skypjack/uvw

Header-only, event based, tiny and easy to use libuv wrapper in modern C++

RUSshy

@RUSshy

ohh nvm, i put it in the wrong folder

hmm next thing i don't get is i consume already libuv as a static library, and when using uvw it complains about not finding libuv.dll

Michele Caini

@skypjack

If you use uvw as header only, it doesn't include and link libuv for you

That's why the linker complains :)

RUSshy

@RUSshy

i did that already: target_link_libraries(${PROJECT_NAME} PRIVATE opengl32 glad glfw arc cmn ws2_32 uv)

oh i think i got it uv => uv_a :trollface:

ok that was that, it works fine now!

Michele Caini

@skypjack

:+1:

DuckVador

@DuckVador

this test cause double free, when call h->type(). I'm wondering what is the reason.

Michele Caini

@skypjack

is it one of the tests from uvw or one you wrote?

DuckVador

@DuckVador

my own test

Michele Caini

@skypjack

ok, did you try with an interval that is larger than 0ms?

DuckVador

@DuckVador

still double free

actually, if I call h->active, seems everything is ok.

I pasted my code here :https://pastebin.com/raw/3xeJHfmp

Commander Keen

@madhat1

Hello people, I'm wondering where I can find real world samples of using UVW.

Official documentation shows an example of a TCP server, I'm looking for Timer and File I/O examples.

Michele Caini

@skypjack

GitHub contains many example if you like

Commander Keen

@madhat1

I couldn't find timer and file I/O examples, can you direct me to them?

smalls12

@smalls12

I can't figure out how to create a PollHandle for polling a socket to indicate when something is ready to be read

I don't see any examples, and the tests only test FsPollHandle

Michele Caini

@skypjack

@smalls12 uvw doesn't add up on libuv, if you know how to do that with the latter, you can just translate it to the former

PollHandle offers start and stop as expected and they work exactly as their counterparts in libuv

smalls12

@smalls12

I should provide more context
I am trying to integrate a 3rdparty library with libuv / uvw similar to how I would use boost::asio
basically I just want the libuv event loop to tell me when there is something to read or write and hand that off to the 3rdparty library

Michele Caini

@skypjack

This doesn't really add much :slight_smile: the documentation for a poll handle in libuv is here, with uvw it's just a matter of invoking a member function rather than a free function

You pass a file descriptor to the constructor and invoke start, that's it

Events are sent when something relevant happens, you can listen to them with a callback

All this stuff is described in the readme file though and it's literally the same for all classes

How you obtain a file descriptor doesn't depende on libuv nor uvw, so it's up to you

smalls12

@smalls12

I'll post the code I have tried when I get back infront of it

smalls12

@smalls12

I'm back looking at this now
this is the code I have tried, it is seg faulting on me

auto loop = uvw::Loop::getDefault();

    auto poller = loop->resource<uvw::PollHandle>(fd);
    poller->on<uvw::PollEvent>(
    [](const auto &, auto &req)
    {
        std::cout << "poller - some event?\n";
    });

    if(poller->init())
    {
        std::cout << "poller - initialized?\n";
        poller->start(uvw::PollHandle::Event::READABLE);
    }
    else
    {
        std::cerr << "poller - error?\n";
    }

    loop->run();

is this what you expected?

fd is the file descriptor from the other library

Michele Caini

@skypjack

No, it's not expected but it's hard to tell what the problem is without a reproducible example. From what I can see, it can be in uvw, it can be in the other library, it can be elsewhere in the middle...

smalls12

@smalls12

ok the fd was actually -1

doh

now it is working

but I do not see any events indicating something is available to read

smalls12

@smalls12

ok that was my problem again

I think I did something wrong with the ::on call

the event is being spammed now with some poll event

instead of only indicating when there is data to read

smalls12

@smalls12

trying to get some more information from the event

poller->on<uvw::PollEvent>(
    [](const uvw::PollEvent& event, uvw::PollHandle& handle)
    {

    });

is there anything to be obtained from event or handle?

Michele Caini

@skypjack

You can look at the documentation of either uvw or libuv, because the event wraps the underlying event (if any) and the handle does the same with a libuv's poll handle

That is, uvw is a layer on top of libuv and makes you available what is exposed by the underlying library

smalls12

@smalls12

I was able to solve it.

Would you accept a PR showing how to use the poller? Since it is not explicitly captured in an example?

Michele Caini

@skypjack

Sure thing, PRs are always welcome :slight_smile:

Stefano Fiorentino

@stefanofiorentino

Sorry to be absent from this room so far ;)

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