[nginx] Resolver: cancelable resend timer event.

[Ruslan Ermilov]

details:   http://hg.nginx.org/nginx/rev/70e65bf8dfd7
branches:  
changeset: 7052:70e65bf8dfd7
user:      Ruslan Ermilov <ru at nginx.com>
date:      Tue Jul 04 18:50:41 2017 +0300
description:
Resolver: cancelable resend timer event.

It is safe because re-sending still works during graceful shutdown as
long as resolving takes place (and resolve tasks set their own timeouts
that are not cancelable).

Also, the new ctx->cancelable flag can be set to make resolve task's
timeout event cancelable.

diffstat:

 src/core/ngx_resolver.c |  2 ++
 src/core/ngx_resolver.h |  1 +
 2 files changed, 3 insertions(+), 0 deletions(-)

diffs (30 lines):

diff -r 137c5be7df09 -r 70e65bf8dfd7 src/core/ngx_resolver.c
--- a/src/core/ngx_resolver.c	Tue Jul 04 18:46:30 2017 +0300
+++ b/src/core/ngx_resolver.c	Tue Jul 04 18:50:41 2017 +0300
@@ -191,6 +191,7 @@ ngx_resolver_create(ngx_conf_t *cf, ngx_
     r->event->handler = ngx_resolver_resend_handler;
     r->event->data = r;
     r->event->log = &cf->cycle->new_log;
+    r->event->cancelable = 1;
     r->ident = -1;
 
     r->resend_timeout = 5;
@@ -4008,6 +4009,7 @@ ngx_resolver_set_timeout(ngx_resolver_t 
     ctx->event->handler = ngx_resolver_timeout_handler;
     ctx->event->data = ctx;
     ctx->event->log = r->log;
+    ctx->event->cancelable = ctx->cancelable;
     ctx->ident = -1;
 
     ngx_add_timer(ctx->event, ctx->timeout);
diff -r 137c5be7df09 -r 70e65bf8dfd7 src/core/ngx_resolver.h
--- a/src/core/ngx_resolver.h	Tue Jul 04 18:46:30 2017 +0300
+++ b/src/core/ngx_resolver.h	Tue Jul 04 18:50:41 2017 +0300
@@ -220,6 +220,7 @@ struct ngx_resolver_ctx_s {
 
     unsigned                  quick:1;
     unsigned                  async:1;
+    unsigned                  cancelable:1;
     ngx_uint_t                recursion;
     ngx_event_t              *event;
 };