Re: [PATCH BlueZ] shared/io-ell: Add support for ELL based IO handling

Hi Luiz,

On 05/17/2018 03:01 AM, Luiz Augusto von Dentz wrote:

Hi,
On Wed, May 16, 2018 at 5:42 PM Denis Kenzior [off-list ref] wrote:

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Hi,

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+
+    do {
+            ret = writev(fd, iov, iovcnt);
+    } while (ret < 0 && errno == EINTR);

explain this one to me. Or maybe Luiz should explain it since he

introduced this.

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I'm curious why not use TEMP_FAILURE_RETRY macro?  ell already uses that
for clarity.

Szymon was actually suggesting that we should have something similar in
ell, e.g. l_io_send, it would be nice if that would handle iovec similarly
to how is done here but perhaps using the TEMP_FAILURE_RETRY as suggested
by Denis.

I would rather not do that actually.  It is already weird that you guys 
have io_send but not io_recv.  And since io is not only used with 
streams / files, but with datagram sockets as well, we would have to add 
a bunch of methods for symmetry.  Not to mention that somehow 'send' 
uses iovecs and the convention inside ell for this is to suffix the 
method with a 'v'.

Also, just a nitpick, but io_send should really be io_writev.   You're 
just confusing every hardcore UNIX user here since a vectorized send is 
'sendmsg'.

By the way, correct me if I'm wrong, but I think there is zero need for 
TEMP_FAILURE_RETRY inside BlueZ since it uses signalfd and non-blocking 
IO anyway.  The only reason ell uses this macro is because we can't 
assume how signals are used in the enclosing application.

Regards,
-Denis