Cache: multiple variants of a resource now can be stored.

If a variant stored can't be used to respond to a request, the variant
hash is used as a secondary key.

Additionally, if we previously switched to a secondary key, while storing
a response to cache we check if the variant hash still apply.  If not, we
switch back to the original key, to handle cases when Vary changes.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/http/ngx_http_cache.h b/src/http/ngx_http_cache.h
index b65fd493f..f89766d58 100644
--- a/src/http/ngx_http_cache.h
+++ b/src/http/ngx_http_cache.h
@@ -65,6 +65,7 @@ struct ngx_http_cache_s {
     ngx_array_t                      keys;
     uint32_t                         crc32;
     u_char                           key[NGX_HTTP_CACHE_KEY_LEN];
+    u_char                           main[NGX_HTTP_CACHE_KEY_LEN];
 
     ngx_file_uniq_t                  uniq;
     time_t                           valid_sec;
@@ -102,6 +103,7 @@ struct ngx_http_cache_s {
     unsigned                         exists:1;
     unsigned                         temp_file:1;
     unsigned                         reading:1;
+    unsigned                         secondary:1;
 };