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.
Previous use of size_t may cause wierd effects on 32bit platforms with certain
big responses transferred in unbuffered mode.
Nuke "if (size > u->length)" check as it's not usefull anyway (preread
body data isn't subject to this check) and now requires additional check
for u->length being positive.
this fixes fastcgi_catch_stderr segfault introduced in r1453
*) ngx_http_upstream_hide_headers_hash()
*) proxy/fastcgi pass_header/hide_header use
ngx_http_upstream_hide_headers_hash()
*) Feature: now is possible to do several redirection using the
"error_page" directive.
*) Bugfix: the "dav_access" directive did not support three parameters.
*) Bugfix: the "error_page" directive did not changes the
"Content-Type" header line after the "X-Accel-Redirect" was used;
the bug had appeared in 0.3.58.
*) Feature: nginx now logs the subrequest information to the error log.
*) Feature: the "proxy_next_upstream", "fastcgi_next_upstream", and
"memcached_next_upstream" directives support the "off" parameter.
*) Feature: the "debug_connection" directive supports the CIDR address
form.
*) Bugfix: if a response of proxied server or FastCGI server was
converted from UTF-8 or back, then it may be transferred incomplete.
*) Bugfix: the $upstream_response_time variable had the time of the
first request to a backend only.
*) Bugfix: nginx could not be built on amd64 platform; the bug had
appeared in 0.3.53.
