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Cache: support for stale-while-revalidate and stale-if-error.
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Previously, there was no way to enable the proxy_cache_use_stale behavior by
reading the backend response.  Now, stale-while-revalidate and stale-if-error
Cache-Control extensions (RFC 5861) are supported.  They specify, how long a
stale response can be used when a cache entry is being updated, or in case of
an error.
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@arut
arut committed Dec 22, 2016
1 parent 42f3dd2 commit da2b2cf
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Showing 3 changed files with 93 additions and 21 deletions.
9 changes: 8 additions & 1 deletion src/http/ngx_http_cache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
#define NGX_HTTP_CACHE_ETAG_LEN 42
#define NGX_HTTP_CACHE_VARY_LEN 42

#define NGX_HTTP_CACHE_VERSION 3
#define NGX_HTTP_CACHE_VERSION 4


typedef struct {
Expand Down Expand Up @@ -71,6 +71,8 @@ struct ngx_http_cache_s {

ngx_file_uniq_t uniq;
time_t valid_sec;
time_t updating_sec;
time_t error_sec;
time_t last_modified;
time_t date;

Expand Down Expand Up @@ -114,12 +116,17 @@ struct ngx_http_cache_s {
unsigned purged:1;
unsigned reading:1;
unsigned secondary:1;

unsigned stale_updating:1;
unsigned stale_error:1;
};


typedef struct {
ngx_uint_t version;
time_t valid_sec;
time_t updating_sec;
time_t error_sec;
time_t last_modified;
time_t date;
uint32_t crc32;
Expand Down
8 changes: 8 additions & 0 deletions src/http/ngx_http_file_cache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -601,6 +601,8 @@ ngx_http_file_cache_read(ngx_http_request_t *r, ngx_http_cache_t *c)
c->buf->last += n;

c->valid_sec = h->valid_sec;
c->updating_sec = h->updating_sec;
c->error_sec = h->error_sec;
c->last_modified = h->last_modified;
c->date = h->date;
c->valid_msec = h->valid_msec;
Expand Down Expand Up @@ -632,6 +634,8 @@ ngx_http_file_cache_read(ngx_http_request_t *r, ngx_http_cache_t *c)
now = ngx_time();

if (c->valid_sec < now) {
c->stale_updating = c->valid_sec + c->updating_sec >= now;
c->stale_error = c->valid_sec + c->error_sec >= now;

ngx_shmtx_lock(&cache->shpool->mutex);

Expand Down Expand Up @@ -1252,6 +1256,8 @@ ngx_http_file_cache_set_header(ngx_http_request_t *r, u_char *buf)

h->version = NGX_HTTP_CACHE_VERSION;
h->valid_sec = c->valid_sec;
h->updating_sec = c->updating_sec;
h->error_sec = c->error_sec;
h->last_modified = c->last_modified;
h->date = c->date;
h->crc32 = c->crc32;
Expand Down Expand Up @@ -1513,6 +1519,8 @@ ngx_http_file_cache_update_header(ngx_http_request_t *r)

h.version = NGX_HTTP_CACHE_VERSION;
h.valid_sec = c->valid_sec;
h.updating_sec = c->updating_sec;
h.error_sec = c->error_sec;
h.last_modified = c->last_modified;
h.date = c->date;
h.crc32 = c->crc32;
Expand Down
97 changes: 77 additions & 20 deletions src/http/ngx_http_upstream.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -871,7 +871,9 @@ 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) {
if ((u->conf->cache_use_stale & NGX_HTTP_UPSTREAM_FT_UPDATING)
|| c->stale_updating)
{
u->cache_status = rc;
rc = NGX_OK;

Expand All @@ -894,6 +896,9 @@ ngx_http_upstream_cache(ngx_http_request_t *r, ngx_http_upstream_t *u)
case NGX_HTTP_CACHE_STALE:

c->valid_sec = 0;
c->updating_sec = 0;
c->error_sec = 0;

u->buffer.start = NULL;
u->cache_status = NGX_HTTP_CACHE_EXPIRED;

Expand Down Expand Up @@ -2340,7 +2345,7 @@ ngx_http_upstream_test_next(ngx_http_request_t *r, ngx_http_upstream_t *u)
#if (NGX_HTTP_CACHE)

if (u->cache_status == NGX_HTTP_CACHE_EXPIRED
&& (u->conf->cache_use_stale & un->mask))
&& ((u->conf->cache_use_stale & un->mask) || r->cache->stale_error))
{
ngx_int_t rc;

Expand All @@ -2364,14 +2369,17 @@ ngx_http_upstream_test_next(ngx_http_request_t *r, ngx_http_upstream_t *u)
&& u->cache_status == NGX_HTTP_CACHE_EXPIRED
&& u->conf->cache_revalidate)
{
time_t now, valid;
time_t now, valid, updating, error;
ngx_int_t rc;

ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
"http upstream not modified");

now = ngx_time();

valid = r->cache->valid_sec;
updating = r->cache->updating_sec;
error = r->cache->error_sec;

rc = u->reinit_request(r);

Expand All @@ -2385,6 +2393,8 @@ ngx_http_upstream_test_next(ngx_http_request_t *r, ngx_http_upstream_t *u)

if (valid == 0) {
valid = r->cache->valid_sec;
updating = r->cache->updating_sec;
error = r->cache->error_sec;
}

if (valid == 0) {
Expand All @@ -2397,6 +2407,9 @@ ngx_http_upstream_test_next(ngx_http_request_t *r, ngx_http_upstream_t *u)

if (valid) {
r->cache->valid_sec = valid;
r->cache->updating_sec = updating;
r->cache->error_sec = error;

r->cache->date = now;

ngx_http_file_cache_update_header(r);
Expand Down Expand Up @@ -4132,7 +4145,7 @@ ngx_http_upstream_next(ngx_http_request_t *r, ngx_http_upstream_t *u,
#if (NGX_HTTP_CACHE)

if (u->cache_status == NGX_HTTP_CACHE_EXPIRED
&& (u->conf->cache_use_stale & ft_type))
&& ((u->conf->cache_use_stale & ft_type) || r->cache->stale_error))
{
ngx_int_t rc;

Expand Down Expand Up @@ -4507,32 +4520,76 @@ ngx_http_upstream_process_cache_control(ngx_http_request_t *r,
offset = 8;
}

if (p == NULL) {
return NGX_OK;
}
if (p) {
n = 0;

n = 0;
for (p += offset; p < last; p++) {
if (*p == ',' || *p == ';' || *p == ' ') {
break;
}

for (p += offset; p < last; p++) {
if (*p == ',' || *p == ';' || *p == ' ') {
break;
if (*p >= '0' && *p <= '9') {
n = n * 10 + *p - '0';
continue;
}

u->cacheable = 0;
return NGX_OK;
}

if (*p >= '0' && *p <= '9') {
n = n * 10 + *p - '0';
continue;
if (n == 0) {
u->cacheable = 0;
return NGX_OK;
}

u->cacheable = 0;
return NGX_OK;
r->cache->valid_sec = ngx_time() + n;
}

if (n == 0) {
u->cacheable = 0;
return NGX_OK;
p = ngx_strlcasestrn(start, last, (u_char *) "stale-while-revalidate=",
23 - 1);

if (p) {
n = 0;

for (p += 23; p < last; p++) {
if (*p == ',' || *p == ';' || *p == ' ') {
break;
}

if (*p >= '0' && *p <= '9') {
n = n * 10 + *p - '0';
continue;
}

u->cacheable = 0;
return NGX_OK;
}

r->cache->updating_sec = n;
r->cache->error_sec = n;
}

r->cache->valid_sec = ngx_time() + n;
p = ngx_strlcasestrn(start, last, (u_char *) "stale-if-error=", 15 - 1);

if (p) {
n = 0;

for (p += 15; p < last; p++) {
if (*p == ',' || *p == ';' || *p == ' ') {
break;
}

if (*p >= '0' && *p <= '9') {
n = n * 10 + *p - '0';
continue;
}

u->cacheable = 0;
return NGX_OK;
}

r->cache->error_sec = n;
}
}
#endif

Expand Down

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