|
| 1 | +package spreadconstraint |
| 2 | + |
| 3 | +import ( |
| 4 | + "fmt" |
| 5 | + "sort" |
| 6 | + |
| 7 | + clusterv1alpha1 "github.com/karmada-io/karmada/pkg/apis/cluster/v1alpha1" |
| 8 | + policyv1alpha1 "github.com/karmada-io/karmada/pkg/apis/policy/v1alpha1" |
| 9 | +) |
| 10 | + |
| 11 | +func selectBestClustersByRegion(spreadConstraintMap map[policyv1alpha1.SpreadFieldValue]policyv1alpha1.SpreadConstraint, |
| 12 | + groupClustersInfo *GroupClustersInfo) ([]*clusterv1alpha1.Cluster, error) { |
| 13 | + var clusters []*clusterv1alpha1.Cluster |
| 14 | + var candidateClusters []ClusterDetailInfo |
| 15 | + |
| 16 | + if len(groupClustersInfo.Regions) < spreadConstraintMap[policyv1alpha1.SpreadByFieldRegion].MinGroups { |
| 17 | + return nil, fmt.Errorf("the number of feasible region is less than spreadConstraint.MinGroups") |
| 18 | + } |
| 19 | + |
| 20 | + // firstly, select regions which have enough clusters to satisfy the cluster and region propagation constraints |
| 21 | + regions := selectRegions(groupClustersInfo.Regions, spreadConstraintMap[policyv1alpha1.SpreadByFieldRegion], spreadConstraintMap[policyv1alpha1.SpreadByFieldCluster]) |
| 22 | + if len(regions) == 0 { |
| 23 | + return nil, fmt.Errorf("the number of clusters is less than the cluster spreadConstraint.MinGroups") |
| 24 | + } |
| 25 | + |
| 26 | + // secondly, select the clusters with the highest score in per region, |
| 27 | + for i := range regions { |
| 28 | + clusters = append(clusters, regions[i].Clusters[0].Cluster) |
| 29 | + candidateClusters = append(candidateClusters, regions[i].Clusters[1:]...) |
| 30 | + } |
| 31 | + |
| 32 | + needCnt := len(candidateClusters) + len(clusters) |
| 33 | + if needCnt > spreadConstraintMap[policyv1alpha1.SpreadByFieldCluster].MaxGroups { |
| 34 | + needCnt = spreadConstraintMap[policyv1alpha1.SpreadByFieldCluster].MaxGroups |
| 35 | + } |
| 36 | + |
| 37 | + // thirdly, select the remaining Clusters based cluster.Score |
| 38 | + sortClusters(candidateClusters) |
| 39 | + restCnt := needCnt - len(clusters) |
| 40 | + for i := 0; i < restCnt; i++ { |
| 41 | + clusters = append(clusters, candidateClusters[i].Cluster) |
| 42 | + } |
| 43 | + |
| 44 | + return clusters, nil |
| 45 | +} |
| 46 | + |
| 47 | +func selectRegions(RegionInfos map[string]RegionInfo, regionConstraint, clusterConstraint policyv1alpha1.SpreadConstraint) []RegionInfo { |
| 48 | + var regions []RegionInfo |
| 49 | + for i := range RegionInfos { |
| 50 | + regions = append(regions, RegionInfos[i]) |
| 51 | + } |
| 52 | + |
| 53 | + sort.Slice(regions, func(i, j int) bool { |
| 54 | + if regions[i].Score != regions[j].Score { |
| 55 | + return regions[i].Score > regions[j].Score |
| 56 | + } |
| 57 | + |
| 58 | + return regions[i].Name < regions[j].Name |
| 59 | + }) |
| 60 | + |
| 61 | + retRegions := regions[:regionConstraint.MinGroups] |
| 62 | + candidateRegions := regions[regionConstraint.MinGroups:] |
| 63 | + var replaceID = len(retRegions) - 1 |
| 64 | + for !checkClusterTotalForRegion(retRegions, clusterConstraint) && replaceID >= 0 { |
| 65 | + regionID := getRegionWithMaxClusters(candidateRegions, len(retRegions[replaceID].Clusters)) |
| 66 | + if regionID == InvalidRegionID { |
| 67 | + replaceID-- |
| 68 | + continue |
| 69 | + } |
| 70 | + |
| 71 | + retRegions[replaceID], candidateRegions[regionID] = candidateRegions[regionID], retRegions[replaceID] |
| 72 | + replaceID-- |
| 73 | + } |
| 74 | + |
| 75 | + if !checkClusterTotalForRegion(retRegions, clusterConstraint) { |
| 76 | + return nil |
| 77 | + } |
| 78 | + |
| 79 | + return retRegions |
| 80 | +} |
| 81 | + |
| 82 | +func checkClusterTotalForRegion(regions []RegionInfo, clusterConstraint policyv1alpha1.SpreadConstraint) bool { |
| 83 | + var sum int |
| 84 | + for i := range regions { |
| 85 | + sum += len(regions[i].Clusters) |
| 86 | + } |
| 87 | + |
| 88 | + return sum >= clusterConstraint.MinGroups |
| 89 | +} |
| 90 | + |
| 91 | +func getRegionWithMaxClusters(candidateRegions []RegionInfo, originClusters int) int { |
| 92 | + var maxClusters = originClusters |
| 93 | + var regionID = -1 |
| 94 | + for i := range candidateRegions { |
| 95 | + if maxClusters < len(candidateRegions[i].Clusters) { |
| 96 | + regionID = i |
| 97 | + maxClusters = len(candidateRegions[i].Clusters) |
| 98 | + } |
| 99 | + } |
| 100 | + |
| 101 | + return regionID |
| 102 | +} |
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