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 <berra...@redhat.com>
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
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