# What's the meaning ctx-\>srv conf = cscfp-\>ctx-\>srv conf **URL:** \ **Category:** NGINX\ **Created:** [December 23, 2010, 4:09am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838 "2010-12-23T04:09:22Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![nikuSESS](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/f17d59/32.png) [@nikuSESS](https://www.ruby-forum.com/u/nikuSESS)\ **Post date:** [December 23, 2010, 4:09am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/1 "2010-12-23T04:09:22Z")
hi~~, now I’m reading the code of nginx-0.9.1. I readed the code “ctx-\>srv\_conf = cscfp[s]-\>ctx-\>srv\_conf” at line 593 in the ngx\_http.c . but I really don’t understand it’s meaning. Who can tell me why do this? I find it will make memory leak. Posted at Nginx Forum: > **[what's the meaning ? ctx-\>srv\_conf = cscfp\[s\]-\>ctx-\>srv\_conf](https://forum.nginx.org/read.php?2,160626,160626#msg-160626)** > > hi~~, now I'm reading the code of nginx-0.9.1. I readed the code "ctx-\>srv\_conf = cscfp\[s\]-\>ctx-\>srv\_conf" at line 593 in the ngx\_http.c . but I really don't understand it's meaning. Who can tell me why do this? I find it will make... ---
**Author:** ![garry.lgr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ea5d25/32.png) [@garry.lgr](https://www.ruby-forum.com/u/garry.lgr)\ **Post date:** [December 23, 2010, 4:51am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/2 "2010-12-23T04:51:36Z")
hi, garry: That code is for changing the context of ‘cf’, and make the ‘cf’ appropriate for the function ‘merge\_srv\_conf’. I can’t see any thing matters can cause memory leak unless the “merge\_srv\_conf” function that the modules provide did this. ---
**Author:** ![garry.lgr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ea5d25/32.png) [@garry.lgr](https://www.ruby-forum.com/u/garry.lgr)\ **Post date:** [December 23, 2010, 7:47am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/3 "2010-12-23T07:47:34Z")
![](http://blog.chinaunix.net/photo/6889_101223144343.jpg) I drawed a picture according to the code of the nginx-0.9.1. The top part in the picture is built in the ngx\_http\_block of ngx\_http.c. When the ngx\_http\_merge\_servers function at line 277 is called, the ctx-\>srv\_conf have hold the address of cf-\>ctx-\>srv\_conf. After ctx-\>srv\_conf = cscfp[s]-\>ctx-\>srv\_conf, ctx-\>srv\_conf discard it’s older address to point to the new address cscfp[s]-\>ctx-\>srv\_conf. So I think it will generate memory leak. Posted at Nginx Forum: > **[Re: what's the meaning ? ctx-\>srv conf = cscfp\[s\]-\>ctx-\>srv conf](https://forum.nginx.org/read.php?2,160635,160645#msg-160645)** > > hi, garry: That code is for changing the context of 'cf', and make the 'cf' appropriate for the function 'merge\_srv\_conf'. I can't see any thing matters can cause memory leak unless the "merge\_srv\_conf" function that the modules provide did... ---
**Author:** ![garry.lgr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ea5d25/32.png) [@garry.lgr](https://www.ruby-forum.com/u/garry.lgr)\ **Post date:** [December 23, 2010, 8:13am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/4 "2010-12-23T08:13:17Z")
On Thu, Dec 23, 2010 at 01:46:15AM -0500, garry.lgr wrote: > ![](http://blog.chinaunix.net/photo/6889_101223144343.jpg) > I drawed a picture according to the code of the nginx-0.9.1. The top > part in the picture is built in the ngx\_http\_block of ngx\_http.c. > > When the ngx\_http\_merge\_servers function at line 277 is called, the > ctx-\>srv\_conf have hold the address of cf-\>ctx-\>srv\_conf. After > ctx-\>srv\_conf = cscfp[s]-\>ctx-\>srv\_conf, ctx-\>srv\_conf discard it’s > older address to point to the new address cscfp[s]-\>ctx-\>srv\_conf. Think ctx-\>srv\_conf like a hidden function parameter available via cf-\>ctx: ``` merge_srv_conf(cf, [cf->ctx->srv_conf], ... ``` > So I think it will generate memory leak. All memory operated in ngx\_http.c and many other files are allocated from memory pools freed at once. For example, memory in ngx\_http.c is freed after each reconfiguration. – Igor S. > **[Igor Sysoev](http://sysoev.ru/en/)** ---
**Author:** ![garry.lgr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ea5d25/32.png) [@garry.lgr](https://www.ruby-forum.com/u/garry.lgr)\ **Post date:** [December 23, 2010, 8:52am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/5 "2010-12-23T08:52:06Z")
Thanks, Igor S… Now I understood your meaning. As a hidden parameter, that’s very smart. but I looked up the code of many http module files, don’t find any where you use this . Could you tell me where you use it ? Posted at Nginx Forum: > **[Re: what's the meaning ? ctx-\>srv conf = cscfp\[s\]-\>ctx-\>srv conf](https://forum.nginx.org/read.php?2,160635,160659#msg-160659)** > > hi, garry: That code is for changing the context of 'cf', and make the 'cf' appropriate for the function 'merge\_srv\_conf'. I can't see any thing matters can cause memory leak unless the "merge\_srv\_conf" function that the modules provide did... ---
**Author:** ![garry.lgr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ea5d25/32.png) [@garry.lgr](https://www.ruby-forum.com/u/garry.lgr)\ **Post date:** [December 23, 2010, 11:11am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/6 "2010-12-23T11:11:29Z")
ooh, thanks Igor S… now I know it. Posted at Nginx Forum: > **[Re: what's the meaning ? ctx-\>srv conf = cscfp\[s\]-\>ctx-\>srv conf](https://forum.nginx.org/read.php?2,160635,160699#msg-160699)** > > hi, garry: That code is for changing the context of 'cf', and make the 'cf' appropriate for the function 'merge\_srv\_conf'. I can't see any thing matters can cause memory leak unless the "merge\_srv\_conf" function that the modules provide did... ---
**Author:** ![garry.lgr](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/ea5d25/32.png) [@garry.lgr](https://www.ruby-forum.com/u/garry.lgr)\ **Post date:** [December 23, 2010, 9:47am UTC](https://www.ruby-forum.com/t/whats-the-meaning-ctx-srv-conf-cscfp-ctx-srv-conf/200838/7 "2010-12-23T09:47:22Z")
On Thu, Dec 23, 2010 at 02:51:01AM -0500, garry.lgr wrote: > Thanks, Igor S.. > > Now I understood your meaning. As a hidden parameter, that’s very > smart. I’m not sure that is smart at least in this context. It appeared here rather for compatibility reason. > but I looked up the code of many http module files, don’t find any > where you use this . > > Could you tell me where you use it ? They are used via macros ngx\_http\_conf\_get\_module\_srv\_conf() and ngx\_http\_conf\_get\_module\_loc\_conf() in merge phases. Currenly only ngx\_http\_conf\_get\_module\_loc\_conf() is used in such context in proxy, fastcgi, uwscgi and scgi modules. – Igor S. > **[Igor Sysoev](http://sysoev.ru/en/)**