| /* |
| * Copyright 2018-present Open Networking Foundation |
| |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package kvstore |
| |
| import ( |
| "context" |
| "errors" |
| "fmt" |
| "sync" |
| "time" |
| |
| "github.com/opencord/voltha-lib-go/v4/pkg/log" |
| v3Client "go.etcd.io/etcd/clientv3" |
| v3Concurrency "go.etcd.io/etcd/clientv3/concurrency" |
| v3rpcTypes "go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes" |
| ) |
| |
| // EtcdClient represents the Etcd KV store client |
| type EtcdClient struct { |
| ectdAPI *v3Client.Client |
| keyReservations map[string]*v3Client.LeaseID |
| watchedChannels sync.Map |
| keyReservationsLock sync.RWMutex |
| lockToMutexMap map[string]*v3Concurrency.Mutex |
| lockToSessionMap map[string]*v3Concurrency.Session |
| lockToMutexLock sync.Mutex |
| } |
| |
| // NewEtcdClient returns a new client for the Etcd KV store |
| func NewEtcdClient(ctx context.Context, addr string, timeout time.Duration, level log.LogLevel) (*EtcdClient, error) { |
| logconfig := log.ConstructZapConfig(log.JSON, level, log.Fields{}) |
| |
| c, err := v3Client.New(v3Client.Config{ |
| Endpoints: []string{addr}, |
| DialTimeout: timeout, |
| LogConfig: &logconfig, |
| }) |
| if err != nil { |
| logger.Error(ctx, err) |
| return nil, err |
| } |
| |
| reservations := make(map[string]*v3Client.LeaseID) |
| lockMutexMap := make(map[string]*v3Concurrency.Mutex) |
| lockSessionMap := make(map[string]*v3Concurrency.Session) |
| |
| return &EtcdClient{ectdAPI: c, keyReservations: reservations, lockToMutexMap: lockMutexMap, |
| lockToSessionMap: lockSessionMap}, nil |
| } |
| |
| // IsConnectionUp returns whether the connection to the Etcd KV store is up. If a timeout occurs then |
| // it is assumed the connection is down or unreachable. |
| func (c *EtcdClient) IsConnectionUp(ctx context.Context) bool { |
| // Let's try to get a non existent key. If the connection is up then there will be no error returned. |
| if _, err := c.Get(ctx, "non-existent-key"); err != nil { |
| return false |
| } |
| //cancel() |
| return true |
| } |
| |
| // List returns an array of key-value pairs with key as a prefix. Timeout defines how long the function will |
| // wait for a response |
| func (c *EtcdClient) List(ctx context.Context, key string) (map[string]*KVPair, error) { |
| resp, err := c.ectdAPI.Get(ctx, key, v3Client.WithPrefix()) |
| if err != nil { |
| logger.Error(ctx, err) |
| return nil, err |
| } |
| m := make(map[string]*KVPair) |
| for _, ev := range resp.Kvs { |
| m[string(ev.Key)] = NewKVPair(string(ev.Key), ev.Value, "", ev.Lease, ev.Version) |
| } |
| return m, nil |
| } |
| |
| // Get returns a key-value pair for a given key. Timeout defines how long the function will |
| // wait for a response |
| func (c *EtcdClient) Get(ctx context.Context, key string) (*KVPair, error) { |
| |
| resp, err := c.ectdAPI.Get(ctx, key) |
| |
| if err != nil { |
| logger.Error(ctx, err) |
| return nil, err |
| } |
| for _, ev := range resp.Kvs { |
| // Only one value is returned |
| return NewKVPair(string(ev.Key), ev.Value, "", ev.Lease, ev.Version), nil |
| } |
| return nil, nil |
| } |
| |
| // Put writes a key-value pair to the KV store. Value can only be a string or []byte since the etcd API |
| // accepts only a string as a value for a put operation. Timeout defines how long the function will |
| // wait for a response |
| func (c *EtcdClient) Put(ctx context.Context, key string, value interface{}) error { |
| |
| // Validate that we can convert value to a string as etcd API expects a string |
| var val string |
| var er error |
| if val, er = ToString(value); er != nil { |
| return fmt.Errorf("unexpected-type-%T", value) |
| } |
| |
| var err error |
| // Check if there is already a lease for this key - if there is then use it, otherwise a PUT will make |
| // that KV key permanent instead of automatically removing it after a lease expiration |
| c.keyReservationsLock.RLock() |
| leaseID, ok := c.keyReservations[key] |
| c.keyReservationsLock.RUnlock() |
| if ok { |
| _, err = c.ectdAPI.Put(ctx, key, val, v3Client.WithLease(*leaseID)) |
| } else { |
| _, err = c.ectdAPI.Put(ctx, key, val) |
| } |
| |
| if err != nil { |
| switch err { |
| case context.Canceled: |
| logger.Warnw(ctx, "context-cancelled", log.Fields{"error": err}) |
| case context.DeadlineExceeded: |
| logger.Warnw(ctx, "context-deadline-exceeded", log.Fields{"error": err}) |
| case v3rpcTypes.ErrEmptyKey: |
| logger.Warnw(ctx, "etcd-client-error", log.Fields{"error": err}) |
| default: |
| logger.Warnw(ctx, "bad-endpoints", log.Fields{"error": err}) |
| } |
| return err |
| } |
| return nil |
| } |
| |
| // Delete removes a key from the KV store. Timeout defines how long the function will |
| // wait for a response |
| func (c *EtcdClient) Delete(ctx context.Context, key string) error { |
| |
| // delete the key |
| if _, err := c.ectdAPI.Delete(ctx, key); err != nil { |
| logger.Errorw(ctx, "failed-to-delete-key", log.Fields{"key": key, "error": err}) |
| return err |
| } |
| logger.Debugw(ctx, "key(s)-deleted", log.Fields{"key": key}) |
| return nil |
| } |
| |
| // Reserve is invoked to acquire a key and set it to a given value. Value can only be a string or []byte since |
| // the etcd API accepts only a string. Timeout defines how long the function will wait for a response. TTL |
| // defines how long that reservation is valid. When TTL expires the key is unreserved by the KV store itself. |
| // If the key is acquired then the value returned will be the value passed in. If the key is already acquired |
| // then the value assigned to that key will be returned. |
| func (c *EtcdClient) Reserve(ctx context.Context, key string, value interface{}, ttl time.Duration) (interface{}, error) { |
| // Validate that we can convert value to a string as etcd API expects a string |
| var val string |
| var er error |
| if val, er = ToString(value); er != nil { |
| return nil, fmt.Errorf("unexpected-type%T", value) |
| } |
| |
| resp, err := c.ectdAPI.Grant(ctx, int64(ttl.Seconds())) |
| if err != nil { |
| logger.Error(ctx, err) |
| return nil, err |
| } |
| // Register the lease id |
| c.keyReservationsLock.Lock() |
| c.keyReservations[key] = &resp.ID |
| c.keyReservationsLock.Unlock() |
| |
| // Revoke lease if reservation is not successful |
| reservationSuccessful := false |
| defer func() { |
| if !reservationSuccessful { |
| if err = c.ReleaseReservation(context.Background(), key); err != nil { |
| logger.Error(ctx, "cannot-release-lease") |
| } |
| } |
| }() |
| |
| // Try to grap the Key with the above lease |
| c.ectdAPI.Txn(context.Background()) |
| txn := c.ectdAPI.Txn(context.Background()) |
| txn = txn.If(v3Client.Compare(v3Client.Version(key), "=", 0)) |
| txn = txn.Then(v3Client.OpPut(key, val, v3Client.WithLease(resp.ID))) |
| txn = txn.Else(v3Client.OpGet(key)) |
| result, er := txn.Commit() |
| if er != nil { |
| return nil, er |
| } |
| |
| if !result.Succeeded { |
| // Verify whether we are already the owner of that Key |
| if len(result.Responses) > 0 && |
| len(result.Responses[0].GetResponseRange().Kvs) > 0 { |
| kv := result.Responses[0].GetResponseRange().Kvs[0] |
| if string(kv.Value) == val { |
| reservationSuccessful = true |
| return value, nil |
| } |
| return kv.Value, nil |
| } |
| } else { |
| // Read the Key to ensure this is our Key |
| m, err := c.Get(ctx, key) |
| if err != nil { |
| return nil, err |
| } |
| if m != nil { |
| if m.Key == key && isEqual(m.Value, value) { |
| // My reservation is successful - register it. For now, support is only for 1 reservation per key |
| // per session. |
| reservationSuccessful = true |
| return value, nil |
| } |
| // My reservation has failed. Return the owner of that key |
| return m.Value, nil |
| } |
| } |
| return nil, nil |
| } |
| |
| // ReleaseAllReservations releases all key reservations previously made (using Reserve API) |
| func (c *EtcdClient) ReleaseAllReservations(ctx context.Context) error { |
| c.keyReservationsLock.Lock() |
| defer c.keyReservationsLock.Unlock() |
| |
| for key, leaseID := range c.keyReservations { |
| _, err := c.ectdAPI.Revoke(ctx, *leaseID) |
| if err != nil { |
| logger.Errorw(ctx, "cannot-release-reservation", log.Fields{"key": key, "error": err}) |
| return err |
| } |
| delete(c.keyReservations, key) |
| } |
| return nil |
| } |
| |
| // ReleaseReservation releases reservation for a specific key. |
| func (c *EtcdClient) ReleaseReservation(ctx context.Context, key string) error { |
| // Get the leaseid using the key |
| logger.Debugw(ctx, "Release-reservation", log.Fields{"key": key}) |
| var ok bool |
| var leaseID *v3Client.LeaseID |
| c.keyReservationsLock.Lock() |
| defer c.keyReservationsLock.Unlock() |
| if leaseID, ok = c.keyReservations[key]; !ok { |
| return nil |
| } |
| |
| if leaseID != nil { |
| _, err := c.ectdAPI.Revoke(ctx, *leaseID) |
| if err != nil { |
| logger.Error(ctx, err) |
| return err |
| } |
| delete(c.keyReservations, key) |
| } |
| return nil |
| } |
| |
| // RenewReservation renews a reservation. A reservation will go stale after the specified TTL (Time To Live) |
| // period specified when reserving the key |
| func (c *EtcdClient) RenewReservation(ctx context.Context, key string) error { |
| // Get the leaseid using the key |
| var ok bool |
| var leaseID *v3Client.LeaseID |
| c.keyReservationsLock.RLock() |
| leaseID, ok = c.keyReservations[key] |
| c.keyReservationsLock.RUnlock() |
| |
| if !ok { |
| return errors.New("key-not-reserved") |
| } |
| |
| if leaseID != nil { |
| _, err := c.ectdAPI.KeepAliveOnce(ctx, *leaseID) |
| if err != nil { |
| logger.Errorw(ctx, "lease-may-have-expired", log.Fields{"error": err}) |
| return err |
| } |
| } else { |
| return errors.New("lease-expired") |
| } |
| return nil |
| } |
| |
| // Watch provides the watch capability on a given key. It returns a channel onto which the callee needs to |
| // listen to receive Events. |
| func (c *EtcdClient) Watch(ctx context.Context, key string, withPrefix bool) chan *Event { |
| w := v3Client.NewWatcher(c.ectdAPI) |
| ctx, cancel := context.WithCancel(ctx) |
| var channel v3Client.WatchChan |
| if withPrefix { |
| channel = w.Watch(ctx, key, v3Client.WithPrefix()) |
| } else { |
| channel = w.Watch(ctx, key) |
| } |
| |
| // Create a new channel |
| ch := make(chan *Event, maxClientChannelBufferSize) |
| |
| // Keep track of the created channels so they can be closed when required |
| channelMap := make(map[chan *Event]v3Client.Watcher) |
| channelMap[ch] = w |
| |
| channelMaps := c.addChannelMap(key, channelMap) |
| |
| // Changing the log field (from channelMaps) as the underlying logger cannot format the map of channels into a |
| // json format. |
| logger.Debugw(ctx, "watched-channels", log.Fields{"len": len(channelMaps)}) |
| // Launch a go routine to listen for updates |
| go c.listenForKeyChange(ctx, channel, ch, cancel) |
| |
| return ch |
| |
| } |
| |
| func (c *EtcdClient) addChannelMap(key string, channelMap map[chan *Event]v3Client.Watcher) []map[chan *Event]v3Client.Watcher { |
| var channels interface{} |
| var exists bool |
| |
| if channels, exists = c.watchedChannels.Load(key); exists { |
| channels = append(channels.([]map[chan *Event]v3Client.Watcher), channelMap) |
| } else { |
| channels = []map[chan *Event]v3Client.Watcher{channelMap} |
| } |
| c.watchedChannels.Store(key, channels) |
| |
| return channels.([]map[chan *Event]v3Client.Watcher) |
| } |
| |
| func (c *EtcdClient) removeChannelMap(key string, pos int) []map[chan *Event]v3Client.Watcher { |
| var channels interface{} |
| var exists bool |
| |
| if channels, exists = c.watchedChannels.Load(key); exists { |
| channels = append(channels.([]map[chan *Event]v3Client.Watcher)[:pos], channels.([]map[chan *Event]v3Client.Watcher)[pos+1:]...) |
| c.watchedChannels.Store(key, channels) |
| } |
| |
| return channels.([]map[chan *Event]v3Client.Watcher) |
| } |
| |
| func (c *EtcdClient) getChannelMaps(key string) ([]map[chan *Event]v3Client.Watcher, bool) { |
| var channels interface{} |
| var exists bool |
| |
| channels, exists = c.watchedChannels.Load(key) |
| |
| if channels == nil { |
| return nil, exists |
| } |
| |
| return channels.([]map[chan *Event]v3Client.Watcher), exists |
| } |
| |
| // CloseWatch closes a specific watch. Both the key and the channel are required when closing a watch as there |
| // may be multiple listeners on the same key. The previously created channel serves as a key |
| func (c *EtcdClient) CloseWatch(ctx context.Context, key string, ch chan *Event) { |
| // Get the array of channels mapping |
| var watchedChannels []map[chan *Event]v3Client.Watcher |
| var ok bool |
| |
| if watchedChannels, ok = c.getChannelMaps(key); !ok { |
| logger.Warnw(ctx, "key-has-no-watched-channels", log.Fields{"key": key}) |
| return |
| } |
| // Look for the channels |
| var pos = -1 |
| for i, chMap := range watchedChannels { |
| if t, ok := chMap[ch]; ok { |
| logger.Debug(ctx, "channel-found") |
| // Close the etcd watcher before the client channel. This should close the etcd channel as well |
| if err := t.Close(); err != nil { |
| logger.Errorw(ctx, "watcher-cannot-be-closed", log.Fields{"key": key, "error": err}) |
| } |
| pos = i |
| break |
| } |
| } |
| |
| channelMaps, _ := c.getChannelMaps(key) |
| // Remove that entry if present |
| if pos >= 0 { |
| channelMaps = c.removeChannelMap(key, pos) |
| } |
| logger.Infow(ctx, "watcher-channel-exiting", log.Fields{"key": key, "channel": channelMaps}) |
| } |
| |
| func (c *EtcdClient) listenForKeyChange(ctx context.Context, channel v3Client.WatchChan, ch chan<- *Event, cancel context.CancelFunc) { |
| logger.Debug(ctx, "start-listening-on-channel ...") |
| defer cancel() |
| defer close(ch) |
| for resp := range channel { |
| for _, ev := range resp.Events { |
| ch <- NewEvent(getEventType(ev), ev.Kv.Key, ev.Kv.Value, ev.Kv.Version) |
| } |
| } |
| logger.Debug(ctx, "stop-listening-on-channel ...") |
| } |
| |
| func getEventType(event *v3Client.Event) int { |
| switch event.Type { |
| case v3Client.EventTypePut: |
| return PUT |
| case v3Client.EventTypeDelete: |
| return DELETE |
| } |
| return UNKNOWN |
| } |
| |
| // Close closes the KV store client |
| func (c *EtcdClient) Close(ctx context.Context) { |
| if err := c.ectdAPI.Close(); err != nil { |
| logger.Errorw(ctx, "error-closing-client", log.Fields{"error": err}) |
| } |
| } |
| |
| func (c *EtcdClient) addLockName(lockName string, lock *v3Concurrency.Mutex, session *v3Concurrency.Session) { |
| c.lockToMutexLock.Lock() |
| defer c.lockToMutexLock.Unlock() |
| c.lockToMutexMap[lockName] = lock |
| c.lockToSessionMap[lockName] = session |
| } |
| |
| func (c *EtcdClient) deleteLockName(lockName string) { |
| c.lockToMutexLock.Lock() |
| defer c.lockToMutexLock.Unlock() |
| delete(c.lockToMutexMap, lockName) |
| delete(c.lockToSessionMap, lockName) |
| } |
| |
| func (c *EtcdClient) getLock(lockName string) (*v3Concurrency.Mutex, *v3Concurrency.Session) { |
| c.lockToMutexLock.Lock() |
| defer c.lockToMutexLock.Unlock() |
| var lock *v3Concurrency.Mutex |
| var session *v3Concurrency.Session |
| if l, exist := c.lockToMutexMap[lockName]; exist { |
| lock = l |
| } |
| if s, exist := c.lockToSessionMap[lockName]; exist { |
| session = s |
| } |
| return lock, session |
| } |
| |
| func (c *EtcdClient) AcquireLock(ctx context.Context, lockName string, timeout time.Duration) error { |
| session, _ := v3Concurrency.NewSession(c.ectdAPI, v3Concurrency.WithContext(ctx)) |
| mu := v3Concurrency.NewMutex(session, "/devicelock_"+lockName) |
| if err := mu.Lock(context.Background()); err != nil { |
| //cancel() |
| return err |
| } |
| c.addLockName(lockName, mu, session) |
| return nil |
| } |
| |
| func (c *EtcdClient) ReleaseLock(lockName string) error { |
| lock, session := c.getLock(lockName) |
| var err error |
| if lock != nil { |
| if e := lock.Unlock(context.Background()); e != nil { |
| err = e |
| } |
| } |
| if session != nil { |
| if e := session.Close(); e != nil { |
| err = e |
| } |
| } |
| c.deleteLockName(lockName) |
| |
| return err |
| } |