> Hi, Thank you for your explanation.
I added comments. Please check it one more time. >>* On 23 Jul 2020, at 08:29, Sangdeuk Kwon <sangdeuk.kwon at quantil.com >><http://mailman.nginx.org/mailman/listinfo/nginx-devel>> wrote: *>> >>* # HG changeset patch >*>* # User Sangdeuk Kwon <sangdeuk.kwon at quantil.com ><http://mailman.nginx.org/mailman/listinfo/nginx-devel> <mailto:sangdeuk.kwon >at quantil.com <http://mailman.nginx.org/mailman/listinfo/nginx-devel>>> *>>* # Date 1595481798 -32400 >*>* # Thu Jul 23 14:23:18 2020 +0900 >*>* # Node ID 90e5ccf7c229322079ba1b61b4241ed69dfc09b2 >*>* # Parent 4f30f75dbdf33d6fae9e70086e0df5cbab7db027 >*>* During background update, nginx can't add "Range" header >*>* >*>* If the configuration is "slice enabled" and "proxy_cache_use_stale >updating" *>>* and "proxy_cache_background_update on", >*>* nginx can't get "$slice_range" value during background update. >*>* nginx sends request to upstream without "Range" header. >*>* The re-fetched content is saved by cache key of absent "$slice_range". *>>* So, nginx always serves stale content even though after re-fetching new content. *> > This is correct. The slice module does not work with background updates. > >>* >*>* slice 1k; >*>* proxy_cache_use_stale updating; >*>* proxy_cache_background_update on; >*>* proxy_cache_key "$host$uri[$slice_range] >*>* >*>* diff -r 4f30f75dbdf3 -r 90e5ccf7c229 >src/http/modules/ngx_http_slice_filter_module.c *>>* --- a/src/http/modules/ngx_http_slice_filter_module.c Tue Jul 21 20:34:29 2020 +0300 *>>* +++ b/src/http/modules/ngx_http_slice_filter_module.c Thu Jul 23 14:23:18 2020 +0900 *>>* @@ -400,9 +400,12 @@ *>>* ngx_http_slice_loc_conf_t *slcf; *>> >>* ctx = ngx_http_get_module_ctx(r, ngx_http_slice_filter_module); *>>* + if (r->background && r != r->main && r->main != r->parent) { *>>* + ctx = ngx_http_get_module_ctx(r->parent, ngx_http_slice_filter_module); *>>* + } *> > Here you’re trying to get the parent request’s context to access the slice > range. > But slice range is being constantly updated. So there’s no guarantee that > you get > the right slice range. > The right solution would be to pass the slice range to the background update > subrequest as an argument or a part of uri. But that does not seem to be > possible > within the current background update implementation. Probably there’s a way > to save > and then access the right slice using njs. > The posted requests are saved as below order in r->main->posted_requests. Subrequest of background update is executed next to same slice request before next slice request. Background update's r->parent refers same slice request. So, r->parent's ngx_http_slice_ctx_t has correct "Range" value for background update. r: slice #1 r->main->posted_requests: -> background update request (slice #1) -> next slice request (slice #2) r: background update request (slice #1) (r->main=slice #1, r->parent=slice #1) r->main->posted_requests: -> next slice request (slice #2) r: slice #2 r->main->posted_requests: -> background update request (slice #2) -> next slice request (slice #3) r: background update request (slice #2) (r->main=slice #1, r->parent=slice #2) r->main->posted_requests: -> next slice request (slice #3) r: slice #3 (if no need background update) r->main->posted_requests: -> next slice request (slice #4) r: slice #4 r->main->posted_requests: -> background update request (slice #4) -> next slice request (slice #5) r: background update request (slice #4) (r->main=slice #1, r->parent=slice #4) r->main->posted_requests: -> next slice request (slice #5) But, in slice #1 case, "Range" value of ctx is already updated to next value (slice #2) when it's created. So, background update of slice #1 can't use r->parent's ctx. When user request has "Range" header(only one slice case), background update can generate "Range" value by "Range" header. "r->main == r->parent" condition is for slice #1 and user request has "Range" header(only one slice case) "r->main != r->parent" condition is for slice #2, slice #3, and ... >> >> >> >> >>* if (ctx == NULL) { *>>* - if (r != r->main || r->headers_out.status) { *>>* + if ((r != r->main && !r->background) || r->headers_out.status) { *>>* v->not_found = 1; *>>* return NGX_OK; *>>* } *> > Here you are creating a new ctx for the background update subrequest, > which suggests that you want to update the entire response rather that > only one slice. > It's created when slice #1 and user request has "Range" header(only one slice case) >>* _______________________________________________ *>>* nginx-devel mailing list *>>* nginx-devel at nginx.org <http://mailman.nginx.org/mailman/listinfo/nginx-devel> *>>* http://mailman.nginx.org/mailman/listinfo/nginx-devel <http://mailman.nginx.org/mailman/listinfo/nginx-devel>*
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