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libwebsockets/minimal-examples/http-client/minimal-http-client
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Andy Green 48366de1d1 unix plat: add minimal wsi fd map option 
An lws context usually contains a processwide fd -> wsi lookup table.

This allows any possible fd returned by a *nix type OS to be immediately
converted to a wsi just by indexing an array of struct lws * the size of
the highest possible fd, as found by ulimit -n or similar.

This works modestly for Linux type systems where the default ulimit -n for
a process is 1024, it means a 4KB or 8KB lookup table for 32-bit or
64-bit systems.

However in the case your lws usage is much simpler, like one outgoing
client connection and no serving, this represents increasing waste.  It's
made much worse if the system has a much larger default ulimit -n, eg 1M,
the table is occupying 4MB or 8MB, of which you will only use one.

Even so, because lws can't be sure the OS won't return a socket fd at any
number up to (ulimit -n - 1), it has to allocate the whole lookup table
at the moment.

This patch looks to see if the context creation info is setting
info->fd_limit_per_thread... if it leaves it at the default 0, then
everything is as it was before this patch.  However if finds that
(info->fd_limit_per_thread * actual_number_of_service_threads) where
the default number of service threads is 1, is less than the fd limit
set by ulimit -n, lws switches to a slower lookup table scheme, which
only allocates the requested number of slots.  Lookups happen then by
iterating the table and comparing rather than indexing the array
directly, which is obviously somewhat of a performance hit.

However in the case where you know lws will only have a very few wsi
maximum, this method can very usefully trade off speed to be able to
avoid the allocation sized by ulimit -n.

minimal examples for client that can make use of this are also modified
by this patch to use the smaller context allocations.
2019-05-18 12:10:19 +01:00
..
CMakeLists.txt refactor: most preparation for -DLWS_ROLE_H1=0 2018-04-27 19:16:50 +08:00
minimal-http-client.c unix plat: add minimal wsi fd map option 2019-05-18 12:10:19 +01:00
README.md minimal: add switches and exit results 2018-04-19 16:16:48 +08:00
selftest.sh selftests 2018-04-19 16:16:48 +08:00
warmcat.com.cer mbedtls: wrapper: client: Force mbedTLS to attemp to verify cert 2018-04-06 10:38:03 +08:00

README.md

lws minimal http client

The application goes to either https://warmcat.com or https://localhost:7681 (with -l option) and receives the page data.

build

 $ cmake . && make

usage

Commandline option Meaning
-d Debug verbosity in decimal, eg, -d15
-l Connect to https://localhost:7681 and accept selfsigned cert
--h1 Specify http/1.1 only using ALPN, rejects h2 even if server supports it 
 $ ./lws-minimal-http-client
[2018/03/04 14:43:20:8562] USER: LWS minimal http client
[2018/03/04 14:43:20:8571] NOTICE: Creating Vhost 'default' port -1, 1 protocols, IPv6 on
[2018/03/04 14:43:20:8616] NOTICE: created client ssl context for default
[2018/03/04 14:43:20:8617] NOTICE: lws_client_connect_2: 0x1814dc0: address warmcat.com
[2018/03/04 14:43:21:1496] NOTICE: lws_client_connect_2: 0x1814dc0: address warmcat.com
[2018/03/04 14:43:22:0154] NOTICE: lws_client_interpret_server_handshake: incoming content length 26520
[2018/03/04 14:43:22:0154] NOTICE: lws_client_interpret_server_handshake: client connection up
[2018/03/04 14:43:22:0169] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0169] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0169] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0169] USER: RECEIVE_CLIENT_HTTP_READ: read 1015
[2018/03/04 14:43:22:0174] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0174] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0174] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0174] USER: RECEIVE_CLIENT_HTTP_READ: read 1015
[2018/03/04 14:43:22:0179] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0179] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0179] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:0179] USER: RECEIVE_CLIENT_HTTP_READ: read 1015
[2018/03/04 14:43:22:3010] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3010] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3010] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3010] USER: RECEIVE_CLIENT_HTTP_READ: read 1015
[2018/03/04 14:43:22:3015] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3015] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3015] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3015] USER: RECEIVE_CLIENT_HTTP_READ: read 1015
[2018/03/04 14:43:22:3020] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3020] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3020] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3020] USER: RECEIVE_CLIENT_HTTP_READ: read 1015
[2018/03/04 14:43:22:3022] USER: RECEIVE_CLIENT_HTTP_READ: read 1024
[2018/03/04 14:43:22:3022] USER: RECEIVE_CLIENT_HTTP_READ: read 974
[2018/03/04 14:43:22:3022] NOTICE: lws_http_client_read: transaction completed says -1
[2018/03/04 14:43:23:3042] USER: Completed