khenaidoo | cfee5f4 | 2018-07-19 22:47:38 -0400 | [diff] [blame^] | 1 | package kvstore |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "errors" |
| 6 | "bytes" |
| 7 | "sync" |
| 8 | "time" |
| 9 | log "github.com/opencord/voltha-go/common/log" |
| 10 | //log "ciena.com/coordinator/common" |
| 11 | consulapi "github.com/hashicorp/consul/api" |
| 12 | ) |
| 13 | |
| 14 | type channelContextMap struct { |
| 15 | ctx context.Context |
| 16 | channel chan *Event |
| 17 | cancel context.CancelFunc |
| 18 | } |
| 19 | |
| 20 | |
| 21 | // ConsulClient represents the consul KV store client |
| 22 | type ConsulClient struct { |
| 23 | session *consulapi.Session |
| 24 | sessionID string |
| 25 | consul *consulapi.Client |
| 26 | doneCh *chan int |
| 27 | keyReservations map[string]interface{} |
| 28 | watchedChannelsContext map[string][]*channelContextMap |
| 29 | writeLock sync.Mutex |
| 30 | } |
| 31 | |
| 32 | // NewConsulClient returns a new client for the Consul KV store |
| 33 | func NewConsulClient(addr string, timeout int) (*ConsulClient, error) { |
| 34 | |
| 35 | duration := GetDuration(timeout) |
| 36 | |
| 37 | config := consulapi.DefaultConfig() |
| 38 | config.Address = addr |
| 39 | config.WaitTime = duration |
| 40 | consul, err := consulapi.NewClient(config) |
| 41 | if err != nil { |
| 42 | log.Error(err) |
| 43 | return nil, err |
| 44 | } |
| 45 | |
| 46 | doneCh := make(chan int, 1) |
| 47 | wChannelsContext := make(map[string][]*channelContextMap) |
| 48 | reservations := make(map[string]interface{}) |
| 49 | return &ConsulClient{consul: consul, doneCh: &doneCh, watchedChannelsContext: wChannelsContext, keyReservations: reservations}, nil |
| 50 | } |
| 51 | |
| 52 | // List returns an array of key-value pairs with key as a prefix. Timeout defines how long the function will |
| 53 | // wait for a response |
| 54 | func (c *ConsulClient) List(key string, timeout int) (map[string]*KVPair, error) { |
| 55 | duration := GetDuration(timeout) |
| 56 | |
| 57 | kv := c.consul.KV() |
| 58 | var queryOptions consulapi.QueryOptions |
| 59 | queryOptions.WaitTime = duration |
| 60 | // For now we ignore meta data |
| 61 | kvps, _, err := kv.List(key, &queryOptions) |
| 62 | if err != nil { |
| 63 | log.Error(err) |
| 64 | return nil, err |
| 65 | } |
| 66 | m := make(map[string]*KVPair) |
| 67 | for _, kvp := range kvps { |
| 68 | m[string(kvp.Key)] = NewKVPair(string(kvp.Key), kvp.Value, string(kvp.Session), 0) |
| 69 | } |
| 70 | return m, nil |
| 71 | } |
| 72 | |
| 73 | // Get returns a key-value pair for a given key. Timeout defines how long the function will |
| 74 | // wait for a response |
| 75 | func (c *ConsulClient) Get(key string, timeout int) (*KVPair, error) { |
| 76 | |
| 77 | duration := GetDuration(timeout) |
| 78 | |
| 79 | kv := c.consul.KV() |
| 80 | var queryOptions consulapi.QueryOptions |
| 81 | queryOptions.WaitTime = duration |
| 82 | // For now we ignore meta data |
| 83 | kvp, _, err := kv.Get(key, &queryOptions) |
| 84 | if err != nil { |
| 85 | log.Error(err) |
| 86 | return nil, err |
| 87 | } |
| 88 | if kvp != nil { |
| 89 | return NewKVPair(string(kvp.Key), kvp.Value, string(kvp.Session), 0), nil |
| 90 | } |
| 91 | |
| 92 | return nil, nil |
| 93 | } |
| 94 | |
| 95 | // Put writes a key-value pair to the KV store. Value can only be a string or []byte since the consul API |
| 96 | // accepts only a []byte as a value for a put operation. Timeout defines how long the function will |
| 97 | // wait for a response |
| 98 | func (c *ConsulClient) Put(key string, value interface{}, timeout int) error { |
| 99 | |
| 100 | // Validate that we can create a byte array from the value as consul API expects a byte array |
| 101 | var val []byte |
| 102 | var er error |
| 103 | if val, er = ToByte(value); er != nil { |
| 104 | log.Error(er) |
| 105 | return er |
| 106 | } |
| 107 | |
| 108 | // Create a key value pair |
| 109 | kvp := consulapi.KVPair{Key: key, Value: val} |
| 110 | kv := c.consul.KV() |
| 111 | var writeOptions consulapi.WriteOptions |
| 112 | c.writeLock.Lock() |
| 113 | defer c.writeLock.Unlock() |
| 114 | _, err := kv.Put(&kvp, &writeOptions) |
| 115 | if err != nil { |
| 116 | log.Error(err) |
| 117 | return err |
| 118 | } |
| 119 | return nil |
| 120 | } |
| 121 | |
| 122 | // Delete removes a key from the KV store. Timeout defines how long the function will |
| 123 | // wait for a response |
| 124 | func (c *ConsulClient) Delete(key string, timeout int) error { |
| 125 | kv := c.consul.KV() |
| 126 | var writeOptions consulapi.WriteOptions |
| 127 | c.writeLock.Lock() |
| 128 | defer c.writeLock.Unlock() |
| 129 | _, err := kv.Delete(key, &writeOptions) |
| 130 | if err != nil { |
| 131 | log.Error(err) |
| 132 | return err |
| 133 | } |
| 134 | return nil |
| 135 | } |
| 136 | |
| 137 | func (c *ConsulClient) deleteSession() { |
| 138 | if c.sessionID != "" { |
| 139 | log.Debug("cleaning-up-session") |
| 140 | session := c.consul.Session() |
| 141 | _, err := session.Destroy(c.sessionID, nil) |
| 142 | if err != nil { |
| 143 | log.Errorw("error-cleaning-session", log.Fields{"session":c.sessionID, "error":err}) |
| 144 | } |
| 145 | } |
| 146 | c.sessionID = "" |
| 147 | c.session = nil |
| 148 | } |
| 149 | |
| 150 | func (c *ConsulClient) createSession(ttl int64, retries int) (*consulapi.Session, string, error) { |
| 151 | session := c.consul.Session() |
| 152 | entry := &consulapi.SessionEntry{ |
| 153 | Behavior: consulapi.SessionBehaviorDelete, |
| 154 | TTL: "10s", // strconv.FormatInt(ttl, 10) + "s", // disable ttl |
| 155 | } |
| 156 | |
| 157 | for { |
| 158 | id, meta, err := session.Create(entry, nil) |
| 159 | if err != nil { |
| 160 | log.Errorw("create-session-error", log.Fields{"error":err}) |
| 161 | if retries == 0 { |
| 162 | return nil, "", err |
| 163 | } |
| 164 | } else if meta.RequestTime == 0 { |
| 165 | log.Errorw("create-session-bad-meta-data", log.Fields{"meta-data":meta}) |
| 166 | if retries == 0 { |
| 167 | return nil, "", errors.New("bad-meta-data") |
| 168 | } |
| 169 | } else if id == "" { |
| 170 | log.Error("create-session-nil-id") |
| 171 | if retries == 0 { |
| 172 | return nil, "", errors.New("ID-nil") |
| 173 | } |
| 174 | } else { |
| 175 | return session, id, nil |
| 176 | } |
| 177 | // If retry param is -1 we will retry indefinitely |
| 178 | if retries > 0 { |
| 179 | retries-- |
| 180 | } |
| 181 | log.Debug("retrying-session-create-after-a-second-delay") |
| 182 | time.Sleep(time.Duration(1) * time.Second) |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | |
| 187 | // Helper function to verify mostly whether the content of two interface types are the same. Focus is []byte and |
| 188 | // string types |
| 189 | func isEqual(val1 interface{}, val2 interface{}) bool { |
| 190 | b1, err := ToByte(val1) |
| 191 | b2, er := ToByte(val2) |
| 192 | if err == nil && er == nil { |
| 193 | return bytes.Equal(b1, b2) |
| 194 | } |
| 195 | return val1 == val2 |
| 196 | } |
| 197 | |
| 198 | // Reserve is invoked to acquire a key and set it to a given value. Value can only be a string or []byte since |
| 199 | // the consul API accepts only a []byte. Timeout defines how long the function will wait for a response. TTL |
| 200 | // defines how long that reservation is valid. When TTL expires the key is unreserved by the KV store itself. |
| 201 | // If the key is acquired then the value returned will be the value passed in. If the key is already acquired |
| 202 | // then the value assigned to that key will be returned. |
| 203 | func (c *ConsulClient) Reserve(key string, value interface{}, ttl int64) (interface{}, error) { |
| 204 | |
| 205 | // Validate that we can create a byte array from the value as consul API expects a byte array |
| 206 | var val []byte |
| 207 | var er error |
| 208 | if val, er = ToByte(value); er != nil { |
| 209 | log.Error(er) |
| 210 | return nil, er |
| 211 | } |
| 212 | |
| 213 | // Cleanup any existing session and recreate new ones. A key is reserved against a session |
| 214 | if c.sessionID != "" { |
| 215 | c.deleteSession() |
| 216 | } |
| 217 | |
| 218 | // Clear session if reservation is not successful |
| 219 | reservationSuccessful := false |
| 220 | defer func() { |
| 221 | if !reservationSuccessful { |
| 222 | log.Debug("deleting-session") |
| 223 | c.deleteSession() |
| 224 | } |
| 225 | }() |
| 226 | |
| 227 | session, sessionID, err := c.createSession(ttl, -1) |
| 228 | if err != nil { |
| 229 | log.Errorw("no-session-created", log.Fields{"error":err}) |
| 230 | return "", errors.New("no-session-created") |
| 231 | } |
| 232 | log.Debugw("session-created", log.Fields{"session-id":sessionID}) |
| 233 | c.sessionID = sessionID |
| 234 | c.session = session |
| 235 | |
| 236 | // Try to grap the Key using the session |
| 237 | kv := c.consul.KV() |
| 238 | kvp := consulapi.KVPair{Key: key, Value: val, Session: c.sessionID} |
| 239 | result, _, err := kv.Acquire(&kvp, nil) |
| 240 | if err != nil { |
| 241 | log.Errorw("error-acquiring-keys", log.Fields{"error":err}) |
| 242 | return nil, err |
| 243 | } |
| 244 | |
| 245 | log.Debugw("key-acquired", log.Fields{"key":key, "status":result}) |
| 246 | |
| 247 | // Irrespective whether we were successful in acquiring the key, let's read it back and see if it's us. |
| 248 | m, err := c.Get(key, defaultKVGetTimeout) |
| 249 | if err != nil { |
| 250 | return nil, err |
| 251 | } |
| 252 | if m != nil { |
| 253 | log.Debugw("response-received", log.Fields{"key":m.Key, "m.value":string(m.Value.([]byte)), "value":value}) |
| 254 | if m.Key == key && isEqual(m.Value, value) { |
| 255 | // My reservation is successful - register it. For now, support is only for 1 reservation per key |
| 256 | // per session. |
| 257 | reservationSuccessful = true |
| 258 | c.writeLock.Lock() |
| 259 | c.keyReservations[key] = m.Value |
| 260 | c.writeLock.Unlock() |
| 261 | return m.Value, nil |
| 262 | } |
| 263 | // My reservation has failed. Return the owner of that key |
| 264 | return m.Value, nil |
| 265 | } |
| 266 | return nil, nil |
| 267 | } |
| 268 | |
| 269 | // ReleaseAllReservations releases all key reservations previously made (using Reserve API) |
| 270 | func (c *ConsulClient) ReleaseAllReservations() error { |
| 271 | kv := c.consul.KV() |
| 272 | var kvp consulapi.KVPair |
| 273 | var result bool |
| 274 | var err error |
| 275 | |
| 276 | c.writeLock.Lock() |
| 277 | defer c.writeLock.Unlock() |
| 278 | |
| 279 | for key, value := range c.keyReservations { |
| 280 | kvp = consulapi.KVPair{Key: key, Value: value.([]byte), Session: c.sessionID} |
| 281 | result, _, err = kv.Release(&kvp, nil) |
| 282 | if err != nil { |
| 283 | log.Errorw("cannot-release-reservation", log.Fields{"key":key, "error":err}) |
| 284 | return err |
| 285 | } |
| 286 | if !result { |
| 287 | log.Errorw("cannot-release-reservation", log.Fields{"key":key}) |
| 288 | } |
| 289 | delete(c.keyReservations, key) |
| 290 | } |
| 291 | return nil |
| 292 | } |
| 293 | |
| 294 | // ReleaseReservation releases reservation for a specific key. |
| 295 | func (c *ConsulClient) ReleaseReservation(key string) error { |
| 296 | var ok bool |
| 297 | var reservedValue interface{} |
| 298 | c.writeLock.Lock() |
| 299 | defer c.writeLock.Unlock() |
| 300 | if reservedValue, ok = c.keyReservations[key]; !ok { |
| 301 | return errors.New("key-not-reserved:" + key) |
| 302 | } |
| 303 | // Release the reservation |
| 304 | kv := c.consul.KV() |
| 305 | kvp := consulapi.KVPair{Key: key, Value: reservedValue.([]byte), Session: c.sessionID} |
| 306 | |
| 307 | result, _, er := kv.Release(&kvp, nil) |
| 308 | if er != nil { |
| 309 | return er |
| 310 | } |
| 311 | // Remove that key entry on success |
| 312 | if result { |
| 313 | delete(c.keyReservations, key) |
| 314 | return nil |
| 315 | } |
| 316 | return errors.New("key-cannot-be-unreserved") |
| 317 | } |
| 318 | |
| 319 | // RenewReservation renews a reservation. A reservation will go stale after the specified TTL (Time To Live) |
| 320 | // period specified when reserving the key |
| 321 | func (c *ConsulClient) RenewReservation(key string) error { |
| 322 | // In the case of Consul, renew reservation of a reserve key only require renewing the client session. |
| 323 | |
| 324 | c.writeLock.Lock() |
| 325 | defer c.writeLock.Unlock() |
| 326 | |
| 327 | // Verify the key was reserved |
| 328 | if _, ok := c.keyReservations[key]; !ok { |
| 329 | return errors.New("key-not-reserved") |
| 330 | } |
| 331 | |
| 332 | if c.session == nil { |
| 333 | return errors.New("no-session-exist") |
| 334 | } |
| 335 | |
| 336 | var writeOptions consulapi.WriteOptions |
| 337 | if _, _, err := c.session.Renew(c.sessionID, &writeOptions); err != nil { |
| 338 | return err |
| 339 | } |
| 340 | return nil |
| 341 | } |
| 342 | |
| 343 | // Watch provides the watch capability on a given key. It returns a channel onto which the callee needs to |
| 344 | // listen to receive Events. |
| 345 | func (c *ConsulClient) Watch(key string) chan *Event { |
| 346 | |
| 347 | // Create a new channel |
| 348 | ch := make(chan *Event, maxClientChannelBufferSize) |
| 349 | |
| 350 | // Create a context to track this request |
| 351 | watchContext, cFunc := context.WithCancel(context.Background()) |
| 352 | |
| 353 | // Save the channel and context reference for later |
| 354 | c.writeLock.Lock() |
| 355 | defer c.writeLock.Unlock() |
| 356 | ccm := channelContextMap{channel: ch, ctx: watchContext, cancel: cFunc} |
| 357 | c.watchedChannelsContext[key] = append(c.watchedChannelsContext[key], &ccm) |
| 358 | |
| 359 | // Launch a go routine to listen for updates |
| 360 | go c.listenForKeyChange(watchContext, key, ch) |
| 361 | |
| 362 | return ch |
| 363 | } |
| 364 | |
| 365 | // CloseWatch closes a specific watch. Both the key and the channel are required when closing a watch as there |
| 366 | // may be multiple listeners on the same key. The previously created channel serves as a key |
| 367 | func (c *ConsulClient) CloseWatch(key string, ch chan *Event) { |
| 368 | // First close the context |
| 369 | var ok bool |
| 370 | var watchedChannelsContexts []*channelContextMap |
| 371 | c.writeLock.Lock() |
| 372 | defer c.writeLock.Unlock() |
| 373 | if watchedChannelsContexts, ok = c.watchedChannelsContext[key]; !ok { |
| 374 | log.Errorw("key-has-no-watched-context-or-channel", log.Fields{"key":key}) |
| 375 | return |
| 376 | } |
| 377 | // Look for the channels |
| 378 | var pos = -1 |
| 379 | for i, chCtxMap := range watchedChannelsContexts { |
| 380 | if chCtxMap.channel == ch { |
| 381 | log.Debug("channel-found") |
| 382 | chCtxMap.cancel() |
| 383 | //close the channel |
| 384 | close(ch) |
| 385 | pos = i |
| 386 | break |
| 387 | } |
| 388 | } |
| 389 | // Remove that entry if present |
| 390 | if pos >= 0 { |
| 391 | c.watchedChannelsContext[key] = append(c.watchedChannelsContext[key][:pos], c.watchedChannelsContext[key][pos+1:]...) |
| 392 | } |
| 393 | log.Debugw("watched-channel-exiting", log.Fields{"key":key, "channel":c.watchedChannelsContext[key]}) |
| 394 | } |
| 395 | |
| 396 | func (c *ConsulClient) isKVEqual(kv1 *consulapi.KVPair, kv2 *consulapi.KVPair) bool { |
| 397 | if (kv1 == nil) && (kv2 == nil) { |
| 398 | return true |
| 399 | } else if (kv1 == nil) || (kv2 == nil) { |
| 400 | return false |
| 401 | } |
| 402 | // Both the KV should be non-null here |
| 403 | if kv1.Key != kv2.Key || |
| 404 | !bytes.Equal(kv1.Value, kv2.Value) || |
| 405 | kv1.Session != kv2.Session || |
| 406 | kv1.LockIndex != kv2.LockIndex || |
| 407 | kv1.ModifyIndex != kv2.ModifyIndex { |
| 408 | return false |
| 409 | } |
| 410 | return true |
| 411 | } |
| 412 | |
| 413 | func (c *ConsulClient) listenForKeyChange(watchContext context.Context, key string, ch chan *Event) { |
| 414 | log.Debugw("start-watching-channel", log.Fields{"key":key, "channel":ch}) |
| 415 | |
| 416 | defer c.CloseWatch(key, ch) |
| 417 | duration := GetDuration(defaultKVGetTimeout) |
| 418 | kv := c.consul.KV() |
| 419 | var queryOptions consulapi.QueryOptions |
| 420 | queryOptions.WaitTime = duration |
| 421 | |
| 422 | // Get the existing value, if any |
| 423 | previousKVPair, meta, err := kv.Get(key, &queryOptions) |
| 424 | if err != nil { |
| 425 | log.Debug(err) |
| 426 | } |
| 427 | lastIndex := meta.LastIndex |
| 428 | |
| 429 | // Wait for change. Push any change onto the channel and keep waiting for new update |
| 430 | //var waitOptions consulapi.QueryOptions |
| 431 | var pair *consulapi.KVPair |
| 432 | //watchContext, _ := context.WithCancel(context.Background()) |
| 433 | waitOptions := queryOptions.WithContext(watchContext) |
| 434 | for { |
| 435 | //waitOptions = consulapi.QueryOptions{WaitIndex: lastIndex} |
| 436 | waitOptions.WaitIndex = lastIndex |
| 437 | pair, meta, err = kv.Get(key, waitOptions) |
| 438 | select { |
| 439 | case <-watchContext.Done(): |
| 440 | log.Debug("done-event-received-exiting") |
| 441 | return |
| 442 | default: |
| 443 | if err != nil { |
| 444 | log.Warnw("error-from-watch", log.Fields{"error":err}) |
| 445 | ch <- NewEvent(CONNECTIONDOWN, key, []byte("")) |
| 446 | } else { |
| 447 | log.Debugw("index-state", log.Fields{"lastindex":lastIndex, "newindex":meta.LastIndex, "key":key}) |
| 448 | } |
| 449 | } |
| 450 | if err != nil { |
| 451 | log.Debug(err) |
| 452 | // On error, block for 10 milliseconds to prevent endless loop |
| 453 | time.Sleep(10 * time.Millisecond) |
| 454 | } else if meta.LastIndex <= lastIndex { |
| 455 | log.Info("no-index-change-or-negative") |
| 456 | } else { |
| 457 | log.Debugw("update-received", log.Fields{"pair":pair}) |
| 458 | if pair == nil { |
| 459 | ch <- NewEvent(DELETE, key, []byte("")) |
| 460 | } else if !c.isKVEqual(pair, previousKVPair) { |
| 461 | // Push the change onto the channel if the data has changed |
| 462 | // For now just assume it's a PUT change |
| 463 | log.Debugw("pair-details", log.Fields{"session":pair.Session, "key":pair.Key, "value":pair.Value}) |
| 464 | ch <- NewEvent(PUT, pair.Key, pair.Value) |
| 465 | } |
| 466 | previousKVPair = pair |
| 467 | lastIndex = meta.LastIndex |
| 468 | } |
| 469 | } |
| 470 | } |
| 471 | |
| 472 | // Close closes the KV store client |
| 473 | func (c *ConsulClient) Close() { |
| 474 | var writeOptions consulapi.WriteOptions |
| 475 | // Inform any goroutine it's time to say goodbye. |
| 476 | c.writeLock.Lock() |
| 477 | defer c.writeLock.Unlock() |
| 478 | if c.doneCh != nil { |
| 479 | close(*c.doneCh) |
| 480 | } |
| 481 | |
| 482 | // Clear the sessionID |
| 483 | if _, err := c.consul.Session().Destroy(c.sessionID, &writeOptions); err != nil { |
| 484 | log.Errorw("error-closing-client", log.Fields{"error":err}) |
| 485 | } |
| 486 | } |