[systemd-devel] Antw: sd_journal_send non-blocking call

[Lennart Poettering]

On Do, 18.07.19 11:06, Mantas Mikulėnas (grawity at gmail.com) wrote:

> On Thu, Jul 18, 2019 at 10:32 AM Ulrich Windl <
> Ulrich.Windl at rz.uni-regensburg.de> wrote:
>
> > >>> Vaibhav Dahiya <vdahiya at ncsu.edu> schrieb am 18.07.2019 um 02:53 in
> > Nachricht
> > <5d2fc2f0.1c69fb81.214d0.1aca at mx.google.com>:
> > > Hello,
> > >
> > > I am using sd_journal_send api() api call to log messages on syslog
> > server.
> > > I see that this uses
> > > sendmsg(fd, &mh, MSG_NOSIGNAL) call.
> >
> > Aren't syslog messages UDP anyway? When would an UDP send block?
> >
>
> No, program APIs use Unix sockets (/dev/log, /run/systemd/journal/socket).
> You only get UDP when your local syslog daemon is configured to forward
> elsewhere.
>
> That said, both are datagram sockets, I'm not sure whether sending to Unix
> dgram sockets can block or not?

Local AF_UNIX/SOCK_DGRAM sockets may block and are reliable.

Lennart

--
Lennart Poettering, Berlin