| /* |
| * 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 ( |
| //log "../common" |
| "context" |
| "errors" |
| "fmt" |
| v3Client "github.com/coreos/etcd/clientv3" |
| v3rpcTypes "github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes" |
| log "github.com/opencord/voltha-go/common/log" |
| "sync" |
| ) |
| |
| // EtcdClient represents the Etcd KV store client |
| type EtcdClient struct { |
| ectdAPI *v3Client.Client |
| leaderRev v3Client.Client |
| keyReservations map[string]*v3Client.LeaseID |
| watchedChannels map[string][]map[chan *Event]v3Client.Watcher |
| writeLock sync.Mutex |
| } |
| |
| // NewEtcdClient returns a new client for the Etcd KV store |
| func NewEtcdClient(addr string, timeout int) (*EtcdClient, error) { |
| |
| duration := GetDuration(timeout) |
| |
| c, err := v3Client.New(v3Client.Config{ |
| Endpoints: []string{addr}, |
| DialTimeout: duration, |
| }) |
| if err != nil { |
| log.Error(err) |
| return nil, err |
| } |
| wc := make(map[string][]map[chan *Event]v3Client.Watcher) |
| reservations := make(map[string]*v3Client.LeaseID) |
| return &EtcdClient{ectdAPI: c, watchedChannels: wc, keyReservations: reservations}, nil |
| } |
| |
| // 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(key string, timeout int) (map[string]*KVPair, error) { |
| duration := GetDuration(timeout) |
| |
| ctx, cancel := context.WithTimeout(context.Background(), duration) |
| resp, err := c.ectdAPI.Get(ctx, key, v3Client.WithPrefix()) |
| cancel() |
| if err != nil { |
| log.Error(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) |
| } |
| 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(key string, timeout int) (*KVPair, error) { |
| duration := GetDuration(timeout) |
| |
| ctx, cancel := context.WithTimeout(context.Background(), duration) |
| resp, err := c.ectdAPI.Get(ctx, key) |
| cancel() |
| if err != nil { |
| log.Error(err) |
| return nil, err |
| } |
| for _, ev := range resp.Kvs { |
| // Only one value is returned |
| return NewKVPair(string(ev.Key), ev.Value, "", ev.Lease), 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(key string, value interface{}, timeout int) 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) |
| } |
| |
| duration := GetDuration(timeout) |
| |
| ctx, cancel := context.WithTimeout(context.Background(), duration) |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| _, err := c.ectdAPI.Put(ctx, key, val) |
| cancel() |
| if err != nil { |
| switch err { |
| case context.Canceled: |
| log.Warnw("context-cancelled", log.Fields{"error": err}) |
| case context.DeadlineExceeded: |
| log.Warnw("context-deadline-exceeded", log.Fields{"error": err}) |
| case v3rpcTypes.ErrEmptyKey: |
| log.Warnw("etcd-client-error", log.Fields{"error": err}) |
| default: |
| log.Warnw("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(key string, timeout int) error { |
| |
| duration := GetDuration(timeout) |
| |
| ctx, cancel := context.WithTimeout(context.Background(), duration) |
| defer cancel() |
| |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| |
| // count keys about to be deleted |
| gresp, err := c.ectdAPI.Get(ctx, key, v3Client.WithPrefix()) |
| if err != nil { |
| log.Error(err) |
| return err |
| } |
| |
| // delete the keys |
| dresp, err := c.ectdAPI.Delete(ctx, key, v3Client.WithPrefix()) |
| if err != nil { |
| log.Error(err) |
| return err |
| } |
| |
| if dresp == nil || gresp == nil { |
| log.Debug("nothing-to-delete") |
| return nil |
| } |
| |
| log.Debugw("delete-keys", log.Fields{"all-keys-deleted": int64(len(gresp.Kvs)) == dresp.Deleted}) |
| if int64(len(gresp.Kvs)) == dresp.Deleted { |
| log.Debug("All-keys-deleted") |
| } else { |
| log.Error("not-all-keys-deleted") |
| err := errors.New("not-all-keys-deleted") |
| return err |
| } |
| 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(key string, value interface{}, ttl int64) (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) |
| } |
| |
| // Create a lease |
| resp, err := c.ectdAPI.Grant(context.Background(), ttl) |
| if err != nil { |
| log.Error(err) |
| return nil, err |
| } |
| // Register the lease id |
| c.writeLock.Lock() |
| c.keyReservations[key] = &resp.ID |
| c.writeLock.Unlock() |
| |
| // Revoke lease if reservation is not successful |
| reservationSuccessful := false |
| defer func() { |
| if !reservationSuccessful { |
| if err = c.ReleaseReservation(key); err != nil { |
| log.Errorf("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(key, defaultKVGetTimeout) |
| 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() error { |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| for key, leaseID := range c.keyReservations { |
| _, err := c.ectdAPI.Revoke(context.Background(), *leaseID) |
| if err != nil { |
| log.Errorw("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(key string) error { |
| // Get the leaseid using the key |
| var ok bool |
| var leaseID *v3Client.LeaseID |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| if leaseID, ok = c.keyReservations[key]; !ok { |
| return errors.New("key-not-reserved") |
| } |
| if leaseID != nil { |
| _, err := c.ectdAPI.Revoke(context.Background(), *leaseID) |
| if err != nil { |
| log.Error(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(key string) error { |
| // Get the leaseid using the key |
| var ok bool |
| var leaseID *v3Client.LeaseID |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| if leaseID, ok = c.keyReservations[key]; !ok { |
| return errors.New("key-not-reserved") |
| } |
| |
| if leaseID != nil { |
| _, err := c.ectdAPI.KeepAliveOnce(context.Background(), *leaseID) |
| if err != nil { |
| log.Errorw("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(key string) chan *Event { |
| w := v3Client.NewWatcher(c.ectdAPI) |
| channel := w.Watch(context.Background(), key, v3Client.WithPrefix()) |
| |
| // 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 |
| //c.writeLock.Lock() |
| //defer c.writeLock.Unlock() |
| c.watchedChannels[key] = append(c.watchedChannels[key], channelMap) |
| |
| log.Debugw("watched-channels", log.Fields{"channels": c.watchedChannels[key]}) |
| // Launch a go routine to listen for updates |
| go c.listenForKeyChange(channel, ch) |
| |
| return ch |
| |
| } |
| |
| // 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(key string, ch chan *Event) { |
| // Get the array of channels mapping |
| var watchedChannels []map[chan *Event]v3Client.Watcher |
| var ok bool |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| |
| if watchedChannels, ok = c.watchedChannels[key]; !ok { |
| log.Warnw("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 { |
| log.Debug("channel-found") |
| // Close the etcd watcher before the client channel. This should close the etcd channel as well |
| if err := t.Close(); err != nil { |
| log.Errorw("watcher-cannot-be-closed", log.Fields{"key": key, "error": err}) |
| } |
| close(ch) |
| pos = i |
| break |
| } |
| } |
| // Remove that entry if present |
| if pos >= 0 { |
| c.watchedChannels[key] = append(c.watchedChannels[key][:pos], c.watchedChannels[key][pos+1:]...) |
| } |
| log.Infow("watcher-channel-exiting", log.Fields{"key": key, "channel": c.watchedChannels[key]}) |
| } |
| |
| func (c *EtcdClient) listenForKeyChange(channel v3Client.WatchChan, ch chan<- *Event) { |
| log.Infow("start-listening-on-channel", log.Fields{"channel": ch}) |
| for resp := range channel { |
| for _, ev := range resp.Events { |
| //log.Debugf("%s %q : %q\n", ev.Type, ev.Kv.Key, ev.Kv.Value) |
| ch <- NewEvent(getEventType(ev), ev.Kv.Key, ev.Kv.Value) |
| } |
| } |
| log.Info("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() { |
| c.writeLock.Lock() |
| defer c.writeLock.Unlock() |
| if err := c.ectdAPI.Close(); err != nil { |
| log.Errorw("error-closing-client", log.Fields{"error": err}) |
| } |
| } |