PHP curl的多线程操作

许多人对php手册中语焉不详的curl_multi一族的函数头疼不已,它们文档少,给的例子 更是简单的让你无从借鉴,我也曾经找了许多网页,都没见一个完整的应用例子。
# curl_multi_add_handle
# curl_multi_close
# curl_multi_exec
# curl_multi_getcontent
# curl_multi_info_read
# curl_multi_init
# curl_multi_remove_handle
# curl_multi_select

一般来说,想到要用这些函数时,目的显然应该是要同时请求多个url,而不是一个一个依次请求,否则不如自己循环去调curl_exec好了。

步骤总结如下:

第一步:调用curl_multi_init
第二步:循环调用curl_multi_add_handle
这一步需要注意的是,curl_multi_add_handle的第二个参数是由curl_init而来的子handle。
第三步:持续调用curl_multi_exec
第四步:根据需要循环调用curl_multi_getcontent获取结果
第五步:调用curl_multi_remove_handle,并为每个字handle调用curl_close
第六步:调用curl_multi_close

这里有一个网上找的简单例子,其作者称为dirty的例子,(稍后我会说明为何dirty):
/*
Here’s a quick and dirty example for curl-multi from PHP, tested on PHP 5.0.0RC1 CLI / FreeBSD 5.2.1
*/

$connomains = array(
“http://www.cnn.com/”,
“http://www.canada.com/”,
“http://www.yahoo.com/”
);

$mh = curl_multi_init();

foreach ($connomains as $i => $url) {
$conn[$i]=curl_init($url);
curl_setopt($conn[$i],CURLOPT_RETURNTRANSFER,1);
curl_multi_add_handle ($mh,$conn[$i]);
}

do { $n=curl_multi_exec($mh,$active); } while ($active);

foreach ($connomains as $i => $url) {
$res[$i]=curl_multi_getcontent($conn[$i]);
curl_close($conn[$i]);
}

print_r($res);

整个使用过程差不多就是这样,但是,这个简单代码有个致命弱点,就是在do循环的那段,在整个url请求期间是个死循环,它会轻易导致CPU占用100%。

现在我们来改进它,这里要用到一个几乎没有任何文档的函数curl_multi_select了,虽然C的curl库对select有说明,但是,php里的接口和用法确与C中有不同。

把上面do的那段改成下面这样:
do {
$mrc = curl_multi_exec($mh,$active);
} while ($mrc == CURLM_CALL_MULTI_PERFORM);
while ($active and $mrc == CURLM_OK) {
if (curl_multi_select($mh) != -1) {
do {
$mrc = curl_multi_exec($mh, $active);
} while ($mrc == CURLM_CALL_MULTI_PERFORM);
}
}

因为$active要等全部url数据接受完毕才变成false,所以这里用到了curl_multi_exec的返回值判断是否还有数据,当有数据的时候就不停调用curl_multi_exec,暂时没有数据就进入select阶段,新数据一来就可以被唤醒继续执行。这里的好处就是CPU的无谓消耗没有了。

另外:还有一些细节的地方可能有时候要遇到:

控制每一个请求的超时时间,在curl_multi_add_handle之前通过curl_setopt去做:
curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);

判断是否超时了或者其他错误,在curl_multi_getcontent之前用:curl_error($conn[$i]);

孤魂写的一个多线程的函数版:

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<?php
$text = remote(array('http://www.kalvin.cn/about-me/','http://www.kalvin.cn/'));
print_r($text);
function remote($urls) {
    if (!is_array($urls) or count($urls) == 0) {
        return false;
    }
    $curl = $text = array();
    $handle = curl_multi_init();
    foreach($urls as $k => $v) {
        $nurl[$k]= preg_replace('~([^:\/\.]+)~ei', "rawurlencode('\\1')", $v);
        $curl[$k] = curl_init($nurl[$k]);
        curl_setopt($curl[$k], CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($curl[$k], CURLOPT_HEADER, 0);
        curl_multi_add_handle ($handle, $curl[$k]);
    }
    $active = null;
    do {
        $mrc = curl_multi_exec($handle, $active);
    } while ($mrc == CURLM_CALL_MULTI_PERFORM);
    while ($active && $mrc == CURLM_OK) {
        if (curl_multi_select($handle) != -1) {
            do {
                $mrc = curl_multi_exec($handle, $active);
            } while ($mrc == CURLM_CALL_MULTI_PERFORM);
        }
    }
    foreach ($curl as $k => $v) {
        if (curl_error($curl[$k]) == "") {
        $text[$k] = (string) curl_multi_getcontent($curl[$k]);
        }
        curl_multi_remove_handle($handle, $curl[$k]);
        curl_close($curl[$k]);
    }
    curl_multi_close($handle);
    return $text;
}

一个多线程的采集类
https://github.com/xfeng/MultiHttpRequest

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<?php
/*
    PHP通用采集
    支持多列表匹配;
    页面内容压缩后匹配,降低规则难度;
    多线程采集,速度更快,为防止目标站限制注意设置并发数量;
    采集后导出content里的内容和images文件夹中图片即可;
    echo str_pad(1,8,"0",STR_PAD_LEFT);00000001
*/
header("Content-type: text/html;charset=utf-8");
set_time_limit(0);
require("libs/class_curl_multi.php");
//连接数据库
$link = mysql_connect("127.0.0.1:3306","root","");
mysql_select_db("test",$link);
//清空数据库
mysql_query("TRUNCATE TABLE content");
//域名前缀
$base = "http://sellbest.net";
//需要采集的规则列表(分页)
$list = array(
    //'http://sellbest.net/by-brand/page[1-14]/1-PRADA.html',
    'http://sellbest.net/by-brand/limit1800/page[1-1]/1-PRADA.html',
);
//在列表页面内容链接表达式
$list_rules = '<p class="productName"><a href="(.*)">.*</a>';
//内容页面信息字段表达式
$detail_rules = array(
    'meta_title'=>'<title>(.*)</title>',
    'meta_keywords'=>'<meta name="keywords" content="(.*)" />',
    'meta_description'=>'<meta name="description" content="(.*)" />',
    'product_name'=>'<h4 class="h4-title float-l"> (.*)</h4>',
    'product_image'=>'<div class="v-inner">.*<a href="(.*)" id="originalImg"><img src=".*" alt=".*" /></a>.*</div>',
    'product_price'=>'Our Price : <strong>(.*)</strong>',
    'product_description'=>'<div class="description-text" id="description"><div class="border-cont">(.*)</div>',
);
//实例
$mp = new MultiHttpRequest();
//调试使用记录采集条目
$j = 1;
//每次并发几个链接
$limit = 10;
//开始采集
foreach ($list as $link) {
    
    //解析列表页数
    preg_match_all('#\[(.*)\]#isU',$link,$_page);
    if($_page[1][0]==''){
        continue;
    }
    $pages = explode('-',$_page[1][0]);
    if(count($pages) != 2){
        continue;
    }
    
    $urls = array();
    
    for($i=$pages[0];$i< =$pages[1];$i++){
        if(count($urls) < $limit){
            $urls[] = preg_replace('#\[(.*)\]#isU',$i,$link);
            if($i != $pages[1]){
                continue;
            }
        }
        //采集列表内容
        $mp->set_urls($urls);
        $contents = $mp->start();
                
        foreach ($contents as $content) {
            
                    $content = _prefilter($content);
                    //debug
                    //exit($content);
                    
                    //匹配内容
                    preg_match_all('#'.addslashes($list_rules).'#isU',$content,$pregArr);
                    
                    $detail_urls = array();
                    foreach($pregArr[1] as $detail_key=>$detail_value){
                        $data = array();
                        if(count($detail_urls) < $limit ){
                                $detail_urls[] = $base.$detail_value;
                                if($pregArr[1][$detail_key+1] != ''){
                                    continue;
                                }
                        }
                        
                        //print_r($detail_urls);
                        //continue;                    
                        $mp->set_urls($detail_urls);
                        
                        $details = $mp->start();
                        //图片路径临时存放
                        $images_urls = array();
                        
                        //采集内容页面
                        foreach ($details as $detail) {
                            $detail = _prefilter($detail);
                            //debug
                            exit($detail);
                            
                            foreach ($detail_rules as $key => $value) {
                                
                                preg_match_all('#'.addslashes($value).'#isU',$detail,$detailArr);
                                //处理特殊这段信息
                                switch ($key) {
                                    case 'product_image':
                                        $data[$key] = "images/".md5($detailArr[1][0]).".jpg";
                                        if(!file_exists($data[$key])){
                                            $images_urls[$data[$key]] = $base.$detailArr[1][0];
                                            //file_put_contents($data[$key],$mp->get_content($base.$detailArr[1][0]));
                                        }
                                        break;
                                    case 'product_description':
                                        $data[$key] = trim(strip_tags($detailArr[1][0]));
                                        break;
                                    default:
                                        $data[$key] = $detailArr[1][0];
                                        break;
                                }
                                                
                            }
                            
                            
                            //产品url        
                            $data['product_url'] = _title($data['product_name']);
                            //转义采集后的数据
                            foreach ($data as $_k => $_v) {
                                $data[$_k] = addslashes($_v);
                            }
                            //入库
                            $r = mysql_query("
                            insert into content values(
                            null,
                            '{$data['meta_title']}',
                            '{$data['meta_keywords']}',
                            '{$data['meta_description']}',
                            '{$data['product_name']}',
                            '{$data['product_image']}',
                            '{$data['product_price']}',
                            '{$data['product_description']}',
                            '{$data['product_url']}')");
                            //打印log
                            _flush($j++."|".$r."|".$data['product_name']."\n");
                            //_flush($data);
                        }
                        //远程图片本地化
                        $mp->set_urls($images_urls);                    
                        $images = $mp->start();                     
                        foreach ((array)$images as $image_key => $image_value) {
                            _flush($image_key."\n");
                            file_put_contents($image_key,$image_value);
                        }
                        //清空内容url并加入本次循环url。不然本次会被跳过
                        $detail_urls = array($base.$detail_value);
            }
        }
        //清空内容url并加入本次循环url。不然本次会被跳过
        $urls = array(preg_replace('#\[(.*)\]#isU',$i,$link));
    }
}
//=========================================================
function _flush($msg)
{
    print_r ($msg);
    ob_flush();
    flush();
}
function _title($title, $separator = '-' )
{
    $title = preg_replace('![^'.preg_quote($separator).'\pL\pN\s]+!u', '', strtolower($title));
    $title = preg_replace('!['.preg_quote($separator).'\s]+!u', $separator, $title);
    return trim($title, $separator);
}
function _prefilter($output) {
    $output=preg_replace("/\/\/[\S\f\t\v ]*?;[\r|\n]/","",$output);
    $output=preg_replace("/\< \!\-\-[\s\S]*?\-\-\>/","",$output);
    $output=preg_replace("/\>[\s]+\< ",$output);
    $output=preg_replace("/;[\s]+/",";",$output);
    $output=preg_replace("/[\s]+\}/","}",$output);
    $output=preg_replace("/}[\s]+/","}",$output);
    $output=preg_replace("/\{[\s]+/","{",$output);
    $output=preg_replace("/([\s]){2,}/","$1",$output);
    $output=preg_replace("/[\s]+\=[\s]+/","=",$output);
    return $output;
}
?>

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