网站统计中的数据收集原理及实现(6)

log_format tick "$msec^A$remote_addr^A$u_domain^A$u_url^A$u_title^A$u_referrer^A$u_sh^A$u_sw^A$u_cd^A$u_lang^A$http_user_agent^A$u_utrace^A$u_account";

location /1.gif {
#伪装成gif文件
    default_type image/gif;   
#本身关闭access_log，通过subrequest记录log
    access_log off;

    access_by_lua "
        -- 用户跟踪cookie名为__utrace
        local uid = ngx.var.cookie___utrace       
        if not uid then
            -- 如果没有则生成一个跟踪cookie，算法为md5(时间戳+IP+客户端信息)
            uid = ngx.md5(ngx.now() .. ngx.var.remote_addr .. ngx.var.http_user_agent)
        end
        ngx.header['Set-Cookie'] = {'__utrace=' .. uid .. '; path=/'}
        if ngx.var.arg_domain then
        -- 通过subrequest到/i-log记录日志，将参数和用户跟踪cookie带过去
            ngx.location.capture('/i-log?' .. ngx.var.args .. '&utrace=' .. uid)
        end
    "; 

    #此请求不缓存
    add_header Expires "Fri, 01 Jan 1980 00:00:00 GMT";
    add_header Pragma "no-cache";
    add_header Cache-Control "no-cache, max-age=0, must-revalidate";

    #返回一个1×1的空gif图片
    empty_gif;
}  

location /i-log {
    #内部location，不允许外部直接访问
    internal;

    #设置变量，注意需要unescape
    set_unescape_uri $u_domain $arg_domain;
    set_unescape_uri $u_url $arg_url;
    set_unescape_uri $u_title $arg_title;
    set_unescape_uri $u_referrer $arg_referrer;
    set_unescape_uri $u_sh $arg_sh;
    set_unescape_uri $u_sw $arg_sw;
    set_unescape_uri $u_cd $arg_cd;
    set_unescape_uri $u_lang $arg_lang;
    set_unescape_uri $u_utrace $arg_utrace;