一个带重试次数的curl 函数

<?php
/**
 * [curl 带重试次数]
 * @param  [type]  $url     [访问的url]
 * @param  [type]  $post    [$POST参数]
 * @param  integer $retries [curl重试次数]
 * @return [type]           [description]
 */
function curl($url, $post = null, $retries = 3,$sleep=1 ){
    $curl = curl_init($url);

    if(is_resource($curl) === true){
        curl_setopt($curl, CURLOPT_FAILONERROR, true);
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);

        if(isset($post) === true){
            curl_setopt($curl, CURLOPT_POST, true);
            curl_setopt($curl, CURLOPT_POSTFIELDS, (is_array($post) === true) ? http_build_query($post, "", "&"): $post);
        }

        $result = false;

        while(($result === false) && (--$retries > 0)){
            sleep($sleep); //阻塞1s
            $result = curl_exec($curl);
        }

        curl_close($curl);
    }

    return $result;
}