
    echo "Foo::bar($value)\n";
    $b = $this->memcache->add('testkey', $value, false, 5);
    echo '  add() returned ', $b ? 'true':'false', "\n";
  }

  public function failureCallback($host, $port) {
    echo " ( Foo::failureCallback: memcache '$host:$port' failed )\n";
  }
}

$foo = new Foo;
$foo->bar(1);

打印（没有在localhost上运行memcached）

Foo::construct
  adding server
  constructor done
Foo::bar(1)
 ( Foo::failureCallback: memcache '127.0.0.1:11211' failed )
  add() returned false

Answer 3

$this->memcache = new Memcache;

$this->memcache->addserver(
    $host,
    $port,
    $persistent,
    $weight,
    $timeout,
    $retryInterval,
    $status,
    function($host, $tcpPort, $udpPort, $errorMessage, $errorCode) {
        $message = strtr('Memcache fail on :host (TCP::tcp/UDP::udp) with message ":msg" (:code)', [
            ':host' => $host,
            ':tcp'  => $tcpPort,
            ':udp'  => $udpPort,
            ':msg'  => $errorMessage,
            ':code' => $errorCode
        ]);

        error_log($message);
    }
);

PHP回调函数未被调用

3 个答案: