├── .gitignore ├── README.md ├── lru_test.go ├── lru.go └── LICENSE /.gitignore: -------------------------------------------------------------------------------- 1 | # Compiled Object files, Static and Dynamic libs (Shared Objects) 2 | *.o 3 | *.a 4 | *.so 5 | 6 | # Folders 7 | _obj 8 | _test 9 | 10 | # Architecture specific extensions/prefixes 11 | *.[568vq] 12 | [568vq].out 13 | 14 | *.cgo1.go 15 | *.cgo2.c 16 | _cgo_defun.c 17 | _cgo_gotypes.go 18 | _cgo_export.* 19 | 20 | _testmain.go 21 | 22 | *.exe 23 | *.test 24 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | golang-lru 2 | ========== 3 | 4 | This provides the `lru` package which implements a fixed-size 5 | thread safe LRU cache. It is based on the cache in Groupcache. 6 | 7 | Documentation 8 | ============= 9 | 10 | Full docs are available on [Godoc](http://godoc.org/github.com/hashicorp/golang-lru) 11 | 12 | Example 13 | ======= 14 | 15 | Using the LRU is very simple: 16 | 17 | ```go 18 | l, _ := New(128) 19 | for i := 0; i < 256; i++ { 20 | l.Add(i, nil) 21 | } 22 | if l.Len() != 128 { 23 | panic(fmt.Sprintf("bad len: %v", l.Len())) 24 | } 25 | ``` 26 | -------------------------------------------------------------------------------- /lru_test.go: -------------------------------------------------------------------------------- 1 | package lru 2 | 3 | import "testing" 4 | 5 | func TestLRU(t *testing.T) { 6 | l, err := New(128) 7 | if err != nil { 8 | t.Fatalf("err: %v", err) 9 | } 10 | for i := 0; i < 256; i++ { 11 | l.Add(i, i) 12 | } 13 | if l.Len() != 128 { 14 | t.Fatalf("bad len: %v", l.Len()) 15 | } 16 | for _, k := range l.Keys() { 17 | if v, ok := l.Get(k); !ok || v != k { 18 | t.Fatalf("bad key: %v", k) 19 | } 20 | } 21 | for i := 0; i < 128; i++ { 22 | _, ok := l.Get(i) 23 | if ok { 24 | t.Fatalf("should be evicted") 25 | } 26 | } 27 | for i := 128; i < 256; i++ { 28 | _, ok := l.Get(i) 29 | if !ok { 30 | t.Fatalf("should not be evicted") 31 | } 32 | } 33 | for i := 128; i < 192; i++ { 34 | l.Remove(i) 35 | _, ok := l.Get(i) 36 | if ok { 37 | t.Fatalf("should be deleted") 38 | } 39 | } 40 | 41 | l.Purge() 42 | if l.Len() != 0 { 43 | t.Fatalf("bad len: %v", l.Len()) 44 | } 45 | if _, ok := l.Get(200); ok { 46 | t.Fatalf("should contain nothing") 47 | } 48 | } 49 | -------------------------------------------------------------------------------- /lru.go: -------------------------------------------------------------------------------- 1 | // This package provides a simple LRU cache. It is based on the 2 | // LRU implementation in groupcache: 3 | // https://github.com/golang/groupcache/tree/master/lru 4 | package lru 5 | 6 | import ( 7 | "container/list" 8 | "errors" 9 | "sync" 10 | ) 11 | 12 | type FillFunc func(key interface{}) interface{} 13 | 14 | // Cache is a thread-safe fixed size LRU cache. 15 | type Cache struct { 16 | fillFunc FillFunc 17 | size int 18 | evictList *list.List 19 | items map[interface{}]*list.Element 20 | lock sync.RWMutex 21 | } 22 | 23 | // entry is used to hold a value in the evictList 24 | type entry struct { 25 | key interface{} 26 | value interface{} 27 | } 28 | 29 | // New creates an LRU of the given size 30 | func New(size int, fillFunc FillFunc) (*Cache, error) { 31 | if size <= 0 { 32 | return nil, errors.New("Must provide a positive size") 33 | } 34 | c := &Cache{ 35 | fillFunc: fillFunc, 36 | size: size, 37 | evictList: list.New(), 38 | items: make(map[interface{}]*list.Element, size), 39 | } 40 | return c, nil 41 | } 42 | 43 | // Purge is used to completely clear the cache 44 | func (c *Cache) Purge() { 45 | c.lock.Lock() 46 | defer c.lock.Unlock() 47 | c.evictList = list.New() 48 | c.items = make(map[interface{}]*list.Element, c.size) 49 | } 50 | 51 | // Add adds a value to the cache. 52 | func (c *Cache) Add(key, value interface{}) { 53 | c.lock.Lock() 54 | defer c.lock.Unlock() 55 | 56 | // Check for existing item 57 | if ent, ok := c.items[key]; ok { 58 | c.evictList.MoveToFront(ent) 59 | ent.Value.(*entry).value = value 60 | return 61 | } 62 | 63 | // Add new item 64 | ent := &entry{key, value} 65 | entry := c.evictList.PushFront(ent) 66 | c.items[key] = entry 67 | 68 | // Verify size not exceeded 69 | if c.evictList.Len() > c.size { 70 | c.removeOldest() 71 | } 72 | } 73 | 74 | // Get looks up a key's value from the cache. 75 | func (c *Cache) Get(key interface{}) (value interface{}, ok bool) { 76 | c.lock.Lock() 77 | defer c.lock.Unlock() 78 | 79 | // Check for existing item 80 | if ent, ok := c.items[key]; ok { 81 | c.evictList.MoveToFront(ent) 82 | return ent.Value.(*entry).value, true 83 | } 84 | 85 | if c.fillFunc != nil { 86 | // Create new item 87 | ent := &entry{key, c.fillFunc(key)} 88 | entry := c.evictList.PushFront(ent) 89 | c.items[key] = entry 90 | 91 | // Verify size not exceeded 92 | if c.evictList.Len() > c.size { 93 | c.removeOldest() 94 | } 95 | 96 | return ent.value, true 97 | } 98 | 99 | return 100 | } 101 | 102 | // Remove removes the provided key from the cache. 103 | func (c *Cache) Remove(key interface{}) { 104 | c.lock.Lock() 105 | defer c.lock.Unlock() 106 | 107 | if ent, ok := c.items[key]; ok { 108 | c.removeElement(ent) 109 | } 110 | } 111 | 112 | // RemoveIfMatch removes the provided key from the cache if the values match. 113 | func (c *Cache) RemoveIfMatch(key interface{}, value interface{}) { 114 | c.lock.Lock() 115 | defer c.lock.Unlock() 116 | 117 | if ent, ok := c.items[key]; ok && ent.Value == value { 118 | c.removeElement(ent) 119 | } 120 | } 121 | 122 | // RemoveOldest removes the oldest item from the cache. 123 | func (c *Cache) RemoveOldest() { 124 | c.lock.Lock() 125 | defer c.lock.Unlock() 126 | c.removeOldest() 127 | } 128 | 129 | // Keys returns a slice of the keys in the cache. 130 | func (c *Cache) Keys() []interface{} { 131 | c.lock.RLock() 132 | defer c.lock.RUnlock() 133 | 134 | keys := make([]interface{}, len(c.items)) 135 | i := 0 136 | for k := range c.items { 137 | keys[i] = k 138 | i++ 139 | } 140 | 141 | return keys 142 | } 143 | 144 | // Len returns the number of items in the cache. 145 | func (c *Cache) Len() int { 146 | c.lock.RLock() 147 | defer c.lock.RUnlock() 148 | return c.evictList.Len() 149 | } 150 | 151 | // removeOldest removes the oldest item from the cache. 152 | func (c *Cache) removeOldest() { 153 | ent := c.evictList.Back() 154 | if ent != nil { 155 | c.removeElement(ent) 156 | } 157 | } 158 | 159 | // removeElement is used to remove a given list element from the cache 160 | func (c *Cache) removeElement(e *list.Element) { 161 | c.evictList.Remove(e) 162 | kv := e.Value.(*entry) 163 | delete(c.items, kv.key) 164 | } 165 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Mozilla Public License, version 2.0 2 | 3 | 1. Definitions 4 | 5 | 1.1. "Contributor" 6 | 7 | means each individual or legal entity that creates, contributes to the 8 | creation of, or owns Covered Software. 9 | 10 | 1.2. "Contributor Version" 11 | 12 | means the combination of the Contributions of others (if any) used by a 13 | Contributor and that particular Contributor's Contribution. 14 | 15 | 1.3. "Contribution" 16 | 17 | means Covered Software of a particular Contributor. 18 | 19 | 1.4. "Covered Software" 20 | 21 | means Source Code Form to which the initial Contributor has attached the 22 | notice in Exhibit A, the Executable Form of such Source Code Form, and 23 | Modifications of such Source Code Form, in each case including portions 24 | thereof. 25 | 26 | 1.5. "Incompatible With Secondary Licenses" 27 | means 28 | 29 | a. that the initial Contributor has attached the notice described in 30 | Exhibit B to the Covered Software; or 31 | 32 | b. that the Covered Software was made available under the terms of 33 | version 1.1 or earlier of the License, but not also under the terms of 34 | a Secondary License. 35 | 36 | 1.6. "Executable Form" 37 | 38 | means any form of the work other than Source Code Form. 39 | 40 | 1.7. "Larger Work" 41 | 42 | means a work that combines Covered Software with other material, in a 43 | separate file or files, that is not Covered Software. 44 | 45 | 1.8. "License" 46 | 47 | means this document. 48 | 49 | 1.9. "Licensable" 50 | 51 | means having the right to grant, to the maximum extent possible, whether 52 | at the time of the initial grant or subsequently, any and all of the 53 | rights conveyed by this License. 54 | 55 | 1.10. "Modifications" 56 | 57 | means any of the following: 58 | 59 | a. any file in Source Code Form that results from an addition to, 60 | deletion from, or modification of the contents of Covered Software; or 61 | 62 | b. any new file in Source Code Form that contains any Covered Software. 63 | 64 | 1.11. "Patent Claims" of a Contributor 65 | 66 | means any patent claim(s), including without limitation, method, 67 | process, and apparatus claims, in any patent Licensable by such 68 | Contributor that would be infringed, but for the grant of the License, 69 | by the making, using, selling, offering for sale, having made, import, 70 | or transfer of either its Contributions or its Contributor Version. 71 | 72 | 1.12. "Secondary License" 73 | 74 | means either the GNU General Public License, Version 2.0, the GNU Lesser 75 | General Public License, Version 2.1, the GNU Affero General Public 76 | License, Version 3.0, or any later versions of those licenses. 77 | 78 | 1.13. "Source Code Form" 79 | 80 | means the form of the work preferred for making modifications. 81 | 82 | 1.14. "You" (or "Your") 83 | 84 | means an individual or a legal entity exercising rights under this 85 | License. For legal entities, "You" includes any entity that controls, is 86 | controlled by, or is under common control with You. For purposes of this 87 | definition, "control" means (a) the power, direct or indirect, to cause 88 | the direction or management of such entity, whether by contract or 89 | otherwise, or (b) ownership of more than fifty percent (50%) of the 90 | outstanding shares or beneficial ownership of such entity. 91 | 92 | 93 | 2. License Grants and Conditions 94 | 95 | 2.1. Grants 96 | 97 | Each Contributor hereby grants You a world-wide, royalty-free, 98 | non-exclusive license: 99 | 100 | a. under intellectual property rights (other than patent or trademark) 101 | Licensable by such Contributor to use, reproduce, make available, 102 | modify, display, perform, distribute, and otherwise exploit its 103 | Contributions, either on an unmodified basis, with Modifications, or 104 | as part of a Larger Work; and 105 | 106 | b. under Patent Claims of such Contributor to make, use, sell, offer for 107 | sale, have made, import, and otherwise transfer either its 108 | Contributions or its Contributor Version. 109 | 110 | 2.2. Effective Date 111 | 112 | The licenses granted in Section 2.1 with respect to any Contribution 113 | become effective for each Contribution on the date the Contributor first 114 | distributes such Contribution. 115 | 116 | 2.3. Limitations on Grant Scope 117 | 118 | The licenses granted in this Section 2 are the only rights granted under 119 | this License. No additional rights or licenses will be implied from the 120 | distribution or licensing of Covered Software under this License. 121 | Notwithstanding Section 2.1(b) above, no patent license is granted by a 122 | Contributor: 123 | 124 | a. for any code that a Contributor has removed from Covered Software; or 125 | 126 | b. for infringements caused by: (i) Your and any other third party's 127 | modifications of Covered Software, or (ii) the combination of its 128 | Contributions with other software (except as part of its Contributor 129 | Version); or 130 | 131 | c. under Patent Claims infringed by Covered Software in the absence of 132 | its Contributions. 133 | 134 | This License does not grant any rights in the trademarks, service marks, 135 | or logos of any Contributor (except as may be necessary to comply with 136 | the notice requirements in Section 3.4). 137 | 138 | 2.4. Subsequent Licenses 139 | 140 | No Contributor makes additional grants as a result of Your choice to 141 | distribute the Covered Software under a subsequent version of this 142 | License (see Section 10.2) or under the terms of a Secondary License (if 143 | permitted under the terms of Section 3.3). 144 | 145 | 2.5. Representation 146 | 147 | Each Contributor represents that the Contributor believes its 148 | Contributions are its original creation(s) or it has sufficient rights to 149 | grant the rights to its Contributions conveyed by this License. 150 | 151 | 2.6. Fair Use 152 | 153 | This License is not intended to limit any rights You have under 154 | applicable copyright doctrines of fair use, fair dealing, or other 155 | equivalents. 156 | 157 | 2.7. Conditions 158 | 159 | Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted in 160 | Section 2.1. 161 | 162 | 163 | 3. Responsibilities 164 | 165 | 3.1. Distribution of Source Form 166 | 167 | All distribution of Covered Software in Source Code Form, including any 168 | Modifications that You create or to which You contribute, must be under 169 | the terms of this License. You must inform recipients that the Source 170 | Code Form of the Covered Software is governed by the terms of this 171 | License, and how they can obtain a copy of this License. You may not 172 | attempt to alter or restrict the recipients' rights in the Source Code 173 | Form. 174 | 175 | 3.2. Distribution of Executable Form 176 | 177 | If You distribute Covered Software in Executable Form then: 178 | 179 | a. such Covered Software must also be made available in Source Code Form, 180 | as described in Section 3.1, and You must inform recipients of the 181 | Executable Form how they can obtain a copy of such Source Code Form by 182 | reasonable means in a timely manner, at a charge no more than the cost 183 | of distribution to the recipient; and 184 | 185 | b. You may distribute such Executable Form under the terms of this 186 | License, or sublicense it under different terms, provided that the 187 | license for the Executable Form does not attempt to limit or alter the 188 | recipients' rights in the Source Code Form under this License. 189 | 190 | 3.3. Distribution of a Larger Work 191 | 192 | You may create and distribute a Larger Work under terms of Your choice, 193 | provided that You also comply with the requirements of this License for 194 | the Covered Software. If the Larger Work is a combination of Covered 195 | Software with a work governed by one or more Secondary Licenses, and the 196 | Covered Software is not Incompatible With Secondary Licenses, this 197 | License permits You to additionally distribute such Covered Software 198 | under the terms of such Secondary License(s), so that the recipient of 199 | the Larger Work may, at their option, further distribute the Covered 200 | Software under the terms of either this License or such Secondary 201 | License(s). 202 | 203 | 3.4. Notices 204 | 205 | You may not remove or alter the substance of any license notices 206 | (including copyright notices, patent notices, disclaimers of warranty, or 207 | limitations of liability) contained within the Source Code Form of the 208 | Covered Software, except that You may alter any license notices to the 209 | extent required to remedy known factual inaccuracies. 210 | 211 | 3.5. Application of Additional Terms 212 | 213 | You may choose to offer, and to charge a fee for, warranty, support, 214 | indemnity or liability obligations to one or more recipients of Covered 215 | Software. However, You may do so only on Your own behalf, and not on 216 | behalf of any Contributor. You must make it absolutely clear that any 217 | such warranty, support, indemnity, or liability obligation is offered by 218 | You alone, and You hereby agree to indemnify every Contributor for any 219 | liability incurred by such Contributor as a result of warranty, support, 220 | indemnity or liability terms You offer. You may include additional 221 | disclaimers of warranty and limitations of liability specific to any 222 | jurisdiction. 223 | 224 | 4. Inability to Comply Due to Statute or Regulation 225 | 226 | If it is impossible for You to comply with any of the terms of this License 227 | with respect to some or all of the Covered Software due to statute, 228 | judicial order, or regulation then You must: (a) comply with the terms of 229 | this License to the maximum extent possible; and (b) describe the 230 | limitations and the code they affect. Such description must be placed in a 231 | text file included with all distributions of the Covered Software under 232 | this License. Except to the extent prohibited by statute or regulation, 233 | such description must be sufficiently detailed for a recipient of ordinary 234 | skill to be able to understand it. 235 | 236 | 5. Termination 237 | 238 | 5.1. The rights granted under this License will terminate automatically if You 239 | fail to comply with any of its terms. However, if You become compliant, 240 | then the rights granted under this License from a particular Contributor 241 | are reinstated (a) provisionally, unless and until such Contributor 242 | explicitly and finally terminates Your grants, and (b) on an ongoing 243 | basis, if such Contributor fails to notify You of the non-compliance by 244 | some reasonable means prior to 60 days after You have come back into 245 | compliance. Moreover, Your grants from a particular Contributor are 246 | reinstated on an ongoing basis if such Contributor notifies You of the 247 | non-compliance by some reasonable means, this is the first time You have 248 | received notice of non-compliance with this License from such 249 | Contributor, and You become compliant prior to 30 days after Your receipt 250 | of the notice. 251 | 252 | 5.2. If You initiate litigation against any entity by asserting a patent 253 | infringement claim (excluding declaratory judgment actions, 254 | counter-claims, and cross-claims) alleging that a Contributor Version 255 | directly or indirectly infringes any patent, then the rights granted to 256 | You by any and all Contributors for the Covered Software under Section 257 | 2.1 of this License shall terminate. 258 | 259 | 5.3. In the event of termination under Sections 5.1 or 5.2 above, all end user 260 | license agreements (excluding distributors and resellers) which have been 261 | validly granted by You or Your distributors under this License prior to 262 | termination shall survive termination. 263 | 264 | 6. Disclaimer of Warranty 265 | 266 | Covered Software is provided under this License on an "as is" basis, 267 | without warranty of any kind, either expressed, implied, or statutory, 268 | including, without limitation, warranties that the Covered Software is free 269 | of defects, merchantable, fit for a particular purpose or non-infringing. 270 | The entire risk as to the quality and performance of the Covered Software 271 | is with You. Should any Covered Software prove defective in any respect, 272 | You (not any Contributor) assume the cost of any necessary servicing, 273 | repair, or correction. This disclaimer of warranty constitutes an essential 274 | part of this License. No use of any Covered Software is authorized under 275 | this License except under this disclaimer. 276 | 277 | 7. Limitation of Liability 278 | 279 | Under no circumstances and under no legal theory, whether tort (including 280 | negligence), contract, or otherwise, shall any Contributor, or anyone who 281 | distributes Covered Software as permitted above, be liable to You for any 282 | direct, indirect, special, incidental, or consequential damages of any 283 | character including, without limitation, damages for lost profits, loss of 284 | goodwill, work stoppage, computer failure or malfunction, or any and all 285 | other commercial damages or losses, even if such party shall have been 286 | informed of the possibility of such damages. This limitation of liability 287 | shall not apply to liability for death or personal injury resulting from 288 | such party's negligence to the extent applicable law prohibits such 289 | limitation. Some jurisdictions do not allow the exclusion or limitation of 290 | incidental or consequential damages, so this exclusion and limitation may 291 | not apply to You. 292 | 293 | 8. Litigation 294 | 295 | Any litigation relating to this License may be brought only in the courts 296 | of a jurisdiction where the defendant maintains its principal place of 297 | business and such litigation shall be governed by laws of that 298 | jurisdiction, without reference to its conflict-of-law provisions. Nothing 299 | in this Section shall prevent a party's ability to bring cross-claims or 300 | counter-claims. 301 | 302 | 9. Miscellaneous 303 | 304 | This License represents the complete agreement concerning the subject 305 | matter hereof. If any provision of this License is held to be 306 | unenforceable, such provision shall be reformed only to the extent 307 | necessary to make it enforceable. Any law or regulation which provides that 308 | the language of a contract shall be construed against the drafter shall not 309 | be used to construe this License against a Contributor. 310 | 311 | 312 | 10. Versions of the License 313 | 314 | 10.1. New Versions 315 | 316 | Mozilla Foundation is the license steward. Except as provided in Section 317 | 10.3, no one other than the license steward has the right to modify or 318 | publish new versions of this License. Each version will be given a 319 | distinguishing version number. 320 | 321 | 10.2. Effect of New Versions 322 | 323 | You may distribute the Covered Software under the terms of the version 324 | of the License under which You originally received the Covered Software, 325 | or under the terms of any subsequent version published by the license 326 | steward. 327 | 328 | 10.3. Modified Versions 329 | 330 | If you create software not governed by this License, and you want to 331 | create a new license for such software, you may create and use a 332 | modified version of this License if you rename the license and remove 333 | any references to the name of the license steward (except to note that 334 | such modified license differs from this License). 335 | 336 | 10.4. Distributing Source Code Form that is Incompatible With Secondary 337 | Licenses If You choose to distribute Source Code Form that is 338 | Incompatible With Secondary Licenses under the terms of this version of 339 | the License, the notice described in Exhibit B of this License must be 340 | attached. 341 | 342 | Exhibit A - Source Code Form License Notice 343 | 344 | This Source Code Form is subject to the 345 | terms of the Mozilla Public License, v. 346 | 2.0. If a copy of the MPL was not 347 | distributed with this file, You can 348 | obtain one at 349 | http://mozilla.org/MPL/2.0/. 350 | 351 | If it is not possible or desirable to put the notice in a particular file, 352 | then You may include the notice in a location (such as a LICENSE file in a 353 | relevant directory) where a recipient would be likely to look for such a 354 | notice. 355 | 356 | You may add additional accurate notices of copyright ownership. 357 | 358 | Exhibit B - "Incompatible With Secondary Licenses" Notice 359 | 360 | This Source Code Form is "Incompatible 361 | With Secondary Licenses", as defined by 362 | the Mozilla Public License, v. 2.0. 363 | --------------------------------------------------------------------------------