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Scott Baker2c1c4822019-10-16 11:02:41 -07001/*
2 * Copyright 2018-present Open Networking Foundation
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 */
16package kvstore
17
18import (
19 "context"
20 "errors"
21 "fmt"
npujar5bf737f2020-01-16 19:35:25 +053022 "sync"
23
serkant.uluderyab38671c2019-11-01 09:35:38 -070024 "github.com/opencord/voltha-lib-go/v3/pkg/log"
Scott Baker2c1c4822019-10-16 11:02:41 -070025 v3Client "go.etcd.io/etcd/clientv3"
26 v3Concurrency "go.etcd.io/etcd/clientv3/concurrency"
27 v3rpcTypes "go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes"
Scott Baker2c1c4822019-10-16 11:02:41 -070028)
29
30// EtcdClient represents the Etcd KV store client
31type EtcdClient struct {
32 ectdAPI *v3Client.Client
33 leaderRev v3Client.Client
34 keyReservations map[string]*v3Client.LeaseID
35 watchedChannels sync.Map
36 writeLock sync.Mutex
37 lockToMutexMap map[string]*v3Concurrency.Mutex
38 lockToSessionMap map[string]*v3Concurrency.Session
39 lockToMutexLock sync.Mutex
40}
41
Thomas Lee S86fc9362019-10-31 11:35:19 +053042// Connection Timeout in Seconds
43var connTimeout int = 2
44
Scott Baker2c1c4822019-10-16 11:02:41 -070045// NewEtcdClient returns a new client for the Etcd KV store
46func NewEtcdClient(addr string, timeout int) (*EtcdClient, error) {
47 duration := GetDuration(timeout)
48
49 c, err := v3Client.New(v3Client.Config{
50 Endpoints: []string{addr},
51 DialTimeout: duration,
52 })
53 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -050054 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -070055 return nil, err
56 }
57
58 reservations := make(map[string]*v3Client.LeaseID)
59 lockMutexMap := make(map[string]*v3Concurrency.Mutex)
60 lockSessionMap := make(map[string]*v3Concurrency.Session)
61
62 return &EtcdClient{ectdAPI: c, keyReservations: reservations, lockToMutexMap: lockMutexMap,
63 lockToSessionMap: lockSessionMap}, nil
64}
65
66// IsConnectionUp returns whether the connection to the Etcd KV store is up. If a timeout occurs then
67// it is assumed the connection is down or unreachable.
npujar5bf737f2020-01-16 19:35:25 +053068func (c *EtcdClient) IsConnectionUp(ctx context.Context) bool {
Scott Baker2c1c4822019-10-16 11:02:41 -070069 // Let's try to get a non existent key. If the connection is up then there will be no error returned.
npujar5bf737f2020-01-16 19:35:25 +053070 if _, err := c.Get(ctx, "non-existent-key"); err != nil {
Scott Baker2c1c4822019-10-16 11:02:41 -070071 return false
72 }
npujar5bf737f2020-01-16 19:35:25 +053073 //cancel()
Scott Baker2c1c4822019-10-16 11:02:41 -070074 return true
75}
76
77// List returns an array of key-value pairs with key as a prefix. Timeout defines how long the function will
78// wait for a response
npujar5bf737f2020-01-16 19:35:25 +053079func (c *EtcdClient) List(ctx context.Context, key string) (map[string]*KVPair, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -070080 resp, err := c.ectdAPI.Get(ctx, key, v3Client.WithPrefix())
Scott Baker2c1c4822019-10-16 11:02:41 -070081 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -050082 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -070083 return nil, err
84 }
85 m := make(map[string]*KVPair)
86 for _, ev := range resp.Kvs {
87 m[string(ev.Key)] = NewKVPair(string(ev.Key), ev.Value, "", ev.Lease, ev.Version)
88 }
89 return m, nil
90}
91
92// Get returns a key-value pair for a given key. Timeout defines how long the function will
93// wait for a response
npujar5bf737f2020-01-16 19:35:25 +053094func (c *EtcdClient) Get(ctx context.Context, key string) (*KVPair, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -070095
96 resp, err := c.ectdAPI.Get(ctx, key)
npujar5bf737f2020-01-16 19:35:25 +053097
Scott Baker2c1c4822019-10-16 11:02:41 -070098 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -050099 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -0700100 return nil, err
101 }
102 for _, ev := range resp.Kvs {
103 // Only one value is returned
104 return NewKVPair(string(ev.Key), ev.Value, "", ev.Lease, ev.Version), nil
105 }
106 return nil, nil
107}
108
109// Put writes a key-value pair to the KV store. Value can only be a string or []byte since the etcd API
110// accepts only a string as a value for a put operation. Timeout defines how long the function will
111// wait for a response
npujar5bf737f2020-01-16 19:35:25 +0530112func (c *EtcdClient) Put(ctx context.Context, key string, value interface{}) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700113
114 // Validate that we can convert value to a string as etcd API expects a string
115 var val string
116 var er error
117 if val, er = ToString(value); er != nil {
118 return fmt.Errorf("unexpected-type-%T", value)
119 }
120
Scott Baker2c1c4822019-10-16 11:02:41 -0700121 c.writeLock.Lock()
122 defer c.writeLock.Unlock()
123
124 var err error
125 // Check if there is already a lease for this key - if there is then use it, otherwise a PUT will make
126 // that KV key permanent instead of automatically removing it after a lease expiration
127 if leaseID, ok := c.keyReservations[key]; ok {
128 _, err = c.ectdAPI.Put(ctx, key, val, v3Client.WithLease(*leaseID))
129 } else {
130 _, err = c.ectdAPI.Put(ctx, key, val)
131 }
npujar5bf737f2020-01-16 19:35:25 +0530132
Scott Baker2c1c4822019-10-16 11:02:41 -0700133 if err != nil {
134 switch err {
135 case context.Canceled:
khenaidoob332f9b2020-01-16 16:25:26 -0500136 logger.Warnw("context-cancelled", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700137 case context.DeadlineExceeded:
khenaidoob332f9b2020-01-16 16:25:26 -0500138 logger.Warnw("context-deadline-exceeded", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700139 case v3rpcTypes.ErrEmptyKey:
khenaidoob332f9b2020-01-16 16:25:26 -0500140 logger.Warnw("etcd-client-error", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700141 default:
khenaidoob332f9b2020-01-16 16:25:26 -0500142 logger.Warnw("bad-endpoints", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700143 }
144 return err
145 }
146 return nil
147}
148
149// Delete removes a key from the KV store. Timeout defines how long the function will
150// wait for a response
npujar5bf737f2020-01-16 19:35:25 +0530151func (c *EtcdClient) Delete(ctx context.Context, key string) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700152
153 c.writeLock.Lock()
154 defer c.writeLock.Unlock()
155
156 // delete the key
157 if _, err := c.ectdAPI.Delete(ctx, key); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500158 logger.Errorw("failed-to-delete-key", log.Fields{"key": key, "error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700159 return err
160 }
khenaidoob332f9b2020-01-16 16:25:26 -0500161 logger.Debugw("key(s)-deleted", log.Fields{"key": key})
Scott Baker2c1c4822019-10-16 11:02:41 -0700162 return nil
163}
164
165// Reserve is invoked to acquire a key and set it to a given value. Value can only be a string or []byte since
166// the etcd API accepts only a string. Timeout defines how long the function will wait for a response. TTL
167// defines how long that reservation is valid. When TTL expires the key is unreserved by the KV store itself.
168// If the key is acquired then the value returned will be the value passed in. If the key is already acquired
169// then the value assigned to that key will be returned.
npujar5bf737f2020-01-16 19:35:25 +0530170func (c *EtcdClient) Reserve(ctx context.Context, key string, value interface{}, ttl int64) (interface{}, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -0700171 // Validate that we can convert value to a string as etcd API expects a string
172 var val string
173 var er error
174 if val, er = ToString(value); er != nil {
175 return nil, fmt.Errorf("unexpected-type%T", value)
176 }
177
Thomas Lee S86fc9362019-10-31 11:35:19 +0530178 resp, err := c.ectdAPI.Grant(ctx, ttl)
Scott Baker2c1c4822019-10-16 11:02:41 -0700179 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500180 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -0700181 return nil, err
182 }
183 // Register the lease id
184 c.writeLock.Lock()
185 c.keyReservations[key] = &resp.ID
186 c.writeLock.Unlock()
187
188 // Revoke lease if reservation is not successful
189 reservationSuccessful := false
190 defer func() {
191 if !reservationSuccessful {
npujar5bf737f2020-01-16 19:35:25 +0530192 if err = c.ReleaseReservation(context.Background(), key); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500193 logger.Error("cannot-release-lease")
Scott Baker2c1c4822019-10-16 11:02:41 -0700194 }
195 }
196 }()
197
198 // Try to grap the Key with the above lease
199 c.ectdAPI.Txn(context.Background())
200 txn := c.ectdAPI.Txn(context.Background())
201 txn = txn.If(v3Client.Compare(v3Client.Version(key), "=", 0))
202 txn = txn.Then(v3Client.OpPut(key, val, v3Client.WithLease(resp.ID)))
203 txn = txn.Else(v3Client.OpGet(key))
204 result, er := txn.Commit()
205 if er != nil {
206 return nil, er
207 }
208
209 if !result.Succeeded {
210 // Verify whether we are already the owner of that Key
211 if len(result.Responses) > 0 &&
212 len(result.Responses[0].GetResponseRange().Kvs) > 0 {
213 kv := result.Responses[0].GetResponseRange().Kvs[0]
214 if string(kv.Value) == val {
215 reservationSuccessful = true
216 return value, nil
217 }
218 return kv.Value, nil
219 }
220 } else {
221 // Read the Key to ensure this is our Key
npujar5bf737f2020-01-16 19:35:25 +0530222 m, err := c.Get(ctx, key)
Scott Baker2c1c4822019-10-16 11:02:41 -0700223 if err != nil {
224 return nil, err
225 }
226 if m != nil {
227 if m.Key == key && isEqual(m.Value, value) {
228 // My reservation is successful - register it. For now, support is only for 1 reservation per key
229 // per session.
230 reservationSuccessful = true
231 return value, nil
232 }
233 // My reservation has failed. Return the owner of that key
234 return m.Value, nil
235 }
236 }
237 return nil, nil
238}
239
240// ReleaseAllReservations releases all key reservations previously made (using Reserve API)
npujar5bf737f2020-01-16 19:35:25 +0530241func (c *EtcdClient) ReleaseAllReservations(ctx context.Context) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700242 c.writeLock.Lock()
243 defer c.writeLock.Unlock()
Thomas Lee S86fc9362019-10-31 11:35:19 +0530244
Scott Baker2c1c4822019-10-16 11:02:41 -0700245 for key, leaseID := range c.keyReservations {
Thomas Lee S86fc9362019-10-31 11:35:19 +0530246 _, err := c.ectdAPI.Revoke(ctx, *leaseID)
Scott Baker2c1c4822019-10-16 11:02:41 -0700247 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500248 logger.Errorw("cannot-release-reservation", log.Fields{"key": key, "error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700249 return err
250 }
251 delete(c.keyReservations, key)
252 }
253 return nil
254}
255
256// ReleaseReservation releases reservation for a specific key.
npujar5bf737f2020-01-16 19:35:25 +0530257func (c *EtcdClient) ReleaseReservation(ctx context.Context, key string) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700258 // Get the leaseid using the key
khenaidoob332f9b2020-01-16 16:25:26 -0500259 logger.Debugw("Release-reservation", log.Fields{"key": key})
Scott Baker2c1c4822019-10-16 11:02:41 -0700260 var ok bool
261 var leaseID *v3Client.LeaseID
262 c.writeLock.Lock()
263 defer c.writeLock.Unlock()
264 if leaseID, ok = c.keyReservations[key]; !ok {
265 return nil
266 }
Thomas Lee S86fc9362019-10-31 11:35:19 +0530267
Scott Baker2c1c4822019-10-16 11:02:41 -0700268 if leaseID != nil {
Thomas Lee S86fc9362019-10-31 11:35:19 +0530269 _, err := c.ectdAPI.Revoke(ctx, *leaseID)
Scott Baker2c1c4822019-10-16 11:02:41 -0700270 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500271 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -0700272 return err
273 }
274 delete(c.keyReservations, key)
275 }
276 return nil
277}
278
279// RenewReservation renews a reservation. A reservation will go stale after the specified TTL (Time To Live)
280// period specified when reserving the key
npujar5bf737f2020-01-16 19:35:25 +0530281func (c *EtcdClient) RenewReservation(ctx context.Context, key string) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700282 // Get the leaseid using the key
283 var ok bool
284 var leaseID *v3Client.LeaseID
285 c.writeLock.Lock()
286 defer c.writeLock.Unlock()
287 if leaseID, ok = c.keyReservations[key]; !ok {
288 return errors.New("key-not-reserved")
289 }
290
291 if leaseID != nil {
Thomas Lee S86fc9362019-10-31 11:35:19 +0530292 _, err := c.ectdAPI.KeepAliveOnce(ctx, *leaseID)
Scott Baker2c1c4822019-10-16 11:02:41 -0700293 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500294 logger.Errorw("lease-may-have-expired", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700295 return err
296 }
297 } else {
298 return errors.New("lease-expired")
299 }
300 return nil
301}
302
303// Watch provides the watch capability on a given key. It returns a channel onto which the callee needs to
304// listen to receive Events.
npujar5bf737f2020-01-16 19:35:25 +0530305func (c *EtcdClient) Watch(ctx context.Context, key string) chan *Event {
Scott Baker2c1c4822019-10-16 11:02:41 -0700306 w := v3Client.NewWatcher(c.ectdAPI)
npujar5bf737f2020-01-16 19:35:25 +0530307 ctx, cancel := context.WithCancel(ctx)
Scott Baker2c1c4822019-10-16 11:02:41 -0700308 channel := w.Watch(ctx, key)
309
310 // Create a new channel
311 ch := make(chan *Event, maxClientChannelBufferSize)
312
313 // Keep track of the created channels so they can be closed when required
314 channelMap := make(map[chan *Event]v3Client.Watcher)
315 channelMap[ch] = w
316
317 channelMaps := c.addChannelMap(key, channelMap)
318
319 // Changing the log field (from channelMaps) as the underlying logger cannot format the map of channels into a
320 // json format.
khenaidoob332f9b2020-01-16 16:25:26 -0500321 logger.Debugw("watched-channels", log.Fields{"len": len(channelMaps)})
Scott Baker2c1c4822019-10-16 11:02:41 -0700322 // Launch a go routine to listen for updates
323 go c.listenForKeyChange(channel, ch, cancel)
324
325 return ch
326
327}
328
329func (c *EtcdClient) addChannelMap(key string, channelMap map[chan *Event]v3Client.Watcher) []map[chan *Event]v3Client.Watcher {
330 var channels interface{}
331 var exists bool
332
333 if channels, exists = c.watchedChannels.Load(key); exists {
334 channels = append(channels.([]map[chan *Event]v3Client.Watcher), channelMap)
335 } else {
336 channels = []map[chan *Event]v3Client.Watcher{channelMap}
337 }
338 c.watchedChannels.Store(key, channels)
339
340 return channels.([]map[chan *Event]v3Client.Watcher)
341}
342
343func (c *EtcdClient) removeChannelMap(key string, pos int) []map[chan *Event]v3Client.Watcher {
344 var channels interface{}
345 var exists bool
346
347 if channels, exists = c.watchedChannels.Load(key); exists {
348 channels = append(channels.([]map[chan *Event]v3Client.Watcher)[:pos], channels.([]map[chan *Event]v3Client.Watcher)[pos+1:]...)
349 c.watchedChannels.Store(key, channels)
350 }
351
352 return channels.([]map[chan *Event]v3Client.Watcher)
353}
354
355func (c *EtcdClient) getChannelMaps(key string) ([]map[chan *Event]v3Client.Watcher, bool) {
356 var channels interface{}
357 var exists bool
358
359 channels, exists = c.watchedChannels.Load(key)
360
361 if channels == nil {
362 return nil, exists
363 }
364
365 return channels.([]map[chan *Event]v3Client.Watcher), exists
366}
367
368// CloseWatch closes a specific watch. Both the key and the channel are required when closing a watch as there
369// may be multiple listeners on the same key. The previously created channel serves as a key
370func (c *EtcdClient) CloseWatch(key string, ch chan *Event) {
371 // Get the array of channels mapping
372 var watchedChannels []map[chan *Event]v3Client.Watcher
373 var ok bool
374 c.writeLock.Lock()
375 defer c.writeLock.Unlock()
376
377 if watchedChannels, ok = c.getChannelMaps(key); !ok {
khenaidoob332f9b2020-01-16 16:25:26 -0500378 logger.Warnw("key-has-no-watched-channels", log.Fields{"key": key})
Scott Baker2c1c4822019-10-16 11:02:41 -0700379 return
380 }
381 // Look for the channels
382 var pos = -1
383 for i, chMap := range watchedChannels {
384 if t, ok := chMap[ch]; ok {
khenaidoob332f9b2020-01-16 16:25:26 -0500385 logger.Debug("channel-found")
Scott Baker2c1c4822019-10-16 11:02:41 -0700386 // Close the etcd watcher before the client channel. This should close the etcd channel as well
387 if err := t.Close(); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500388 logger.Errorw("watcher-cannot-be-closed", log.Fields{"key": key, "error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700389 }
390 pos = i
391 break
392 }
393 }
394
395 channelMaps, _ := c.getChannelMaps(key)
396 // Remove that entry if present
397 if pos >= 0 {
398 channelMaps = c.removeChannelMap(key, pos)
399 }
khenaidoob332f9b2020-01-16 16:25:26 -0500400 logger.Infow("watcher-channel-exiting", log.Fields{"key": key, "channel": channelMaps})
Scott Baker2c1c4822019-10-16 11:02:41 -0700401}
402
403func (c *EtcdClient) listenForKeyChange(channel v3Client.WatchChan, ch chan<- *Event, cancel context.CancelFunc) {
khenaidoob332f9b2020-01-16 16:25:26 -0500404 logger.Debug("start-listening-on-channel ...")
Scott Baker2c1c4822019-10-16 11:02:41 -0700405 defer cancel()
406 defer close(ch)
407 for resp := range channel {
408 for _, ev := range resp.Events {
409 ch <- NewEvent(getEventType(ev), ev.Kv.Key, ev.Kv.Value, ev.Kv.Version)
410 }
411 }
khenaidoob332f9b2020-01-16 16:25:26 -0500412 logger.Debug("stop-listening-on-channel ...")
Scott Baker2c1c4822019-10-16 11:02:41 -0700413}
414
415func getEventType(event *v3Client.Event) int {
416 switch event.Type {
417 case v3Client.EventTypePut:
418 return PUT
419 case v3Client.EventTypeDelete:
420 return DELETE
421 }
422 return UNKNOWN
423}
424
425// Close closes the KV store client
426func (c *EtcdClient) Close() {
427 c.writeLock.Lock()
428 defer c.writeLock.Unlock()
429 if err := c.ectdAPI.Close(); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500430 logger.Errorw("error-closing-client", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700431 }
432}
433
434func (c *EtcdClient) addLockName(lockName string, lock *v3Concurrency.Mutex, session *v3Concurrency.Session) {
435 c.lockToMutexLock.Lock()
436 defer c.lockToMutexLock.Unlock()
437 c.lockToMutexMap[lockName] = lock
438 c.lockToSessionMap[lockName] = session
439}
440
441func (c *EtcdClient) deleteLockName(lockName string) {
442 c.lockToMutexLock.Lock()
443 defer c.lockToMutexLock.Unlock()
444 delete(c.lockToMutexMap, lockName)
445 delete(c.lockToSessionMap, lockName)
446}
447
448func (c *EtcdClient) getLock(lockName string) (*v3Concurrency.Mutex, *v3Concurrency.Session) {
449 c.lockToMutexLock.Lock()
450 defer c.lockToMutexLock.Unlock()
451 var lock *v3Concurrency.Mutex
452 var session *v3Concurrency.Session
453 if l, exist := c.lockToMutexMap[lockName]; exist {
454 lock = l
455 }
456 if s, exist := c.lockToSessionMap[lockName]; exist {
457 session = s
458 }
459 return lock, session
460}
461
npujar5bf737f2020-01-16 19:35:25 +0530462func (c *EtcdClient) AcquireLock(ctx context.Context, lockName string, timeout int) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700463 session, _ := v3Concurrency.NewSession(c.ectdAPI, v3Concurrency.WithContext(ctx))
464 mu := v3Concurrency.NewMutex(session, "/devicelock_"+lockName)
465 if err := mu.Lock(context.Background()); err != nil {
npujar5bf737f2020-01-16 19:35:25 +0530466 //cancel()
Scott Baker2c1c4822019-10-16 11:02:41 -0700467 return err
468 }
469 c.addLockName(lockName, mu, session)
470 return nil
471}
472
473func (c *EtcdClient) ReleaseLock(lockName string) error {
474 lock, session := c.getLock(lockName)
475 var err error
476 if lock != nil {
477 if e := lock.Unlock(context.Background()); e != nil {
478 err = e
479 }
480 }
481 if session != nil {
482 if e := session.Close(); e != nil {
483 err = e
484 }
485 }
486 c.deleteLockName(lockName)
487
488 return err
489}