When we have to send a response before terminating a stream,
we call info. The state returned by this info call was
discarded when we called terminate after that. This commit
fixes it.
There are no tests for this, however the new metrics test
in the next commit requires the correct behavior so this
is ultimately covered.
It collects metrics and passes them to a configurable callback
once the stream terminates. It will be documented in a future
release. More tests incoming.
The documentation was correct, the code was not.
This should make it easier to implement new protocols. Note that
for HTTP/2 we will need to add some form of counting later on to
check for malformed requests, but we can do simpler and just
reduce from the expected length and then check if that's 0 when
IsFin=fin.
It is completely removed for connection processes, because
assuming Cowboy is written properly this should bring us
nothing anymore in 2.0.
It is reworked for request processes, there we want to
always propagate the stacktrace (including for exits)
because we will print a report to help with debugging
and proc_lib doesn't propagate it for exits.
At the same time the initial callback for connection
and request processes has been changed to connection_process
and request_process, which should help with identifying
processes when inspecting.
When the request process exits with a {request_error, Reason, Human}
exit reason, Cowboy will return a 400 status code instead of 500.
Cowboy may also return a more specific status code depending on
the error. Currently it may also return 408 or 413.
This should prove to be more solid that looking inside the stack
trace.
I have decided not to include a manual page for
cowboy_stream_h at this point because it clashes
with the cowboy_stream manual page. This decision
will be revisited in the future.
