PHP Memcached getByKey()函数

Memcached::getByKey()函数是PHP中 Memcached 类的内置函数，用于从特定服务器检索项目。这个函数在功能上等价于 Memcached::get()函数，只是可以使用自由格式的 server_key 将密钥映射到特定的服务器。

句法：

public Memcached::getByKey($server_key, 
    $key, $cache_cb = ?, $flags = ?): mixed

必需参数：此函数接受下面讨论的四个参数：

• server_key：标识服务器的键，用于存储值或从中检索值。
• key：要获取的项目的键。
• cache_cb:通读缓存回调或 null
• flags：控制返回结果的标志。当给定 Memcached::GET_EXTENDED 的值时，它将返回 CAS 令牌。

预期返回值：如果我们使用 Memcached::getByKey() 从特定服务器中查找键的值，我们可以预期两种类型的值，或者存储在缓存中的值，否则为 false。如果服务器中不存在 key，则 Memcached::getResultCode() 将返回 Memcached::RES_NOTFOUND 作为错误。

下面的示例说明了PHP中的 Memcached::getByKey()函数：

示例 1：

PHP

echo "
";
  
// Server & port details
$server = '127.0.0.1';
$port = 11211;
  
// Initiate a new object of memcache
$memcacheD = new Memcached();
  
// Add server
if ($memcacheD->addServer($server, $port)) {
    echo "**  server added ** \n";
}
else {
    echo "** issue while creating a server **\n";
}
  
// Set key & value with TTL
$key = "GEEKSFORGEEKS1";
$value = "computer science portal";
$ttl = 3600;
  
if ($memcacheD->addByKey( "serverkey", $key, $value, $ttl))
      echo "** added key-value (" . $key . ":" 
      . $value . ")to cache successfully!! **\n";
else 
      echo "** error while adding value to cache!! **\n";
  
// Get value of key
echo "****   FETCHED VALUE   FOR KEY :" . $key . " ****\n";
$valD = $memcacheD->getByKey("serverKey", $key);
var_dump($valD);
  
?>

输出：

*  server added **
** added key-value (GEEKSFORGEEKS1:computer science portal)to cache successfully!! **
****   FETCHED VALUE   FOR KEY :GEEKSFORGEEKS1 ****
string(23) “computer science portal”

示例 2：

PHP

";
  
// Server & port details
$server = '127.0.0.1';
$port = 11211;
  
// Initiate a new object of memcache
$memcacheD = new Memcached();
  
// Add server
if ($memcacheD->addServer($server, $port)) {
    echo "**  server added ** \n";
}
else {
    echo "** issue while creating a server **\n";
}
  
// Set key & value with TTL
$key = "GEEKSFORGEEKS2";
$value = "computer science portal";
$ttl = 3600;
  
if ($memcacheD->addByKey( "serverkey", $key, $value, $ttl)) 
      echo "** added key-value (" . $key . ":" 
      . $value . ")to cache successfully!! **\n";
  
// Already added, try it once
if ($memcacheD->addByKey( "serverkey", $key, $value, $ttl)) 
      echo "** added key-value (" . $key . ":" 
      . $value . ")to cache successfully!! **\n";
else 
      echo "** error while adding value to cache!! **\n";
  
// Get value of key
echo "****   FETCHED VALUE   FOR KEY :" . $key . " ****\n";
$valD = $memcacheD->getByKey("serverKey", $key);
var_dump($valD);
  
?>

输出：

**  server added **
** added key-value (GEEKSFORGEEKS2:computer science portal)to cache successfully!! **
** error while adding value to cache!! **
****   FETCHED VALUE   FOR KEY :GEEKSFORGEEKS2 ****
string(23) “computer science portal”

参考：https://www. PHP.net/manual/en/memcached.getbykey。 PHP