php 限制用户接口请求频率

有时候我们需要限制一个API访问的频率，例如单用户一分钟之内只能访问多少次。   
类似于这样的需求很容易用Redis来实现。  

<?php   

$redis = new PredisClient(array(  
    "scheme" => "tcp",  
    "host"   => "127.0.0.1",  
    "port"   => "6379"  
));  

$redis->auth("123456");  

//这个key记录该用户1的访问次数   
$key = "user:1:api_count";  

//限制次数为10   
$limit = 10;  

$check = $redis->exists($key);  
if($check){  
    $redis->incr($key);  //键值递增
    $count = $redis->get($key);  
    if($count > 10){  
        exit("your have too many request");  
    }  
}else{  
    $redis->incr($key);  
    //限制时间为60秒   
    $redis->expire($key,60);  
}  

$count = $redis->get($key);  
echo "You have ".$count." request";