Mercurial > hg > nginx
view src/core/ngx_syslog.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 | 7f9935f07fe9 |
children | 29adacffdefa |
line wrap: on
line source
/* * Copyright (C) Nginx, Inc. */ #ifndef _NGX_SYSLOG_H_INCLUDED_ #define _NGX_SYSLOG_H_INCLUDED_ typedef struct { ngx_uint_t facility; ngx_uint_t severity; ngx_str_t tag; ngx_addr_t server; ngx_connection_t conn; unsigned busy:1; unsigned nohostname:1; } ngx_syslog_peer_t; char *ngx_syslog_process_conf(ngx_conf_t *cf, ngx_syslog_peer_t *peer); u_char *ngx_syslog_add_header(ngx_syslog_peer_t *peer, u_char *buf); void ngx_syslog_writer(ngx_log_t *log, ngx_uint_t level, u_char *buf, size_t len); ssize_t ngx_syslog_send(ngx_syslog_peer_t *peer, u_char *buf, size_t len); #endif /* _NGX_SYSLOG_H_INCLUDED_ */