forked from prysmaticlabs/prysm
-
Notifications
You must be signed in to change notification settings - Fork 0
/
blocks_queue.go
409 lines (367 loc) · 12 KB
/
blocks_queue.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
package initialsync
import (
"context"
"errors"
"time"
eth "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
"github.com/prysmaticlabs/prysm/beacon-chain/blockchain"
"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
"github.com/prysmaticlabs/prysm/beacon-chain/p2p"
"github.com/prysmaticlabs/prysm/shared/params"
"github.com/sirupsen/logrus"
)
const (
// queueStopCallTimeout is time allowed for queue to release resources when quitting.
queueStopCallTimeout = 1 * time.Second
// pollingInterval defines how often state machine needs to check for new events.
pollingInterval = 200 * time.Millisecond
// staleEpochTimeout is an period after which epoch's state is considered stale.
staleEpochTimeout = 5 * pollingInterval
// lookaheadEpochs is a default limit on how many forward epochs are loaded into queue.
lookaheadEpochs = 4
)
var (
errQueueCtxIsDone = errors.New("queue's context is done, reinitialize")
errQueueTakesTooLongToStop = errors.New("queue takes too long to stop")
errNoEpochState = errors.New("epoch state not found")
errInputNotFetchRequestParams = errors.New("input data is not type *fetchRequestParams")
)
// blocksProvider exposes enough methods for queue to fetch incoming blocks.
type blocksProvider interface {
requestResponses() <-chan *fetchRequestResponse
scheduleRequest(ctx context.Context, start, count uint64) error
nonSkippedSlotAfter(ctx context.Context, slot uint64) (uint64, error)
bestFinalizedSlot() uint64
start() error
stop()
}
// blocksQueueConfig is a config to setup block queue service.
type blocksQueueConfig struct {
blocksFetcher blocksProvider
headFetcher blockchain.HeadFetcher
startSlot uint64
highestExpectedSlot uint64
p2p p2p.P2P
}
// blocksQueue is a priority queue that serves as a intermediary between block fetchers (producers)
// and block processing goroutine (consumer). Consumer can rely on order of incoming blocks.
type blocksQueue struct {
ctx context.Context
cancel context.CancelFunc
highestExpectedSlot uint64
state *stateMachine
blocksFetcher blocksProvider
headFetcher blockchain.HeadFetcher
fetchedBlocks chan *eth.SignedBeaconBlock // output channel for ready blocks
quit chan struct{} // termination notifier
}
// newBlocksQueue creates initialized priority queue.
func newBlocksQueue(ctx context.Context, cfg *blocksQueueConfig) *blocksQueue {
ctx, cancel := context.WithCancel(ctx)
blocksFetcher := cfg.blocksFetcher
if blocksFetcher == nil {
blocksFetcher = newBlocksFetcher(ctx, &blocksFetcherConfig{
headFetcher: cfg.headFetcher,
p2p: cfg.p2p,
})
}
highestExpectedSlot := cfg.highestExpectedSlot
if highestExpectedSlot <= cfg.startSlot {
highestExpectedSlot = blocksFetcher.bestFinalizedSlot()
}
queue := &blocksQueue{
ctx: ctx,
cancel: cancel,
highestExpectedSlot: highestExpectedSlot,
blocksFetcher: blocksFetcher,
headFetcher: cfg.headFetcher,
fetchedBlocks: make(chan *eth.SignedBeaconBlock, allowedBlocksPerSecond),
quit: make(chan struct{}),
}
// Configure state machine.
queue.state = newStateMachine()
queue.state.addHandler(stateNew, eventSchedule, queue.onScheduleEvent(ctx))
queue.state.addHandler(stateScheduled, eventDataReceived, queue.onDataReceivedEvent(ctx))
queue.state.addHandler(stateDataParsed, eventReadyToSend, queue.onReadyToSendEvent(ctx))
queue.state.addHandler(stateSkipped, eventExtendWindow, queue.onExtendWindowEvent(ctx))
queue.state.addHandler(stateSent, eventCheckStale, queue.onCheckStaleEvent(ctx))
return queue
}
// start boots up the queue processing.
func (q *blocksQueue) start() error {
select {
case <-q.ctx.Done():
return errQueueCtxIsDone
default:
go q.loop()
return nil
}
}
// stop terminates all queue operations.
func (q *blocksQueue) stop() error {
q.cancel()
select {
case <-q.quit:
return nil
case <-time.After(queueStopCallTimeout):
return errQueueTakesTooLongToStop
}
}
// loop is a main queue loop.
func (q *blocksQueue) loop() {
defer close(q.quit)
defer func() {
q.blocksFetcher.stop()
close(q.fetchedBlocks)
}()
if err := q.blocksFetcher.start(); err != nil {
log.WithError(err).Debug("Can not start blocks provider")
}
startEpoch := helpers.SlotToEpoch(q.headFetcher.HeadSlot())
slotsPerEpoch := params.BeaconConfig().SlotsPerEpoch
// Define epoch states as finite state machines.
for i := startEpoch; i < startEpoch+lookaheadEpochs; i++ {
q.state.addEpochState(i)
}
ticker := time.NewTicker(pollingInterval)
tickerEvents := []eventID{eventSchedule, eventReadyToSend, eventCheckStale, eventExtendWindow}
for {
if q.headFetcher.HeadSlot() >= q.highestExpectedSlot {
// By the time initial sync is complete, highest slot may increase, re-check.
if q.highestExpectedSlot < q.blocksFetcher.bestFinalizedSlot() {
q.highestExpectedSlot = q.blocksFetcher.bestFinalizedSlot()
continue
}
log.Debug("Highest expected slot reached")
q.cancel()
}
select {
case <-ticker.C:
for _, state := range q.state.epochs {
data := &fetchRequestParams{
start: helpers.StartSlot(state.epoch),
count: slotsPerEpoch,
}
// Trigger events on each epoch's state machine.
for _, event := range tickerEvents {
if err := q.state.trigger(event, state.epoch, data); err != nil {
log.WithFields(logrus.Fields{
"event": event,
"epoch": state.epoch,
"error": err.Error(),
}).Debug("Can not trigger event")
}
}
// Do garbage collection, and advance sliding window forward.
if q.headFetcher.HeadSlot() >= helpers.StartSlot(state.epoch+1) {
highestEpoch, err := q.state.highestEpoch()
if err != nil {
log.WithError(err).Debug("Cannot obtain highest epoch state number")
continue
}
if err := q.state.removeEpochState(state.epoch); err != nil {
log.WithError(err).Debug("Can not remove epoch state")
}
if len(q.state.epochs) < lookaheadEpochs {
q.state.addEpochState(highestEpoch + 1)
}
}
}
case response, ok := <-q.blocksFetcher.requestResponses():
if !ok {
log.Debug("Fetcher closed output channel")
q.cancel()
return
}
// Update state of an epoch for which data is received.
epoch := helpers.SlotToEpoch(response.start)
if ind, ok := q.state.findEpochState(epoch); ok {
state := q.state.epochs[ind]
if err := q.state.trigger(eventDataReceived, state.epoch, response); err != nil {
log.WithFields(logrus.Fields{
"event": eventDataReceived,
"epoch": state.epoch,
"error": err.Error(),
}).Debug("Can not trigger event")
state.setState(stateNew)
continue
}
}
case <-q.ctx.Done():
log.Debug("Context closed, exiting goroutine (blocks queue)")
ticker.Stop()
return
}
}
}
// onScheduleEvent is an event called on newly arrived epochs. Transforms state to scheduled.
func (q *blocksQueue) onScheduleEvent(ctx context.Context) eventHandlerFn {
return func(es *epochState, in interface{}) (stateID, error) {
data, ok := in.(*fetchRequestParams)
if !ok {
return 0, errInputNotFetchRequestParams
}
if err := q.blocksFetcher.scheduleRequest(ctx, data.start, data.count); err != nil {
return es.state, err
}
return stateScheduled, nil
}
}
// onDataReceivedEvent is an event called when data is received from fetcher.
func (q *blocksQueue) onDataReceivedEvent(ctx context.Context) eventHandlerFn {
return func(es *epochState, in interface{}) (stateID, error) {
if ctx.Err() != nil {
return es.state, ctx.Err()
}
response, ok := in.(*fetchRequestResponse)
if !ok {
return 0, errInputNotFetchRequestParams
}
epoch := helpers.SlotToEpoch(response.start)
if response.err != nil {
// Current window is already too big, re-request previous epochs.
if response.err == errSlotIsTooHigh {
for _, state := range q.state.epochs {
isSkipped := state.state == stateSkipped || state.state == stateSkippedExt
if state.epoch < epoch && isSkipped {
state.setState(stateNew)
}
}
}
return es.state, response.err
}
ind, ok := q.state.findEpochState(epoch)
if !ok {
return es.state, errNoEpochState
}
q.state.epochs[ind].blocks = response.blocks
return stateDataParsed, nil
}
}
// onReadyToSendEvent is an event called to allow epochs with available blocks to send them downstream.
func (q *blocksQueue) onReadyToSendEvent(ctx context.Context) eventHandlerFn {
return func(es *epochState, in interface{}) (stateID, error) {
if ctx.Err() != nil {
return es.state, ctx.Err()
}
data, ok := in.(*fetchRequestParams)
if !ok {
return 0, errInputNotFetchRequestParams
}
epoch := helpers.SlotToEpoch(data.start)
ind, ok := q.state.findEpochState(epoch)
if !ok {
return es.state, errNoEpochState
}
if len(q.state.epochs[ind].blocks) == 0 {
return stateSkipped, nil
}
send := func() (stateID, error) {
for _, block := range q.state.epochs[ind].blocks {
select {
case <-ctx.Done():
return es.state, ctx.Err()
case q.fetchedBlocks <- block:
}
}
return stateSent, nil
}
// Make sure that we send epochs in a correct order.
if q.state.isLowestEpochState(epoch) {
return send()
}
// Make sure that previous epoch is already processed.
for _, state := range q.state.epochs {
// Review only previous slots.
if state.epoch < epoch {
switch state.state {
case stateNew, stateScheduled, stateDataParsed:
return es.state, nil
default:
}
}
}
return send()
}
}
// onExtendWindowEvent is and event allowing handlers to extend sliding window,
// in case where progress is not possible otherwise.
func (q *blocksQueue) onExtendWindowEvent(ctx context.Context) eventHandlerFn {
return func(es *epochState, in interface{}) (stateID, error) {
if ctx.Err() != nil {
return es.state, ctx.Err()
}
data, ok := in.(*fetchRequestParams)
if !ok {
return 0, errInputNotFetchRequestParams
}
epoch := helpers.SlotToEpoch(data.start)
if _, ok := q.state.findEpochState(epoch); !ok {
return es.state, errNoEpochState
}
// Only the highest epoch with skipped state can trigger extension.
highestEpoch, err := q.state.highestEpoch()
if err != nil {
return es.state, err
}
if highestEpoch != epoch {
return es.state, nil
}
// Check if window is expanded recently, if so, time to reset and re-request the same blocks.
resetWindow := false
skippedEpochs := 0
for _, state := range q.state.epochs {
if state.state == stateSkippedExt {
resetWindow = true
break
}
if state.state == stateSkipped || state.state == stateSkippedExt {
skippedEpochs++
}
}
// Reset if everything is skipped or extension took place during previous iteration.
if resetWindow || (skippedEpochs == len(q.state.epochs)) {
for _, state := range q.state.epochs {
state.setState(stateNew)
}
// Fill the gaps between epochs.
start, err := q.state.lowestEpoch()
if err != nil {
return es.state, err
}
end, err := q.state.highestEpoch()
if err != nil {
return es.state, err
}
for i := start; i < end; i++ {
if _, ok := q.state.findEpochState(i); !ok {
q.state.addEpochState(i)
}
}
return stateNew, nil
}
// Extend sliding window.
nonSkippedSlot, err := q.blocksFetcher.nonSkippedSlotAfter(ctx, helpers.StartSlot(highestEpoch+1))
if err != nil {
return es.state, err
}
if nonSkippedSlot > q.highestExpectedSlot {
return es.state, nil
}
q.state.addEpochState(helpers.SlotToEpoch(nonSkippedSlot))
return stateSkippedExt, nil
}
}
// onCheckStaleEvent is an event that allows to mark stale epochs,
// so that they can be re-processed.
func (q *blocksQueue) onCheckStaleEvent(ctx context.Context) eventHandlerFn {
return func(es *epochState, in interface{}) (stateID, error) {
if ctx.Err() != nil {
return es.state, ctx.Err()
}
if time.Since(es.updated) > staleEpochTimeout {
return stateSkipped, nil
}
return es.state, nil
}
}