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Background subrequests for cache updates.

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Previously, cache background update might not work as expected, making client
wait for it to complete before receiving the final part of a stale response.
This could happen if the response could not be sent to the client socket in one
filter chain call.

Now background cache update is done in a background subrequest.  This type of
subrequest does not block any other subrequests or the main request.
This commit is contained in:
Roman Arutyunyan 2017-05-25 15:57:59 +03:00
parent c83922b18d
commit 8644d9491a
4 changed files with 49 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
src/http/ngx_http_core_module.c
View File

@ -2518,6 +2518,7 @@ ngx_http_subrequest(ngx_http_request_t *r,
sr->subrequest_in_memory = (flags & NGX_HTTP_SUBREQUEST_IN_MEMORY) != 0;
sr->waited = (flags & NGX_HTTP_SUBREQUEST_WAITED) != 0;
sr->background = (flags & NGX_HTTP_SUBREQUEST_BACKGROUND) != 0;
sr->unparsed_uri = r->unparsed_uri;
sr->method_name = ngx_http_core_get_method;
@ -2531,29 +2532,31 @@ ngx_http_subrequest(ngx_http_request_t *r,
sr->read_event_handler = ngx_http_request_empty_handler;
sr->write_event_handler = ngx_http_handler;
if (c->data == r && r->postponed == NULL) {
c->data = sr;
}
sr->variables = r->variables;
sr->log_handler = r->log_handler;
pr = ngx_palloc(r->pool, sizeof(ngx_http_postponed_request_t));
if (pr == NULL) {
return NGX_ERROR;
}
if (!sr->background) {
if (c->data == r && r->postponed == NULL) {
c->data = sr;
}
pr->request = sr;
pr->out = NULL;
pr->next = NULL;
pr = ngx_palloc(r->pool, sizeof(ngx_http_postponed_request_t));
if (pr == NULL) {
return NGX_ERROR;
}
if (r->postponed) {
for (p = r->postponed; p->next; p = p->next) { /* void */ }
p->next = pr;
pr->request = sr;
pr->out = NULL;
pr->next = NULL;
} else {
r->postponed = pr;
if (r->postponed) {
for (p = r->postponed; p->next; p = p->next) { /* void */ }
p->next = pr;
} else {
r->postponed = pr;
}
}
sr->internal = 1;

27
src/http/ngx_http_request.c
View File

@ -2357,6 +2357,26 @@ ngx_http_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
}
if (r != r->main) {
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
if (r->background) {
if (!r->logged) {
if (clcf->log_subrequest) {
ngx_http_log_request(r);
}
r->logged = 1;
} else {
ngx_log_error(NGX_LOG_ALERT, c->log, 0,
"subrequest: \"%V?%V\" logged again",
&r->uri, &r->args);
}
r->done = 1;
ngx_http_finalize_connection(r);
return;
}
if (r->buffered || r->postponed) {
@ -2374,9 +2394,6 @@ ngx_http_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
r->main->count--;
if (!r->logged) {
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
if (clcf->log_subrequest) {
ngx_http_log_request(r);
}
@ -2440,6 +2457,8 @@ ngx_http_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
}
r->done = 1;
r->read_event_handler = ngx_http_block_reading;
r->write_event_handler = ngx_http_request_empty_handler;
if (!r->post_action) {
@ -2558,6 +2577,8 @@ ngx_http_finalize_connection(ngx_http_request_t *r)
return;
}
r = r->main;
if (r->reading_body) {
r->keepalive = 0;
r->lingering_close = 1;

3
src/http/ngx_http_request.h
View File

@ -64,6 +64,7 @@
#define NGX_HTTP_SUBREQUEST_IN_MEMORY 2
#define NGX_HTTP_SUBREQUEST_WAITED 4
#define NGX_HTTP_SUBREQUEST_CLONE 8
#define NGX_HTTP_SUBREQUEST_BACKGROUND 16
#define NGX_HTTP_LOG_UNSAFE 1
@ -486,7 +487,6 @@ struct ngx_http_request_s {
#if (NGX_HTTP_CACHE)
unsigned cached:1;
unsigned cache_updater:1;
#endif
#if (NGX_HTTP_GZIP)
@ -543,6 +543,7 @@ struct ngx_http_request_s {
unsigned stat_writing:1;
unsigned stat_processing:1;
unsigned background:1;
unsigned health_check:1;
/* used to parse HTTP headers */

8
src/http/ngx_http_upstream.c
View File

@ -879,7 +879,7 @@ ngx_http_upstream_cache(ngx_http_request_t *r, ngx_http_upstream_t *u)
case NGX_HTTP_CACHE_STALE:
if (((u->conf->cache_use_stale & NGX_HTTP_UPSTREAM_FT_UPDATING)
|| c->stale_updating) && !r->cache_updater
|| c->stale_updating) && !r->background
&& u->conf->cache_background_update)
{
r->cache->background = 1;
@ -892,7 +892,7 @@ ngx_http_upstream_cache(ngx_http_request_t *r, ngx_http_upstream_t *u)
case NGX_HTTP_CACHE_UPDATING:
if (((u->conf->cache_use_stale & NGX_HTTP_UPSTREAM_FT_UPDATING)
|| c->stale_updating) && !r->cache_updater)
|| c->stale_updating) && !r->background)
{
u->cache_status = rc;
rc = NGX_OK;
@ -1076,14 +1076,14 @@ ngx_http_upstream_cache_background_update(ngx_http_request_t *r,
}
if (ngx_http_subrequest(r, &r->uri, &r->args, &sr, NULL,
NGX_HTTP_SUBREQUEST_CLONE)
NGX_HTTP_SUBREQUEST_CLONE
|NGX_HTTP_SUBREQUEST_BACKGROUND)
!= NGX_OK)
{
return NGX_ERROR;
}
sr->header_only = 1;
sr->cache_updater = 1;
return NGX_OK;
}