Re: [libvirt] RFC [2/3]: The lock manager plugin driver API

On 09/10/2010 10:00 AM, Daniel P. Berrange wrote: > >typedef struct _virLockManagerDriver virLockManagerDriver; >typedef virLockManagerDriver *virLockManagerDriverPtr; > >/* Which callbacks are supported */ >typedef enum { > VIR_LOCK_MANAGER_DRIVER_RESOURCES = (1<< 0), > VIR_LOCK_MANAGER_DRIVER_MIGRATE = (1<< 0), Same value? > VIR_LOCK_MANAGER_DRIVER_HOTPLUG = (1<< 1), >}; > >struct _virLockManagerDriver { > /** > * @version: the newest implemented plugin ABI version > * @flags: the implemented plugin optional extras > */ > unsigned int version; > unsigned int flags; > > /** > * load_drv: > * @version: the libvirt requested plugin ABI version > * @flags: the libvirt requested plugin optional extras > * > * Allow the plugin to validate the libvirt requested > * plugin version / flags. This allows it to reject > * use of versions which are too old. A plugin may > * be loaded multiple times, for different libvirt > * drivers > * > * Returns -1 if the requested version/flags were inadequate > */ > int (*load_drv)(unsigned int version, > unsigned int flags); > > /** > * unload_drv: > * > * Called to release any resources prior to the plugin > * being unloaded from memory. Returns -1 to prevent > * plugin unloading. > */ > int (*load_drv)(void); s/load_drv/unload_drv/ or this won't compile. Are these two callbacks mandatory, or can they be NULL in the case that the driver only supports exactly what it recorded in version/flags? >/** > * virLockManagerPluginLoad: > * @name: the name of the plugin > * > * Attempt to load the plugin $(libdir)/libvirt/lock-manager/(a)name.so > * The plugin driver entry point will be resolved& invoked to obtain > * the lock manager driver Returns NULL on failure, but is there any way to distinguish between levels of failure (file not found vs. plugin_init failed vs. load_drv callback failed), since that might be useful in diagnosing the problem?