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.
This should work very similar to normal supervisors,
in particular during the shutdown sequence when the
connection process goes down or switches to Websocket.
Processes that need to enforce the shutdown timeout
will be required to trap exits, just like in a supervisor.
In a vanilla Cowboy, this only matters at connection
shutdown, as Cowboy will otherwise wait for the request
process to be down before stopping the stream.
Tests are currently missing.
Cowboy was encoding the headers then decoding them when initializing
the request. The problem is that the encoding and decoding contexts
are not the same. Now, Cowboy will directly use the headers it
received in the push command for the new request. This is also
more efficient.
I am surprised it worked at all considering the issue.
None of these workarounds currently exist in Cowboy 2.0.
We can resurrect the chapter later if it's still necessary,
once we've added the workarounds back in some other form.
Hooks are gone, and we won't be able to stream body in REST
in Cowboy 2.0-rc.1, and might not in 2.0 either. That is,
other than via halting the processing.
There are two important changes in this commit.
Constraints are now producing an error tuple. This error tuple
in turn can be provided to a function for formatting a human
readable error message. Both the error tuple and the formatting
code are controlled by and part of the constraint function.
Constraints now also implement the reverse operation.
When constraint functions only validate, the reverse operation
will be the same as the forward operation. When they also do
some conversion then the reverse operation will reverse it.
Since constraints are now performing 3 different operations
(forward, reverse and format_error), they now take the form
of a function accepting two separate arguments. The operation
is the first argument.
In addition, the return value was changed to take the form
of {ok, Value} | {error, Reason}. The value must be returned
as-is if it was not modified.
