memcache（缓存）

此模块使用了函数zlib来支持数据压缩，因此安装此模块需要安装 Zlib 模块。PHP 4.3.3 及以后版本需要使用 memcache 扩展。

此PECL 扩展未与 PHP 捆绑。 Note:可以关闭memcache session处理器的支持。使用pecl install进行安装时，在静态编译到php中时使用选项 --disable-memcache-session 可以关闭memcache的session 支持（默认时开启的）。

It is very important to note when reading the information supplied by others on this page that there are two *distinct* memcache PHP implementations for the service "memcached".
1) pecl-memcache
2) pecl-memcached
This page is for the first, pecl-memcache.
If you are looking for pecl-memcached information, visit here:
http://www.php.net/manual/en/book.memcached.php

#if apt-get, rpm, or yum doesn't work
cd /usr/src/
wget http://pecl.php.net/get/memcache-2.2.4.tgz
tar -zxvf memcached-2.2.4.tgz
cd memcached-2.2.4
phpize && ./configure --enable-memcache && make
cp modules/memcache.so /usr/lib/php/modules/
# Note: packaged extension modules are now loaded via the .ini files
# found in the directory /etc/php.d
touch /etc/php.d/memcached.ini
echo 'extension=memcache.so' > /etc/php.d/memcached.ini
service httpd restart

运行时配置

这些函数的行为受php.ini中的设置影响。

Memcache类

表示连接到一个服务器组的连接。

Memcache
{
	add ( string $key , mixed $var [, int $flag [, int $expire ]] ) : bool
	addServer ( string $host [, int $port = 11211 [, bool $persistent [, int $weight [, int $timeout [, int $retry_interval [, bool $status [, callback $failure_callback [, int $timeoutms ]]]]]]]] ) : bool
	close ( void ) : bool
	connect ( string $host [, int $port [, int $timeout ]] ) : bool
	decrement ( string $key [, int $value = 1 ] ) : int
	delete ( string $key [, int $timeout = 0 ] ) : bool
	flush ( void ) : bool
	get ( string $key [, int &$flags ] ) : string
	getExtendedStats ([ string $type [, int $slabid [, int $limit = 100 ]]] ) : array
	getServerStatus ( string $host [, int $port = 11211 ] ) : int
	getStats ([ string $type [, int $slabid [, int $limit = 100 ]]] ) : array
	getVersion ( void ) : string
	increment ( string $key [, int $value = 1 ] ) : int
	pconnect ( string $host [, int $port [, int $timeout ]] ) : mixed
	replace ( string $key , mixed $var [, int $flag [, int $expire ]] ) : bool
	set ( string $key , mixed $var [, int $flag [, int $expire ]] ) : bool
	setCompressThreshold ( int $threshold [, float $min_savings ] ) : bool
	setServerParams ( string $host [, int $port = 11211 [, int $timeout [, int $retry_interval = false [, bool $status [, callback $failure_callback ]]]]] ) : bool
}
  

Here is a simple memcached aggregator class which distributes the cache among multiple cache servers. If a server fails, the load is redistributed automatically. It uses persistent connections.
The constructor takes an array of arrays, with each inner array representing a server, with a 'server' (string) attribute that is the IP addres or host name of the memcached server, and a 'port' (int) attribute that is the port number on which memcached is running on the server.
All of the existing memcached API functions are implemented except getStats() and getVersion(), which are server-specific.
<?php
class MemcachedAggregator {
  var $connections;
  public function __construct($servers) {
  // Attempt to establish/retrieve persistent connections to all servers.
  // If any of them fail, they just don't get put into our list of active
  // connections.
  $this->connections = array();
  for ($i = 0, $n = count($servers); $i < $n; $i++) {
    $server = $servers[$i];
    $con = memcache_pconnect($server['host'], $server['port']);
    if (!($con == false)) {
    $this->connections[] = $con;
    }
  }
  }
  private function _getConForKey($key) {
  $hashCode = 0;
  for ($i = 0, $len = strlen($key); $i < $len; $i++) {
    $hashCode = (int)(($hashCode*33)+ord($key[$i])) & 0x7fffffff;
  }
  if (($ns = count($this->connections)) > 0) {
    return $this->connections[$hashCode%$ns];
  }
  return false;
  }
  public function debug($on_off) {
  $result = false;
  for ($i = 0; $i < count($connections); $i++) {
    if ($this->connections[$i]->debug($on_off)) $result = true;
  }
  return $result;
  }
  public function flush() {
  $result = false;
  for ($i = 0; $i < count($connections); $i++) {
    if ($this->connections[$i]->flush()) $result = true;
  }
  return $result;
  }
/// The following are not implemented:
///getStats()
///getVersion()
  public function get($key) {
  if (is_array($key)) {
    $dest = array();
    foreach ($key as $subkey) {
    $val = get($subkey);
    if (!($val === false)) $dest[$subkey] = $val;
    }
    return $dest;
  } else {
    return $this->_getConForKey($key)->get($key);
  }
  }
  public function set($key, $var, $compress=0, $expire=0) {
  return $this->_getConForKey($key)->set($key, $var, $compress, $expire);
  }
  public function add($key, $var, $compress=0, $expire=0) {
  return $this->_getConForKey($key)->add($key, $var, $compress, $expire);
  }
  public function replace($key, $var, $compress=0, $expire=0) {
  return $this->_getConForKey($key)->replace
    ($key, $var, $compress, $expire);
  }
  public function delete($key, $timeout=0) {
  return $this->_getConForKey($key)->delete($key, $timeout);
  }
  public function increment($key, $value=1) {
  return $this->_getConForKey($key)->increment($key, $value);
  }
  public function decrement($key, $value=1) {
  return $this->_getConForKey($key)->decrement($key, $value);
  }
}
?>