forked from etcd-io/etcd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
watch.go
380 lines (336 loc) · 9.38 KB
/
watch.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
// Copyright 2015 The etcd Authors
//
// 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 v3rpc
import (
"io"
"sync"
"time"
"golang.org/x/net/context"
"github.com/coreos/etcd/etcdserver"
"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
"github.com/coreos/etcd/mvcc"
"github.com/coreos/etcd/mvcc/mvccpb"
)
type watchServer struct {
clusterID int64
memberID int64
raftTimer etcdserver.RaftTimer
watchable mvcc.WatchableKV
}
func NewWatchServer(s *etcdserver.EtcdServer) pb.WatchServer {
return &watchServer{
clusterID: int64(s.Cluster().ID()),
memberID: int64(s.ID()),
raftTimer: s,
watchable: s.Watchable(),
}
}
var (
// External test can read this with GetProgressReportInterval()
// and change this to a small value to finish fast with
// SetProgressReportInterval().
progressReportInterval = 10 * time.Minute
progressReportIntervalMu sync.RWMutex
)
func GetProgressReportInterval() time.Duration {
progressReportIntervalMu.RLock()
defer progressReportIntervalMu.RUnlock()
return progressReportInterval
}
func SetProgressReportInterval(newTimeout time.Duration) {
progressReportIntervalMu.Lock()
defer progressReportIntervalMu.Unlock()
progressReportInterval = newTimeout
}
const (
// We send ctrl response inside the read loop. We do not want
// send to block read, but we still want ctrl response we sent to
// be serialized. Thus we use a buffered chan to solve the problem.
// A small buffer should be OK for most cases, since we expect the
// ctrl requests are infrequent.
ctrlStreamBufLen = 16
)
// serverWatchStream is an etcd server side stream. It receives requests
// from client side gRPC stream. It receives watch events from mvcc.WatchStream,
// and creates responses that forwarded to gRPC stream.
// It also forwards control message like watch created and canceled.
type serverWatchStream struct {
clusterID int64
memberID int64
raftTimer etcdserver.RaftTimer
watchable mvcc.WatchableKV
gRPCStream pb.Watch_WatchServer
watchStream mvcc.WatchStream
ctrlStream chan *pb.WatchResponse
// mu protects progress, prevKV
mu sync.Mutex
// progress tracks the watchID that stream might need to send
// progress to.
// TODO: combine progress and prevKV into a single struct?
progress map[mvcc.WatchID]bool
prevKV map[mvcc.WatchID]bool
// closec indicates the stream is closed.
closec chan struct{}
// wg waits for the send loop to complete
wg sync.WaitGroup
}
func (ws *watchServer) Watch(stream pb.Watch_WatchServer) (err error) {
sws := serverWatchStream{
clusterID: ws.clusterID,
memberID: ws.memberID,
raftTimer: ws.raftTimer,
watchable: ws.watchable,
gRPCStream: stream,
watchStream: ws.watchable.NewWatchStream(),
// chan for sending control response like watcher created and canceled.
ctrlStream: make(chan *pb.WatchResponse, ctrlStreamBufLen),
progress: make(map[mvcc.WatchID]bool),
prevKV: make(map[mvcc.WatchID]bool),
closec: make(chan struct{}),
}
sws.wg.Add(1)
go func() {
sws.sendLoop()
sws.wg.Done()
}()
errc := make(chan error, 1)
// Ideally recvLoop would also use sws.wg to signal its completion
// but when stream.Context().Done() is closed, the stream's recv
// may continue to block since it uses a different context, leading to
// deadlock when calling sws.close().
go func() { errc <- sws.recvLoop() }()
select {
case err = <-errc:
case <-stream.Context().Done():
err = stream.Context().Err()
// the only server-side cancellation is noleader for now.
if err == context.Canceled {
err = rpctypes.ErrGRPCNoLeader
}
}
sws.close()
return err
}
func (sws *serverWatchStream) recvLoop() error {
defer close(sws.ctrlStream)
for {
req, err := sws.gRPCStream.Recv()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
switch uv := req.RequestUnion.(type) {
case *pb.WatchRequest_CreateRequest:
if uv.CreateRequest == nil {
break
}
creq := uv.CreateRequest
if len(creq.Key) == 0 {
// \x00 is the smallest key
creq.Key = []byte{0}
}
if len(creq.RangeEnd) == 1 && creq.RangeEnd[0] == 0 {
// support >= key queries
creq.RangeEnd = []byte{}
}
filters := FiltersFromRequest(creq)
wsrev := sws.watchStream.Rev()
rev := creq.StartRevision
if rev == 0 {
rev = wsrev + 1
}
id := sws.watchStream.Watch(creq.Key, creq.RangeEnd, rev, filters...)
if id != -1 {
sws.mu.Lock()
if creq.ProgressNotify {
sws.progress[id] = true
}
if creq.PrevKv {
sws.prevKV[id] = true
}
sws.mu.Unlock()
}
wr := &pb.WatchResponse{
Header: sws.newResponseHeader(wsrev),
WatchId: int64(id),
Created: true,
Canceled: id == -1,
}
select {
case sws.ctrlStream <- wr:
case <-sws.closec:
return nil
}
case *pb.WatchRequest_CancelRequest:
if uv.CancelRequest != nil {
id := uv.CancelRequest.WatchId
err := sws.watchStream.Cancel(mvcc.WatchID(id))
if err == nil {
sws.ctrlStream <- &pb.WatchResponse{
Header: sws.newResponseHeader(sws.watchStream.Rev()),
WatchId: id,
Canceled: true,
}
sws.mu.Lock()
delete(sws.progress, mvcc.WatchID(id))
delete(sws.prevKV, mvcc.WatchID(id))
sws.mu.Unlock()
}
}
default:
// we probably should not shutdown the entire stream when
// receive an valid command.
// so just do nothing instead.
continue
}
}
}
func (sws *serverWatchStream) sendLoop() {
// watch ids that are currently active
ids := make(map[mvcc.WatchID]struct{})
// watch responses pending on a watch id creation message
pending := make(map[mvcc.WatchID][]*pb.WatchResponse)
interval := GetProgressReportInterval()
progressTicker := time.NewTicker(interval)
defer func() {
progressTicker.Stop()
// drain the chan to clean up pending events
for ws := range sws.watchStream.Chan() {
mvcc.ReportEventReceived(len(ws.Events))
}
for _, wrs := range pending {
for _, ws := range wrs {
mvcc.ReportEventReceived(len(ws.Events))
}
}
}()
for {
select {
case wresp, ok := <-sws.watchStream.Chan():
if !ok {
return
}
// TODO: evs is []mvccpb.Event type
// either return []*mvccpb.Event from the mvcc package
// or define protocol buffer with []mvccpb.Event.
evs := wresp.Events
events := make([]*mvccpb.Event, len(evs))
sws.mu.Lock()
needPrevKV := sws.prevKV[wresp.WatchID]
sws.mu.Unlock()
for i := range evs {
events[i] = &evs[i]
if needPrevKV {
opt := mvcc.RangeOptions{Rev: evs[i].Kv.ModRevision - 1}
r, err := sws.watchable.Range(evs[i].Kv.Key, nil, opt)
if err == nil && len(r.KVs) != 0 {
events[i].PrevKv = &(r.KVs[0])
}
}
}
wr := &pb.WatchResponse{
Header: sws.newResponseHeader(wresp.Revision),
WatchId: int64(wresp.WatchID),
Events: events,
CompactRevision: wresp.CompactRevision,
}
if _, hasId := ids[wresp.WatchID]; !hasId {
// buffer if id not yet announced
wrs := append(pending[wresp.WatchID], wr)
pending[wresp.WatchID] = wrs
continue
}
mvcc.ReportEventReceived(len(evs))
if err := sws.gRPCStream.Send(wr); err != nil {
return
}
sws.mu.Lock()
if len(evs) > 0 && sws.progress[wresp.WatchID] {
// elide next progress update if sent a key update
sws.progress[wresp.WatchID] = false
}
sws.mu.Unlock()
case c, ok := <-sws.ctrlStream:
if !ok {
return
}
if err := sws.gRPCStream.Send(c); err != nil {
return
}
// track id creation
wid := mvcc.WatchID(c.WatchId)
if c.Canceled {
delete(ids, wid)
continue
}
if c.Created {
// flush buffered events
ids[wid] = struct{}{}
for _, v := range pending[wid] {
mvcc.ReportEventReceived(len(v.Events))
if err := sws.gRPCStream.Send(v); err != nil {
return
}
}
delete(pending, wid)
}
case <-progressTicker.C:
sws.mu.Lock()
for id, ok := range sws.progress {
if ok {
sws.watchStream.RequestProgress(id)
}
sws.progress[id] = true
}
sws.mu.Unlock()
case <-sws.closec:
return
}
}
}
func (sws *serverWatchStream) close() {
sws.watchStream.Close()
close(sws.closec)
sws.wg.Wait()
}
func (sws *serverWatchStream) newResponseHeader(rev int64) *pb.ResponseHeader {
return &pb.ResponseHeader{
ClusterId: uint64(sws.clusterID),
MemberId: uint64(sws.memberID),
Revision: rev,
RaftTerm: sws.raftTimer.Term(),
}
}
func filterNoDelete(e mvccpb.Event) bool {
return e.Type == mvccpb.DELETE
}
func filterNoPut(e mvccpb.Event) bool {
return e.Type == mvccpb.PUT
}
func FiltersFromRequest(creq *pb.WatchCreateRequest) []mvcc.FilterFunc {
filters := make([]mvcc.FilterFunc, 0, len(creq.Filters))
for _, ft := range creq.Filters {
switch ft {
case pb.WatchCreateRequest_NOPUT:
filters = append(filters, filterNoPut)
case pb.WatchCreateRequest_NODELETE:
filters = append(filters, filterNoDelete)
default:
}
}
return filters
}