aboutsummaryrefslogtreecommitdiffstats
path: root/eth/downloader/peer.go
blob: c4846194ba854c9b72622eb7da54cd9d6d70d14b (plain) (blame)
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
// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

// Contains the active peer-set of the downloader, maintaining both failures
// as well as reputation metrics to prioritize the block retrievals.

package downloader

import (
    "errors"
    "fmt"
    "math"
    "sync"
    "sync/atomic"
    "time"

    "github.com/ethereum/go-ethereum/common"
)

const (
    maxLackingHashes = 4096 // Maximum number of entries allowed on the list or lacking items
    throughputImpact = 0.1  // The impact a single measurement has on a peer's final throughput value.
)

// Hash and block fetchers belonging to eth/61 and below
type relativeHashFetcherFn func(common.Hash) error
type absoluteHashFetcherFn func(uint64, int) error
type blockFetcherFn func([]common.Hash) error

// Block header and body fetchers belonging to eth/62 and above
type relativeHeaderFetcherFn func(common.Hash, int, int, bool) error
type absoluteHeaderFetcherFn func(uint64, int, int, bool) error
type blockBodyFetcherFn func([]common.Hash) error
type receiptFetcherFn func([]common.Hash) error
type stateFetcherFn func([]common.Hash) error

var (
    errAlreadyFetching   = errors.New("already fetching blocks from peer")
    errAlreadyRegistered = errors.New("peer is already registered")
    errNotRegistered     = errors.New("peer is not registered")
)

// peer represents an active peer from which hashes and blocks are retrieved.
type peer struct {
    id   string      // Unique identifier of the peer
    head common.Hash // Hash of the peers latest known block

    blockIdle   int32 // Current block activity state of the peer (idle = 0, active = 1)
    receiptIdle int32 // Current receipt activity state of the peer (idle = 0, active = 1)
    stateIdle   int32 // Current node data activity state of the peer (idle = 0, active = 1)

    blockThroughput   float64 // Number of blocks (bodies) measured to be retrievable per second
    receiptThroughput float64 // Number of receipts measured to be retrievable per second
    stateThroughput   float64 // Number of node data pieces measured to be retrievable per second

    blockStarted   time.Time // Time instance when the last block (body)fetch was started
    receiptStarted time.Time // Time instance when the last receipt fetch was started
    stateStarted   time.Time // Time instance when the last node data fetch was started

    lacking map[common.Hash]struct{} // Set of hashes not to request (didn't have previously)

    getRelHashes relativeHashFetcherFn // [eth/61] Method to retrieve a batch of hashes from an origin hash
    getAbsHashes absoluteHashFetcherFn // [eth/61] Method to retrieve a batch of hashes from an absolute position
    getBlocks    blockFetcherFn        // [eth/61] Method to retrieve a batch of blocks

    getRelHeaders  relativeHeaderFetcherFn // [eth/62] Method to retrieve a batch of headers from an origin hash
    getAbsHeaders  absoluteHeaderFetcherFn // [eth/62] Method to retrieve a batch of headers from an absolute position
    getBlockBodies blockBodyFetcherFn      // [eth/62] Method to retrieve a batch of block bodies

    getReceipts receiptFetcherFn // [eth/63] Method to retrieve a batch of block transaction receipts
    getNodeData stateFetcherFn   // [eth/63] Method to retrieve a batch of state trie data

    version int // Eth protocol version number to switch strategies
    lock    sync.RWMutex
}

// newPeer create a new downloader peer, with specific hash and block retrieval
// mechanisms.
func newPeer(id string, version int, head common.Hash,
    getRelHashes relativeHashFetcherFn, getAbsHashes absoluteHashFetcherFn, getBlocks blockFetcherFn, // eth/61 callbacks, remove when upgrading
    getRelHeaders relativeHeaderFetcherFn, getAbsHeaders absoluteHeaderFetcherFn, getBlockBodies blockBodyFetcherFn,
    getReceipts receiptFetcherFn, getNodeData stateFetcherFn) *peer {
    return &peer{
        id:      id,
        head:    head,
        lacking: make(map[common.Hash]struct{}),

        getRelHashes: getRelHashes,
        getAbsHashes: getAbsHashes,
        getBlocks:    getBlocks,

        getRelHeaders:  getRelHeaders,
        getAbsHeaders:  getAbsHeaders,
        getBlockBodies: getBlockBodies,

        getReceipts: getReceipts,
        getNodeData: getNodeData,

        version: version,
    }
}

// Reset clears the internal state of a peer entity.
func (p *peer) Reset() {
    p.lock.Lock()
    defer p.lock.Unlock()

    atomic.StoreInt32(&p.blockIdle, 0)
    atomic.StoreInt32(&p.receiptIdle, 0)
    atomic.StoreInt32(&p.stateIdle, 0)

    p.blockThroughput = 0
    p.receiptThroughput = 0
    p.stateThroughput = 0

    p.lacking = make(map[common.Hash]struct{})
}

// Fetch61 sends a block retrieval request to the remote peer.
func (p *peer) Fetch61(request *fetchRequest) error {
    // Sanity check the protocol version
    if p.version != 61 {
        panic(fmt.Sprintf("block fetch [eth/61] requested on eth/%d", p.version))
    }
    // Short circuit if the peer is already fetching
    if !atomic.CompareAndSwapInt32(&p.blockIdle, 0, 1) {
        return errAlreadyFetching
    }
    p.blockStarted = time.Now()

    // Convert the hash set to a retrievable slice
    hashes := make([]common.Hash, 0, len(request.Hashes))
    for hash, _ := range request.Hashes {
        hashes = append(hashes, hash)
    }
    go p.getBlocks(hashes)

    return nil
}

// FetchBodies sends a block body retrieval request to the remote peer.
func (p *peer) FetchBodies(request *fetchRequest) error {
    // Sanity check the protocol version
    if p.version < 62 {
        panic(fmt.Sprintf("body fetch [eth/62+] requested on eth/%d", p.version))
    }
    // Short circuit if the peer is already fetching
    if !atomic.CompareAndSwapInt32(&p.blockIdle, 0, 1) {
        return errAlreadyFetching
    }
    p.blockStarted = time.Now()

    // Convert the header set to a retrievable slice
    hashes := make([]common.Hash, 0, len(request.Headers))
    for _, header := range request.Headers {
        hashes = append(hashes, header.Hash())
    }
    go p.getBlockBodies(hashes)

    return nil
}

// FetchReceipts sends a receipt retrieval request to the remote peer.
func (p *peer) FetchReceipts(request *fetchRequest) error {
    // Sanity check the protocol version
    if p.version < 63 {
        panic(fmt.Sprintf("body fetch [eth/63+] requested on eth/%d", p.version))
    }
    // Short circuit if the peer is already fetching
    if !atomic.CompareAndSwapInt32(&p.receiptIdle, 0, 1) {
        return errAlreadyFetching
    }
    p.receiptStarted = time.Now()

    // Convert the header set to a retrievable slice
    hashes := make([]common.Hash, 0, len(request.Headers))
    for _, header := range request.Headers {
        hashes = append(hashes, header.Hash())
    }
    go p.getReceipts(hashes)

    return nil
}

// FetchNodeData sends a node state data retrieval request to the remote peer.
func (p *peer) FetchNodeData(request *fetchRequest) error {
    // Sanity check the protocol version
    if p.version < 63 {
        panic(fmt.Sprintf("node data fetch [eth/63+] requested on eth/%d", p.version))
    }
    // Short circuit if the peer is already fetching
    if !atomic.CompareAndSwapInt32(&p.stateIdle, 0, 1) {
        return errAlreadyFetching
    }
    p.stateStarted = time.Now()

    // Convert the hash set to a retrievable slice
    hashes := make([]common.Hash, 0, len(request.Hashes))
    for hash, _ := range request.Hashes {
        hashes = append(hashes, hash)
    }
    go p.getNodeData(hashes)

    return nil
}

// SetBlocksIdle sets the peer to idle, allowing it to execute new block retrieval
// requests. Its estimated block retrieval throughput is updated with that measured
// just now.
func (p *peer) SetBlocksIdle(delivered int) {
    p.setIdle(p.blockStarted, delivered, &p.blockThroughput, &p.blockIdle)
}

// SetBodiesIdle sets the peer to idle, allowing it to execute block body retrieval
// requests. Its estimated body retrieval throughput is updated with that measured
// just now.
func (p *peer) SetBodiesIdle(delivered int) {
    p.setIdle(p.blockStarted, delivered, &p.blockThroughput, &p.blockIdle)
}

// SetReceiptsIdle sets the peer to idle, allowing it to execute new receipt
// retrieval requests. Its estimated receipt retrieval throughput is updated
// with that measured just now.
func (p *peer) SetReceiptsIdle(delivered int) {
    p.setIdle(p.receiptStarted, delivered, &p.receiptThroughput, &p.receiptIdle)
}

// SetNodeDataIdle sets the peer to idle, allowing it to execute new state trie
// data retrieval requests. Its estimated state retrieval throughput is updated
// with that measured just now.
func (p *peer) SetNodeDataIdle(delivered int) {
    p.setIdle(p.stateStarted, delivered, &p.stateThroughput, &p.stateIdle)
}

// setIdle sets the peer to idle, allowing it to execute new retrieval requests.
// Its estimated retrieval throughput is updated with that measured just now.
func (p *peer) setIdle(started time.Time, delivered int, throughput *float64, idle *int32) {
    // Irrelevant of the scaling, make sure the peer ends up idle
    defer atomic.StoreInt32(idle, 0)

    p.lock.Lock()
    defer p.lock.Unlock()

    // If nothing was delivered (hard timeout / unavailable data), reduce throughput to minimum
    if delivered == 0 {
        *throughput = 0
        return
    }
    // Otherwise update the throughput with a new measurement
    measured := float64(delivered) / (float64(time.Since(started)+1) / float64(time.Second)) // +1 (ns) to ensure non-zero divisor
    *throughput = (1-throughputImpact)*(*throughput) + throughputImpact*measured
}

// BlockCapacity retrieves the peers block download allowance based on its
// previously discovered throughput.
func (p *peer) BlockCapacity() int {
    p.lock.RLock()
    defer p.lock.RUnlock()

    return int(math.Max(1, math.Min(p.blockThroughput*float64(blockTargetRTT)/float64(time.Second), float64(MaxBlockFetch))))
}

// ReceiptCapacity retrieves the peers receipt download allowance based on its
// previously discovered throughput.
func (p *peer) ReceiptCapacity() int {
    p.lock.RLock()
    defer p.lock.RUnlock()

    return int(math.Max(1, math.Min(p.receiptThroughput*float64(receiptTargetRTT)/float64(time.Second), float64(MaxReceiptFetch))))
}

// NodeDataCapacity retrieves the peers state download allowance based on its
// previously discovered throughput.
func (p *peer) NodeDataCapacity() int {
    p.lock.RLock()
    defer p.lock.RUnlock()

    return int(math.Max(1, math.Min(p.stateThroughput*float64(stateTargetRTT)/float64(time.Second), float64(MaxStateFetch))))
}

// MarkLacking appends a new entity to the set of items (blocks, receipts, states)
// that a peer is known not to have (i.e. have been requested before). If the
// set reaches its maximum allowed capacity, items are randomly dropped off.
func (p *peer) MarkLacking(hash common.Hash) {
    p.lock.Lock()
    defer p.lock.Unlock()

    for len(p.lacking) >= maxLackingHashes {
        for drop, _ := range p.lacking {
            delete(p.lacking, drop)
            break
        }
    }
    p.lacking[hash] = struct{}{}
}

// Lacks retrieves whether the hash of a blockchain item is on the peers lacking
// list (i.e. whether we know that the peer does not have it).
func (p *peer) Lacks(hash common.Hash) bool {
    p.lock.RLock()
    defer p.lock.RUnlock()

    _, ok := p.lacking[hash]
    return ok
}

// String implements fmt.Stringer.
func (p *peer) String() string {
    p.lock.RLock()
    defer p.lock.RUnlock()

    return fmt.Sprintf("Peer %s [%s]", p.id,
        fmt.Sprintf("blocks %3.2f/s, ", p.blockThroughput)+
            fmt.Sprintf("receipts %3.2f/s, ", p.receiptThroughput)+
            fmt.Sprintf("states %3.2f/s, ", p.stateThroughput)+
            fmt.Sprintf("lacking %4d", len(p.lacking)),
    )
}

// peerSet represents the collection of active peer participating in the block
// download procedure.
type peerSet struct {
    peers map[string]*peer
    lock  sync.RWMutex
}

// newPeerSet creates a new peer set top track the active download sources.
func newPeerSet() *peerSet {
    return &peerSet{
        peers: make(map[string]*peer),
    }
}

// Reset iterates over the current peer set, and resets each of the known peers
// to prepare for a next batch of block retrieval.
func (ps *peerSet) Reset() {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    for _, peer := range ps.peers {
        peer.Reset()
    }
}

// Register injects a new peer into the working set, or returns an error if the
// peer is already known.
//
// The method also sets the starting throughput values of the new peer to the
// average of all existing peers, to give it a realistic change of being used
// for data retrievals.
func (ps *peerSet) Register(p *peer) error {
    ps.lock.Lock()
    defer ps.lock.Unlock()

    if _, ok := ps.peers[p.id]; ok {
        return errAlreadyRegistered
    }
    if len(ps.peers) > 0 {
        p.blockThroughput, p.receiptThroughput, p.stateThroughput = 0, 0, 0

        for _, peer := range ps.peers {
            peer.lock.RLock()
            p.blockThroughput += peer.blockThroughput
            p.receiptThroughput += peer.receiptThroughput
            p.stateThroughput += peer.stateThroughput
            peer.lock.RUnlock()
        }
        p.blockThroughput /= float64(len(ps.peers))
        p.receiptThroughput /= float64(len(ps.peers))
        p.stateThroughput /= float64(len(ps.peers))
    }
    ps.peers[p.id] = p
    return nil
}

// Unregister removes a remote peer from the active set, disabling any further
// actions to/from that particular entity.
func (ps *peerSet) Unregister(id string) error {
    ps.lock.Lock()
    defer ps.lock.Unlock()

    if _, ok := ps.peers[id]; !ok {
        return errNotRegistered
    }
    delete(ps.peers, id)
    return nil
}

// Peer retrieves the registered peer with the given id.
func (ps *peerSet) Peer(id string) *peer {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    return ps.peers[id]
}

// Len returns if the current number of peers in the set.
func (ps *peerSet) Len() int {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    return len(ps.peers)
}

// AllPeers retrieves a flat list of all the peers within the set.
func (ps *peerSet) AllPeers() []*peer {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    list := make([]*peer, 0, len(ps.peers))
    for _, p := range ps.peers {
        list = append(list, p)
    }
    return list
}

// BlockIdlePeers retrieves a flat list of all the currently idle peers within the
// active peer set, ordered by their reputation.
func (ps *peerSet) BlockIdlePeers() ([]*peer, int) {
    idle := func(p *peer) bool {
        return atomic.LoadInt32(&p.blockIdle) == 0
    }
    throughput := func(p *peer) float64 {
        p.lock.RLock()
        defer p.lock.RUnlock()
        return p.blockThroughput
    }
    return ps.idlePeers(61, 61, idle, throughput)
}

// BodyIdlePeers retrieves a flat list of all the currently body-idle peers within
// the active peer set, ordered by their reputation.
func (ps *peerSet) BodyIdlePeers() ([]*peer, int) {
    idle := func(p *peer) bool {
        return atomic.LoadInt32(&p.blockIdle) == 0
    }
    throughput := func(p *peer) float64 {
        p.lock.RLock()
        defer p.lock.RUnlock()
        return p.blockThroughput
    }
    return ps.idlePeers(62, 64, idle, throughput)
}

// ReceiptIdlePeers retrieves a flat list of all the currently receipt-idle peers
// within the active peer set, ordered by their reputation.
func (ps *peerSet) ReceiptIdlePeers() ([]*peer, int) {
    idle := func(p *peer) bool {
        return atomic.LoadInt32(&p.receiptIdle) == 0
    }
    throughput := func(p *peer) float64 {
        p.lock.RLock()
        defer p.lock.RUnlock()
        return p.receiptThroughput
    }
    return ps.idlePeers(63, 64, idle, throughput)
}

// NodeDataIdlePeers retrieves a flat list of all the currently node-data-idle
// peers within the active peer set, ordered by their reputation.
func (ps *peerSet) NodeDataIdlePeers() ([]*peer, int) {
    idle := func(p *peer) bool {
        return atomic.LoadInt32(&p.stateIdle) == 0
    }
    throughput := func(p *peer) float64 {
        p.lock.RLock()
        defer p.lock.RUnlock()
        return p.stateThroughput
    }
    return ps.idlePeers(63, 64, idle, throughput)
}

// idlePeers retrieves a flat list of all currently idle peers satisfying the
// protocol version constraints, using the provided function to check idleness.
// The resulting set of peers are sorted by their measure throughput.
func (ps *peerSet) idlePeers(minProtocol, maxProtocol int, idleCheck func(*peer) bool, throughput func(*peer) float64) ([]*peer, int) {
    ps.lock.RLock()
    defer ps.lock.RUnlock()

    idle, total := make([]*peer, 0, len(ps.peers)), 0
    for _, p := range ps.peers {
        if p.version >= minProtocol && p.version <= maxProtocol {
            if idleCheck(p) {
                idle = append(idle, p)
            }
            total++
        }
    }
    for i := 0; i < len(idle); i++ {
        for j := i + 1; j < len(idle); j++ {
            if throughput(idle[i]) < throughput(idle[j]) {
                idle[i], idle[j] = idle[j], idle[i]
            }
        }
    }
    return idle, total
}