|
| 1 | +package model |
| 2 | + |
| 3 | +import ( |
| 4 | + "cmp" |
| 5 | + "errors" |
| 6 | + "fmt" |
| 7 | + "slices" |
| 8 | + "sort" |
| 9 | + "strings" |
| 10 | + |
| 11 | + "golang.org/x/exp/maps" |
| 12 | + "k8s.io/apimachinery/pkg/util/sets" |
| 13 | +) |
| 14 | + |
| 15 | +type graph struct { |
| 16 | + nodes map[string]*node |
| 17 | +} |
| 18 | + |
| 19 | +func newNode(b *Bundle) *node { |
| 20 | + return &node{ |
| 21 | + bundle: b, |
| 22 | + replacedBy: make(map[string]*node), |
| 23 | + skippedBy: make(map[string]*node), |
| 24 | + skips: make(map[string]*node), |
| 25 | + } |
| 26 | +} |
| 27 | + |
| 28 | +func newGraph(c *Channel) *graph { |
| 29 | + nodes := map[string]*node{} |
| 30 | + |
| 31 | + // Add all nodes (without edges) |
| 32 | + for _, b := range c.Bundles { |
| 33 | + nodes[b.Name] = newNode(b) |
| 34 | + } |
| 35 | + |
| 36 | + // Populate edges between nodes |
| 37 | + for _, b := range c.Bundles { |
| 38 | + n := nodes[b.Name] |
| 39 | + |
| 40 | + if b.Replaces != "" { |
| 41 | + replaces, ok := nodes[b.Replaces] |
| 42 | + if !ok { |
| 43 | + // the "replaces" edge points to a node outside the channel |
| 44 | + replaces = newNode(&Bundle{Name: b.Replaces}) |
| 45 | + replaces.externalToChannel = true |
| 46 | + nodes[b.Replaces] = replaces |
| 47 | + } |
| 48 | + n.replaces = replaces |
| 49 | + n.replaces.replacedBy[n.bundle.Name] = n |
| 50 | + } |
| 51 | + |
| 52 | + for _, skipName := range b.Skips { |
| 53 | + skip, ok := nodes[skipName] |
| 54 | + if !ok { |
| 55 | + // the "skips" edge points to a node outside the channel |
| 56 | + skip = newNode(&Bundle{Name: skipName}) |
| 57 | + skip.externalToChannel = true |
| 58 | + } |
| 59 | + skip.skippedBy[b.Name] = n |
| 60 | + n.skips[skipName] = skip |
| 61 | + } |
| 62 | + } |
| 63 | + |
| 64 | + return &graph{ |
| 65 | + nodes: nodes, |
| 66 | + } |
| 67 | +} |
| 68 | + |
| 69 | +type node struct { |
| 70 | + bundle *Bundle |
| 71 | + replacedBy map[string]*node |
| 72 | + replaces *node |
| 73 | + skippedBy map[string]*node |
| 74 | + skips map[string]*node |
| 75 | + externalToChannel bool |
| 76 | +} |
| 77 | + |
| 78 | +func (n *node) pathsTo(other *node) [][]*node { |
| 79 | + var pathsToInternal func(existingPath []*node, froms map[string]*node, to *node) [][]*node |
| 80 | + pathsToInternal = func(existingPath []*node, froms map[string]*node, to *node) [][]*node { |
| 81 | + if len(froms) == 0 { |
| 82 | + // we never found a path to "to" |
| 83 | + return nil |
| 84 | + } |
| 85 | + var allPaths [][]*node |
| 86 | + for _, f := range froms { |
| 87 | + path := append(slices.Clone(existingPath), f) |
| 88 | + if f == to { |
| 89 | + // we found "to"! |
| 90 | + allPaths = append(allPaths, path) |
| 91 | + } else { |
| 92 | + // From an intermediate node, look only in replacedBy, so that we don't stray off the replaces chain. |
| 93 | + allPaths = append(allPaths, pathsToInternal(path, f.replacedBy, to)...) |
| 94 | + } |
| 95 | + } |
| 96 | + return allPaths |
| 97 | + } |
| 98 | + |
| 99 | + // From the starting node, look in all ancestors (replacedBy and skippedBy). |
| 100 | + ancestors := map[string]*node{} |
| 101 | + maps.Copy(ancestors, n.replacedBy) |
| 102 | + maps.Copy(ancestors, n.skippedBy) |
| 103 | + return pathsToInternal(nil, ancestors, other) |
| 104 | +} |
| 105 | + |
| 106 | +func (g *graph) validate() error { |
| 107 | + result := newValidationError("invalid upgrade graph") |
| 108 | + if err := g.validateNoCycles(); err != nil { |
| 109 | + result.subErrors = append(result.subErrors, err) |
| 110 | + } |
| 111 | + if err := g.validateNoStranded(); err != nil { |
| 112 | + result.subErrors = append(result.subErrors, err) |
| 113 | + } |
| 114 | + return result.orNil() |
| 115 | +} |
| 116 | + |
| 117 | +func (g *graph) cycles() [][]*node { |
| 118 | + allCycles := [][]*node{} |
| 119 | + for _, n := range g.nodes { |
| 120 | + allCycles = append(allCycles, n.pathsTo(n)...) |
| 121 | + } |
| 122 | + dedupSameRotations(&allCycles) |
| 123 | + for i, cycle := range allCycles { |
| 124 | + allCycles[i] = append(cycle, cycle[0]) |
| 125 | + } |
| 126 | + return allCycles |
| 127 | +} |
| 128 | + |
| 129 | +func (g *graph) validateNoCycles() error { |
| 130 | + cycles := g.cycles() |
| 131 | + if len(cycles) == 0 { |
| 132 | + return nil |
| 133 | + } |
| 134 | + result := newValidationError("cycles found in graph") |
| 135 | + for _, cycle := range cycles { |
| 136 | + result.subErrors = append(result.subErrors, errors.New(nodeCycleString(cycle))) |
| 137 | + } |
| 138 | + return result.orNil() |
| 139 | +} |
| 140 | + |
| 141 | +// dedupSameRotations removes rotations of the same cycle. |
| 142 | +// dedupSameRotations sorts the cycles so that shorter paths |
| 143 | +// and paths with lower versions appear earlier in the list. |
| 144 | +func dedupSameRotations(paths *[][]*node) { |
| 145 | + slices.SortFunc(*paths, func(a, b []*node) int { |
| 146 | + if len(a) == 0 && len(b) == 0 { |
| 147 | + return 0 |
| 148 | + } |
| 149 | + if v := cmp.Compare(len(a), len(b)); v != 0 { |
| 150 | + return v |
| 151 | + } |
| 152 | + return a[0].bundle.Version.Compare(b[0].bundle.Version) |
| 153 | + }) |
| 154 | + seen := map[string]struct{}{} |
| 155 | + tmp := (*paths)[:0] |
| 156 | + for _, path := range *paths { |
| 157 | + rotate(&path) |
| 158 | + k := nodeCycleString(path) |
| 159 | + if _, ok := seen[k]; ok { |
| 160 | + continue |
| 161 | + } |
| 162 | + seen[k] = struct{}{} |
| 163 | + tmp = append(tmp, path) |
| 164 | + } |
| 165 | + *paths = tmp |
| 166 | +} |
| 167 | + |
| 168 | +func rotate(in *[]*node) { |
| 169 | + if len(*in) == 0 { |
| 170 | + return |
| 171 | + } |
| 172 | + maxIndex := 0 |
| 173 | + for i, n := range (*in)[1:] { |
| 174 | + if n.bundle.Version.GT((*in)[maxIndex].bundle.Version) { |
| 175 | + maxIndex = i + 1 |
| 176 | + } |
| 177 | + } |
| 178 | + slices.Reverse((*in)[:maxIndex]) |
| 179 | + slices.Reverse((*in)[maxIndex:]) |
| 180 | + slices.Reverse((*in)) |
| 181 | +} |
| 182 | + |
| 183 | +func nodeCycleString(nodes []*node) string { |
| 184 | + return strings.Join(mapSlice(nodes, nodeName), " -> ") |
| 185 | +} |
| 186 | + |
| 187 | +func (g *graph) strandedNodes() ([]*node, error) { |
| 188 | + head, err := g.head() |
| 189 | + if err != nil { |
| 190 | + return nil, err |
| 191 | + } |
| 192 | + all := sets.New[*node](maps.Values(g.nodes)...) |
| 193 | + chain := sets.New[*node]() |
| 194 | + skipped := sets.New[*node]() |
| 195 | + |
| 196 | + cur := head |
| 197 | + for cur != nil && !skipped.Has(cur) && !chain.Has(cur) { |
| 198 | + chain.Insert(cur) |
| 199 | + skipped.Insert(maps.Values(cur.skips)...) |
| 200 | + cur = cur.replaces |
| 201 | + } |
| 202 | + |
| 203 | + stranded := all.Difference(chain).Difference(skipped).UnsortedList() |
| 204 | + slices.SortFunc(stranded, func(a, b *node) int { |
| 205 | + return a.bundle.Compare(b.bundle) |
| 206 | + }) |
| 207 | + return stranded, nil |
| 208 | +} |
| 209 | + |
| 210 | +func (g *graph) validateNoStranded() error { |
| 211 | + stranded, err := g.strandedNodes() |
| 212 | + if err != nil { |
| 213 | + return err |
| 214 | + } |
| 215 | + if len(stranded) == 0 { |
| 216 | + return nil |
| 217 | + } |
| 218 | + |
| 219 | + return fmt.Errorf("channel contains one or more stranded bundles: %s", strings.Join(mapSlice(stranded, nodeName), ", ")) |
| 220 | +} |
| 221 | + |
| 222 | +func (g *graph) head() (*node, error) { |
| 223 | + heads := []*node{} |
| 224 | + for _, n := range g.nodes { |
| 225 | + if len(n.replacedBy) == 0 && len(n.skippedBy) == 0 { |
| 226 | + heads = append(heads, n) |
| 227 | + } |
| 228 | + } |
| 229 | + if len(heads) == 0 { |
| 230 | + return nil, fmt.Errorf("no channel head found in graph") |
| 231 | + } |
| 232 | + if len(heads) > 1 { |
| 233 | + headNames := mapSlice(heads, nodeName) |
| 234 | + sort.Strings(headNames) |
| 235 | + return nil, fmt.Errorf("multiple channel heads found in graph: %s", strings.Join(headNames, ", ")) |
| 236 | + } |
| 237 | + return heads[0], nil |
| 238 | +} |
| 239 | + |
| 240 | +func nodeName(n *node) string { |
| 241 | + return n.bundle.Name |
| 242 | +} |
| 243 | + |
| 244 | +func mapSlice[I, O any](s []I, fn func(I) O) []O { |
| 245 | + result := make([]O, 0, len(s)) |
| 246 | + for _, i := range s { |
| 247 | + result = append(result, fn(i)) |
| 248 | + } |
| 249 | + return result |
| 250 | +} |
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