buildDepgraph

def buildDepgraph( self ):
        all_depends = self.status.all_depends //所有依赖的pn
        pn_provides = self.status.pn_provides // 所有pn provider
        localdata = data.createCopy(self.configuration.data)
        bb.data.update_data(localdata)
        def calc_bbfile_priority(filename): // 计算bbfile的优先级
            for (regex, pri) in self.status.bbfile_config_priorities:
                if regex.match(filename):
                    return pri
            return 0
        # Handle PREFERRED_PROVIDERS
        for p in (bb.data.getVar('PREFERRED_PROVIDERS', localdata, 1) or "").split():   //得到PREFERRED_PROVIDES变量
            (providee, provider) = p.split(':')被提供者：提供者
            if providee in self.status.preferred and self.status.preferred[providee] != provider:
                bb.msg.error(bb.msg.domain.Provider, "conflicting preferences for %s: both %s and %s specified" % (providee, provider, self.status.preferred[providee]))
            self.status.preferred[providee] = provider //填充stuff
        # Calculate priorities for each file
        for p in self.status.pkg_fn.keys(): //计算每个bbfile的 优先级
            self.status.bbfile_priority[p] = calc_bbfile_priority(p)