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eth/downloader: fetch data proportionally to peer capacity

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This commit is contained in:
Péter Szilágyi
2015-10-29 18:37:26 +02:00
parent 4c2933ad82
commit b6f5523bdc
3 changed files with 257 additions and 245 deletions
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229
eth/downloader/peer.go
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@ -30,8 +30,10 @@ import (
"github.com/ethereum/go-ethereum/common"
)
// Maximum number of entries allowed on the list or lacking items.
const maxLackingHashes = 4096
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
@ -59,18 +61,16 @@ type peer struct {
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)
rep int32 // Simple peer reputation
blockCapacity int32 // Number of blocks (bodies) allowed to fetch per request
receiptCapacity int32 // Number of receipts allowed to fetch per request
stateCapacity int32 // Number of node data pieces allowed to fetch per request
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)
lackingLock sync.RWMutex // Lock protecting the lacking hashes list
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
@ -84,6 +84,7 @@ type peer struct {
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
@ -93,12 +94,9 @@ func newPeer(id string, version int, head common.Hash,
getRelHeaders relativeHeaderFetcherFn, getAbsHeaders absoluteHeaderFetcherFn, getBlockBodies blockBodyFetcherFn,
getReceipts receiptFetcherFn, getNodeData stateFetcherFn) *peer {
return &peer{
id: id,
head: head,
blockCapacity: 1,
receiptCapacity: 1,
stateCapacity: 1,
lacking: make(map[common.Hash]struct{}),
id: id,
head: head,
lacking: make(map[common.Hash]struct{}),
getRelHashes: getRelHashes,
getAbsHashes: getAbsHashes,
@ -117,15 +115,18 @@ func newPeer(id string, version int, head common.Hash,
// 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.blockCapacity, 1)
atomic.StoreInt32(&p.receiptCapacity, 1)
atomic.StoreInt32(&p.stateCapacity, 1)
atomic.StoreInt32(&p.stateIdle, 0)
p.blockThroughput = 0
p.receiptThroughput = 0
p.stateThroughput = 0
p.lackingLock.Lock()
p.lacking = make(map[common.Hash]struct{})
p.lackingLock.Unlock()
}
// Fetch61 sends a block retrieval request to the remote peer.
@ -216,107 +217,86 @@ func (p *peer) FetchNodeData(request *fetchRequest) error {
return nil
}
// SetBlocksIdle sets the peer to idle, allowing it to execute new retrieval requests.
// Its block retrieval allowance will also be updated either up- or downwards,
// depending on whether the previous fetch completed in time.
func (p *peer) SetBlocksIdle() {
p.setIdle(p.blockStarted, blockSoftTTL, blockHardTTL, MaxBlockFetch, &p.blockCapacity, &p.blockIdle)
// 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 new retrieval requests.
// Its block body retrieval allowance will also be updated either up- or downwards,
// depending on whether the previous fetch completed in time.
func (p *peer) SetBodiesIdle() {
p.setIdle(p.blockStarted, bodySoftTTL, bodyHardTTL, MaxBodyFetch, &p.blockCapacity, &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 retrieval requests.
// Its receipt retrieval allowance will also be updated either up- or downwards,
// depending on whether the previous fetch completed in time.
func (p *peer) SetReceiptsIdle() {
p.setIdle(p.receiptStarted, receiptSoftTTL, receiptHardTTL, MaxReceiptFetch, &p.receiptCapacity, &p.receiptIdle)
// 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 retrieval
// requests. Its node data retrieval allowance will also be updated either up- or
// downwards, depending on whether the previous fetch completed in time.
func (p *peer) SetNodeDataIdle() {
p.setIdle(p.stateStarted, stateSoftTTL, stateSoftTTL, MaxStateFetch, &p.stateCapacity, &p.stateIdle)
// 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 data retrieval allowance will also be updated either up- or downwards,
// depending on whether the previous fetch completed in time.
func (p *peer) setIdle(started time.Time, softTTL, hardTTL time.Duration, maxFetch int, capacity, idle *int32) {
// Update the peer's download allowance based on previous performance
scale := 2.0
if time.Since(started) > softTTL {
scale = 0.5
if time.Since(started) > hardTTL {
scale = 1 / float64(maxFetch) // reduces capacity to 1
}
}
for {
// Calculate the new download bandwidth allowance
prev := atomic.LoadInt32(capacity)
next := int32(math.Max(1, math.Min(float64(maxFetch), float64(prev)*scale)))
// 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)
// Try to update the old value
if atomic.CompareAndSwapInt32(capacity, prev, next) {
// If we're having problems at 1 capacity, try to find better peers
if next == 1 {
p.Demote()
}
break
}
p.lock.RLock()
defer p.lock.RUnlock()
// If nothing was delivered (hard timeout / unavailable data), reduce throughput to minimum
if delivered == 0 {
*throughput = 0
return
}
// Set the peer to idle to allow further fetch requests
atomic.StoreInt32(idle, 0)
// 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 bandwidth capacity.
// previously discovered throughput.
func (p *peer) BlockCapacity() int {
return int(atomic.LoadInt32(&p.blockCapacity))
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 block download allowance based on its
// previously discovered bandwidth capacity.
// ReceiptCapacity retrieves the peers receipt download allowance based on its
// previously discovered throughput.
func (p *peer) ReceiptCapacity() int {
return int(atomic.LoadInt32(&p.receiptCapacity))
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 block download allowance based on its
// previously discovered bandwidth capacity.
// NodeDataCapacity retrieves the peers state download allowance based on its
// previously discovered throughput.
func (p *peer) NodeDataCapacity() int {
return int(atomic.LoadInt32(&p.stateCapacity))
}
p.lock.RLock()
defer p.lock.RUnlock()
// Promote increases the peer's reputation.
func (p *peer) Promote() {
atomic.AddInt32(&p.rep, 1)
}
// Demote decreases the peer's reputation or leaves it at 0.
func (p *peer) Demote() {
for {
// Calculate the new reputation value
prev := atomic.LoadInt32(&p.rep)
next := prev / 2
// Try to update the old value
if atomic.CompareAndSwapInt32(&p.rep, prev, next) {
return
}
}
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.lackingLock.Lock()
defer p.lackingLock.Unlock()
p.lock.Lock()
defer p.lock.Unlock()
for len(p.lacking) >= maxLackingHashes {
for drop, _ := range p.lacking {
@ -330,8 +310,8 @@ func (p *peer) MarkLacking(hash common.Hash) {
// 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.lackingLock.RLock()
defer p.lackingLock.RUnlock()
p.lock.RLock()
defer p.lock.RUnlock()
_, ok := p.lacking[hash]
return ok
@ -339,13 +319,13 @@ func (p *peer) Lacks(hash common.Hash) bool {
// String implements fmt.Stringer.
func (p *peer) String() string {
p.lackingLock.RLock()
defer p.lackingLock.RUnlock()
p.lock.RLock()
defer p.lock.RUnlock()
return fmt.Sprintf("Peer %s [%s]", p.id,
fmt.Sprintf("reputation %3d, ", atomic.LoadInt32(&p.rep))+
fmt.Sprintf("block cap %3d, ", atomic.LoadInt32(&p.blockCapacity))+
fmt.Sprintf("receipt cap %3d, ", atomic.LoadInt32(&p.receiptCapacity))+
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)),
)
}
@ -377,6 +357,10 @@ func (ps *peerSet) 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()
@ -384,6 +368,20 @@ func (ps *peerSet) Register(p *peer) error {
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
}
@ -435,7 +433,12 @@ func (ps *peerSet) BlockIdlePeers() ([]*peer, int) {
idle := func(p *peer) bool {
return atomic.LoadInt32(&p.blockIdle) == 0
}
return ps.idlePeers(61, 61, idle)
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
@ -444,7 +447,12 @@ func (ps *peerSet) BodyIdlePeers() ([]*peer, int) {
idle := func(p *peer) bool {
return atomic.LoadInt32(&p.blockIdle) == 0
}
return ps.idlePeers(62, 64, idle)
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
@ -453,7 +461,12 @@ func (ps *peerSet) ReceiptIdlePeers() ([]*peer, int) {
idle := func(p *peer) bool {
return atomic.LoadInt32(&p.receiptIdle) == 0
}
return ps.idlePeers(63, 64, idle)
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
@ -462,12 +475,18 @@ func (ps *peerSet) NodeDataIdlePeers() ([]*peer, int) {
idle := func(p *peer) bool {
return atomic.LoadInt32(&p.stateIdle) == 0
}
return ps.idlePeers(63, 64, idle)
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.
func (ps *peerSet) idlePeers(minProtocol, maxProtocol int, idleCheck func(*peer) bool) ([]*peer, int) {
// 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()
@ -482,7 +501,7 @@ func (ps *peerSet) idlePeers(minProtocol, maxProtocol int, idleCheck func(*peer)
}
for i := 0; i < len(idle); i++ {
for j := i + 1; j < len(idle); j++ {
if atomic.LoadInt32(&idle[i].rep) < atomic.LoadInt32(&idle[j].rep) {
if throughput(idle[i]) < throughput(idle[j]) {
idle[i], idle[j] = idle[j], idle[i]
}
}