From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49839) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yuzrv-0007dV-BQ for qemu-devel@nongnu.org; Wed, 20 May 2015 05:00:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Yuzrs-0008WH-3t for qemu-devel@nongnu.org; Wed, 20 May 2015 05:00:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33923) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Yuzrr-0008W3-V0 for qemu-devel@nongnu.org; Wed, 20 May 2015 05:00:48 -0400 Date: Wed, 20 May 2015 10:00:43 +0100 From: "Daniel P. Berrange" Message-ID: <20150520090043.GD23989@redhat.com> References: <33183CC9F5247A488A2544077AF1902086E86BFF@SZXEMA503-MBS.china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <33183CC9F5247A488A2544077AF1902086E86BFF@SZXEMA503-MBS.china.huawei.com> Subject: Re: [Qemu-devel] [RFC] Can we convert UTC time to local time in Qemu Reply-To: "Daniel P. Berrange" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Gonglei (Arei)" Cc: "Herongguang (Stephen)" , "qemu-devel@nongnu.org" , "Huangpeng (Peter)" 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 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 :|