Cache: support for stale-while-revalidate and stale-if-error.

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.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
index a5a9300ac..731f6b09c 100644
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -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;
@@ -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);
 
@@ -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;
@@ -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;