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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 {
Matteo Scandoloed128822020-02-10 15:52:35 -080032 ectdAPI *v3Client.Client
33 keyReservations map[string]*v3Client.LeaseID
34 watchedChannels sync.Map
35 keyReservationsLock sync.RWMutex
36 lockToMutexMap map[string]*v3Concurrency.Mutex
37 lockToSessionMap map[string]*v3Concurrency.Session
38 lockToMutexLock sync.Mutex
Scott Baker2c1c4822019-10-16 11:02:41 -070039}
40
41// NewEtcdClient returns a new client for the Etcd KV store
Rohan Agrawalee87e642020-04-14 10:22:18 +000042func NewEtcdClient(addr string, timeout int, level log.LogLevel) (*EtcdClient, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -070043 duration := GetDuration(timeout)
Rohan Agrawalee87e642020-04-14 10:22:18 +000044 logconfig := log.ConstructZapConfig(log.JSON, level, log.Fields{})
Scott Baker2c1c4822019-10-16 11:02:41 -070045
46 c, err := v3Client.New(v3Client.Config{
47 Endpoints: []string{addr},
48 DialTimeout: duration,
Rohan Agrawalee87e642020-04-14 10:22:18 +000049 LogConfig: &logconfig,
Scott Baker2c1c4822019-10-16 11:02:41 -070050 })
51 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -050052 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -070053 return nil, err
54 }
55
56 reservations := make(map[string]*v3Client.LeaseID)
57 lockMutexMap := make(map[string]*v3Concurrency.Mutex)
58 lockSessionMap := make(map[string]*v3Concurrency.Session)
59
60 return &EtcdClient{ectdAPI: c, keyReservations: reservations, lockToMutexMap: lockMutexMap,
61 lockToSessionMap: lockSessionMap}, nil
62}
63
64// IsConnectionUp returns whether the connection to the Etcd KV store is up. If a timeout occurs then
65// it is assumed the connection is down or unreachable.
npujar5bf737f2020-01-16 19:35:25 +053066func (c *EtcdClient) IsConnectionUp(ctx context.Context) bool {
Scott Baker2c1c4822019-10-16 11:02:41 -070067 // 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 +053068 if _, err := c.Get(ctx, "non-existent-key"); err != nil {
Scott Baker2c1c4822019-10-16 11:02:41 -070069 return false
70 }
npujar5bf737f2020-01-16 19:35:25 +053071 //cancel()
Scott Baker2c1c4822019-10-16 11:02:41 -070072 return true
73}
74
75// List returns an array of key-value pairs with key as a prefix. Timeout defines how long the function will
76// wait for a response
npujar5bf737f2020-01-16 19:35:25 +053077func (c *EtcdClient) List(ctx context.Context, key string) (map[string]*KVPair, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -070078 resp, err := c.ectdAPI.Get(ctx, key, v3Client.WithPrefix())
Scott Baker2c1c4822019-10-16 11:02:41 -070079 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -050080 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -070081 return nil, err
82 }
83 m := make(map[string]*KVPair)
84 for _, ev := range resp.Kvs {
85 m[string(ev.Key)] = NewKVPair(string(ev.Key), ev.Value, "", ev.Lease, ev.Version)
86 }
87 return m, nil
88}
89
90// Get returns a key-value pair for a given key. Timeout defines how long the function will
91// wait for a response
npujar5bf737f2020-01-16 19:35:25 +053092func (c *EtcdClient) Get(ctx context.Context, key string) (*KVPair, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -070093
94 resp, err := c.ectdAPI.Get(ctx, key)
npujar5bf737f2020-01-16 19:35:25 +053095
Scott Baker2c1c4822019-10-16 11:02:41 -070096 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -050097 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -070098 return nil, err
99 }
100 for _, ev := range resp.Kvs {
101 // Only one value is returned
102 return NewKVPair(string(ev.Key), ev.Value, "", ev.Lease, ev.Version), nil
103 }
104 return nil, nil
105}
106
107// Put writes a key-value pair to the KV store. Value can only be a string or []byte since the etcd API
108// accepts only a string as a value for a put operation. Timeout defines how long the function will
109// wait for a response
npujar5bf737f2020-01-16 19:35:25 +0530110func (c *EtcdClient) Put(ctx context.Context, key string, value interface{}) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700111
112 // Validate that we can convert value to a string as etcd API expects a string
113 var val string
114 var er error
115 if val, er = ToString(value); er != nil {
116 return fmt.Errorf("unexpected-type-%T", value)
117 }
118
Scott Baker2c1c4822019-10-16 11:02:41 -0700119 var err error
120 // Check if there is already a lease for this key - if there is then use it, otherwise a PUT will make
121 // that KV key permanent instead of automatically removing it after a lease expiration
Matteo Scandoloed128822020-02-10 15:52:35 -0800122 c.keyReservationsLock.RLock()
123 leaseID, ok := c.keyReservations[key]
124 c.keyReservationsLock.RUnlock()
125 if ok {
Scott Baker2c1c4822019-10-16 11:02:41 -0700126 _, err = c.ectdAPI.Put(ctx, key, val, v3Client.WithLease(*leaseID))
127 } else {
128 _, err = c.ectdAPI.Put(ctx, key, val)
129 }
npujar5bf737f2020-01-16 19:35:25 +0530130
Scott Baker2c1c4822019-10-16 11:02:41 -0700131 if err != nil {
132 switch err {
133 case context.Canceled:
khenaidoob332f9b2020-01-16 16:25:26 -0500134 logger.Warnw("context-cancelled", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700135 case context.DeadlineExceeded:
khenaidoob332f9b2020-01-16 16:25:26 -0500136 logger.Warnw("context-deadline-exceeded", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700137 case v3rpcTypes.ErrEmptyKey:
khenaidoob332f9b2020-01-16 16:25:26 -0500138 logger.Warnw("etcd-client-error", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700139 default:
khenaidoob332f9b2020-01-16 16:25:26 -0500140 logger.Warnw("bad-endpoints", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700141 }
142 return err
143 }
144 return nil
145}
146
147// Delete removes a key from the KV store. Timeout defines how long the function will
148// wait for a response
npujar5bf737f2020-01-16 19:35:25 +0530149func (c *EtcdClient) Delete(ctx context.Context, key string) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700150
Scott Baker2c1c4822019-10-16 11:02:41 -0700151 // delete the key
152 if _, err := c.ectdAPI.Delete(ctx, key); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500153 logger.Errorw("failed-to-delete-key", log.Fields{"key": key, "error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700154 return err
155 }
khenaidoob332f9b2020-01-16 16:25:26 -0500156 logger.Debugw("key(s)-deleted", log.Fields{"key": key})
Scott Baker2c1c4822019-10-16 11:02:41 -0700157 return nil
158}
159
160// Reserve is invoked to acquire a key and set it to a given value. Value can only be a string or []byte since
161// the etcd API accepts only a string. Timeout defines how long the function will wait for a response. TTL
162// defines how long that reservation is valid. When TTL expires the key is unreserved by the KV store itself.
163// If the key is acquired then the value returned will be the value passed in. If the key is already acquired
164// then the value assigned to that key will be returned.
npujar5bf737f2020-01-16 19:35:25 +0530165func (c *EtcdClient) Reserve(ctx context.Context, key string, value interface{}, ttl int64) (interface{}, error) {
Scott Baker2c1c4822019-10-16 11:02:41 -0700166 // Validate that we can convert value to a string as etcd API expects a string
167 var val string
168 var er error
169 if val, er = ToString(value); er != nil {
170 return nil, fmt.Errorf("unexpected-type%T", value)
171 }
172
Thomas Lee S86fc9362019-10-31 11:35:19 +0530173 resp, err := c.ectdAPI.Grant(ctx, ttl)
Scott Baker2c1c4822019-10-16 11:02:41 -0700174 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500175 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -0700176 return nil, err
177 }
178 // Register the lease id
Matteo Scandoloed128822020-02-10 15:52:35 -0800179 c.keyReservationsLock.Lock()
Scott Baker2c1c4822019-10-16 11:02:41 -0700180 c.keyReservations[key] = &resp.ID
Matteo Scandoloed128822020-02-10 15:52:35 -0800181 c.keyReservationsLock.Unlock()
Scott Baker2c1c4822019-10-16 11:02:41 -0700182
183 // Revoke lease if reservation is not successful
184 reservationSuccessful := false
185 defer func() {
186 if !reservationSuccessful {
npujar5bf737f2020-01-16 19:35:25 +0530187 if err = c.ReleaseReservation(context.Background(), key); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500188 logger.Error("cannot-release-lease")
Scott Baker2c1c4822019-10-16 11:02:41 -0700189 }
190 }
191 }()
192
193 // Try to grap the Key with the above lease
194 c.ectdAPI.Txn(context.Background())
195 txn := c.ectdAPI.Txn(context.Background())
196 txn = txn.If(v3Client.Compare(v3Client.Version(key), "=", 0))
197 txn = txn.Then(v3Client.OpPut(key, val, v3Client.WithLease(resp.ID)))
198 txn = txn.Else(v3Client.OpGet(key))
199 result, er := txn.Commit()
200 if er != nil {
201 return nil, er
202 }
203
204 if !result.Succeeded {
205 // Verify whether we are already the owner of that Key
206 if len(result.Responses) > 0 &&
207 len(result.Responses[0].GetResponseRange().Kvs) > 0 {
208 kv := result.Responses[0].GetResponseRange().Kvs[0]
209 if string(kv.Value) == val {
210 reservationSuccessful = true
211 return value, nil
212 }
213 return kv.Value, nil
214 }
215 } else {
216 // Read the Key to ensure this is our Key
npujar5bf737f2020-01-16 19:35:25 +0530217 m, err := c.Get(ctx, key)
Scott Baker2c1c4822019-10-16 11:02:41 -0700218 if err != nil {
219 return nil, err
220 }
221 if m != nil {
222 if m.Key == key && isEqual(m.Value, value) {
223 // My reservation is successful - register it. For now, support is only for 1 reservation per key
224 // per session.
225 reservationSuccessful = true
226 return value, nil
227 }
228 // My reservation has failed. Return the owner of that key
229 return m.Value, nil
230 }
231 }
232 return nil, nil
233}
234
235// ReleaseAllReservations releases all key reservations previously made (using Reserve API)
npujar5bf737f2020-01-16 19:35:25 +0530236func (c *EtcdClient) ReleaseAllReservations(ctx context.Context) error {
Matteo Scandoloed128822020-02-10 15:52:35 -0800237 c.keyReservationsLock.Lock()
238 defer c.keyReservationsLock.Unlock()
Thomas Lee S86fc9362019-10-31 11:35:19 +0530239
Scott Baker2c1c4822019-10-16 11:02:41 -0700240 for key, leaseID := range c.keyReservations {
Thomas Lee S86fc9362019-10-31 11:35:19 +0530241 _, err := c.ectdAPI.Revoke(ctx, *leaseID)
Scott Baker2c1c4822019-10-16 11:02:41 -0700242 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500243 logger.Errorw("cannot-release-reservation", log.Fields{"key": key, "error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700244 return err
245 }
246 delete(c.keyReservations, key)
247 }
248 return nil
249}
250
251// ReleaseReservation releases reservation for a specific key.
npujar5bf737f2020-01-16 19:35:25 +0530252func (c *EtcdClient) ReleaseReservation(ctx context.Context, key string) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700253 // Get the leaseid using the key
khenaidoob332f9b2020-01-16 16:25:26 -0500254 logger.Debugw("Release-reservation", log.Fields{"key": key})
Scott Baker2c1c4822019-10-16 11:02:41 -0700255 var ok bool
256 var leaseID *v3Client.LeaseID
Matteo Scandoloed128822020-02-10 15:52:35 -0800257 c.keyReservationsLock.Lock()
258 defer c.keyReservationsLock.Unlock()
Scott Baker2c1c4822019-10-16 11:02:41 -0700259 if leaseID, ok = c.keyReservations[key]; !ok {
260 return nil
261 }
Thomas Lee S86fc9362019-10-31 11:35:19 +0530262
Scott Baker2c1c4822019-10-16 11:02:41 -0700263 if leaseID != nil {
Thomas Lee S86fc9362019-10-31 11:35:19 +0530264 _, err := c.ectdAPI.Revoke(ctx, *leaseID)
Scott Baker2c1c4822019-10-16 11:02:41 -0700265 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500266 logger.Error(err)
Scott Baker2c1c4822019-10-16 11:02:41 -0700267 return err
268 }
269 delete(c.keyReservations, key)
270 }
271 return nil
272}
273
274// RenewReservation renews a reservation. A reservation will go stale after the specified TTL (Time To Live)
275// period specified when reserving the key
npujar5bf737f2020-01-16 19:35:25 +0530276func (c *EtcdClient) RenewReservation(ctx context.Context, key string) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700277 // Get the leaseid using the key
278 var ok bool
279 var leaseID *v3Client.LeaseID
Matteo Scandoloed128822020-02-10 15:52:35 -0800280 c.keyReservationsLock.RLock()
281 leaseID, ok = c.keyReservations[key]
282 c.keyReservationsLock.RUnlock()
283
284 if !ok {
Scott Baker2c1c4822019-10-16 11:02:41 -0700285 return errors.New("key-not-reserved")
286 }
287
288 if leaseID != nil {
Thomas Lee S86fc9362019-10-31 11:35:19 +0530289 _, err := c.ectdAPI.KeepAliveOnce(ctx, *leaseID)
Scott Baker2c1c4822019-10-16 11:02:41 -0700290 if err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500291 logger.Errorw("lease-may-have-expired", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700292 return err
293 }
294 } else {
295 return errors.New("lease-expired")
296 }
297 return nil
298}
299
300// Watch provides the watch capability on a given key. It returns a channel onto which the callee needs to
301// listen to receive Events.
divyadesai8bf96862020-02-07 12:24:26 +0000302func (c *EtcdClient) Watch(ctx context.Context, key string, withPrefix bool) chan *Event {
Scott Baker2c1c4822019-10-16 11:02:41 -0700303 w := v3Client.NewWatcher(c.ectdAPI)
npujar5bf737f2020-01-16 19:35:25 +0530304 ctx, cancel := context.WithCancel(ctx)
divyadesai8bf96862020-02-07 12:24:26 +0000305 var channel v3Client.WatchChan
306 if withPrefix {
307 channel = w.Watch(ctx, key, v3Client.WithPrefix())
308 } else {
309 channel = w.Watch(ctx, key)
310 }
Scott Baker2c1c4822019-10-16 11:02:41 -0700311
312 // Create a new channel
313 ch := make(chan *Event, maxClientChannelBufferSize)
314
315 // Keep track of the created channels so they can be closed when required
316 channelMap := make(map[chan *Event]v3Client.Watcher)
317 channelMap[ch] = w
318
319 channelMaps := c.addChannelMap(key, channelMap)
320
321 // Changing the log field (from channelMaps) as the underlying logger cannot format the map of channels into a
322 // json format.
khenaidoob332f9b2020-01-16 16:25:26 -0500323 logger.Debugw("watched-channels", log.Fields{"len": len(channelMaps)})
Scott Baker2c1c4822019-10-16 11:02:41 -0700324 // Launch a go routine to listen for updates
325 go c.listenForKeyChange(channel, ch, cancel)
326
327 return ch
328
329}
330
331func (c *EtcdClient) addChannelMap(key string, channelMap map[chan *Event]v3Client.Watcher) []map[chan *Event]v3Client.Watcher {
332 var channels interface{}
333 var exists bool
334
335 if channels, exists = c.watchedChannels.Load(key); exists {
336 channels = append(channels.([]map[chan *Event]v3Client.Watcher), channelMap)
337 } else {
338 channels = []map[chan *Event]v3Client.Watcher{channelMap}
339 }
340 c.watchedChannels.Store(key, channels)
341
342 return channels.([]map[chan *Event]v3Client.Watcher)
343}
344
345func (c *EtcdClient) removeChannelMap(key string, pos int) []map[chan *Event]v3Client.Watcher {
346 var channels interface{}
347 var exists bool
348
349 if channels, exists = c.watchedChannels.Load(key); exists {
350 channels = append(channels.([]map[chan *Event]v3Client.Watcher)[:pos], channels.([]map[chan *Event]v3Client.Watcher)[pos+1:]...)
351 c.watchedChannels.Store(key, channels)
352 }
353
354 return channels.([]map[chan *Event]v3Client.Watcher)
355}
356
357func (c *EtcdClient) getChannelMaps(key string) ([]map[chan *Event]v3Client.Watcher, bool) {
358 var channels interface{}
359 var exists bool
360
361 channels, exists = c.watchedChannels.Load(key)
362
363 if channels == nil {
364 return nil, exists
365 }
366
367 return channels.([]map[chan *Event]v3Client.Watcher), exists
368}
369
370// CloseWatch closes a specific watch. Both the key and the channel are required when closing a watch as there
371// may be multiple listeners on the same key. The previously created channel serves as a key
372func (c *EtcdClient) CloseWatch(key string, ch chan *Event) {
373 // Get the array of channels mapping
374 var watchedChannels []map[chan *Event]v3Client.Watcher
375 var ok bool
Scott Baker2c1c4822019-10-16 11:02:41 -0700376
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() {
Scott Baker2c1c4822019-10-16 11:02:41 -0700427 if err := c.ectdAPI.Close(); err != nil {
khenaidoob332f9b2020-01-16 16:25:26 -0500428 logger.Errorw("error-closing-client", log.Fields{"error": err})
Scott Baker2c1c4822019-10-16 11:02:41 -0700429 }
430}
431
432func (c *EtcdClient) addLockName(lockName string, lock *v3Concurrency.Mutex, session *v3Concurrency.Session) {
433 c.lockToMutexLock.Lock()
434 defer c.lockToMutexLock.Unlock()
435 c.lockToMutexMap[lockName] = lock
436 c.lockToSessionMap[lockName] = session
437}
438
439func (c *EtcdClient) deleteLockName(lockName string) {
440 c.lockToMutexLock.Lock()
441 defer c.lockToMutexLock.Unlock()
442 delete(c.lockToMutexMap, lockName)
443 delete(c.lockToSessionMap, lockName)
444}
445
446func (c *EtcdClient) getLock(lockName string) (*v3Concurrency.Mutex, *v3Concurrency.Session) {
447 c.lockToMutexLock.Lock()
448 defer c.lockToMutexLock.Unlock()
449 var lock *v3Concurrency.Mutex
450 var session *v3Concurrency.Session
451 if l, exist := c.lockToMutexMap[lockName]; exist {
452 lock = l
453 }
454 if s, exist := c.lockToSessionMap[lockName]; exist {
455 session = s
456 }
457 return lock, session
458}
459
npujar5bf737f2020-01-16 19:35:25 +0530460func (c *EtcdClient) AcquireLock(ctx context.Context, lockName string, timeout int) error {
Scott Baker2c1c4822019-10-16 11:02:41 -0700461 session, _ := v3Concurrency.NewSession(c.ectdAPI, v3Concurrency.WithContext(ctx))
462 mu := v3Concurrency.NewMutex(session, "/devicelock_"+lockName)
463 if err := mu.Lock(context.Background()); err != nil {
npujar5bf737f2020-01-16 19:35:25 +0530464 //cancel()
Scott Baker2c1c4822019-10-16 11:02:41 -0700465 return err
466 }
467 c.addLockName(lockName, mu, session)
468 return nil
469}
470
471func (c *EtcdClient) ReleaseLock(lockName string) error {
472 lock, session := c.getLock(lockName)
473 var err error
474 if lock != nil {
475 if e := lock.Unlock(context.Background()); e != nil {
476 err = e
477 }
478 }
479 if session != nil {
480 if e := session.Close(); e != nil {
481 err = e
482 }
483 }
484 c.deleteLockName(lockName)
485
486 return err
487}