Add generic http compression layer eanbled at cmake with LWS_WITH_HTTP_STREAM_COMPRESSION.
This is wholly a feature of the HTTP role (used by h1 and h2 roles) and doesn't exist
outside that context.
Currently provides 'deflate' and 'br' compression methods for server side only.
'br' requires also -DLWS_WITH_HTTP_BROTLI=1 at cmake and the brotli libraries (available in
your distro already) and dev package.
Other compression methods can be added nicely using an ops struct.
The built-in file serving stuff will use this is the client says he can handle it, and the
mimetype of the file either starts with "text/" (html and css etc) or is the mimetype of
Javascript.
zlib allocates quite a bit while in use, it seems to be around 256KiB per stream. So this
is only useful on relatively strong servers with lots of memory. However for some usecases
where you are serving a lot of css and js assets, it's a nice help.
The patch performs special treatment for http/1.1 pipelining, since the compression is
performed on the fly the compressed content-length is not known until the end. So for h1
only, chunked transfer-encoding is automatically added so pipelining can continue of the
connection.
For h2 the chunking is neither supported nor required, so it "just works".
User code can also request to add a compression transform before the reply headers were
sent using the new api
LWS_VISIBLE int
lws_http_compression_apply(struct lws *wsi, const char *name,
unsigned char **p, unsigned char *end, char decomp);
... this allows transparent compression of dynamically generated HTTP. The requested
compression (eg, "deflate") is only applied if the client headers indicated it was
supported, otherwise it's a NOP.
Name may be NULL in which case the first compression method in the internal table at
stream.c that is mentioned as acceptable by the client will be used.
NOTE: the compression translation, same as h2 support, relies on the user code using
LWS_WRITE_HTTP and then LWS_WRITE_HTTP_FINAL on the last part written. The internal
lws fileserving code already does this.
Various kinds of input stashing were replaced with a single buflist before
v3.0... this patch replaces the partial send arrangements with its own buflist
in the same way.
Buflists as the name says are growable lists of allocations in a linked-list
that take care of book-keeping what's added and removed (even if what is
removed is less than the current buffer on the list).
The immediate result is that we no longer have to freak out if we had a partial
buffered and new output is coming... we can just pile it on the end of the
buflist and keep draining the front of it.
Likewise we no longer need to be rabid about reporting multiple attempts to
send stuff without going back to the event loop, although not doing that
will introduce inefficiencies we don't have to term it "illegal" any more.
Since buflists have proven reliable on the input side and the logic for dealing
with truncated "non-network events" was already there this internal-only change
should be relatively self-contained.
WSASetEvent(pt->events) just makes WSAWaitForMultipleEvents()
return, it will not set LWS_POLLOUT in pfd->revents and thus
has IMHO no effect. If WSAWaitForMultipleEvents() will set
LWS_POLLOUT it will also signal the event automatically.
1) This moves the service tid detection stuff from context to pt.
2) If LWS_MAX_SMP > 1, a default pthread tid detection callback is provided
on the dummy callback. Callback handlers that call through to the dummy
handler will inherit this. It provides an int truncation of the pthread
tid.
3) If there has been any service calls on the service threads, the pts now
know the low sizeof(int) bytes of their tid. When you ask for a client
connection to be created, it looks through the pts to see if the calling
thread is a pt service thread. If so, the new client is set to use the
same pt as the caller.
When a large deflate frame been received, WSAEnumNetworkEvents will indicate the socket is ready to read. And because the frame is compressed, it may not be consumed entirely(not all bytes ready to receive have been received), since WSAEnumNetworkEvents is edge triggered, and the socket read buffer never been drained, WSAEnumNetworkEvents will never indicate the socket is ready to read again. What here need is level trigger behavior, thus add additional recv with empty buffer to reset edge status.
