sslobodr | d046be8 | 2019-01-16 10:02:22 -0500 | [diff] [blame] | 1 | // Copyright 2016 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package naming |
| 16 | |
| 17 | import ( |
| 18 | "context" |
| 19 | "encoding/json" |
| 20 | "fmt" |
| 21 | |
| 22 | etcd "github.com/coreos/etcd/clientv3" |
| 23 | |
| 24 | "google.golang.org/grpc/codes" |
| 25 | "google.golang.org/grpc/naming" |
| 26 | "google.golang.org/grpc/status" |
| 27 | ) |
| 28 | |
| 29 | var ErrWatcherClosed = fmt.Errorf("naming: watch closed") |
| 30 | |
| 31 | // GRPCResolver creates a grpc.Watcher for a target to track its resolution changes. |
| 32 | type GRPCResolver struct { |
| 33 | // Client is an initialized etcd client. |
| 34 | Client *etcd.Client |
| 35 | } |
| 36 | |
| 37 | func (gr *GRPCResolver) Update(ctx context.Context, target string, nm naming.Update, opts ...etcd.OpOption) (err error) { |
| 38 | switch nm.Op { |
| 39 | case naming.Add: |
| 40 | var v []byte |
| 41 | if v, err = json.Marshal(nm); err != nil { |
| 42 | return status.Error(codes.InvalidArgument, err.Error()) |
| 43 | } |
| 44 | _, err = gr.Client.KV.Put(ctx, target+"/"+nm.Addr, string(v), opts...) |
| 45 | case naming.Delete: |
| 46 | _, err = gr.Client.Delete(ctx, target+"/"+nm.Addr, opts...) |
| 47 | default: |
| 48 | return status.Error(codes.InvalidArgument, "naming: bad naming op") |
| 49 | } |
| 50 | return err |
| 51 | } |
| 52 | |
| 53 | func (gr *GRPCResolver) Resolve(target string) (naming.Watcher, error) { |
| 54 | ctx, cancel := context.WithCancel(context.Background()) |
| 55 | w := &gRPCWatcher{c: gr.Client, target: target + "/", ctx: ctx, cancel: cancel} |
| 56 | return w, nil |
| 57 | } |
| 58 | |
| 59 | type gRPCWatcher struct { |
| 60 | c *etcd.Client |
| 61 | target string |
| 62 | ctx context.Context |
| 63 | cancel context.CancelFunc |
| 64 | wch etcd.WatchChan |
| 65 | err error |
| 66 | } |
| 67 | |
| 68 | // Next gets the next set of updates from the etcd resolver. |
| 69 | // Calls to Next should be serialized; concurrent calls are not safe since |
| 70 | // there is no way to reconcile the update ordering. |
| 71 | func (gw *gRPCWatcher) Next() ([]*naming.Update, error) { |
| 72 | if gw.wch == nil { |
| 73 | // first Next() returns all addresses |
| 74 | return gw.firstNext() |
| 75 | } |
| 76 | if gw.err != nil { |
| 77 | return nil, gw.err |
| 78 | } |
| 79 | |
| 80 | // process new events on target/* |
| 81 | wr, ok := <-gw.wch |
| 82 | if !ok { |
| 83 | gw.err = status.Error(codes.Unavailable, ErrWatcherClosed.Error()) |
| 84 | return nil, gw.err |
| 85 | } |
| 86 | if gw.err = wr.Err(); gw.err != nil { |
| 87 | return nil, gw.err |
| 88 | } |
| 89 | |
| 90 | updates := make([]*naming.Update, 0, len(wr.Events)) |
| 91 | for _, e := range wr.Events { |
| 92 | var jupdate naming.Update |
| 93 | var err error |
| 94 | switch e.Type { |
| 95 | case etcd.EventTypePut: |
| 96 | err = json.Unmarshal(e.Kv.Value, &jupdate) |
| 97 | jupdate.Op = naming.Add |
| 98 | case etcd.EventTypeDelete: |
| 99 | err = json.Unmarshal(e.PrevKv.Value, &jupdate) |
| 100 | jupdate.Op = naming.Delete |
| 101 | } |
| 102 | if err == nil { |
| 103 | updates = append(updates, &jupdate) |
| 104 | } |
| 105 | } |
| 106 | return updates, nil |
| 107 | } |
| 108 | |
| 109 | func (gw *gRPCWatcher) firstNext() ([]*naming.Update, error) { |
| 110 | // Use serialized request so resolution still works if the target etcd |
| 111 | // server is partitioned away from the quorum. |
| 112 | resp, err := gw.c.Get(gw.ctx, gw.target, etcd.WithPrefix(), etcd.WithSerializable()) |
| 113 | if gw.err = err; err != nil { |
| 114 | return nil, err |
| 115 | } |
| 116 | |
| 117 | updates := make([]*naming.Update, 0, len(resp.Kvs)) |
| 118 | for _, kv := range resp.Kvs { |
| 119 | var jupdate naming.Update |
| 120 | if err := json.Unmarshal(kv.Value, &jupdate); err != nil { |
| 121 | continue |
| 122 | } |
| 123 | updates = append(updates, &jupdate) |
| 124 | } |
| 125 | |
| 126 | opts := []etcd.OpOption{etcd.WithRev(resp.Header.Revision + 1), etcd.WithPrefix(), etcd.WithPrevKV()} |
| 127 | gw.wch = gw.c.Watch(gw.ctx, gw.target, opts...) |
| 128 | return updates, nil |
| 129 | } |
| 130 | |
| 131 | func (gw *gRPCWatcher) Close() { gw.cancel() } |