| OLD | NEW |
|---|
| (Empty) |
| 1 // Copyright 2015 The LUCI Authors. All rights reserved. | |
| 2 // Use of this source code is governed under the Apache License, Version 2.0 | |
| 3 // that can be found in the LICENSE file. | |
| 4 | |
| 5 package caching | |
| 6 | |
| 7 import ( | |
| 8 "bytes" | |
| 9 "compress/zlib" | |
| 10 "encoding/json" | |
| 11 "errors" | |
| 12 "io/ioutil" | |
| 13 "net/url" | |
| 14 "strings" | |
| 15 "time" | |
| 16 | |
| 17 "github.com/luci/luci-go/common/config" | |
| 18 "golang.org/x/net/context" | |
| 19 ) | |
| 20 | |
| 21 const ( | |
| 22 version = "v2" | |
| 23 ) | |
| 24 | |
| 25 var errCacheMiss = errors.New("cache miss") | |
| 26 | |
| 27 type contentKey byte | |
| 28 | |
| 29 const ( | |
| 30 contentHit = contentKey(iota) | |
| 31 contentErrNoConfig | |
| 32 ) | |
| 33 | |
| 34 // Cache implements a generic caching layer. | |
| 35 // | |
| 36 // The layer has no consistency expectations. | |
| 37 type Cache interface { | |
| 38 // Store adds data to the cache. If value is nil, the cache should inval
idate | |
| 39 // the supplied key. | |
| 40 Store(c context.Context, key string, expire time.Duration, value []byte) | |
| 41 | |
| 42 // Retrieve pulls data from the cache. If no data is available, nil will
be | |
| 43 // returned with no error. | |
| 44 Retrieve(c context.Context, key string) []byte | |
| 45 } | |
| 46 | |
| 47 // Options is the set of configuration options for the caching layer. | |
| 48 type Options struct { | |
| 49 // Cache is the caching layer to use. | |
| 50 Cache Cache | |
| 51 | |
| 52 // Expiration is the maximum amount of time that the configuration shoul
d be | |
| 53 // retained before it must be refreshed. | |
| 54 // | |
| 55 // Due to implementation details of the cache layer, the configuration m
ay be | |
| 56 // retained for less time if necessary. | |
| 57 Expiration time.Duration | |
| 58 } | |
| 59 | |
| 60 // Wrap returns Interface object that adds caching layer on top of given one. | |
| 61 func Wrap(cc config.Interface, o Options) config.Interface { | |
| 62 return &cacheConfig{ | |
| 63 opts: o, | |
| 64 inner: cc, | |
| 65 } | |
| 66 } | |
| 67 | |
| 68 // cacheConfig implements a config.Interface that caches results in MemCache. | |
| 69 type cacheConfig struct { | |
| 70 opts Options | |
| 71 inner config.Interface | |
| 72 } | |
| 73 | |
| 74 func (cc *cacheConfig) ServiceURL(ctx context.Context) url.URL { | |
| 75 return cc.inner.ServiceURL(ctx) | |
| 76 } | |
| 77 | |
| 78 func (cc *cacheConfig) GetConfig(ctx context.Context, configSet, path string, ha
shOnly bool) (*config.Config, error) { | |
| 79 // If we're doing hash-only lookup, we're okay with either full or hash-
only | |
| 80 // result. However, if we have to do the lookup, we will store the resul
t in | |
| 81 // a hash-only cache bucket. | |
| 82 c := config.Config{} | |
| 83 key := cc.cacheKey("configs", "full", configSet, path) | |
| 84 switch err := cc.retrieve(ctx, key, &c); err { | |
| 85 case nil: | |
| 86 // Cache hit. | |
| 87 return &c, nil | |
| 88 case errCacheMiss: | |
| 89 // Cache miss, load from service. | |
| 90 break | |
| 91 default: | |
| 92 // Return cached error. | |
| 93 return nil, err | |
| 94 } | |
| 95 | |
| 96 if hashOnly { | |
| 97 key = cc.cacheKey("configs", "hashOnly", configSet, path) | |
| 98 switch err := cc.retrieve(ctx, key, &c); err { | |
| 99 case nil: | |
| 100 // Cache hit. | |
| 101 return &c, nil | |
| 102 case errCacheMiss: | |
| 103 // Cache miss, load from service. | |
| 104 break | |
| 105 default: | |
| 106 // Return cached error. | |
| 107 return nil, err | |
| 108 } | |
| 109 } | |
| 110 | |
| 111 ic, err := cc.inner.GetConfig(ctx, configSet, path, hashOnly) | |
| 112 if err != nil { | |
| 113 cc.storeErr(ctx, key, err) | |
| 114 return nil, err | |
| 115 } | |
| 116 | |
| 117 cc.store(ctx, key, ic) | |
| 118 if !hashOnly { | |
| 119 cc.store(ctx, cc.configByHashCacheKey(ic.ContentHash), ic.Conten
t) | |
| 120 } | |
| 121 return ic, nil | |
| 122 } | |
| 123 | |
| 124 func (cc *cacheConfig) GetConfigByHash(ctx context.Context, contentHash string)
(string, error) { | |
| 125 c := "" | |
| 126 key := cc.configByHashCacheKey(contentHash) | |
| 127 switch err := cc.retrieve(ctx, key, &c); err { | |
| 128 case nil: | |
| 129 // Cache hit. | |
| 130 return c, nil | |
| 131 case errCacheMiss: | |
| 132 // Cache miss, load from service. | |
| 133 break | |
| 134 default: | |
| 135 // Return cached error. | |
| 136 return "", err | |
| 137 } | |
| 138 | |
| 139 c, err := cc.inner.GetConfigByHash(ctx, contentHash) | |
| 140 if err != nil { | |
| 141 cc.storeErr(ctx, key, err) | |
| 142 return "", err | |
| 143 } | |
| 144 | |
| 145 cc.store(ctx, key, c) | |
| 146 return c, nil | |
| 147 } | |
| 148 | |
| 149 func (cc *cacheConfig) configByHashCacheKey(contentHash string) string { | |
| 150 return cc.cacheKey("configsByHash", contentHash) | |
| 151 } | |
| 152 | |
| 153 func (cc *cacheConfig) GetConfigSetLocation(ctx context.Context, configSet strin
g) (*url.URL, error) { | |
| 154 v := "" | |
| 155 key := cc.cacheKey("configSet", "location", configSet) | |
| 156 switch err := cc.retrieve(ctx, key, &v); err { | |
| 157 case nil: | |
| 158 // Cache hit. | |
| 159 u, err := url.Parse(v) | |
| 160 if err != nil { | |
| 161 return nil, err | |
| 162 } | |
| 163 return u, nil | |
| 164 | |
| 165 case errCacheMiss: | |
| 166 // Cache miss, load from service. | |
| 167 break | |
| 168 default: | |
| 169 // Return cached error. | |
| 170 return nil, err | |
| 171 } | |
| 172 | |
| 173 u, err := cc.inner.GetConfigSetLocation(ctx, configSet) | |
| 174 if err != nil { | |
| 175 cc.storeErr(ctx, key, err) | |
| 176 return nil, err | |
| 177 } | |
| 178 | |
| 179 cc.store(ctx, key, u.String()) | |
| 180 return u, nil | |
| 181 } | |
| 182 | |
| 183 func (cc *cacheConfig) GetProjectConfigs(ctx context.Context, path string, hashe
sOnly bool) ([]config.Config, error) { | |
| 184 var c []config.Config | |
| 185 key := cc.cacheKey("projectConfigs", "full", path) | |
| 186 switch err := cc.retrieve(ctx, key, &c); err { | |
| 187 case nil: | |
| 188 // Cache hit. | |
| 189 return c, nil | |
| 190 case errCacheMiss: | |
| 191 // Cache miss, load from service. | |
| 192 break | |
| 193 default: | |
| 194 // Return cached error. | |
| 195 return nil, err | |
| 196 } | |
| 197 | |
| 198 if hashesOnly { | |
| 199 key = cc.cacheKey("projectConfigs", "hashesOnly", path) | |
| 200 } | |
| 201 | |
| 202 c, err := cc.inner.GetProjectConfigs(ctx, path, hashesOnly) | |
| 203 if err != nil { | |
| 204 cc.storeErr(ctx, key, err) | |
| 205 return nil, err | |
| 206 } | |
| 207 | |
| 208 cc.store(ctx, key, c) | |
| 209 return c, nil | |
| 210 } | |
| 211 | |
| 212 func (cc *cacheConfig) GetProjects(ctx context.Context) ([]config.Project, error
) { | |
| 213 p := []config.Project(nil) | |
| 214 key := cc.cacheKey("projects") | |
| 215 switch err := cc.retrieve(ctx, key, &p); err { | |
| 216 case nil: | |
| 217 // Cache hit. | |
| 218 return p, nil | |
| 219 case errCacheMiss: | |
| 220 // Cache miss, load from service. | |
| 221 break | |
| 222 default: | |
| 223 // Return cached error. | |
| 224 return nil, err | |
| 225 } | |
| 226 | |
| 227 p, err := cc.inner.GetProjects(ctx) | |
| 228 if err != nil { | |
| 229 cc.storeErr(ctx, key, err) | |
| 230 return nil, err | |
| 231 } | |
| 232 | |
| 233 cc.store(ctx, key, p) | |
| 234 return p, nil | |
| 235 } | |
| 236 | |
| 237 func (cc *cacheConfig) GetRefConfigs(ctx context.Context, path string, hashesOnl
y bool) ([]config.Config, error) { | |
| 238 c := []config.Config(nil) | |
| 239 key := cc.cacheKey("refConfigs", "full", path) | |
| 240 switch err := cc.retrieve(ctx, key, &c); err { | |
| 241 case nil: | |
| 242 // Cache hit. | |
| 243 return c, nil | |
| 244 case errCacheMiss: | |
| 245 // Cache miss, load from service. | |
| 246 break | |
| 247 default: | |
| 248 // Return cached error. | |
| 249 return nil, err | |
| 250 } | |
| 251 | |
| 252 if hashesOnly { | |
| 253 key = cc.cacheKey("refConfigs", "hashesOnly", path) | |
| 254 } | |
| 255 | |
| 256 c, err := cc.inner.GetRefConfigs(ctx, path, hashesOnly) | |
| 257 if err != nil { | |
| 258 cc.storeErr(ctx, key, err) | |
| 259 return nil, err | |
| 260 } | |
| 261 | |
| 262 cc.store(ctx, key, c) | |
| 263 return c, nil | |
| 264 } | |
| 265 | |
| 266 func (cc *cacheConfig) GetRefs(ctx context.Context, projectID string) ([]string,
error) { | |
| 267 var refs []string | |
| 268 key := cc.cacheKey("refs", projectID) | |
| 269 switch err := cc.retrieve(ctx, key, &refs); err { | |
| 270 case nil: | |
| 271 // Cache hit. | |
| 272 return refs, nil | |
| 273 case errCacheMiss: | |
| 274 // Cache miss, load from service. | |
| 275 break | |
| 276 default: | |
| 277 // Return cached error. | |
| 278 return nil, err | |
| 279 } | |
| 280 | |
| 281 refs, err := cc.inner.GetRefs(ctx, projectID) | |
| 282 if err != nil { | |
| 283 cc.storeErr(ctx, key, err) | |
| 284 return nil, err | |
| 285 } | |
| 286 | |
| 287 cc.store(ctx, key, refs) | |
| 288 return refs, nil | |
| 289 } | |
| 290 | |
| 291 func (cc *cacheConfig) retrieve(ctx context.Context, key string, v interface{})
error { | |
| 292 if cc.opts.Cache == nil { | |
| 293 return errCacheMiss | |
| 294 } | |
| 295 | |
| 296 // Load the cache value. | |
| 297 d := cc.opts.Cache.Retrieve(ctx, key) | |
| 298 if len(d) == 0 { | |
| 299 return errCacheMiss | |
| 300 } | |
| 301 | |
| 302 // Handle the content key. | |
| 303 switch contentKey(d[0]) { | |
| 304 case contentHit: | |
| 305 d = d[1:] | |
| 306 break | |
| 307 | |
| 308 case contentErrNoConfig: | |
| 309 return config.ErrNoConfig | |
| 310 | |
| 311 default: | |
| 312 // Unknown content key, treat as cache miss. | |
| 313 return errCacheMiss | |
| 314 } | |
| 315 | |
| 316 // Unzip. | |
| 317 zr, err := zlib.NewReader(bytes.NewBuffer(d)) | |
| 318 if err != nil { | |
| 319 return errCacheMiss | |
| 320 } | |
| 321 defer zr.Close() | |
| 322 | |
| 323 rd, err := ioutil.ReadAll(zr) | |
| 324 if err != nil { | |
| 325 return errCacheMiss | |
| 326 } | |
| 327 | |
| 328 // Unpack. | |
| 329 if err := json.Unmarshal(rd, v); err != nil { | |
| 330 return errCacheMiss | |
| 331 } | |
| 332 | |
| 333 return nil | |
| 334 } | |
| 335 | |
| 336 func (cc *cacheConfig) store(ctx context.Context, key string, v interface{}) { | |
| 337 if cc.opts.Cache == nil { | |
| 338 return | |
| 339 } | |
| 340 | |
| 341 // Convert "v" to zlib-compressed JSON. | |
| 342 d, err := json.Marshal(v) | |
| 343 if err != nil { | |
| 344 return | |
| 345 } | |
| 346 | |
| 347 // Write a "content hit" record. | |
| 348 buf := bytes.Buffer{} | |
| 349 buf.WriteByte(byte(contentHit)) | |
| 350 w := zlib.NewWriter(&buf) | |
| 351 _, err = w.Write(d) | |
| 352 if err != nil { | |
| 353 w.Close() | |
| 354 return | |
| 355 } | |
| 356 if err := w.Close(); err != nil { | |
| 357 return | |
| 358 } | |
| 359 | |
| 360 cc.opts.Cache.Store(ctx, key, cc.opts.Expiration, buf.Bytes()) | |
| 361 } | |
| 362 | |
| 363 func (cc *cacheConfig) storeErr(ctx context.Context, key string, err error) { | |
| 364 if cc.opts.Cache == nil { | |
| 365 return | |
| 366 } | |
| 367 | |
| 368 switch err { | |
| 369 case config.ErrNoConfig: | |
| 370 cc.opts.Cache.Store(ctx, key, cc.opts.Expiration, []byte{byte(co
ntentErrNoConfig)}) | |
| 371 | |
| 372 default: | |
| 373 // Don't know how to store this error type. | |
| 374 return | |
| 375 } | |
| 376 } | |
| 377 | |
| 378 // cacheKey constructs a cache key from a set of value segments. | |
| 379 // | |
| 380 // In order to ensure that segments remain distinct in the resulting key, each | |
| 381 // segment is URL query escaped, and segments are joined by the non-escaped | |
| 382 // character, "|". | |
| 383 // | |
| 384 // For example, ["a|b", "c"] => "a%7Cb|c" | |
| 385 func (cc *cacheConfig) cacheKey(values ...string) string { | |
| 386 enc := url.QueryEscape | |
| 387 parts := make([]string, 0, len(values)+1) | |
| 388 parts = append(parts, enc(version)) | |
| 389 for _, v := range values { | |
| 390 parts = append(parts, enc(v)) | |
| 391 } | |
| 392 | |
| 393 return strings.Join(parts, "|") | |
| 394 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2575383002:
Add server/cache support to gaeconfig. (Closed)
