Matthias Andreas Benkard | 832a54e | 2019-01-29 09:27:38 +0100 | [diff] [blame] | 1 | /* |
| 2 | Copyright 2014 The Kubernetes Authors. |
| 3 | |
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | you may not use this file except in compliance with the License. |
| 6 | You may obtain a copy of the License at |
| 7 | |
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | |
| 10 | Unless required by applicable law or agreed to in writing, software |
| 11 | distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | See the License for the specific language governing permissions and |
| 14 | limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package cache |
| 18 | |
| 19 | import ( |
| 20 | "fmt" |
| 21 | "sync" |
| 22 | |
| 23 | "k8s.io/apimachinery/pkg/util/sets" |
| 24 | ) |
| 25 | |
| 26 | // ThreadSafeStore is an interface that allows concurrent access to a storage backend. |
| 27 | // TL;DR caveats: you must not modify anything returned by Get or List as it will break |
| 28 | // the indexing feature in addition to not being thread safe. |
| 29 | // |
| 30 | // The guarantees of thread safety provided by List/Get are only valid if the caller |
| 31 | // treats returned items as read-only. For example, a pointer inserted in the store |
| 32 | // through `Add` will be returned as is by `Get`. Multiple clients might invoke `Get` |
| 33 | // on the same key and modify the pointer in a non-thread-safe way. Also note that |
| 34 | // modifying objects stored by the indexers (if any) will *not* automatically lead |
| 35 | // to a re-index. So it's not a good idea to directly modify the objects returned by |
| 36 | // Get/List, in general. |
| 37 | type ThreadSafeStore interface { |
| 38 | Add(key string, obj interface{}) |
| 39 | Update(key string, obj interface{}) |
| 40 | Delete(key string) |
| 41 | Get(key string) (item interface{}, exists bool) |
| 42 | List() []interface{} |
| 43 | ListKeys() []string |
| 44 | Replace(map[string]interface{}, string) |
| 45 | Index(indexName string, obj interface{}) ([]interface{}, error) |
| 46 | IndexKeys(indexName, indexKey string) ([]string, error) |
| 47 | ListIndexFuncValues(name string) []string |
| 48 | ByIndex(indexName, indexKey string) ([]interface{}, error) |
| 49 | GetIndexers() Indexers |
| 50 | |
| 51 | // AddIndexers adds more indexers to this store. If you call this after you already have data |
| 52 | // in the store, the results are undefined. |
| 53 | AddIndexers(newIndexers Indexers) error |
| 54 | Resync() error |
| 55 | } |
| 56 | |
| 57 | // threadSafeMap implements ThreadSafeStore |
| 58 | type threadSafeMap struct { |
| 59 | lock sync.RWMutex |
| 60 | items map[string]interface{} |
| 61 | |
| 62 | // indexers maps a name to an IndexFunc |
| 63 | indexers Indexers |
| 64 | // indices maps a name to an Index |
| 65 | indices Indices |
| 66 | } |
| 67 | |
| 68 | func (c *threadSafeMap) Add(key string, obj interface{}) { |
| 69 | c.lock.Lock() |
| 70 | defer c.lock.Unlock() |
| 71 | oldObject := c.items[key] |
| 72 | c.items[key] = obj |
| 73 | c.updateIndices(oldObject, obj, key) |
| 74 | } |
| 75 | |
| 76 | func (c *threadSafeMap) Update(key string, obj interface{}) { |
| 77 | c.lock.Lock() |
| 78 | defer c.lock.Unlock() |
| 79 | oldObject := c.items[key] |
| 80 | c.items[key] = obj |
| 81 | c.updateIndices(oldObject, obj, key) |
| 82 | } |
| 83 | |
| 84 | func (c *threadSafeMap) Delete(key string) { |
| 85 | c.lock.Lock() |
| 86 | defer c.lock.Unlock() |
| 87 | if obj, exists := c.items[key]; exists { |
| 88 | c.deleteFromIndices(obj, key) |
| 89 | delete(c.items, key) |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | func (c *threadSafeMap) Get(key string) (item interface{}, exists bool) { |
| 94 | c.lock.RLock() |
| 95 | defer c.lock.RUnlock() |
| 96 | item, exists = c.items[key] |
| 97 | return item, exists |
| 98 | } |
| 99 | |
| 100 | func (c *threadSafeMap) List() []interface{} { |
| 101 | c.lock.RLock() |
| 102 | defer c.lock.RUnlock() |
| 103 | list := make([]interface{}, 0, len(c.items)) |
| 104 | for _, item := range c.items { |
| 105 | list = append(list, item) |
| 106 | } |
| 107 | return list |
| 108 | } |
| 109 | |
| 110 | // ListKeys returns a list of all the keys of the objects currently |
| 111 | // in the threadSafeMap. |
| 112 | func (c *threadSafeMap) ListKeys() []string { |
| 113 | c.lock.RLock() |
| 114 | defer c.lock.RUnlock() |
| 115 | list := make([]string, 0, len(c.items)) |
| 116 | for key := range c.items { |
| 117 | list = append(list, key) |
| 118 | } |
| 119 | return list |
| 120 | } |
| 121 | |
| 122 | func (c *threadSafeMap) Replace(items map[string]interface{}, resourceVersion string) { |
| 123 | c.lock.Lock() |
| 124 | defer c.lock.Unlock() |
| 125 | c.items = items |
| 126 | |
| 127 | // rebuild any index |
| 128 | c.indices = Indices{} |
| 129 | for key, item := range c.items { |
| 130 | c.updateIndices(nil, item, key) |
| 131 | } |
| 132 | } |
| 133 | |
| 134 | // Index returns a list of items that match on the index function |
| 135 | // Index is thread-safe so long as you treat all items as immutable |
| 136 | func (c *threadSafeMap) Index(indexName string, obj interface{}) ([]interface{}, error) { |
| 137 | c.lock.RLock() |
| 138 | defer c.lock.RUnlock() |
| 139 | |
| 140 | indexFunc := c.indexers[indexName] |
| 141 | if indexFunc == nil { |
| 142 | return nil, fmt.Errorf("Index with name %s does not exist", indexName) |
| 143 | } |
| 144 | |
| 145 | indexKeys, err := indexFunc(obj) |
| 146 | if err != nil { |
| 147 | return nil, err |
| 148 | } |
| 149 | index := c.indices[indexName] |
| 150 | |
| 151 | // need to de-dupe the return list. Since multiple keys are allowed, this can happen. |
| 152 | returnKeySet := sets.String{} |
| 153 | for _, indexKey := range indexKeys { |
| 154 | set := index[indexKey] |
| 155 | for _, key := range set.UnsortedList() { |
| 156 | returnKeySet.Insert(key) |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | list := make([]interface{}, 0, returnKeySet.Len()) |
| 161 | for absoluteKey := range returnKeySet { |
| 162 | list = append(list, c.items[absoluteKey]) |
| 163 | } |
| 164 | return list, nil |
| 165 | } |
| 166 | |
| 167 | // ByIndex returns a list of items that match an exact value on the index function |
| 168 | func (c *threadSafeMap) ByIndex(indexName, indexKey string) ([]interface{}, error) { |
| 169 | c.lock.RLock() |
| 170 | defer c.lock.RUnlock() |
| 171 | |
| 172 | indexFunc := c.indexers[indexName] |
| 173 | if indexFunc == nil { |
| 174 | return nil, fmt.Errorf("Index with name %s does not exist", indexName) |
| 175 | } |
| 176 | |
| 177 | index := c.indices[indexName] |
| 178 | |
| 179 | set := index[indexKey] |
| 180 | list := make([]interface{}, 0, set.Len()) |
| 181 | for _, key := range set.List() { |
| 182 | list = append(list, c.items[key]) |
| 183 | } |
| 184 | |
| 185 | return list, nil |
| 186 | } |
| 187 | |
| 188 | // IndexKeys returns a list of keys that match on the index function. |
| 189 | // IndexKeys is thread-safe so long as you treat all items as immutable. |
| 190 | func (c *threadSafeMap) IndexKeys(indexName, indexKey string) ([]string, error) { |
| 191 | c.lock.RLock() |
| 192 | defer c.lock.RUnlock() |
| 193 | |
| 194 | indexFunc := c.indexers[indexName] |
| 195 | if indexFunc == nil { |
| 196 | return nil, fmt.Errorf("Index with name %s does not exist", indexName) |
| 197 | } |
| 198 | |
| 199 | index := c.indices[indexName] |
| 200 | |
| 201 | set := index[indexKey] |
| 202 | return set.List(), nil |
| 203 | } |
| 204 | |
| 205 | func (c *threadSafeMap) ListIndexFuncValues(indexName string) []string { |
| 206 | c.lock.RLock() |
| 207 | defer c.lock.RUnlock() |
| 208 | |
| 209 | index := c.indices[indexName] |
| 210 | names := make([]string, 0, len(index)) |
| 211 | for key := range index { |
| 212 | names = append(names, key) |
| 213 | } |
| 214 | return names |
| 215 | } |
| 216 | |
| 217 | func (c *threadSafeMap) GetIndexers() Indexers { |
| 218 | return c.indexers |
| 219 | } |
| 220 | |
| 221 | func (c *threadSafeMap) AddIndexers(newIndexers Indexers) error { |
| 222 | c.lock.Lock() |
| 223 | defer c.lock.Unlock() |
| 224 | |
| 225 | if len(c.items) > 0 { |
| 226 | return fmt.Errorf("cannot add indexers to running index") |
| 227 | } |
| 228 | |
| 229 | oldKeys := sets.StringKeySet(c.indexers) |
| 230 | newKeys := sets.StringKeySet(newIndexers) |
| 231 | |
| 232 | if oldKeys.HasAny(newKeys.List()...) { |
| 233 | return fmt.Errorf("indexer conflict: %v", oldKeys.Intersection(newKeys)) |
| 234 | } |
| 235 | |
| 236 | for k, v := range newIndexers { |
| 237 | c.indexers[k] = v |
| 238 | } |
| 239 | return nil |
| 240 | } |
| 241 | |
| 242 | // updateIndices modifies the objects location in the managed indexes, if this is an update, you must provide an oldObj |
| 243 | // updateIndices must be called from a function that already has a lock on the cache |
| 244 | func (c *threadSafeMap) updateIndices(oldObj interface{}, newObj interface{}, key string) { |
| 245 | // if we got an old object, we need to remove it before we add it again |
| 246 | if oldObj != nil { |
| 247 | c.deleteFromIndices(oldObj, key) |
| 248 | } |
| 249 | for name, indexFunc := range c.indexers { |
| 250 | indexValues, err := indexFunc(newObj) |
| 251 | if err != nil { |
| 252 | panic(fmt.Errorf("unable to calculate an index entry for key %q on index %q: %v", key, name, err)) |
| 253 | } |
| 254 | index := c.indices[name] |
| 255 | if index == nil { |
| 256 | index = Index{} |
| 257 | c.indices[name] = index |
| 258 | } |
| 259 | |
| 260 | for _, indexValue := range indexValues { |
| 261 | set := index[indexValue] |
| 262 | if set == nil { |
| 263 | set = sets.String{} |
| 264 | index[indexValue] = set |
| 265 | } |
| 266 | set.Insert(key) |
| 267 | } |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | // deleteFromIndices removes the object from each of the managed indexes |
| 272 | // it is intended to be called from a function that already has a lock on the cache |
| 273 | func (c *threadSafeMap) deleteFromIndices(obj interface{}, key string) { |
| 274 | for name, indexFunc := range c.indexers { |
| 275 | indexValues, err := indexFunc(obj) |
| 276 | if err != nil { |
| 277 | panic(fmt.Errorf("unable to calculate an index entry for key %q on index %q: %v", key, name, err)) |
| 278 | } |
| 279 | |
| 280 | index := c.indices[name] |
| 281 | if index == nil { |
| 282 | continue |
| 283 | } |
| 284 | for _, indexValue := range indexValues { |
| 285 | set := index[indexValue] |
| 286 | if set != nil { |
| 287 | set.Delete(key) |
| 288 | } |
| 289 | } |
| 290 | } |
| 291 | } |
| 292 | |
| 293 | func (c *threadSafeMap) Resync() error { |
| 294 | // Nothing to do |
| 295 | return nil |
| 296 | } |
| 297 | |
| 298 | func NewThreadSafeStore(indexers Indexers, indices Indices) ThreadSafeStore { |
| 299 | return &threadSafeMap{ |
| 300 | items: map[string]interface{}{}, |
| 301 | indexers: indexers, |
| 302 | indices: indices, |
| 303 | } |
| 304 | } |