Re: [libvirt] [RFC PATCH 3/3] libvirt: Implement two-tier driver loading

This implements a two-tier driver loading system into libvirt. The two classes of drivers are "Libvirt" drivers and "Hypervisor" drivers. Hypervisor drivers are fairly self-explanatory, they provide domain services. Libvirt drivers are sort of the backend drivers for those, like the secret and storage drivers. In the two-tier loading system here, the "Libvirt" drivers are all loaded and auto-started. Once those have finished, the "Hypervisor" drivers are loaded and auto-started. By doing things in this manner, we do not have to hard-code a driver loading order or roll our own dynamic dependency-based loading algorithm, while still gaining the benefits of a more orderly driver loading approach, which should help minimize the possibility of a race condition during startup. If another race condition is found, the code can be extended to provide any number of extra tiers without much trouble.

Signed-off-by: Adam Walters <adam(a)pandorasboxen.com&gt; --- src/libvirt.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 49 insertions(+), 8 deletions(-) diff --git a/src/libvirt.c b/src/libvirt.c index 77f481e..9c00491 100644 --- a/src/libvirt.c +++ b/src/libvirt.c @@ -837,31 +837,72 @@ int virStateInitialize(bool privileged, void *opaque) { size_t i; + virStateDriverPtr virLibvirtStateDriverTab[MAX_DRIVERS]; + int virLibvirtStateDriverTabCount = 0; + virStateDriverPtr virHypervisorStateDriverTab[MAX_DRIVERS]; + int virHypervisorStateDriverTabCount = 0; if (virInitialize() < 0) return -1; for (i = 0; i < virStateDriverTabCount; i++) { - if (virStateDriverTab[i]->stateInitialize) { + switch (virStateDriverTab[i]->stateType) { + case VIR_DRV_STATE_DRV_LIBVIRT: + virLibvirtStateDriverTab[virLibvirtStateDriverTabCount++] = + virStateDriverTab[i]; + break; + case VIR_DRV_STATE_DRV_HYPERVISOR: + virHypervisorStateDriverTab[virHypervisorStateDriverTabCount++] = + virStateDriverTab[i]; + break; + } + }