Re: [libvirt] [PATCH 0/5] Make virDomainObjListFindByName run in O(1)
On 24.04.2015 07:40, zhang bo wrote:
On 2015/4/24 1:14, Michal Privoznik wrote:
> As discussed here:
>
> https://www.redhat.com/archives/libvir-list/2015-April/msg01135.html
>
> Michal Privoznik (5):
> virDomainObjListAddLocked: s/false/NULL/ for @oldDef
> virDomainObjListNew: Use virObjectFreeHashData
> Introduce virDomainObjEndAPI
> virDomainObjListFindByName: Return referenced object
> virDomainObjList: Introduce yet another hash table
>
> src/bhyve/bhyve_driver.c | 3 +-
> src/conf/domain_conf.c | 83 +++++++++++++++++++++++------------
> src/conf/domain_conf.h | 2 +
> src/libvirt_private.syms | 1 +
> src/libxl/libxl_driver.c | 10 ++---
> src/lxc/lxc_driver.c | 3 +-
> src/openvz/openvz_driver.c | 11 +++--
> src/parallels/parallels_driver.c | 3 +-
> src/qemu/qemu_domain.c | 7 +--
> src/qemu/qemu_driver.c | 14 ++----
> src/test/test_driver.c | 93 +++++++++++++---------------------------
> src/uml/uml_driver.c | 15 +++----
> 12 files changed, 110 insertions(+), 135 deletions(-)
>
BTW, we just dealt with virDomainObjListFindByName() here, without caring about
virDomainObjListFindByID().
virDomainObjListFindByID() is now called by umlDomainDestroyFlags() and
umlDomainShutdownFlags(),
if we simultaneously shutdown multiple vms on hypervisor UML, then similar problem comes
out:
some guest maybe unable to shutdown immediately, until other guests get shutoff, and even
'virsh list' blocks.
so, shall we:
1 don't take such problem as a problem
2 use virDomainObjListFindByName() instead of virDomainObjListFindByID() there.
In fact I'd prefer FindByUUID() everywhere except for those few places
where other lookup functions are necessary (e.g. virDomainLookupByID()).
3 add a third hash table for domid
No. even two hash tables duplicate information enough.
If we use virDomainObjListFindByName() there, and forbids developers from using **ByID(),
it seems unacceptable for
any developers.
Why?
If we add a third hash table, it may become not easy to maintain the
high-complexity codes. Is there a better solution other
than adding more hash tables?
The ultimate solution would be to have multi key hash table, so that any
item from tuple (uuid, name, id) would suffice to find domain object.
Michal