Mercurial > hg > nginx
view src/event/ngx_event_posted.h @ 8045:aa28c802409f
Resolver: make TCP write timer event cancelable.
Similar to 70e65bf8dfd7, the change is made to ensure that the ability to
cancel resolver tasks is fully controlled by the caller. As mentioned in the
referenced commit, it is safe to make this timer cancelable because resolve
tasks can have their own timeouts that are not cancelable.
The scenario where this may become a problem is a periodic background resolve
task (not tied to a specific request or a client connection), which receives a
response with short TTL, large enough to warrant fallback to a TCP query.
With each event loop wakeup, we either have a previously set write timer
instance or schedule a new one. The non-cancelable write timer can delay or
block graceful shutdown of a worker even if the ngx_resolver_ctx_t->cancelable
flag is set by the API user, and there are no other tasks or connections.
We use the resolver API in this way to maintain the list of upstream server
addresses specified with the 'resolve' parameter, and there could be third-party
modules implementing similar logic.
author | Aleksei Bavshin <a.bavshin@f5.com> |
---|---|
date | Wed, 01 Jun 2022 20:17:23 -0700 |
parents | f1720934c45b |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_EVENT_POSTED_H_INCLUDED_ #define _NGX_EVENT_POSTED_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #define ngx_post_event(ev, q) \ \ if (!(ev)->posted) { \ (ev)->posted = 1; \ ngx_queue_insert_tail(q, &(ev)->queue); \ \ ngx_log_debug1(NGX_LOG_DEBUG_CORE, (ev)->log, 0, "post event %p", ev);\ \ } else { \ ngx_log_debug1(NGX_LOG_DEBUG_CORE, (ev)->log, 0, \ "update posted event %p", ev); \ } #define ngx_delete_posted_event(ev) \ \ (ev)->posted = 0; \ ngx_queue_remove(&(ev)->queue); \ \ ngx_log_debug1(NGX_LOG_DEBUG_CORE, (ev)->log, 0, \ "delete posted event %p", ev); void ngx_event_process_posted(ngx_cycle_t *cycle, ngx_queue_t *posted); void ngx_event_move_posted_next(ngx_cycle_t *cycle); extern ngx_queue_t ngx_posted_accept_events; extern ngx_queue_t ngx_posted_next_events; extern ngx_queue_t ngx_posted_events; #endif /* _NGX_EVENT_POSTED_H_INCLUDED_ */