On 01/09/2014 01:18 PM, Ben Noordhuis wrote:
On Wed, Jan 8, 2014 at 10:33 PM, Fedor Indutny <[email protected]> wrote:
Hey people!
I'm currently trying to work around problem with receiving fds over
IPC pipe on SmartOS. The thing is that SmartOS may concatenate
multiple fds and emit them at once in a single SCM_RIGHTS message.
I decided to queue them up on a stream instance, but notifying users
about pending fds requires an API change. Initially, I thought about
passing NULL-buffer as a `read2_cb` with zero `nread`, when there's
pending fd (see:
https://github.com/joyent/libuv/pull/1056/files#diff-56343bd7ad8bf449c2693082fb3e4081R379
). But we are afraid that many users are not prepared for such
circumstances, and, considering that this situation is quite rare and
platform-specific, users may not ever observe it, when developing
their apps.
Thus, I want to collect some feedback from you, people! Please let me
know if it'll break existing code for you, or if you have any better
ideas for this!
This does break my current code on pyuv, since I assume the buffer won't
be NULL in case nread >= 0. But more importantly, until now alloc_cb and
read_cb came in pairs, which wouldn't be the case anymore and someone
may rely on it. FWIW I was going to, but ended up not doing it.
Here is a suggestion: make it explicit in the API. How about changing
the prototype of uv_read2_cb from:
void (*)(uv_pipe_t* pipe, ssize_t nread, const uv_buf_t* buf,
uv_handle_type type);
To something like:
void (*)(uv_pipe_t* pipe, ssize_t nread, const uv_buf_t* buf,
unsigned npending);
And then have the user execute the following code:
for (i = 0; i < npending; i++) {
uv_handle_type type = uv_pipe_pending_handle_type(pipe);
if (type == UV_TCP) {
uv_tcp_t* tcp_handle = /* ... */;
uv_tcp_init(pipe->loop, tcp_handle);
uv_accept((uv_stream_t*) pipe, tcp_handle);
} else if (type == UV_PIPE) {
// etc.
}
}
Maybe shuffle the uv_read2_cb parameters around so that code still
using the old function prototype will fail to build. Not everyone
compiles with -Wall -Wextra or pays attention to the warnings it
generates.
You could even drop the uv_read2_cb prototype altogether, replace it
with uv_read_cb and have the user call uv_pipe_pending_handles_count()
from his callback.
Hey Ben! You mean just calling the read_cb once and having the user
consume all pending descritors? That sounds good to me!
Cheers,
--
Saúl Ibarra Corretgé
bettercallsaghul.com
--
You received this message because you are subscribed to the Google Groups
"libuv" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/libuv.
For more options, visit https://groups.google.com/groups/opt_out.
