We have added "dns" parameter to backend option. If specified, name
lookup is done dynamically. If not, name lookup is done at start up,
or configuration reloading. nghttpx caches DNS result including error
case in 30 seconds in this commit. Later commit makes this
configurable.
DNS resolution is done asynchronously using c-ares library.
std::make_shared in Xcode 7, 7.1, and 7.2 does not perform
value-initialization, and causes undefined behaviour if struct does
not have user defined default constructor. This workaround explicitly
defines user defined default constructor, and initializes values.
Previously, we didn't retry request on connection failure. Sometimes
we hit the edge case where connection is about to lost just when we
write request. To avoid this situation, we now retry request to
failed attempt. We also add ConnectBlocker to MemcachedConnection not
to attempt to connect to memcached if connection could not be made
previously.
To reduce TTFB with large number of incoming connections, we now
intentionally accept one connection at a time, so that it does not
delay the TTFB of the existing connection. This is significant
especially for TLS connections.
Suppose the wildcard patterns follows:
- *.nghttp2.org/foo
- *.img.nghttp2.org/bar
Previously, s.img.nghttp2.org/foo does not match anything. Now it
matches first pattern.
The --backend-tls-sni-field is deprecated in favor of sni keyword.
--backend-tls-sni-field still works, and it overrides all sni keyword
in --backend option. But it will be removed in the future release.
It is very hard to support multiple protocols in backend while
retaining multiple mode settings. Therefore, we dropped modes except
for default and HTTP/2 proxy mode. The other removed modes can be
emulated using combinations of options. Now the backend connection is
not encrypted by default. To enable encryption on backend connection,
use --backend-tls option.
Previously, we use one Http2Session object per DownstreamAddrGroup.
This is not flexible, and we have to provision how many HTTP/2
connection is required in advance. The new strategy is we add
Http2Session object on demand. We measure the number of attached
downstream connection object and server advertised concurrency limit.
As long as former is smaller than the latter, we attach new downstream
connection to it. Once the limit is reached, we create new
Http2Session object. If the number lowers the limit, we start to
share Http2Session object again.
Tatsuhiro Tsujikawa