func GenerateRebalancePlan(method string, cluster *topo.Cluster, targetIds []string, ratio int) ([]*MigratePlan, error) {
rss := cluster.ReplicaSets()
regions := meta.AllRegions()
ss := []*topo.Node{} // 有slots的Master
tm := map[string]*topo.Node{} // 空slots的Master
for _, rs := range rss {
master := rs.Master
// 忽略主挂掉和region覆盖不全的rs
if master.Fail || !rs.IsCoverAllRegions(regions) || master.Free {
continue
}
if master.Empty() {
tm[master.Id] = master
} else {
ss = append(ss, master)
}
}
if method == "mergetail" {
merger := MergerTable[method]
if merger == nil {
return nil, fmt.Errorf("Rebalancing method %s not exist.", method)
}
plans := merger(ss, 0)
return plans, nil
} else if method == "mergeall" {
merger := MergerTable[method]
if merger == nil {
return nil, fmt.Errorf("Rebalancing method %s not exist.", method)
}
plans := merger(ss, ratio)
return plans, nil
} else {
var ts []*topo.Node
// 如果没传TargetId，则选择所有可以作为迁移目标的rs
if len(targetIds) == 0 {
for _, node := range tm {
ts = append(ts, node)
}
} else {
for _, id := range targetIds {
if tm[id] == nil {
return nil, fmt.Errorf("Master %s not found.", id)
}
ts = append(ts, tm[id])
}
}
if len(ts) == 0 {
return nil, fmt.Errorf("No available empty target replicasets.")
}
rebalancer := RebalancerTable[method]
if rebalancer == nil {
return nil, fmt.Errorf("Rebalancing method %s not exist.", method)
}
plans := rebalancer(ss, ts)
return plans, nil
}
return nil, nil
}
