If use_temp_path is set to off, a subdirectory "temp" is created in the cache
directory. It's used instead of proxy_temp_path and friends for caching
upstream response.
Some parts of code related to handling variants of a resource moved into
a separate function that is called earlier. This allows to use cache file
name as a prefix for temporary file in the following patch.
Once this age is reached, the cache lock is discarded and another
request can acquire the lock. Requests which failed to acquire
the lock are not allowed to cache the response.
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.
To cache responses with Vary, we now calculate hash of headers listed
in Vary, and return the response from cache only if new request headers
match.
As of now, only one variant of the same resource can be stored in cache.
The following new directives are introduced: proxy_cache_revalidate,
fastcgi_cache_revalidate, scgi_cache_revalidate, uwsgi_cache_revalidate.
Default is off. When set to on, they enable cache revalidation using
conditional requests with If-Modified-Since for expired cache items.
As of now, no attempts are made to merge headers given in a 304 response
during cache revalidation with headers previously stored in a cache item.
Headers in a 304 response are only used to calculate new validity time
of a cache item.
New directives: proxy_cache_lock on/off, proxy_cache_lock_timeout. With
proxy_cache_lock set to on, only one request will be allowed to go to
upstream for a particular cache item. Others will wait for a response
to appear in cache (or cache lock released) up to proxy_cache_lock_timeout.
Waiting requests will recheck if they have cached response ready (or are
allowed to run) every 500ms.
Note: we intentionally don't intercept NGX_DECLINED possibly returned by
ngx_http_file_cache_read(). This needs more work (possibly safe, but needs
further investigation). Anyway, it's exceptional situation.
Note: probably there should be a way to disable caching of responses
if there is already one request fetching resource to cache (without waiting
at all). Two possible ways include another cache lock option ("no_cache")
or using proxy_no_cache with some supplied variable.
Note: probably there should be a way to lock updating requests as well. For
now "proxy_cache_use_stale updating" is available.
to delete old inactive entries: one of them removes a entry just locked by
other manager from the queue and the rbtree as long inactive entry,
causes the latter manager to segfault leaving cache mutex locked,
the bug has been introduced in r3727
*) now ngx_http_file_cache_cleanup() uses ngx_http_file_cache_free()
*) ngx_http_file_cache_free() interface has been changed to accept r->cache
ngx_http_file_cache_cleanup() must use r->cache, but not r, because
there can be several r->cache's during request processing, r->cache may
be NULL at request finalising, etc.
*) test if updating request does not complete correctly
*) Feature: the server_names_hash and server_names_hash_threshold
directives.
*) Bugfix: the *.domain.tld names in the "server_name" directive did
not work.
*) Bugfix: the %request_length log parameter logged the incorrect
length.
*) Feature: the worker_priority directive.
*) Change: both tcp_nopush and tcp_nodelay directives affect the
transferred response.
*) Bugfix: nginx did not call initgroups().
Thanks to Andrew Sitnikov and Andrei Nigmatulin.
*) Change: now the ngx_http_autoindex_module shows the file size in the
bytes.
*) Bugfix: the ngx_http_autoindex_module returned the 500 error if the
broken symlink was in a directory.
*) Bugfix: the files bigger than 4G could not be transferred using
sendfile.
*) Bugfix: if the backend was resolved to several backends and there
was an error while the response waiting then process may got caught
in an endless loop.
*) Bugfix: the worker process may exit with the "unknown cycle" message
when the /dev/poll method was used.
*) Bugfix: "close() channel failed" errors.
*) Bugfix: the autodetection of the "nobody" and "nogroup" groups.
*) Bugfix: the send_lowat directive did not work on Linux.
*) Bugfix: the segmentation fault occurred if there was no events
section in configuration.
*) Bugfix: nginx could not be built on OpenBSD.
*) Bugfix: the double slashes in "://" in the URI were converted to
":/".
*) Bugfix: the proxied request was sent without arguments if the
request contains "//", "/./", "/../" or "%XX".
*) Bugfix: the large compressed responses may be transferred not
completely.
*) Bugfix: the files bigger than 2G was not transferred on Linux that
does not support sendfile64().
*) Bugfix: while the build configuration on Linux the
--with-poll_module parameter was required; the bug had appeared in
0.1.8.
