[Libwebsockets] How to send data asynchronously to the client?
bas at appelo.nl
Fri Jun 20 14:49:01 CEST 2014
Ah, yes, I'm on the development version, I can recommend using it, it
has some extra (badly needed as you discovered) functions, but I did not
discover any drawback yet, I do consider it stable, I'm using it quite a
git clone git://git.libwebsockets.org/libwebsockets
On 06/20/2014 02:39 PM, Mike M wrote:
> Unfortunately, that call doesn't seem to exist in the version I'm
> using. What version is the latest stable version?
> On 06/20/2014 08:29 AM, Bas Appelo wrote:
>> libwebsocket_service(context, LARGE_NUMBER); //blocks
>> libwebsocket_cancel_service(context); // wakes up thread-1
>> libwebsocket_callback_on_writable(context, wsi);
>> libwebsocket_service(context, LARGE_NUMBER); //blocks <= will
>> call the callback!
>> Now you will receive a callback, it works like a charm.
>> So to write data you'll need to be in a callback, but the way above
>> shows you how to get there/enforce one.
>> On 06/20/2014 02:18 PM, Mike M wrote:
>>> >>/ Hi,
>>> />>/ 1)Is there a way to asynchronously send the data to the client? That is,
>>> />>/ without being in a callback, server spontaneously initiating data
>>> />>/ transfer to the client..!!
>>> >Libwebsockets is basically single-threaded. But, with care from another
>>> >server thread, you can call either
>>> >libwebsocket_callback_on_writable(), or
>>> >but you need to manage your own list of live wsi / connections with the
>>> >first option (by tracking their creating and destruction in the
>>> >ESTABLISHED and CLOSED callbacks).
>>> >You will get a LWS_CALLBACK_SERVER_WRITABLE as soon as it's possible to
>>> >write on that connection then, and you should figure out what to write
>>> >and write it from there.
>>> I am doing exactly this, but it doesn't work.
>>> I have a thread that calls libwebsocket_service with a huge
>>> timeout. Writes, etc, are only ever done from within the callback.
>>> When I need to write something from another thread, I queue up the
>>> message that needs to be written and then immediately call
>>> libwebsocket_callback_on_writeable_all_protocol on the proto I'm
>>> writing for.
>>> Unfortunately, I never get LWS_CALLBACK_SERVER_WRITEABLE until the
>>> libwebsocket_service times out and gets called again. This is
>>> totally broken. I saw a trac issue (#56) about using ppoll.
>>> Unfortunately, the version of the library we're using doesn't seem
>>> to have that code in it. Any ideas?
>>> Libwebsockets mailing list
>>> Libwebsockets at ml.libwebsockets.org
>> Libwebsockets mailing list
>> Libwebsockets at ml.libwebsockets.org
> Libwebsockets mailing list
> Libwebsockets at ml.libwebsockets.org
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