forked from etcd-io/etcd
-
Notifications
You must be signed in to change notification settings - Fork 0
/
lease.go
461 lines (396 loc) · 10.7 KB
/
lease.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
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
// Copyright 2016 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 clientv3
import (
"sync"
"time"
"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
"golang.org/x/net/context"
)
type (
LeaseRevokeResponse pb.LeaseRevokeResponse
LeaseID int64
)
// LeaseGrantResponse is used to convert the protobuf grant response.
type LeaseGrantResponse struct {
*pb.ResponseHeader
ID LeaseID
TTL int64
Error string
}
// LeaseKeepAliveResponse is used to convert the protobuf keepalive response.
type LeaseKeepAliveResponse struct {
*pb.ResponseHeader
ID LeaseID
TTL int64
}
const (
// defaultTTL is the assumed lease TTL used for the first keepalive
// deadline before the actual TTL is known to the client.
defaultTTL = 5 * time.Second
// a small buffer to store unsent lease responses.
leaseResponseChSize = 16
// NoLease is a lease ID for the absence of a lease.
NoLease LeaseID = 0
)
type Lease interface {
// Grant creates a new lease.
Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error)
// Revoke revokes the given lease.
Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error)
// KeepAlive keeps the given lease alive forever.
KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error)
// KeepAliveOnce renews the lease once. In most of the cases, Keepalive
// should be used instead of KeepAliveOnce.
KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error)
// Close releases all resources Lease keeps for efficient communication
// with the etcd server.
Close() error
}
type lessor struct {
mu sync.Mutex // guards all fields
// donec is closed when recvKeepAliveLoop stops
donec chan struct{}
remote pb.LeaseClient
stream pb.Lease_LeaseKeepAliveClient
streamCancel context.CancelFunc
stopCtx context.Context
stopCancel context.CancelFunc
keepAlives map[LeaseID]*keepAlive
// firstKeepAliveTimeout is the timeout for the first keepalive request
// before the actual TTL is known to the lease client
firstKeepAliveTimeout time.Duration
}
// keepAlive multiplexes a keepalive for a lease over multiple channels
type keepAlive struct {
chs []chan<- *LeaseKeepAliveResponse
ctxs []context.Context
// deadline is the time the keep alive channels close if no response
deadline time.Time
// nextKeepAlive is when to send the next keep alive message
nextKeepAlive time.Time
// donec is closed on lease revoke, expiration, or cancel.
donec chan struct{}
}
func NewLease(c *Client) Lease {
l := &lessor{
donec: make(chan struct{}),
keepAlives: make(map[LeaseID]*keepAlive),
remote: pb.NewLeaseClient(c.conn),
firstKeepAliveTimeout: c.cfg.DialTimeout + time.Second,
}
if l.firstKeepAliveTimeout == time.Second {
l.firstKeepAliveTimeout = defaultTTL
}
l.stopCtx, l.stopCancel = context.WithCancel(context.Background())
go l.recvKeepAliveLoop()
go l.deadlineLoop()
return l
}
func (l *lessor) Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error) {
cctx, cancel := context.WithCancel(ctx)
done := cancelWhenStop(cancel, l.stopCtx.Done())
defer close(done)
for {
r := &pb.LeaseGrantRequest{TTL: ttl}
resp, err := l.remote.LeaseGrant(cctx, r)
if err == nil {
gresp := &LeaseGrantResponse{
ResponseHeader: resp.GetHeader(),
ID: LeaseID(resp.ID),
TTL: resp.TTL,
Error: resp.Error,
}
return gresp, nil
}
if isHaltErr(cctx, err) {
return nil, toErr(ctx, err)
}
if nerr := l.newStream(); nerr != nil {
return nil, nerr
}
}
}
func (l *lessor) Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error) {
cctx, cancel := context.WithCancel(ctx)
done := cancelWhenStop(cancel, l.stopCtx.Done())
defer close(done)
for {
r := &pb.LeaseRevokeRequest{ID: int64(id)}
resp, err := l.remote.LeaseRevoke(cctx, r)
if err == nil {
return (*LeaseRevokeResponse)(resp), nil
}
if isHaltErr(ctx, err) {
return nil, toErr(ctx, err)
}
if nerr := l.newStream(); nerr != nil {
return nil, nerr
}
}
}
func (l *lessor) KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error) {
ch := make(chan *LeaseKeepAliveResponse, leaseResponseChSize)
l.mu.Lock()
ka, ok := l.keepAlives[id]
if !ok {
// create fresh keep alive
ka = &keepAlive{
chs: []chan<- *LeaseKeepAliveResponse{ch},
ctxs: []context.Context{ctx},
deadline: time.Now().Add(l.firstKeepAliveTimeout),
nextKeepAlive: time.Now(),
donec: make(chan struct{}),
}
l.keepAlives[id] = ka
} else {
// add channel and context to existing keep alive
ka.ctxs = append(ka.ctxs, ctx)
ka.chs = append(ka.chs, ch)
}
l.mu.Unlock()
go l.keepAliveCtxCloser(id, ctx, ka.donec)
return ch, nil
}
func (l *lessor) KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
cctx, cancel := context.WithCancel(ctx)
done := cancelWhenStop(cancel, l.stopCtx.Done())
defer close(done)
for {
resp, err := l.keepAliveOnce(cctx, id)
if err == nil {
if resp.TTL == 0 {
err = rpctypes.ErrLeaseNotFound
}
return resp, err
}
if isHaltErr(ctx, err) {
return nil, toErr(ctx, err)
}
if nerr := l.newStream(); nerr != nil {
return nil, nerr
}
}
}
func (l *lessor) Close() error {
l.stopCancel()
<-l.donec
return nil
}
func (l *lessor) keepAliveCtxCloser(id LeaseID, ctx context.Context, donec <-chan struct{}) {
select {
case <-donec:
return
case <-l.donec:
return
case <-ctx.Done():
}
l.mu.Lock()
defer l.mu.Unlock()
ka, ok := l.keepAlives[id]
if !ok {
return
}
// close channel and remove context if still associated with keep alive
for i, c := range ka.ctxs {
if c == ctx {
close(ka.chs[i])
ka.ctxs = append(ka.ctxs[:i], ka.ctxs[i+1:]...)
ka.chs = append(ka.chs[:i], ka.chs[i+1:]...)
break
}
}
// remove if no one more listeners
if len(ka.chs) == 0 {
delete(l.keepAlives, id)
}
}
func (l *lessor) keepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error) {
cctx, cancel := context.WithCancel(ctx)
defer cancel()
stream, err := l.remote.LeaseKeepAlive(cctx)
if err != nil {
return nil, toErr(ctx, err)
}
err = stream.Send(&pb.LeaseKeepAliveRequest{ID: int64(id)})
if err != nil {
return nil, toErr(ctx, err)
}
resp, rerr := stream.Recv()
if rerr != nil {
return nil, toErr(ctx, rerr)
}
karesp := &LeaseKeepAliveResponse{
ResponseHeader: resp.GetHeader(),
ID: LeaseID(resp.ID),
TTL: resp.TTL,
}
return karesp, nil
}
func (l *lessor) recvKeepAliveLoop() {
defer func() {
l.mu.Lock()
close(l.donec)
for _, ka := range l.keepAlives {
ka.Close()
}
l.keepAlives = make(map[LeaseID]*keepAlive)
l.mu.Unlock()
}()
stream, serr := l.resetRecv()
for serr == nil {
resp, err := stream.Recv()
if err != nil {
if isHaltErr(l.stopCtx, err) {
return
}
stream, serr = l.resetRecv()
continue
}
l.recvKeepAlive(resp)
}
}
// resetRecv opens a new lease stream and starts sending LeaseKeepAliveRequests
func (l *lessor) resetRecv() (pb.Lease_LeaseKeepAliveClient, error) {
if err := l.newStream(); err != nil {
return nil, err
}
stream := l.getKeepAliveStream()
go l.sendKeepAliveLoop(stream)
return stream, nil
}
// recvKeepAlive updates a lease based on its LeaseKeepAliveResponse
func (l *lessor) recvKeepAlive(resp *pb.LeaseKeepAliveResponse) {
karesp := &LeaseKeepAliveResponse{
ResponseHeader: resp.GetHeader(),
ID: LeaseID(resp.ID),
TTL: resp.TTL,
}
l.mu.Lock()
defer l.mu.Unlock()
ka, ok := l.keepAlives[karesp.ID]
if !ok {
return
}
if karesp.TTL <= 0 {
// lease expired; close all keep alive channels
delete(l.keepAlives, karesp.ID)
ka.Close()
return
}
// send update to all channels
nextKeepAlive := time.Now().Add(1 + time.Duration(karesp.TTL/3)*time.Second)
ka.deadline = time.Now().Add(time.Duration(karesp.TTL) * time.Second)
for _, ch := range ka.chs {
select {
case ch <- karesp:
ka.nextKeepAlive = nextKeepAlive
default:
}
}
}
// deadlineLoop reaps any keep alive channels that have not received a response
// within the lease TTL
func (l *lessor) deadlineLoop() {
for {
select {
case <-time.After(time.Second):
case <-l.donec:
return
}
now := time.Now()
l.mu.Lock()
for id, ka := range l.keepAlives {
if ka.deadline.Before(now) {
// waited too long for response; lease may be expired
ka.Close()
delete(l.keepAlives, id)
}
}
l.mu.Unlock()
}
}
// sendKeepAliveLoop sends LeaseKeepAliveRequests for the lifetime of a lease stream
func (l *lessor) sendKeepAliveLoop(stream pb.Lease_LeaseKeepAliveClient) {
for {
select {
case <-time.After(500 * time.Millisecond):
case <-stream.Context().Done():
return
case <-l.donec:
return
case <-l.stopCtx.Done():
return
}
tosend := make([]LeaseID, 0)
now := time.Now()
l.mu.Lock()
for id, ka := range l.keepAlives {
if ka.nextKeepAlive.Before(now) {
tosend = append(tosend, id)
}
}
l.mu.Unlock()
for _, id := range tosend {
r := &pb.LeaseKeepAliveRequest{ID: int64(id)}
if err := stream.Send(r); err != nil {
// TODO do something with this error?
return
}
}
}
}
func (l *lessor) getKeepAliveStream() pb.Lease_LeaseKeepAliveClient {
l.mu.Lock()
defer l.mu.Unlock()
return l.stream
}
func (l *lessor) newStream() error {
sctx, cancel := context.WithCancel(l.stopCtx)
stream, err := l.remote.LeaseKeepAlive(sctx)
if err != nil {
cancel()
return toErr(sctx, err)
}
l.mu.Lock()
defer l.mu.Unlock()
if l.stream != nil && l.streamCancel != nil {
l.stream.CloseSend()
l.streamCancel()
}
l.streamCancel = cancel
l.stream = stream
return nil
}
func (ka *keepAlive) Close() {
close(ka.donec)
for _, ch := range ka.chs {
close(ch)
}
}
// cancelWhenStop calls cancel when the given stopc fires. It returns a done chan. done
// should be closed when the work is finished. When done fires, cancelWhenStop will release
// its internal resource.
func cancelWhenStop(cancel context.CancelFunc, stopc <-chan struct{}) chan<- struct{} {
done := make(chan struct{}, 1)
go func() {
select {
case <-stopc:
case <-done:
}
cancel()
}()
return done
}