khenaidoo | 59ce9dd | 2019-11-11 13:05:32 -0500 | [diff] [blame^] | 1 | // Copyright 2015 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package v2store |
| 16 | |
| 17 | import ( |
| 18 | "path" |
| 19 | "sort" |
| 20 | "time" |
| 21 | |
| 22 | "go.etcd.io/etcd/etcdserver/api/v2error" |
| 23 | |
| 24 | "github.com/jonboulle/clockwork" |
| 25 | ) |
| 26 | |
| 27 | // explanations of Compare function result |
| 28 | const ( |
| 29 | CompareMatch = iota |
| 30 | CompareIndexNotMatch |
| 31 | CompareValueNotMatch |
| 32 | CompareNotMatch |
| 33 | ) |
| 34 | |
| 35 | var Permanent time.Time |
| 36 | |
| 37 | // node is the basic element in the store system. |
| 38 | // A key-value pair will have a string value |
| 39 | // A directory will have a children map |
| 40 | type node struct { |
| 41 | Path string |
| 42 | |
| 43 | CreatedIndex uint64 |
| 44 | ModifiedIndex uint64 |
| 45 | |
| 46 | Parent *node `json:"-"` // should not encode this field! avoid circular dependency. |
| 47 | |
| 48 | ExpireTime time.Time |
| 49 | Value string // for key-value pair |
| 50 | Children map[string]*node // for directory |
| 51 | |
| 52 | // A reference to the store this node is attached to. |
| 53 | store *store |
| 54 | } |
| 55 | |
| 56 | // newKV creates a Key-Value pair |
| 57 | func newKV(store *store, nodePath string, value string, createdIndex uint64, parent *node, expireTime time.Time) *node { |
| 58 | return &node{ |
| 59 | Path: nodePath, |
| 60 | CreatedIndex: createdIndex, |
| 61 | ModifiedIndex: createdIndex, |
| 62 | Parent: parent, |
| 63 | store: store, |
| 64 | ExpireTime: expireTime, |
| 65 | Value: value, |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | // newDir creates a directory |
| 70 | func newDir(store *store, nodePath string, createdIndex uint64, parent *node, expireTime time.Time) *node { |
| 71 | return &node{ |
| 72 | Path: nodePath, |
| 73 | CreatedIndex: createdIndex, |
| 74 | ModifiedIndex: createdIndex, |
| 75 | Parent: parent, |
| 76 | ExpireTime: expireTime, |
| 77 | Children: make(map[string]*node), |
| 78 | store: store, |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | // IsHidden function checks if the node is a hidden node. A hidden node |
| 83 | // will begin with '_' |
| 84 | // A hidden node will not be shown via get command under a directory |
| 85 | // For example if we have /foo/_hidden and /foo/notHidden, get "/foo" |
| 86 | // will only return /foo/notHidden |
| 87 | func (n *node) IsHidden() bool { |
| 88 | _, name := path.Split(n.Path) |
| 89 | |
| 90 | return name[0] == '_' |
| 91 | } |
| 92 | |
| 93 | // IsPermanent function checks if the node is a permanent one. |
| 94 | func (n *node) IsPermanent() bool { |
| 95 | // we use a uninitialized time.Time to indicate the node is a |
| 96 | // permanent one. |
| 97 | // the uninitialized time.Time should equal zero. |
| 98 | return n.ExpireTime.IsZero() |
| 99 | } |
| 100 | |
| 101 | // IsDir function checks whether the node is a directory. |
| 102 | // If the node is a directory, the function will return true. |
| 103 | // Otherwise the function will return false. |
| 104 | func (n *node) IsDir() bool { |
| 105 | return n.Children != nil |
| 106 | } |
| 107 | |
| 108 | // Read function gets the value of the node. |
| 109 | // If the receiver node is not a key-value pair, a "Not A File" error will be returned. |
| 110 | func (n *node) Read() (string, *v2error.Error) { |
| 111 | if n.IsDir() { |
| 112 | return "", v2error.NewError(v2error.EcodeNotFile, "", n.store.CurrentIndex) |
| 113 | } |
| 114 | |
| 115 | return n.Value, nil |
| 116 | } |
| 117 | |
| 118 | // Write function set the value of the node to the given value. |
| 119 | // If the receiver node is a directory, a "Not A File" error will be returned. |
| 120 | func (n *node) Write(value string, index uint64) *v2error.Error { |
| 121 | if n.IsDir() { |
| 122 | return v2error.NewError(v2error.EcodeNotFile, "", n.store.CurrentIndex) |
| 123 | } |
| 124 | |
| 125 | n.Value = value |
| 126 | n.ModifiedIndex = index |
| 127 | |
| 128 | return nil |
| 129 | } |
| 130 | |
| 131 | func (n *node) expirationAndTTL(clock clockwork.Clock) (*time.Time, int64) { |
| 132 | if !n.IsPermanent() { |
| 133 | /* compute ttl as: |
| 134 | ceiling( (expireTime - timeNow) / nanosecondsPerSecond ) |
| 135 | which ranges from 1..n |
| 136 | rather than as: |
| 137 | ( (expireTime - timeNow) / nanosecondsPerSecond ) + 1 |
| 138 | which ranges 1..n+1 |
| 139 | */ |
| 140 | ttlN := n.ExpireTime.Sub(clock.Now()) |
| 141 | ttl := ttlN / time.Second |
| 142 | if (ttlN % time.Second) > 0 { |
| 143 | ttl++ |
| 144 | } |
| 145 | t := n.ExpireTime.UTC() |
| 146 | return &t, int64(ttl) |
| 147 | } |
| 148 | return nil, 0 |
| 149 | } |
| 150 | |
| 151 | // List function return a slice of nodes under the receiver node. |
| 152 | // If the receiver node is not a directory, a "Not A Directory" error will be returned. |
| 153 | func (n *node) List() ([]*node, *v2error.Error) { |
| 154 | if !n.IsDir() { |
| 155 | return nil, v2error.NewError(v2error.EcodeNotDir, "", n.store.CurrentIndex) |
| 156 | } |
| 157 | |
| 158 | nodes := make([]*node, len(n.Children)) |
| 159 | |
| 160 | i := 0 |
| 161 | for _, node := range n.Children { |
| 162 | nodes[i] = node |
| 163 | i++ |
| 164 | } |
| 165 | |
| 166 | return nodes, nil |
| 167 | } |
| 168 | |
| 169 | // GetChild function returns the child node under the directory node. |
| 170 | // On success, it returns the file node |
| 171 | func (n *node) GetChild(name string) (*node, *v2error.Error) { |
| 172 | if !n.IsDir() { |
| 173 | return nil, v2error.NewError(v2error.EcodeNotDir, n.Path, n.store.CurrentIndex) |
| 174 | } |
| 175 | |
| 176 | child, ok := n.Children[name] |
| 177 | |
| 178 | if ok { |
| 179 | return child, nil |
| 180 | } |
| 181 | |
| 182 | return nil, nil |
| 183 | } |
| 184 | |
| 185 | // Add function adds a node to the receiver node. |
| 186 | // If the receiver is not a directory, a "Not A Directory" error will be returned. |
| 187 | // If there is an existing node with the same name under the directory, a "Already Exist" |
| 188 | // error will be returned |
| 189 | func (n *node) Add(child *node) *v2error.Error { |
| 190 | if !n.IsDir() { |
| 191 | return v2error.NewError(v2error.EcodeNotDir, "", n.store.CurrentIndex) |
| 192 | } |
| 193 | |
| 194 | _, name := path.Split(child.Path) |
| 195 | |
| 196 | if _, ok := n.Children[name]; ok { |
| 197 | return v2error.NewError(v2error.EcodeNodeExist, "", n.store.CurrentIndex) |
| 198 | } |
| 199 | |
| 200 | n.Children[name] = child |
| 201 | |
| 202 | return nil |
| 203 | } |
| 204 | |
| 205 | // Remove function remove the node. |
| 206 | func (n *node) Remove(dir, recursive bool, callback func(path string)) *v2error.Error { |
| 207 | if !n.IsDir() { // key-value pair |
| 208 | _, name := path.Split(n.Path) |
| 209 | |
| 210 | // find its parent and remove the node from the map |
| 211 | if n.Parent != nil && n.Parent.Children[name] == n { |
| 212 | delete(n.Parent.Children, name) |
| 213 | } |
| 214 | |
| 215 | if callback != nil { |
| 216 | callback(n.Path) |
| 217 | } |
| 218 | |
| 219 | if !n.IsPermanent() { |
| 220 | n.store.ttlKeyHeap.remove(n) |
| 221 | } |
| 222 | |
| 223 | return nil |
| 224 | } |
| 225 | |
| 226 | if !dir { |
| 227 | // cannot delete a directory without dir set to true |
| 228 | return v2error.NewError(v2error.EcodeNotFile, n.Path, n.store.CurrentIndex) |
| 229 | } |
| 230 | |
| 231 | if len(n.Children) != 0 && !recursive { |
| 232 | // cannot delete a directory if it is not empty and the operation |
| 233 | // is not recursive |
| 234 | return v2error.NewError(v2error.EcodeDirNotEmpty, n.Path, n.store.CurrentIndex) |
| 235 | } |
| 236 | |
| 237 | for _, child := range n.Children { // delete all children |
| 238 | child.Remove(true, true, callback) |
| 239 | } |
| 240 | |
| 241 | // delete self |
| 242 | _, name := path.Split(n.Path) |
| 243 | if n.Parent != nil && n.Parent.Children[name] == n { |
| 244 | delete(n.Parent.Children, name) |
| 245 | |
| 246 | if callback != nil { |
| 247 | callback(n.Path) |
| 248 | } |
| 249 | |
| 250 | if !n.IsPermanent() { |
| 251 | n.store.ttlKeyHeap.remove(n) |
| 252 | } |
| 253 | } |
| 254 | |
| 255 | return nil |
| 256 | } |
| 257 | |
| 258 | func (n *node) Repr(recursive, sorted bool, clock clockwork.Clock) *NodeExtern { |
| 259 | if n.IsDir() { |
| 260 | node := &NodeExtern{ |
| 261 | Key: n.Path, |
| 262 | Dir: true, |
| 263 | ModifiedIndex: n.ModifiedIndex, |
| 264 | CreatedIndex: n.CreatedIndex, |
| 265 | } |
| 266 | node.Expiration, node.TTL = n.expirationAndTTL(clock) |
| 267 | |
| 268 | if !recursive { |
| 269 | return node |
| 270 | } |
| 271 | |
| 272 | children, _ := n.List() |
| 273 | node.Nodes = make(NodeExterns, len(children)) |
| 274 | |
| 275 | // we do not use the index in the children slice directly |
| 276 | // we need to skip the hidden one |
| 277 | i := 0 |
| 278 | |
| 279 | for _, child := range children { |
| 280 | |
| 281 | if child.IsHidden() { // get will not list hidden node |
| 282 | continue |
| 283 | } |
| 284 | |
| 285 | node.Nodes[i] = child.Repr(recursive, sorted, clock) |
| 286 | |
| 287 | i++ |
| 288 | } |
| 289 | |
| 290 | // eliminate hidden nodes |
| 291 | node.Nodes = node.Nodes[:i] |
| 292 | if sorted { |
| 293 | sort.Sort(node.Nodes) |
| 294 | } |
| 295 | |
| 296 | return node |
| 297 | } |
| 298 | |
| 299 | // since n.Value could be changed later, so we need to copy the value out |
| 300 | value := n.Value |
| 301 | node := &NodeExtern{ |
| 302 | Key: n.Path, |
| 303 | Value: &value, |
| 304 | ModifiedIndex: n.ModifiedIndex, |
| 305 | CreatedIndex: n.CreatedIndex, |
| 306 | } |
| 307 | node.Expiration, node.TTL = n.expirationAndTTL(clock) |
| 308 | return node |
| 309 | } |
| 310 | |
| 311 | func (n *node) UpdateTTL(expireTime time.Time) { |
| 312 | if !n.IsPermanent() { |
| 313 | if expireTime.IsZero() { |
| 314 | // from ttl to permanent |
| 315 | n.ExpireTime = expireTime |
| 316 | // remove from ttl heap |
| 317 | n.store.ttlKeyHeap.remove(n) |
| 318 | return |
| 319 | } |
| 320 | |
| 321 | // update ttl |
| 322 | n.ExpireTime = expireTime |
| 323 | // update ttl heap |
| 324 | n.store.ttlKeyHeap.update(n) |
| 325 | return |
| 326 | } |
| 327 | |
| 328 | if expireTime.IsZero() { |
| 329 | return |
| 330 | } |
| 331 | |
| 332 | // from permanent to ttl |
| 333 | n.ExpireTime = expireTime |
| 334 | // push into ttl heap |
| 335 | n.store.ttlKeyHeap.push(n) |
| 336 | } |
| 337 | |
| 338 | // Compare function compares node index and value with provided ones. |
| 339 | // second result value explains result and equals to one of Compare.. constants |
| 340 | func (n *node) Compare(prevValue string, prevIndex uint64) (ok bool, which int) { |
| 341 | indexMatch := prevIndex == 0 || n.ModifiedIndex == prevIndex |
| 342 | valueMatch := prevValue == "" || n.Value == prevValue |
| 343 | ok = valueMatch && indexMatch |
| 344 | switch { |
| 345 | case valueMatch && indexMatch: |
| 346 | which = CompareMatch |
| 347 | case indexMatch && !valueMatch: |
| 348 | which = CompareValueNotMatch |
| 349 | case valueMatch && !indexMatch: |
| 350 | which = CompareIndexNotMatch |
| 351 | default: |
| 352 | which = CompareNotMatch |
| 353 | } |
| 354 | return ok, which |
| 355 | } |
| 356 | |
| 357 | // Clone function clone the node recursively and return the new node. |
| 358 | // If the node is a directory, it will clone all the content under this directory. |
| 359 | // If the node is a key-value pair, it will clone the pair. |
| 360 | func (n *node) Clone() *node { |
| 361 | if !n.IsDir() { |
| 362 | newkv := newKV(n.store, n.Path, n.Value, n.CreatedIndex, n.Parent, n.ExpireTime) |
| 363 | newkv.ModifiedIndex = n.ModifiedIndex |
| 364 | return newkv |
| 365 | } |
| 366 | |
| 367 | clone := newDir(n.store, n.Path, n.CreatedIndex, n.Parent, n.ExpireTime) |
| 368 | clone.ModifiedIndex = n.ModifiedIndex |
| 369 | |
| 370 | for key, child := range n.Children { |
| 371 | clone.Children[key] = child.Clone() |
| 372 | } |
| 373 | |
| 374 | return clone |
| 375 | } |
| 376 | |
| 377 | // recoverAndclean function help to do recovery. |
| 378 | // Two things need to be done: 1. recovery structure; 2. delete expired nodes |
| 379 | // |
| 380 | // If the node is a directory, it will help recover children's parent pointer and recursively |
| 381 | // call this function on its children. |
| 382 | // We check the expire last since we need to recover the whole structure first and add all the |
| 383 | // notifications into the event history. |
| 384 | func (n *node) recoverAndclean() { |
| 385 | if n.IsDir() { |
| 386 | for _, child := range n.Children { |
| 387 | child.Parent = n |
| 388 | child.store = n.store |
| 389 | child.recoverAndclean() |
| 390 | } |
| 391 | } |
| 392 | |
| 393 | if !n.ExpireTime.IsZero() { |
| 394 | n.store.ttlKeyHeap.push(n) |
| 395 | } |
| 396 | } |