The examples test suite is only useful once in a while
in order to know whether examples were broken, for example
before issuing a release.
The new ws_autobahn test suite isolates the autobahn test
suite so that it can be ignored by default. It's only
useful to run it when working on the Websocket code or
before issuing a release.
It allows disabling the chunked transfer-encoding. It
can also be disabled on a per-request basis, although
it will be ignored for responses that are not streamed.
It allows to temporarily disable Websocket compression
when it was negotiated. It's ignored otherwise. This
can be used as fine-grained control when some frames
do not compress well.
They allow the server to configure what it is willing to accept
for both the negotiated configuration (takeover and window bits)
and the other zlib options (level, mem_level and strategy).
This can be used to reduce the memory and/or CPU footprint of
the compressed data, which comes with a cost in compression ratio.
Returning the atom auto instead of a callback informs Cowboy
that it needs to handle range requests automatically. This
changes the behavior so that the ProvideCallback function
is called and then Cowboy splits the data on its own and
sends the response without any other user involvement other
than defining the ranges_provided/2 callback.
This is a quick and dirty way to add range request support
to resources, and will be good enough for many cases including
for cowboy_static as it also works when the normal response
body is a sendfile tuple.
It is now possible to stream one or more sendfile tuples.
A simple example of what can now be done would be for
example to build a tar file on the fly using the sendfile
syscall for sending the files, or to support Range requests
with more than one range with the sendfile syscall.
When using cowboy_compress_h unfortunately we have to read
the file in order to send it. More options will be added
at a later time to make sure users don't read too much
into memory. This is a new feature however so existing
code is not affected.
Also rework cowboy_http's data sending to be flatter.
