├── LICENSE ├── Makefile ├── drl.go ├── drl_test.go ├── go.mod ├── go.sum ├── item.go ├── ttlcache.go ├── ttlcache_test.go └── util.go /LICENSE: -------------------------------------------------------------------------------- 1 | Mozilla Public License Version 2.0 2 | ================================== 3 | 4 | 1. Definitions 5 | -------------- 6 | 7 | 1.1. "Contributor" 8 | means each individual or legal entity that creates, contributes to 9 | the creation of, or owns Covered Software. 10 | 11 | 1.2. "Contributor Version" 12 | means the combination of the Contributions of others (if any) used 13 | by a Contributor and that particular Contributor's Contribution. 14 | 15 | 1.3. "Contribution" 16 | means Covered Software of a particular Contributor. 17 | 18 | 1.4. "Covered Software" 19 | means Source Code Form to which the initial Contributor has attached 20 | the notice in Exhibit A, the Executable Form of such Source Code 21 | Form, and Modifications of such Source Code Form, in each case 22 | including portions thereof. 23 | 24 | 1.5. "Incompatible With Secondary Licenses" 25 | means 26 | 27 | (a) that the initial Contributor has attached the notice described 28 | in Exhibit B to the Covered Software; or 29 | 30 | (b) that the Covered Software was made available under the terms of 31 | version 1.1 or earlier of the License, but not also under the 32 | terms of a Secondary License. 33 | 34 | 1.6. "Executable Form" 35 | means any form of the work other than Source Code Form. 36 | 37 | 1.7. "Larger Work" 38 | means a work that combines Covered Software with other material, in 39 | a separate file or files, that is not Covered Software. 40 | 41 | 1.8. "License" 42 | means this document. 43 | 44 | 1.9. "Licensable" 45 | means having the right to grant, to the maximum extent possible, 46 | whether at the time of the initial grant or subsequently, any and 47 | all of the rights conveyed by this License. 48 | 49 | 1.10. "Modifications" 50 | means any of the following: 51 | 52 | (a) any file in Source Code Form that results from an addition to, 53 | deletion from, or modification of the contents of Covered 54 | Software; or 55 | 56 | (b) any new file in Source Code Form that contains any Covered 57 | Software. 58 | 59 | 1.11. "Patent Claims" of a Contributor 60 | means any patent claim(s), including without limitation, method, 61 | process, and apparatus claims, in any patent Licensable by such 62 | Contributor that would be infringed, but for the grant of the 63 | License, by the making, using, selling, offering for sale, having 64 | made, import, or transfer of either its Contributions or its 65 | Contributor Version. 66 | 67 | 1.12. "Secondary License" 68 | means either the GNU General Public License, Version 2.0, the GNU 69 | Lesser General Public License, Version 2.1, the GNU Affero General 70 | Public License, Version 3.0, or any later versions of those 71 | licenses. 72 | 73 | 1.13. "Source Code Form" 74 | means the form of the work preferred for making modifications. 75 | 76 | 1.14. "You" (or "Your") 77 | means an individual or a legal entity exercising rights under this 78 | License. For legal entities, "You" includes any entity that 79 | controls, is controlled by, or is under common control with You. For 80 | purposes of this definition, "control" means (a) the power, direct 81 | or indirect, to cause the direction or management of such entity, 82 | whether by contract or otherwise, or (b) ownership of more than 83 | fifty percent (50%) of the outstanding shares or beneficial 84 | ownership of such entity. 85 | 86 | 2. License Grants and Conditions 87 | -------------------------------- 88 | 89 | 2.1. Grants 90 | 91 | Each Contributor hereby grants You a world-wide, royalty-free, 92 | non-exclusive license: 93 | 94 | (a) under intellectual property rights (other than patent or trademark) 95 | Licensable by such Contributor to use, reproduce, make available, 96 | modify, display, perform, distribute, and otherwise exploit its 97 | Contributions, either on an unmodified basis, with Modifications, or 98 | as part of a Larger Work; and 99 | 100 | (b) under Patent Claims of such Contributor to make, use, sell, offer 101 | for sale, have made, import, and otherwise transfer either its 102 | Contributions or its Contributor Version. 103 | 104 | 2.2. Effective Date 105 | 106 | The licenses granted in Section 2.1 with respect to any Contribution 107 | become effective for each Contribution on the date the Contributor first 108 | distributes such Contribution. 109 | 110 | 2.3. Limitations on Grant Scope 111 | 112 | The licenses granted in this Section 2 are the only rights granted under 113 | this License. No additional rights or licenses will be implied from the 114 | distribution or licensing of Covered Software under this License. 115 | Notwithstanding Section 2.1(b) above, no patent license is granted by a 116 | Contributor: 117 | 118 | (a) for any code that a Contributor has removed from Covered Software; 119 | or 120 | 121 | (b) for infringements caused by: (i) Your and any other third party's 122 | modifications of Covered Software, or (ii) the combination of its 123 | Contributions with other software (except as part of its Contributor 124 | Version); or 125 | 126 | (c) under Patent Claims infringed by Covered Software in the absence of 127 | its Contributions. 128 | 129 | This License does not grant any rights in the trademarks, service marks, 130 | or logos of any Contributor (except as may be necessary to comply with 131 | the notice requirements in Section 3.4). 132 | 133 | 2.4. Subsequent Licenses 134 | 135 | No Contributor makes additional grants as a result of Your choice to 136 | distribute the Covered Software under a subsequent version of this 137 | License (see Section 10.2) or under the terms of a Secondary License (if 138 | permitted under the terms of Section 3.3). 139 | 140 | 2.5. Representation 141 | 142 | Each Contributor represents that the Contributor believes its 143 | Contributions are its original creation(s) or it has sufficient rights 144 | to grant the rights to its Contributions conveyed by this License. 145 | 146 | 2.6. Fair Use 147 | 148 | This License is not intended to limit any rights You have under 149 | applicable copyright doctrines of fair use, fair dealing, or other 150 | equivalents. 151 | 152 | 2.7. Conditions 153 | 154 | Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted 155 | in Section 2.1. 156 | 157 | 3. Responsibilities 158 | ------------------- 159 | 160 | 3.1. Distribution of Source Form 161 | 162 | All distribution of Covered Software in Source Code Form, including any 163 | Modifications that You create or to which You contribute, must be under 164 | the terms of this License. You must inform recipients that the Source 165 | Code Form of the Covered Software is governed by the terms of this 166 | License, and how they can obtain a copy of this License. You may not 167 | attempt to alter or restrict the recipients' rights in the Source Code 168 | Form. 169 | 170 | 3.2. Distribution of Executable Form 171 | 172 | If You distribute Covered Software in Executable Form then: 173 | 174 | (a) such Covered Software must also be made available in Source Code 175 | Form, as described in Section 3.1, and You must inform recipients of 176 | the Executable Form how they can obtain a copy of such Source Code 177 | Form by reasonable means in a timely manner, at a charge no more 178 | than the cost of distribution to the recipient; and 179 | 180 | (b) You may distribute such Executable Form under the terms of this 181 | License, or sublicense it under different terms, provided that the 182 | license for the Executable Form does not attempt to limit or alter 183 | the recipients' rights in the Source Code Form under this License. 184 | 185 | 3.3. Distribution of a Larger Work 186 | 187 | You may create and distribute a Larger Work under terms of Your choice, 188 | provided that You also comply with the requirements of this License for 189 | the Covered Software. If the Larger Work is a combination of Covered 190 | Software with a work governed by one or more Secondary Licenses, and the 191 | Covered Software is not Incompatible With Secondary Licenses, this 192 | License permits You to additionally distribute such Covered Software 193 | under the terms of such Secondary License(s), so that the recipient of 194 | the Larger Work may, at their option, further distribute the Covered 195 | Software under the terms of either this License or such Secondary 196 | License(s). 197 | 198 | 3.4. Notices 199 | 200 | You may not remove or alter the substance of any license notices 201 | (including copyright notices, patent notices, disclaimers of warranty, 202 | or limitations of liability) contained within the Source Code Form of 203 | the Covered Software, except that You may alter any license notices to 204 | the extent required to remedy known factual inaccuracies. 205 | 206 | 3.5. Application of Additional Terms 207 | 208 | You may choose to offer, and to charge a fee for, warranty, support, 209 | indemnity or liability obligations to one or more recipients of Covered 210 | Software. However, You may do so only on Your own behalf, and not on 211 | behalf of any Contributor. You must make it absolutely clear that any 212 | such warranty, support, indemnity, or liability obligation is offered by 213 | You alone, and You hereby agree to indemnify every Contributor for any 214 | liability incurred by such Contributor as a result of warranty, support, 215 | indemnity or liability terms You offer. You may include additional 216 | disclaimers of warranty and limitations of liability specific to any 217 | jurisdiction. 218 | 219 | 4. Inability to Comply Due to Statute or Regulation 220 | --------------------------------------------------- 221 | 222 | If it is impossible for You to comply with any of the terms of this 223 | License with respect to some or all of the Covered Software due to 224 | statute, judicial order, or regulation then You must: (a) comply with 225 | the terms of this License to the maximum extent possible; and (b) 226 | describe the limitations and the code they affect. Such description must 227 | be placed in a text file included with all distributions of the Covered 228 | Software under this License. Except to the extent prohibited by statute 229 | or regulation, such description must be sufficiently detailed for a 230 | recipient of ordinary skill to be able to understand it. 231 | 232 | 5. Termination 233 | -------------- 234 | 235 | 5.1. The rights granted under this License will terminate automatically 236 | if You fail to comply with any of its terms. However, if You become 237 | compliant, then the rights granted under this License from a particular 238 | Contributor are reinstated (a) provisionally, unless and until such 239 | Contributor explicitly and finally terminates Your grants, and (b) on an 240 | ongoing basis, if such Contributor fails to notify You of the 241 | non-compliance by some reasonable means prior to 60 days after You have 242 | come back into compliance. Moreover, Your grants from a particular 243 | Contributor are reinstated on an ongoing basis if such Contributor 244 | notifies You of the non-compliance by some reasonable means, this is the 245 | first time You have received notice of non-compliance with this License 246 | from such Contributor, and You become compliant prior to 30 days after 247 | Your receipt of the notice. 248 | 249 | 5.2. If You initiate litigation against any entity by asserting a patent 250 | infringement claim (excluding declaratory judgment actions, 251 | counter-claims, and cross-claims) alleging that a Contributor Version 252 | directly or indirectly infringes any patent, then the rights granted to 253 | You by any and all Contributors for the Covered Software under Section 254 | 2.1 of this License shall terminate. 255 | 256 | 5.3. In the event of termination under Sections 5.1 or 5.2 above, all 257 | end user license agreements (excluding distributors and resellers) which 258 | have been validly granted by You or Your distributors under this License 259 | prior to termination shall survive termination. 260 | 261 | ************************************************************************ 262 | * * 263 | * 6. Disclaimer of Warranty * 264 | * ------------------------- * 265 | * * 266 | * Covered Software is provided under this License on an "as is" * 267 | * basis, without warranty of any kind, either expressed, implied, or * 268 | * statutory, including, without limitation, warranties that the * 269 | * Covered Software is free of defects, merchantable, fit for a * 270 | * particular purpose or non-infringing. The entire risk as to the * 271 | * quality and performance of the Covered Software is with You. * 272 | * Should any Covered Software prove defective in any respect, You * 273 | * (not any Contributor) assume the cost of any necessary servicing, * 274 | * repair, or correction. This disclaimer of warranty constitutes an * 275 | * essential part of this License. No use of any Covered Software is * 276 | * authorized under this License except under this disclaimer. * 277 | * * 278 | ************************************************************************ 279 | 280 | ************************************************************************ 281 | * * 282 | * 7. Limitation of Liability * 283 | * -------------------------- * 284 | * * 285 | * Under no circumstances and under no legal theory, whether tort * 286 | * (including negligence), contract, or otherwise, shall any * 287 | * Contributor, or anyone who distributes Covered Software as * 288 | * permitted above, be liable to You for any direct, indirect, * 289 | * special, incidental, or consequential damages of any character * 290 | * including, without limitation, damages for lost profits, loss of * 291 | * goodwill, work stoppage, computer failure or malfunction, or any * 292 | * and all other commercial damages or losses, even if such party * 293 | * shall have been informed of the possibility of such damages. This * 294 | * limitation of liability shall not apply to liability for death or * 295 | * personal injury resulting from such party's negligence to the * 296 | * extent applicable law prohibits such limitation. Some * 297 | * jurisdictions do not allow the exclusion or limitation of * 298 | * incidental or consequential damages, so this exclusion and * 299 | * limitation may not apply to You. * 300 | * * 301 | ************************************************************************ 302 | 303 | 8. Litigation 304 | ------------- 305 | 306 | Any litigation relating to this License may be brought only in the 307 | courts of a jurisdiction where the defendant maintains its principal 308 | place of business and such litigation shall be governed by laws of that 309 | jurisdiction, without reference to its conflict-of-law provisions. 310 | Nothing in this Section shall prevent a party's ability to bring 311 | cross-claims or counter-claims. 312 | 313 | 9. Miscellaneous 314 | ---------------- 315 | 316 | This License represents the complete agreement concerning the subject 317 | matter hereof. If any provision of this License is held to be 318 | unenforceable, such provision shall be reformed only to the extent 319 | necessary to make it enforceable. Any law or regulation which provides 320 | that the language of a contract shall be construed against the drafter 321 | shall not be used to construe this License against a Contributor. 322 | 323 | 10. Versions of the License 324 | --------------------------- 325 | 326 | 10.1. New Versions 327 | 328 | Mozilla Foundation is the license steward. Except as provided in Section 329 | 10.3, no one other than the license steward has the right to modify or 330 | publish new versions of this License. Each version will be given a 331 | distinguishing version number. 332 | 333 | 10.2. Effect of New Versions 334 | 335 | You may distribute the Covered Software under the terms of the version 336 | of the License under which You originally received the Covered Software, 337 | or under the terms of any subsequent version published by the license 338 | steward. 339 | 340 | 10.3. Modified Versions 341 | 342 | If you create software not governed by this License, and you want to 343 | create a new license for such software, you may create and use a 344 | modified version of this License if you rename the license and remove 345 | any references to the name of the license steward (except to note that 346 | such modified license differs from this License). 347 | 348 | 10.4. Distributing Source Code Form that is Incompatible With Secondary 349 | Licenses 350 | 351 | If You choose to distribute Source Code Form that is Incompatible With 352 | Secondary Licenses under the terms of this version of the License, the 353 | notice described in Exhibit B of this License must be attached. 354 | 355 | Exhibit A - Source Code Form License Notice 356 | ------------------------------------------- 357 | 358 | This Source Code Form is subject to the terms of the Mozilla Public 359 | License, v. 2.0. If a copy of the MPL was not distributed with this 360 | file, You can obtain one at http://mozilla.org/MPL/2.0/. 361 | 362 | If it is not possible or desirable to put the notice in a particular 363 | file, then You may include the notice in a location (such as a LICENSE 364 | file in a relevant directory) where a recipient would be likely to look 365 | for such a notice. 366 | 367 | You may add additional accurate notices of copyright ownership. 368 | 369 | Exhibit B - "Incompatible With Secondary Licenses" Notice 370 | --------------------------------------------------------- 371 | 372 | This Source Code Form is "Incompatible With Secondary Licenses", as 373 | defined by the Mozilla Public License, v. 2.0. 374 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | .PHONY: all fmt test stresstest tidy 2 | 3 | all: fmt test tidy 4 | 5 | fmt: 6 | go fmt ./... 7 | 8 | test: 9 | go test -race -v -count=1 -cover . 10 | 11 | stresstest: 12 | go test -race -failfast -count=1000 -cover . 13 | 14 | tidy: 15 | go mod tidy -------------------------------------------------------------------------------- /drl.go: -------------------------------------------------------------------------------- 1 | package drl 2 | 3 | import ( 4 | "context" 5 | "errors" 6 | "fmt" 7 | "sync" 8 | "sync/atomic" 9 | "time" 10 | ) 11 | 12 | type Server struct { 13 | HostName string 14 | ID string 15 | LoadPerSec int64 16 | Percentage float64 17 | TagHash string 18 | } 19 | 20 | type DRL struct { 21 | Servers *Cache 22 | mutex sync.Mutex 23 | serverIndex map[string]Server 24 | ThisServerID string 25 | CurrentTotal int64 26 | RequestTokenValue int 27 | currentTokenValue int64 28 | isClosed int32 29 | stopC chan struct{} 30 | } 31 | 32 | func (d *DRL) Ready() bool { 33 | return d.IsOpen() 34 | } 35 | 36 | func (d *DRL) IsOpen() bool { 37 | return atomic.LoadInt32(&d.isClosed) == OPEN 38 | } 39 | 40 | func (d *DRL) SetCurrentTokenValue(newValue int64) { 41 | atomic.StoreInt64(&d.currentTokenValue, newValue) 42 | } 43 | 44 | func (d *DRL) CurrentTokenValue() int64 { 45 | return atomic.LoadInt64(&d.currentTokenValue) 46 | } 47 | 48 | func (d *DRL) Init(ctx context.Context) { 49 | d.Servers = NewCache(4 * time.Second) 50 | d.RequestTokenValue = 100 51 | d.currentTokenValue = 100 52 | d.serverIndex = make(map[string]Server) 53 | d.stopC = make(chan struct{}) 54 | 55 | go d.startLoop(ctx) 56 | } 57 | 58 | func (d *DRL) startLoop(ctx context.Context) { 59 | t := time.NewTicker(5 * time.Second) 60 | defer t.Stop() 61 | for { 62 | select { 63 | case <-ctx.Done(): 64 | d.Close() 65 | return 66 | case <-d.stopC: 67 | return 68 | case <-t.C: 69 | d.mutex.Lock() 70 | d.cleanServerList() 71 | d.mutex.Unlock() 72 | } 73 | } 74 | } 75 | 76 | func (d *DRL) uniqueID(s Server) string { 77 | uniqueID := s.ID + "|" + s.HostName 78 | return uniqueID 79 | } 80 | 81 | func (d *DRL) Close() { 82 | wasClosed := atomic.SwapInt32(&d.isClosed, CLOSED) 83 | if wasClosed == 0 { 84 | close(d.stopC) 85 | d.Servers.Close() 86 | } 87 | } 88 | 89 | func (d *DRL) totalLoadAcrossServers() int64 { 90 | var total int64 91 | for s := range d.serverIndex { 92 | _, found := d.Servers.GetNoExtend(s) 93 | if found { 94 | total += d.serverIndex[s].LoadPerSec 95 | } 96 | } 97 | 98 | d.CurrentTotal = total 99 | 100 | return total 101 | } 102 | 103 | func (d *DRL) cleanServerList() { 104 | toRemove := map[string]bool{} 105 | for s := range d.serverIndex { 106 | _, found := d.Servers.GetNoExtend(s) 107 | if !found { 108 | toRemove[s] = true 109 | } 110 | } 111 | 112 | // Update the server list 113 | for s := range toRemove { 114 | delete(d.serverIndex, s) 115 | } 116 | } 117 | 118 | func (d *DRL) percentagesAcrossServers() { 119 | for s := range d.serverIndex { 120 | _, found := d.Servers.GetNoExtend(s) 121 | if found { 122 | thisServerObject := d.serverIndex[s] 123 | 124 | // The compensation should be flat out based on servers, 125 | // not on current load, it tends to skew too conservative 126 | thisServerObject.Percentage = 1 / float64(d.Servers.Count()) 127 | d.serverIndex[s] = thisServerObject 128 | } 129 | } 130 | } 131 | 132 | func (d *DRL) calculateTokenBucketValue() error { 133 | _, found := d.Servers.Get(d.ThisServerID) 134 | if !found { 135 | return errors.New("Apparently this server does not exist!") 136 | } 137 | // Use our own index 138 | thisServerObject := d.serverIndex[d.ThisServerID] 139 | 140 | var thisTokenValue float64 141 | thisTokenValue = float64(d.RequestTokenValue) 142 | 143 | if thisServerObject.Percentage > 0 { 144 | thisTokenValue = float64(d.RequestTokenValue) / thisServerObject.Percentage 145 | } 146 | 147 | rounded := Round(thisTokenValue, .5, 0) 148 | d.SetCurrentTokenValue(int64(rounded)) 149 | return nil 150 | } 151 | 152 | func (d *DRL) AddOrUpdateServer(s Server) error { 153 | // Add or update the cache 154 | d.mutex.Lock() 155 | defer d.mutex.Unlock() 156 | 157 | if d.uniqueID(s) != d.ThisServerID { 158 | thisServer, found := d.Servers.GetNoExtend(d.ThisServerID) 159 | if found { 160 | if thisServer.TagHash != s.TagHash { 161 | return errors.New("Node notification from different tag group, ignoring.") 162 | } 163 | } else { 164 | // We don't know enough about our own host, so let's skip for now until we do 165 | return errors.New("DRL has no information on current host, waiting...") 166 | } 167 | } 168 | 169 | if d.serverIndex != nil { 170 | d.serverIndex[d.uniqueID(s)] = s 171 | } 172 | d.Servers.Set(d.uniqueID(s), s) 173 | 174 | // Recalculate totals 175 | d.totalLoadAcrossServers() 176 | 177 | // Recalculate percentages 178 | d.percentagesAcrossServers() 179 | 180 | // Get the current token bucket value: 181 | calcErr := d.calculateTokenBucketValue() 182 | if calcErr != nil { 183 | return calcErr 184 | } 185 | 186 | return nil 187 | } 188 | 189 | func (d *DRL) Report() string { 190 | thisServer, found := d.Servers.GetNoExtend(d.ThisServerID) 191 | if found { 192 | return fmt.Sprintf("[Active Nodes]: %d [Token Bucket Value]: %d [Current Load p/s]: %d [%% of Rate]: %f", 193 | d.Servers.Count(), 194 | d.CurrentTokenValue(), 195 | thisServer.LoadPerSec, 196 | thisServer.Percentage) 197 | } 198 | 199 | return "Error: server doesn't exist!" 200 | } 201 | -------------------------------------------------------------------------------- /drl_test.go: -------------------------------------------------------------------------------- 1 | package drl_test 2 | 3 | import ( 4 | "context" 5 | "errors" 6 | "testing" 7 | "time" 8 | 9 | "github.com/stretchr/testify/assert" 10 | 11 | "github.com/TykTechnologies/drl" 12 | ) 13 | 14 | // This is a black-box test suite for verifying the DRL 15 | 16 | func TestDRLInit(t *testing.T) { 17 | t.Parallel() 18 | 19 | ctx := context.Background() 20 | 21 | ratelimiter := setupDRL(ctx) 22 | 23 | t.Run("add server", func(t *testing.T) { 24 | t.Parallel() 25 | 26 | server := drl.Server{ 27 | HostName: "127.0.0.1", 28 | ID: "testing-node-id", 29 | LoadPerSec: 5, 30 | } 31 | err := addOrUpdateServer(ratelimiter, server) 32 | assert.NoError(t, err) 33 | }) 34 | } 35 | 36 | func TestDRLCancellation(t *testing.T) { 37 | t.Parallel() 38 | 39 | ctx, cancel := context.WithTimeout(context.Background(), 10*time.Millisecond) 40 | defer cancel() 41 | 42 | ratelimiter := setupDRL(ctx) 43 | defer ratelimiter.Close() 44 | 45 | <-ctx.Done() 46 | } 47 | 48 | func TestDRLCloser(t *testing.T) { 49 | t.Parallel() 50 | 51 | ratelimiter := setupDRL(context.Background()) 52 | ratelimiter.Close() 53 | } 54 | 55 | func setupDRL(ctx context.Context) *drl.DRL { 56 | result := &drl.DRL{} 57 | result.Init(ctx) 58 | result.ThisServerID = "testing-node-id|127.0.0.1" 59 | return result 60 | } 61 | 62 | func addOrUpdateServer(dest *drl.DRL, server drl.Server) error { 63 | if dest == nil || !dest.Ready() { 64 | return errors.New("DRL not ready") 65 | } 66 | return dest.AddOrUpdateServer(server) 67 | } 68 | -------------------------------------------------------------------------------- /go.mod: -------------------------------------------------------------------------------- 1 | module github.com/TykTechnologies/drl 2 | 3 | go 1.12 4 | 5 | require ( 6 | github.com/davecgh/go-spew v1.1.1 // indirect 7 | github.com/stretchr/testify v1.6.1 8 | gopkg.in/yaml.v3 v3.0.1 // indirect 9 | ) 10 | -------------------------------------------------------------------------------- /go.sum: -------------------------------------------------------------------------------- 1 | github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= 2 | github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c= 3 | github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38= 4 | github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM= 5 | github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4= 6 | github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME= 7 | github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0= 8 | github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg= 9 | gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM= 10 | gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0= 11 | gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM= 12 | gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA= 13 | gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM= 14 | -------------------------------------------------------------------------------- /item.go: -------------------------------------------------------------------------------- 1 | package drl 2 | 3 | import ( 4 | "sync" 5 | "time" 6 | ) 7 | 8 | // Item represents a record in the cache map 9 | type Item struct { 10 | mu sync.RWMutex 11 | data Server 12 | expires *time.Time 13 | } 14 | 15 | func (item *Item) touch(duration time.Duration) { 16 | item.mu.Lock() 17 | expiration := time.Now().Add(duration) 18 | item.expires = &expiration 19 | item.mu.Unlock() 20 | } 21 | 22 | func (item *Item) expired() bool { 23 | var value bool 24 | item.mu.RLock() 25 | if item.expires == nil { 26 | value = true 27 | } else { 28 | value = item.expires.Before(time.Now()) 29 | } 30 | item.mu.RUnlock() 31 | return value 32 | } 33 | -------------------------------------------------------------------------------- /ttlcache.go: -------------------------------------------------------------------------------- 1 | package drl 2 | 3 | import ( 4 | "sync" 5 | "sync/atomic" 6 | "time" 7 | ) 8 | 9 | // Cache is a synchronized map of items that auto-expire once stale 10 | type Cache struct { 11 | mutex sync.RWMutex 12 | ttl time.Duration 13 | items map[string]*Item 14 | stopC chan struct{} 15 | 16 | isClosed int32 17 | } 18 | 19 | // IsOpen returns true if cache is open. If true this means the cache is 20 | // operational, since the cache uses a background goroutine to manage ttl, this 21 | // will be false when that background process has been terminated marking this 22 | // cache unsuitable for use. 23 | func (c *Cache) IsOpen() bool { 24 | return atomic.LoadInt32(&c.isClosed) == OPEN 25 | } 26 | 27 | // Set is a thread-safe way to add new items to the map 28 | func (c *Cache) Set(key string, data Server) { 29 | c.mutex.Lock() 30 | item := &Item{data: data} 31 | item.touch(c.ttl) 32 | c.items[key] = item 33 | c.mutex.Unlock() 34 | } 35 | 36 | // Get is a thread-safe way to lookup items 37 | // Every lookup, also touches the item, hence extending it's life 38 | func (c *Cache) Get(key string) (data Server, found bool) { 39 | c.mutex.Lock() 40 | item, exists := c.items[key] 41 | if !exists || item.expired() { 42 | data = Server{} 43 | found = false 44 | } else { 45 | item.touch(c.ttl) 46 | data = item.data 47 | found = true 48 | } 49 | c.mutex.Unlock() 50 | return 51 | } 52 | 53 | // GetNoExtend is a thread-safe way to lookup items 54 | // Every lookup, also touches the item, hence extending it's life 55 | func (c *Cache) GetNoExtend(key string) (data Server, found bool) { 56 | c.mutex.Lock() 57 | item, exists := c.items[key] 58 | if !exists || item.expired() { 59 | data = Server{} 60 | found = false 61 | } else { 62 | data = item.data 63 | found = true 64 | } 65 | c.mutex.Unlock() 66 | return 67 | } 68 | 69 | // Count returns the number of items in the cache 70 | // (helpful for tracking memory leaks) 71 | func (c *Cache) Count() int { 72 | c.mutex.RLock() 73 | count := len(c.items) 74 | c.mutex.RUnlock() 75 | return count 76 | } 77 | 78 | // Close frees up resources used by the cache. 79 | func (c *Cache) Close() { 80 | wasClosed := atomic.SwapInt32(&c.isClosed, CLOSED) 81 | if wasClosed == 0 { 82 | c.stopC <- struct{}{} 83 | c.clear() 84 | close(c.stopC) 85 | } 86 | } 87 | 88 | func (c *Cache) clear() { 89 | c.mutex.Lock() 90 | c.items = nil 91 | c.mutex.Unlock() 92 | } 93 | 94 | func (c *Cache) cleanup() { 95 | c.mutex.Lock() 96 | for key, item := range c.items { 97 | if item.expired() { 98 | delete(c.items, key) 99 | } 100 | } 101 | c.mutex.Unlock() 102 | } 103 | 104 | var minimumCleanupInterval = time.Second 105 | 106 | func (c *Cache) startCleanupTimer() { 107 | duration := c.ttl 108 | if duration < minimumCleanupInterval { 109 | duration = minimumCleanupInterval 110 | } 111 | t := time.NewTicker(duration) 112 | defer t.Stop() 113 | for { 114 | select { 115 | case <-c.stopC: 116 | return 117 | case <-t.C: 118 | c.cleanup() 119 | } 120 | } 121 | } 122 | 123 | // NewCache is a helper to create instance of the Cache struct 124 | func NewCache(duration time.Duration) *Cache { 125 | cache := &Cache{ 126 | ttl: duration, 127 | items: map[string]*Item{}, 128 | stopC: make(chan struct{}), 129 | } 130 | go cache.startCleanupTimer() 131 | return cache 132 | } 133 | -------------------------------------------------------------------------------- /ttlcache_test.go: -------------------------------------------------------------------------------- 1 | package drl 2 | 3 | import ( 4 | "strconv" 5 | "testing" 6 | "time" 7 | 8 | "github.com/stretchr/testify/assert" 9 | ) 10 | 11 | func init() { 12 | // Modify the minimumCleanupInterval to make expiry faster 13 | minimumCleanupInterval = 100 * time.Millisecond 14 | } 15 | 16 | func TestCache(t *testing.T) { 17 | t.Parallel() 18 | 19 | t.Run("IsOpen", func(t *testing.T) { 20 | t.Parallel() 21 | 22 | c := NewCache(0) 23 | defer c.Close() 24 | 25 | assert.True(t, c.IsOpen(), "expected the cache to be open") 26 | }) 27 | 28 | t.Run("Close", func(t *testing.T) { 29 | t.Parallel() 30 | 31 | c := NewCache(0) 32 | c.Close() 33 | 34 | assert.False(t, c.IsOpen(), "expected the cache to be closed") 35 | }) 36 | 37 | t.Run("Set, Get valid", func(t *testing.T) { 38 | t.Parallel() 39 | 40 | c := NewCache(10 * time.Millisecond) 41 | defer c.Close() 42 | 43 | key := "key" 44 | c.Set(key, Server{}) 45 | _, ok := c.Get(key) 46 | assert.True(t, ok, "expected valid key") 47 | }) 48 | 49 | t.Run("Set, Get expired", func(t *testing.T) { 50 | t.Parallel() 51 | 52 | c := NewCache(0) 53 | defer c.Close() 54 | 55 | key := "key" 56 | c.Set(key, Server{}) 57 | _, ok := c.Get(key) 58 | assert.False(t, ok, "expected key to be expired") 59 | }) 60 | 61 | t.Run("Item evictions", func(t *testing.T) { 62 | t.Parallel() 63 | 64 | // Test with 10 items, calculate tick to hit cleanup interval. 65 | 66 | addItemInterval := minimumCleanupInterval / 10 67 | 68 | // This test ensures that we are correctly evicting expired items. 69 | // The expiry is very short, so we know that all the items added until 70 | // the first expiry will immediately expire. 71 | 72 | c := NewCache(time.Microsecond) 73 | defer c.Close() 74 | 75 | // Offset adding items by half of an addTicketInterval, so we can 76 | // reliably predict how many items will be left in the cache at expiry. 77 | 78 | time.Sleep(addItemInterval / 2) 79 | 80 | // Start a ticker so we may add a new cache item every addItemInterval. 81 | // Add 14 items, 5 of which will be added in the next expiry interval. 82 | 83 | tick := time.NewTicker(addItemInterval) 84 | defer tick.Stop() 85 | 86 | var n int64 87 | for range tick.C { 88 | n++ 89 | if n == 15 { 90 | break 91 | } 92 | c.Set(strconv.FormatInt(n, 10), Server{}) 93 | } 94 | 95 | // Assert the expected cache item count. 96 | 97 | got := c.Count() 98 | want := 5 99 | assert.Equal(t, want, got, "expected %d items to remain in the cache got %d instead", want, got) 100 | }) 101 | } 102 | 103 | func BenchmarkCache_Set(b *testing.B) { 104 | c := NewCache(time.Millisecond) 105 | s := Server{} 106 | key := "1" 107 | defer c.Close() 108 | b.ResetTimer() 109 | b.ReportAllocs() 110 | b.RunParallel(func(pb *testing.PB) { 111 | for pb.Next() { 112 | c.Set(key, s) 113 | } 114 | }) 115 | } 116 | -------------------------------------------------------------------------------- /util.go: -------------------------------------------------------------------------------- 1 | package drl 2 | 3 | import ( 4 | "math" 5 | ) 6 | 7 | // Constants for IsOpen indicators. 8 | // 9 | // Go 1.17 adds atomic.Value.Swap which is great, but 1.19 10 | // adds atomic.Bool and other types. This is a go <1.13 cludge. 11 | const ( 12 | // Zero value - the cache is open and ready to use 13 | OPEN = 0 14 | 15 | // Closed value - the cache shouldn't be used 16 | CLOSED = 1 17 | ) 18 | 19 | func Round(val float64, roundOn float64, places int) (newVal float64) { 20 | var round float64 21 | pow := math.Pow(10, float64(places)) 22 | digit := pow * val 23 | _, div := math.Modf(digit) 24 | if div >= roundOn { 25 | round = math.Ceil(digit) 26 | } else { 27 | round = math.Floor(digit) 28 | } 29 | newVal = round / pow 30 | return 31 | } 32 | --------------------------------------------------------------------------------