用PHP实现memcache客户端

2019-11-08 20:14:10

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1、缘起

偶然翻看openresty安装文件的目录，看到lualib/resty目录下有一些用lua写的模块，其中有个memcached.lua，原来是memcache客户端的源码，突然想起memcached协议是基于命令行的。他这个模块用到了ngx.socket.tcp模块，粗略看了下，发现也不是特别复杂，就是用socket收发数据。于是心血来潮，百度了下memcached协议，来造个轮子。

2、代码

memcached协议可参考：memcached协议中文版，讲得挺详细的。

废话少说，上代码（只实现了get,set,add,replace,flush_all共5个命令）。

/** 封装的异常类 */class MemcacheException extends Exception { public function __construct($message, $code = 0) { parent::__construct($message, $code); }}class MyMemcacheClient { PRivate $host; private $port; private $socket; public function __construct() { $this->socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); } /** * 获取最后一次的socket错误 * @return string 最后一次socket错误字符串 */ public function getSocketError() { return socket_strerror(socket_last_error($this->socket)); } /** * 抛出异常封装函数 * @return MemcacheException MemcacheException实例 */ private function throwException() { throw new MemcacheException($this->getSocketError()); } /** * 链接memcached服务器 * @param string $host memcached监听的ip * @param integer $port memcached监听的端口 * @return boolean true表示连接成功，false表示连接失败 */ public function connect($host = '127.0.0.1', $port = 11211) { $this->host = $host; $this->port = $port; $result = socket_connect($this->socket, $host, $port); if ($result === false) { return false; } else { return true; } } /** * 执行set|add|replace命令 * @param string $cmd 命令(set|add|replace) * @param string $key 键 * @param string $value 值 * @param nteger $ttl 生存时间 * @return boolean true for success, false for fail */ private function _set_add_replace($cmd, $key, $value, $ttl = 10) { $line1 = sprintf("$cmd %s 0 %d %d/r/n", $key, $ttl, strlen($value)); $line2 = $value . "/r/n"; $data = $line1 . $line2; $result = socket_write($this->socket, $data, strlen($data)); if ($result === false) { $this->throwException(); } $response = socket_read($this->socket, 1024, php_NORMAL_READ); /** 读取最后一个 /n 字符 */ socket_read($this->socket, 1, PHP_BINARY_READ); if ($response === false) { $this->throwException(); } /** 操作成功会返回STORED/r/n */ if (!strncmp($response, 'STORED', 6)) { return true; } return false; } public function set($key, $value, $ttl = 10) { return $this->_set_add_replace('set', $key, $value, $ttl); } public function add($key, $value, $ttl = 10) { return $this->_set_add_replace('add', $key, $value, $ttl); } public function replace($key, $value, $ttl = 10) { return $this->_set_add_replace('replace', $key, $value, $ttl); } /** * 获取一个键的值 * @param string $key 键 * @return string|boolean 值, false表示没有这个键或者已过期 */ public function get($key) { $data = sprintf("get %s/r/n", $key); $result = socket_write($this->socket, $data, strlen($data)); if ($result === false) { $this->throwException(); } $line1 = socket_read($this->socket, 1024, PHP_NORMAL_READ); /** 读取最后一个 /n 字符 */ socket_read($this->socket, 1, PHP_BINARY_READ); if (!$line1) { $this->throwException(); } /** 获取成功，第一行返回 VALUE <key> <flags> <bytes>/r/n */ if (!strncmp($line1, "VALUE", 5)) { $line1 = rtrim($line1, "/r/n"); $arr = explode(' ', $line1); /** 获取数据长度 */ $dataLen = intval(end($arr)); /** 获取数据 */ $response = socket_read($this->socket, $dataLen, PHP_BINARY_READ); /** 读取最后7个字符 /r/nEND/r/n */ socket_read($this->socket, 7, PHP_BINARY_READ); if ($response === false) { $this->throwException(); } return $response; } else { return false; } } /** * 设置所有的键过期 * @return boolean success */ public function flushAll() { $data = "flush_all/r/n"; $result = socket_write($this->socket, $data, strlen($data)); /** 读取返回结果，固定为 OK/r/n */ socket_read($this->socket, 4, PHP_BINARY_READ); return true; }}

3、测试

测试代码try { $memcache = new MyMemcacheClient(); $memcache->connect(); $memcache->flushAll(); echo "a=", $memcache->get("a"), PHP_EOL; $memcache->set("a", "This is a"); $data = $memcache->get("a"); echo "a: ", $data, PHP_EOL; $memcache->set("a", "This is modified a"); echo "a: ", $memcache->get("a"), PHP_EOL; $memcache->add("b", "This is b"); echo "b: ", $memcache->get("b"), PHP_EOL; $memcache->replace("b", "This is replaced b"); echo "b: ", $memcache->get("b"), PHP_EOL;} catch (MemcacheException $e) { echo $e->getMessage();}测试结果a=a: This is aa: This is modified ab: This is bb: This is replaced b

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