For those connections via frontend with api parameter, they use solely
APIDownstreamConnection.
In this commit, APIDownstreamConnection just consumes all request
body, and do nothing. The next few commits implements our first API
endpoint: /v1/api/dynamicconfig.
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.
This is required to avoid creation of temporary ImmutableString
like so:
std::string x;
ImmutableString y = ...;
StringRef ref = !x.empty() ? x : y;
First, temporary ImmutableString is created with x since
ImmutableString has constructor to accept std::string. After
StringRef gets this, the temporary ImmutableString is destroyed, and
ref has dangling pointer.
We won't add operator[] to StringRef. This is because it may be
undefined if pos == size(), and StringRef's base + len does not point
to the valid region. This solely depends on the given buffer, so we
cannot do anything to fix. For workaround, if we need this kind of
operator, we may add it under another name, like char_at(size_type).
Tatsuhiro Tsujikawa