In a few places in libvirt we busy-wait for events, for example qemu
creating a monitor socket. This is problematic because:
- We need to choose a sufficiently small polling period so that
libvirt doesn't add unnecessary delays.
- We need to choose a sufficiently large polling period so that
the effect of busy-waiting doesn't affect the system.
The solution to this conflict is to use an exponential backoff.
This patch adds two functions to hide the details, and modifies a few
places where we currently busy-wait.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
virTimeFieldsThenRaw will never return negative result, so I clean up
the related meaningless judgements to make it better.
Signed-off-by: James <james.wangyufei@huawei.com>
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Since there isn't a single libc API to get this value, this patch
supplies one which gets the value by grabbing current time, then
converting that into a struct tm with gmtime_r(), then back to a
time_t using mktime.
The returned value is the difference between UTC and localtime in
seconds. If localtime is ahead of UTC (east) the offset will be a
positive number, and if localtime is behind UTC (west) the offset will
be negative.
This function should be POSIX-compliant, and is threadsafe, but not
async signal safe. If it was ever necessary to know this value in a
child process, we could cache it with a one-time init function when
libvirtd starts, then just supply the cached value, but that
complexity isn't needed for current usage; that would also have the
problem that it might not be accurate after a local daylight savings
boundary.
(If it weren't for DST, we could simply replace this entire function
with "-timezone"; timezone contains the offset of the current timezone
(negated from what we want) but doesn't account for DST. And in spite
of being guaranteed by POSIX, it isn't available on older versions of
mingw.)
Signed-off-by: Eric Blake <eblake@redhat.com>
https://www.gnu.org/licenses/gpl-howto.html recommends that
the 'If not, see <url>.' phrase be a separate sentence.
* tests/securityselinuxhelper.c: Remove doubled line.
* tests/securityselinuxtest.c: Likewise.
* globally: s/; If/. If/
Per the FSF address could be changed from time to time, and GNU
recommends the following now: (http://www.gnu.org/licenses/gpl-howto.html)
You should have received a copy of the GNU General Public License
along with Foobar. If not, see <http://www.gnu.org/licenses/>.
This patch removes the explicit FSF address, and uses above instead
(of course, with inserting 'Lesser' before 'General').
Except a bunch of files for security driver, all others are changed
automatically, the copyright for securify files are not complete,
that's why to do it manually:
src/security/security_selinux.h
src/security/security_driver.h
src/security/security_selinux.c
src/security/security_apparmor.h
src/security/security_apparmor.c
src/security/security_driver.c
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
* src/Makefile.am, src/util/virtime.c, src/util/virtime.h: New files
* src/libvirt_private.syms: New APis
* configure.ac: Check for clock_gettime in -lrt
* tests/virtimetest.c, tests/Makefile.am: Test new APIs
