memcache的基本使用

1.memcache的基本使用

輸出效果：

上代碼：

<?php

//連接Memcache
$mem = new Memcache;
$mem->connect("localhost", 11211) or die ("Could not connect");
//保存數據
$mem->set('key1', 'This is first value', 0, 60);
$val = $mem->get('key1');
echo "Get key1 value: " . $val ."<br>";
//替換數據
$mem->replace('key1', 'This is replace value', 0, 60);
$val = $mem->get('key1');
echo "Get key1 value: " . $val . "<br>";

// 後面追加數據
$mem->append('key1', 'This is afterzhuijia value', 0, 60);
$val = $mem->get('key1');
echo "Get key1 value: " . $val . "<br>";

// 前面追加數據
$mem->prepend('key1', 'This is prezhuijia value', 0, 60);
$val = $mem->get('key1');
echo "Get key1 value: " . $val . "<br>";

//保存數組數據
$arr = array('aaa', 'bbb', 'ccc', 'ddd');
$mem->set('key2', $arr, 0, 60);
$val2 = $mem->get('key2');
echo "Get key2 value: ";
print_r($val2);
echo "<br>";

//添加對象
class Dog{
    public $name;
    public $age;
    public function __construct($name,$age){
        $this->name=$name;
        $this->age=$age;
    }
}
$dog3=new Dog('小狗',50);
$mem->set('key3',$dog3,MEMCACHE_COMPRESSED,60);
$val3 = $mem->get('key3');
echo "Get key3 value name: ";
print_r($val3->name);
echo "<br>";

//獲取版本信息
$version = $mem->getversion();
echo "Get version value: ";
print_r($version);
echo "<br>";

//刪除數據
$mem->delete('key1');
$val = $mem->get('key1');
echo "Get key1 value: " . $val . "<br>";

//清除所有數據
$mem->flush();
$val2 = $mem->get('key2');
echo "Get key2 value: ";
print_r($val2);
echo "<br>";
$val3 = $mem->get('key3');
echo "Get key3 value: ";
print_r($val3);
echo "<br>";

//關閉連接
$mem->close();

2.先從緩存讀數據，無數據在調用數據庫

效果圖：

上代碼：

<?php
$mem = new Memcache();
$mem->connect('localhost',11211);
$users = $mem->get('users');//從memcached中讀取users數據
if(empty($users)){
    $dsn = 'mysql:host=localhost;dbname=pzkc';
    $pdo = new PDO($dsn,'root','root');
    $sql = 'select * from lyy_member;';
    $st = $pdo->prepare($sql);
    $st->execute();
    $users = $st->fetchAll(PDO::FETCH_ASSOC);
    $mem->add('users',$users,false,5);//將users數據添加到memcached中並保存5秒
    echo 'from mysql'.'<br/>';
}else{
    echo 'from cache'.'<br/>';
}
print_r($users);
?>

3.構造簡單消息列隊

參考：https://www.cnblogs.com/ximu/articles/2118323.html

性能特點

1. 無差錯高併發寫入

2.內部指針以int計數, 一個隊列當寫入次數超過int範圍時,出錯

<?php
/**
 * Memcache 消息隊列類
 * @author  xiaowu <[email protected]>
 */

class QMC {
    const PREFIX = 'ASDFASDFFWQKE';

    /**
     * 初始化mc
     * @staticvar string $mc
     * @return Memcache
     */
    static private function mc_init() {
        static $mc = null;
        if (is_null($mc)) {
            $mc = new Memcache;
            $mc->connect('127.0.0.1', 11211);
        }
        return $mc;
    }
    /**
     * mc 計數器,增加計數並返回新的計數
     * @param string $key    計數器
     * @param int $offset    計數增量,可爲負數.0爲不改變計數
     * @param int $time        時間
     * @return int/false    失敗是返回false,成功時返回更新計數器後的計數
     */
    static public function set_counter( $key, $offset, $time=0 ){
        $mc = self::mc_init();
        $val = $mc->get($key);
        if( !is_numeric($val) || $val < 0 ){
            $ret = $mc->set( $key, 0, $time );
            if( !$ret ) return false;
            $val = 0;
        }
        $offset = intval( $offset );
        if( $offset > 0 ){
            return $mc->increment( $key, $offset );
        }elseif( $offset < 0 ){
            return $mc->decrement( $key, -$offset );
        }
        return $val;
    }

    /**
     * 寫入隊列
     * @param string $key
     * @param mixed $value
     * @return bool
     */
    static public function input( $key, $value ){
        $mc = self::mc_init();
        $w_key = self::PREFIX.$key.'W';
        $v_key = self::PREFIX.$key.self::set_counter($w_key, 1);
        return $mc->set( $v_key, $value );
    }
    /**
     * 讀取隊列裏的數據
     * @param string $key
     * @param int $max  最多讀取條數
     * @return array
     */
    static public function output( $key, $max=100 ){
        $out = array();
        $mc = self::mc_init();
        $r_key = self::PREFIX.$key.'R';
        $w_key = self::PREFIX.$key.'W';
        $r_p   = self::set_counter( $r_key, 0 );//讀指針
        $w_p   = self::set_counter( $w_key, 0 );//寫指針
        if( $r_p == 0 ) $r_p = 1;
        while( $w_p >= $r_p ){
            if( --$max < 0 ) break;
            $v_key = self::PREFIX.$key.$r_p;
            $r_p = self::set_counter( $r_key, 1 );
            $out[] = $mc->get( $v_key );
            $mc->delete($v_key);
        }
        return $out;
    }
}
/**
使用方法:
QMC::input($key, $value );//寫入隊列
$list = QMC::output($key);//讀取隊列
 */

QMC::input(1, 1 );//寫入隊列
QMC::input(1, 2 );//寫入隊列
QMC::input(1, 3 );//寫入隊列
QMC::input(1, 4 );//寫入隊列
$list = QMC::output(1);//讀取隊列
print_r($list);
?>