We tried several times about this subject, but for the current
HTTP/2.0 priority scheme, we think it is best to serve the highest
priroty streams first (interleaving streams if there are several
higest ones). There are an issue when aggregating several frontend
connections to one connection in backend, but it is HTTP/2.0
spec issue, rather than implementation.
Previously we use largest stream ID received so far as last-stream-ID,
and it is irrevant that it is passed to the callback (thus upper layer).
Now the stream ID which is passed to callback is eligible to
last-stream-ID.
nghttp2_session_client_new2 and nghttp2_session_server_new2 take
additional parameters which specifies session options.
nghttp2_set_option is somewhat crumsy because of type checking.
Now we use nghttp2_opt_set, which specifies individual options with
types. We changed the value of nghttp2_opt, so this change will
require re-compile.
It is not clear that SETTINGS_ENABLE_PUSH = 0 disallows HEADERS
to the reserved streams. For now, we just check the reception
and transmission of PUSH_PROMISE against SETTINGS_ENABLE_PUSH.
Now we have SETTINGS synchronization, flow control error can be
detected strictly. If DATA frame is received with length > 0 and
current received window size is equal to or larger than local
window size (latter happens when we shirnk window size), it is
subject to FLOW_CONTROL_ERROR,
Use NGHTTP2_ERR_INVALID_STREAM_STATE when trying to send DATA or
WINDOW_UPDATE to reserved stream.
Also a bit refactored nghttp2_session_predicate_window_update_send
and nghttp2_session_predicate_data_send
The NGHTTP2_ERR_PAUSE library error code is introduced to pause
the execution of nghttp2_session_mem_recv() when that error code
is returned from nghttp2_on_frame_recv_callback or
nghttp2_on_data_chunk_recv_callback. If this happens, the parameters
available for both callbacks are retained until the application
calls nghttp2_session_continue(). The application must retain
input bytes which was used to produce the frame.
After successful call of nghttp2_session_continue, the application
can continue to call nghttp2_session_mem_recv() to process
additional data.
We call on_stream_close_callback even if stream->state is
NGHTTP2_STREAM_INITIAL. This will happen while sending request
HEADERS, a local endpoint receives RST_STREAM for that
stream. It may be PROTOCOL_ERROR, but without notifying stream
closure will hang the stream in a local endpoint.
Tatsuhiro Tsujikawa