[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [RFC] Can we convert UTC time to local time in Qemu
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [RFC] Can we convert UTC time to local time in Qemu |
Date: |
Wed, 20 May 2015 10:00:43 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Wed, May 20, 2015 at 06:29:55AM +0000, Gonglei (Arei) wrote:
> Hi,
>
> At present, Qemu use g_time_val_to_iso8601() to get the UTC added to
> error_report()
> (commit 5e2ac5191), TBH this way is very simply, we just need invoke standard
> glib functions to
> complete the job.
>
> But in the cloud computing and data center scenarios, there are many
> Other open source components, such as kernel, libvirt, openstack which are
> all using local time
> to record the message logs, only Qemu is using the UTC time. When we want to
> find a error
> message of Qemu, we should convert the UTC time to local time manually, and
> unfortunately
> different countries have different local time, what a trouble thing the
> converting is.
>
> So, my question is: Can we convert the UTC time to local time in Qemu?
>
> Any thoughts? Thanks.
Actually, libvirt uses UTC for logging almost exclusively for quite a
while, because AFAIK, there is no async signal safe way to convert to
localtime in POSIX / glibc
commit 3ec128989606278635a7c5dfbeee959692d12e15
Author: Daniel P. Berrange <address@hidden>
Date: Tue Nov 29 12:11:01 2011 +0000
Add internal APIs for dealing with time
The logging APIs need to be able to generate formatted timestamps
using only async signal safe functions. This rules out using
gmtime/localtime/malloc/gettimeday(!) and much more.
Introduce a new internal API which is async signal safe.
virTimeMillisNowRaw replacement for gettimeofday. Uses clock_gettime
where available, otherwise falls back to the unsafe
gettimeofday
virTimeFieldsNowRaw replacements for gmtime(), convert a timestamp
virTimeFieldsThenRaw into a broken out set of fields. No localtime()
replacement is provided, because converting to
local time is not practical with only async signal
safe APIs.
virTimeStringNowRaw replacements for strftime() which print a timestamp
virTimeStringThenRaw into a string, using a pre-determined format, with
a fixed size buffer (VIR_TIME_STRING_BUFLEN)
For each of these there is also a version without the Raw postfix
which raises a full libvirt error. These versions are not async
signal safe
Regards,
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|