c6c7ab2b44
Event lib support as it has been isn't scaling well, at the low level libevent and libev headers have a namespace conflict so they can't both be built into the same image, and at the distro level, binding all the event libs to libwebsockets.so makes a bloaty situation for packaging, lws will drag in all the event libs every time. This patch implements the plan discussed here https://github.com/warmcat/libwebsockets/issues/1980 and refactors the event lib support so they are built into isolated plugins and bound at runtime according to what the application says it wants to use. The event lib plugins can be packaged individually so that only the needed sets of support are installed (perhaps none of them if the user code is OK with the default poll() loop). And dependent user code can mark the specific event loop plugin package as required so pieces are added as needed. The eventlib-foreign example is also refactored to build the selected lib support isolated. A readme is added detailing the changes and how to use them. https://libwebsockets.org/git/libwebsockets/tree/READMEs/README.event-libs.md |
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|---|---|---|
| .. | ||
| mount-origin | ||
| CMakeLists.txt | ||
| glib.c | ||
| libev.c | ||
| libevent.c | ||
| libuv.c | ||
| localhost-100y.cert | ||
| localhost-100y.key | ||
| minimal-http-server-eventlib-foreign.c | ||
| private.h | ||
| README.md | ||
lws minimal http server eventlib foreign
| Commandline option | Meaning |
|---|---|
| -d | Debug verbosity in decimal, eg, -d15 |
| --uv | Use the libuv event library (lws must have been configured with -DLWS_WITH_LIBUV=1) |
| --event | Use the libevent library (lws must have been configured with -DLWS_WITH_LIBEVENT=1) |
| --ev | Use the libev event library (lws must have been configured with -DLWS_WITH_LIBEV=1) |
Notice libevent and libev cannot coexist in the one library. But all the other combinations are OK.
| x | libuv | libevent | libev |
|---|---|---|---|
| libuv | - | OK | OK |
| libevent | OK | - | no |
| libev | OK | no | - |
This demonstrates having lws take part in a libuv loop owned by something else, with its own objects running in the loop.
Lws can join the loop, and clean up perfectly after itself without leaving anything behind or making trouble in the larger loop, which does not need to stop during lws creation or destruction.
First the foreign loop is created with a 1s timer, and runs alone for 5s.
Then the lws context is created inside the timer callback and runs for 10s... during this period you can visit http://localhost:7681 for normal lws service using the foreign loop.
After the 10s are up, the lws context is destroyed inside the foreign loop timer. The foreign loop runs alone again for a further 5s and then exits itself.
build
$ cmake . && make
usage
$ ./lws-minimal-http-server-eventlib-foreign
[2018/03/29 12:19:31:3480] USER: LWS minimal http server eventlib + foreign loop | visit http://localhost:7681
[2018/03/29 12:19:31:3724] NOTICE: Creating Vhost 'default' port 7681, 1 protocols, IPv6 off
[2018/03/29 12:19:31:3804] NOTICE: Using foreign event loop...
[2018/03/29 12:19:31:3938] USER: Foreign 1Hz timer
[2018/03/29 12:19:32:4011] USER: Foreign 1Hz timer
[2018/03/29 12:19:33:4024] USER: Foreign 1Hz timer
^C[2018/03/29 12:19:33:8868] NOTICE: Signal 2 caught, exiting...
[2018/03/29 12:19:33:8963] USER: main: starting exit cleanup...
[2018/03/29 12:19:33:9064] USER: main: lws context destroyed: cleaning the foreign loop
[2018/03/29 12:19:33:9108] USER: main: exiting...
Visit http://localhost:7681