/
client.go
599 lines (489 loc) · 17.6 KB
/
client.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
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
package sarama
import (
"sort"
"sync"
"time"
)
// Client is a generic Kafka client. It manages connections to one or more Kafka brokers.
// You MUST call Close() on a client to avoid leaks, it will not be garbage-collected
// automatically when it passes out of scope. A single client can be safely shared by
// multiple concurrent Producers and Consumers.
type Client interface {
// Config returns the Config struct of the client. This struct should not be altered after it
// has been created.
Config() *Config
// Topics returns the set of available topics as retrieved from the cluster metadata.
Topics() ([]string, error)
// Partitions returns the sorted list of all partition IDs for the given topic.
Partitions(topic string) ([]int32, error)
// WritablePartitions returns the sorted list of all writable partition IDs for the given topic,
// where "writable" means "having a valid leader accepting writes".
WritablePartitions(topic string) ([]int32, error)
// Leader returns the broker object that is the leader of the current topic/partition, as
// determined by querying the cluster metadata.
Leader(topic string, partitionID int32) (*Broker, error)
// Replicas returns the set of all replica IDs for the given partition.
Replicas(topic string, partitionID int32) ([]int32, error)
// RefreshMetadata takes a list of topics and queries the cluster to refresh the
// available metadata for those topics. If no topics are provided, it will refresh metadata
// for all topics.
RefreshMetadata(topics ...string) error
// GetOffset queries the cluster to get the most recent available offset at the given
// time on the topic/partition combination. Time should be OffsetOldest for the earliest available
// offset, OffsetNewest for the offset of the message that will be produced next, or a time.
GetOffset(topic string, partitionID int32, time int64) (int64, error)
// Close shuts down all broker connections managed by this client. It is required to call this function before
// a client object passes out of scope, as it will otherwise leak memory. You must close any Producers or Consumers
// using a client before you close the client.
Close() error
// Closed returns true if the client has already had Close called on it
Closed() bool
}
const (
// OffsetNewest stands for the log head offset, i.e. the offset that will be assigned to the next message
// that will be produced to the partition. You can send this to a client's GetOffset method to get this
// offset, or when calling ConsumePartition to start consuming new messages.
OffsetNewest int64 = -1
// OffsetOldest stands for the oldest offset available on the broker for a partition. You can send this
// to a client's GetOffset method to get this offset, or when calling ConsumePartition to start consuming
// from the oldest offset that is still available on the broker.
OffsetOldest int64 = -2
)
type client struct {
conf *Config
closer chan none
// the broker addresses given to us through the constructor are not guaranteed to be returned in
// the cluster metadata (I *think* it only returns brokers who are currently leading partitions?)
// so we store them separately
seedBrokerAddrs []string
seedBroker *Broker
deadBrokerAddrs map[string]none
brokers map[int32]*Broker // maps broker ids to brokers
metadata map[string]map[int32]*PartitionMetadata // maps topics to partition ids to metadata
// If the number of partitions is large, we can get some churn calling cachedPartitions,
// so the result is cached. It is important to update this value whenever metadata is changed
cachedPartitionsResults map[string][maxPartitionIndex][]int32
lock sync.RWMutex // protects access to the maps, only one since they're always written together
}
// NewClient creates a new Client. It connects to one of the given broker addresses
// and uses that broker to automatically fetch metadata on the rest of the kafka cluster. If metadata cannot
// be retrieved from any of the given broker addresses, the client is not created.
func NewClient(addrs []string, conf *Config) (Client, error) {
Logger.Println("Initializing new client")
if conf == nil {
conf = NewConfig()
}
if err := conf.Validate(); err != nil {
return nil, err
}
if len(addrs) < 1 {
return nil, ConfigurationError("You must provide at least one broker address")
}
client := &client{
conf: conf,
closer: make(chan none),
seedBrokerAddrs: addrs,
seedBroker: NewBroker(addrs[0]),
deadBrokerAddrs: make(map[string]none),
brokers: make(map[int32]*Broker),
metadata: make(map[string]map[int32]*PartitionMetadata),
cachedPartitionsResults: make(map[string][maxPartitionIndex][]int32),
}
_ = client.seedBroker.Open(conf)
// do an initial fetch of all cluster metadata by specifing an empty list of topics
err := client.RefreshMetadata()
switch err {
case nil:
break
case ErrLeaderNotAvailable, ErrReplicaNotAvailable:
// indicates that maybe part of the cluster is down, but is not fatal to creating the client
Logger.Println(err)
default:
_ = client.Close()
return nil, err
}
go withRecover(client.backgroundMetadataUpdater)
Logger.Println("Successfully initialized new client")
return client, nil
}
func (client *client) Config() *Config {
return client.conf
}
func (client *client) Close() error {
// Check to see whether the client is closed
if client.Closed() {
// Chances are this is being called from a defer() and the error will go unobserved
// so we go ahead and log the event in this case.
Logger.Printf("Close() called on already closed client")
return ErrClosedClient
}
client.lock.Lock()
defer client.lock.Unlock()
Logger.Println("Closing Client")
for _, broker := range client.brokers {
safeAsyncClose(broker)
}
client.brokers = nil
client.metadata = nil
if client.seedBroker != nil {
safeAsyncClose(client.seedBroker)
}
close(client.closer)
return nil
}
func (client *client) Closed() bool {
return client.brokers == nil
}
func (client *client) Topics() ([]string, error) {
// Check to see whether the client is closed
if client.Closed() {
return nil, ErrClosedClient
}
client.lock.RLock()
defer client.lock.RUnlock()
ret := make([]string, 0, len(client.metadata))
for topic := range client.metadata {
ret = append(ret, topic)
}
return ret, nil
}
func (client *client) Partitions(topic string) ([]int32, error) {
// Check to see whether the client is closed
if client.Closed() {
return nil, ErrClosedClient
}
partitions := client.cachedPartitions(topic, allPartitions)
if len(partitions) == 0 {
err := client.RefreshMetadata(topic)
if err != nil {
return nil, err
}
partitions = client.cachedPartitions(topic, allPartitions)
}
if partitions == nil {
return nil, ErrUnknownTopicOrPartition
}
return partitions, nil
}
func (client *client) WritablePartitions(topic string) ([]int32, error) {
// Check to see whether the client is closed
if client.Closed() {
return nil, ErrClosedClient
}
partitions := client.cachedPartitions(topic, writablePartitions)
// len==0 catches when it's nil (no such topic) and the odd case when every single
// partition is undergoing leader election simultaneously. Callers have to be able to handle
// this function returning an empty slice (which is a valid return value) but catching it
// here the first time (note we *don't* catch it below where we return ErrUnknownTopicOrPartition) triggers
// a metadata refresh as a nicety so callers can just try again and don't have to manually
// trigger a refresh (otherwise they'd just keep getting a stale cached copy).
if len(partitions) == 0 {
err := client.RefreshMetadata(topic)
if err != nil {
return nil, err
}
partitions = client.cachedPartitions(topic, writablePartitions)
}
if partitions == nil {
return nil, ErrUnknownTopicOrPartition
}
return partitions, nil
}
func (client *client) Replicas(topic string, partitionID int32) ([]int32, error) {
if client.Closed() {
return nil, ErrClosedClient
}
metadata := client.cachedMetadata(topic, partitionID)
if metadata == nil {
err := client.RefreshMetadata(topic)
if err != nil {
return nil, err
}
metadata = client.cachedMetadata(topic, partitionID)
}
if metadata == nil {
return nil, ErrUnknownTopicOrPartition
}
if metadata.Err == ErrReplicaNotAvailable {
return nil, metadata.Err
}
return dupeAndSort(metadata.Replicas), nil
}
func (client *client) Leader(topic string, partitionID int32) (*Broker, error) {
leader, err := client.cachedLeader(topic, partitionID)
if leader == nil {
err := client.RefreshMetadata(topic)
if err != nil {
return nil, err
}
leader, err = client.cachedLeader(topic, partitionID)
}
return leader, err
}
func (client *client) RefreshMetadata(topics ...string) error {
if client.Closed() {
return ErrClosedClient
}
// Prior to 0.8.2, Kafka will throw exceptions on an empty topic and not return a proper
// error. This handles the case by returning an error instead of sending it
// off to Kafka. See: https://github.com/Shopify/sarama/pull/38#issuecomment-26362310
for _, topic := range topics {
if len(topic) == 0 {
return ErrInvalidTopic // this is the error that 0.8.2 and later correctly return
}
}
return client.tryRefreshMetadata(topics, client.conf.Metadata.Retry.Max)
}
func (client *client) GetOffset(topic string, partitionID int32, time int64) (int64, error) {
broker, err := client.Leader(topic, partitionID)
if err != nil {
return -1, err
}
request := &OffsetRequest{}
request.AddBlock(topic, partitionID, time, 1)
response, err := broker.GetAvailableOffsets(request)
if err != nil {
return -1, err
}
block := response.GetBlock(topic, partitionID)
if block == nil {
return -1, ErrIncompleteResponse
}
if block.Err != ErrNoError {
return -1, block.Err
}
if len(block.Offsets) != 1 {
return -1, ErrOffsetOutOfRange
}
return block.Offsets[0], nil
}
// private broker management helpers
func (client *client) disconnectBroker(broker *Broker) {
client.lock.Lock()
defer client.lock.Unlock()
client.deadBrokerAddrs[broker.addr] = none{}
if broker == client.seedBroker {
client.seedBrokerAddrs = client.seedBrokerAddrs[1:]
if len(client.seedBrokerAddrs) > 0 {
client.seedBroker = NewBroker(client.seedBrokerAddrs[0])
_ = client.seedBroker.Open(client.conf)
} else {
client.seedBroker = nil
}
} else {
// we do this so that our loop in `tryRefreshMetadata` doesn't go on forever,
// but we really shouldn't have to; once that loop is made better this case can be
// removed, and the function generally can be renamed from `disconnectBroker` to
// `nextSeedBroker` or something
delete(client.brokers, broker.ID())
}
}
func (client *client) resurrectDeadBrokers() {
client.lock.Lock()
defer client.lock.Unlock()
for _, addr := range client.seedBrokerAddrs {
client.deadBrokerAddrs[addr] = none{}
}
client.seedBrokerAddrs = []string{}
for addr := range client.deadBrokerAddrs {
client.seedBrokerAddrs = append(client.seedBrokerAddrs, addr)
}
client.deadBrokerAddrs = make(map[string]none)
client.seedBroker = NewBroker(client.seedBrokerAddrs[0])
_ = client.seedBroker.Open(client.conf)
}
func (client *client) any() *Broker {
client.lock.RLock()
defer client.lock.RUnlock()
if client.seedBroker != nil {
_ = client.seedBroker.Open(client.conf)
return client.seedBroker
}
for _, broker := range client.brokers {
_ = broker.Open(client.conf)
return broker
}
return nil
}
// private caching/lazy metadata helpers
type partitionType int
const (
allPartitions partitionType = iota
writablePartitions
// If you add any more types, update the partition cache in update()
// Ensure this is the last partition type value
maxPartitionIndex
)
func (client *client) cachedMetadata(topic string, partitionID int32) *PartitionMetadata {
client.lock.RLock()
defer client.lock.RUnlock()
partitions := client.metadata[topic]
if partitions != nil {
return partitions[partitionID]
}
return nil
}
func (client *client) cachedPartitions(topic string, partitionSet partitionType) []int32 {
client.lock.RLock()
defer client.lock.RUnlock()
partitions, exists := client.cachedPartitionsResults[topic]
if !exists {
return nil
}
return partitions[partitionSet]
}
func (client *client) setPartitionCache(topic string, partitionSet partitionType) []int32 {
partitions := client.metadata[topic]
if partitions == nil {
return nil
}
ret := make([]int32, 0, len(partitions))
for _, partition := range partitions {
if partitionSet == writablePartitions && partition.Err == ErrLeaderNotAvailable {
continue
}
ret = append(ret, partition.ID)
}
sort.Sort(int32Slice(ret))
return ret
}
func (client *client) cachedLeader(topic string, partitionID int32) (*Broker, error) {
client.lock.RLock()
defer client.lock.RUnlock()
partitions := client.metadata[topic]
if partitions != nil {
metadata, ok := partitions[partitionID]
if ok {
if metadata.Err == ErrLeaderNotAvailable {
return nil, ErrLeaderNotAvailable
}
b := client.brokers[metadata.Leader]
if b == nil {
return nil, ErrLeaderNotAvailable
}
_ = b.Open(client.conf)
return b, nil
}
}
return nil, ErrUnknownTopicOrPartition
}
// core metadata update logic
func (client *client) backgroundMetadataUpdater() {
if client.conf.Metadata.RefreshFrequency == time.Duration(0) {
return
}
ticker := time.NewTicker(client.conf.Metadata.RefreshFrequency)
for {
select {
case <-ticker.C:
if err := client.RefreshMetadata(); err != nil {
Logger.Println("Client background metadata update:", err)
}
case <-client.closer:
ticker.Stop()
return
}
}
}
func (client *client) tryRefreshMetadata(topics []string, retriesRemaining int) error {
for broker := client.any(); broker != nil; broker = client.any() {
if len(topics) > 0 {
Logger.Printf("Fetching metadata for %v from broker %s\n", topics, broker.addr)
} else {
Logger.Printf("Fetching metadata for all topics from broker %s\n", broker.addr)
}
response, err := broker.GetMetadata(&MetadataRequest{Topics: topics})
switch err.(type) {
case nil:
// valid response, use it
retry, err := client.updateMetadata(response)
if len(retry) > 0 {
if retriesRemaining <= 0 {
Logger.Println("Some partitions are leaderless, but we're out of retries")
return err
}
Logger.Printf("Some partitions are leaderless, waiting %dms for election... (%d retries remaining)\n",
client.conf.Metadata.Retry.Backoff/time.Millisecond, retriesRemaining)
time.Sleep(client.conf.Metadata.Retry.Backoff) // wait for leader election
return client.tryRefreshMetadata(retry, retriesRemaining-1)
}
return err
case PacketEncodingError:
// didn't even send, return the error
return err
default:
// some other error, remove that broker and try again
Logger.Println("Error from broker while fetching metadata:", err)
_ = broker.Close()
client.disconnectBroker(broker)
}
}
Logger.Println("Out of available brokers.")
if retriesRemaining > 0 {
Logger.Printf("Resurrecting dead brokers after %dms... (%d retries remaining)\n",
client.conf.Metadata.Retry.Backoff/time.Millisecond, retriesRemaining)
time.Sleep(client.conf.Metadata.Retry.Backoff)
client.resurrectDeadBrokers()
return client.tryRefreshMetadata(topics, retriesRemaining-1)
}
return ErrOutOfBrokers
}
// if no fatal error, returns a list of topics that need retrying due to ErrLeaderNotAvailable
func (client *client) updateMetadata(data *MetadataResponse) ([]string, error) {
client.lock.Lock()
defer client.lock.Unlock()
// For all the brokers we received:
// - if it is a new ID, save it
// - if it is an existing ID, but the address we have is stale, discard the old one and save it
// - otherwise ignore it, replacing our existing one would just bounce the connection
for _, broker := range data.Brokers {
if client.brokers[broker.ID()] == nil {
client.brokers[broker.ID()] = broker
Logger.Printf("Registered new broker #%d at %s", broker.ID(), broker.Addr())
} else if broker.Addr() != client.brokers[broker.ID()].Addr() {
safeAsyncClose(client.brokers[broker.ID()])
client.brokers[broker.ID()] = broker
Logger.Printf("Replaced registered broker #%d with %s", broker.ID(), broker.Addr())
}
}
toRetry := make(map[string]bool)
var err error
for _, topic := range data.Topics {
delete(client.metadata, topic.Name)
delete(client.cachedPartitionsResults, topic.Name)
switch topic.Err {
case ErrNoError:
break
case ErrInvalidTopic: // don't retry, don't store partial results
err = topic.Err
continue
case ErrUnknownTopicOrPartition: // retry, do not store partial partition results
err = topic.Err
toRetry[topic.Name] = true
continue
case ErrLeaderNotAvailable: // retry, but store partiial partition results
toRetry[topic.Name] = true
break
default: // don't retry, don't store partial results
Logger.Printf("Unexpected topic-level metadata error: %s", topic.Err)
err = topic.Err
continue
}
client.metadata[topic.Name] = make(map[int32]*PartitionMetadata, len(topic.Partitions))
for _, partition := range topic.Partitions {
client.metadata[topic.Name][partition.ID] = partition
if partition.Err == ErrLeaderNotAvailable {
toRetry[topic.Name] = true
}
}
var partitionCache [maxPartitionIndex][]int32
partitionCache[allPartitions] = client.setPartitionCache(topic.Name, allPartitions)
partitionCache[writablePartitions] = client.setPartitionCache(topic.Name, writablePartitions)
client.cachedPartitionsResults[topic.Name] = partitionCache
}
ret := make([]string, 0, len(toRetry))
for topic := range toRetry {
ret = append(ret, topic)
}
return ret, err
}