eth, eth/fetcher: separate notification sync mechanism
This commit is contained in:
Péter Szilágyi
258
eth/fetcher/fetcher.go
Normal file
258
eth/fetcher/fetcher.go
Normal file
@ -0,0 +1,258 @@
|
||||
// Package fetcher contains the block announcement based synchonisation.
|
||||
package fetcher
|
||||
|
||||
import (
|
||||
"errors"
|
||||
"math/rand"
|
||||
"time"
|
||||
|
||||
"github.com/ethereum/go-ethereum/common"
|
||||
"github.com/ethereum/go-ethereum/core/types"
|
||||
"github.com/ethereum/go-ethereum/logger"
|
||||
"github.com/ethereum/go-ethereum/logger/glog"
|
||||
)
|
||||
|
||||
const (
|
||||
arriveTimeout = 500 * time.Millisecond // Time allowance before an announced block is explicitly requested
|
||||
fetchTimeout = 5 * time.Second // Maximum alloted time to return an explicitly requested block
|
||||
)
|
||||
|
||||
var (
|
||||
errTerminated = errors.New("terminated")
|
||||
)
|
||||
|
||||
// hashCheckFn is a callback type for verifying a hash's presence in the local chain.
|
||||
type hashCheckFn func(common.Hash) bool
|
||||
|
||||
// blockRequesterFn is a callback type for sending a block retrieval request.
|
||||
type blockRequesterFn func([]common.Hash) error
|
||||
|
||||
// blockImporterFn is a callback type for trying to inject a block into the local chain.
|
||||
type blockImporterFn func(peer string, block *types.Block) error
|
||||
|
||||
// announce is the hash notification of the availability of a new block in the
|
||||
// network.
|
||||
type announce struct {
|
||||
hash common.Hash // Hash of the block being announced
|
||||
time time.Time // Timestamp of the announcement
|
||||
|
||||
origin string // Identifier of the peer originating the notification
|
||||
fetch blockRequesterFn // Fetcher function to retrieve
|
||||
}
|
||||
|
||||
// Fetcher is responsible for accumulating block announcements from various peers
|
||||
// and scheduling them for retrieval.
|
||||
type Fetcher struct {
|
||||
// Various event channels
|
||||
notify chan *announce
|
||||
filter chan chan []*types.Block
|
||||
quit chan struct{}
|
||||
|
||||
// Callbacks
|
||||
hasBlock hashCheckFn // Checks if a block is present in the chain
|
||||
importBlock blockImporterFn // Injects a block from an origin peer into the chain
|
||||
}
|
||||
|
||||
// New creates a block fetcher to retrieve blocks based on hash announcements.
|
||||
func New(hasBlock hashCheckFn, importBlock blockImporterFn) *Fetcher {
|
||||
return &Fetcher{
|
||||
notify: make(chan *announce),
|
||||
filter: make(chan chan []*types.Block),
|
||||
quit: make(chan struct{}),
|
||||
hasBlock: hasBlock,
|
||||
importBlock: importBlock,
|
||||
}
|
||||
}
|
||||
|
||||
// Start boots up the announcement based synchoniser, accepting and processing
|
||||
// hash notifications and block fetches until termination requested.
|
||||
func (f *Fetcher) Start() {
|
||||
go f.loop()
|
||||
}
|
||||
|
||||
// Stop terminates the announcement based synchroniser, canceling all pending
|
||||
// operations.
|
||||
func (f *Fetcher) Stop() {
|
||||
close(f.quit)
|
||||
}
|
||||
|
||||
// Notify announces the fetcher of the potential availability of a new block in
|
||||
// the network.
|
||||
func (f *Fetcher) Notify(peer string, hash common.Hash, time time.Time, fetcher blockRequesterFn) error {
|
||||
block := &announce{
|
||||
hash: hash,
|
||||
time: time,
|
||||
origin: peer,
|
||||
fetch: fetcher,
|
||||
}
|
||||
select {
|
||||
case f.notify <- block:
|
||||
return nil
|
||||
case <-f.quit:
|
||||
return errTerminated
|
||||
}
|
||||
}
|
||||
|
||||
// Filter extracts all the blocks that were explicitly requested by the fetcher,
|
||||
// returning those that should be handled differently.
|
||||
func (f *Fetcher) Filter(blocks types.Blocks) types.Blocks {
|
||||
// Send the filter channel to the fetcher
|
||||
filter := make(chan []*types.Block)
|
||||
|
||||
select {
|
||||
case f.filter <- filter:
|
||||
case <-f.quit:
|
||||
return nil
|
||||
}
|
||||
// Request the filtering of the block list
|
||||
select {
|
||||
case filter <- blocks:
|
||||
case <-f.quit:
|
||||
return nil
|
||||
}
|
||||
// Retrieve the blocks remaining after filtering
|
||||
select {
|
||||
case blocks := <-filter:
|
||||
return blocks
|
||||
case <-f.quit:
|
||||
return nil
|
||||
}
|
||||
}
|
||||
|
||||
// Loop is the main fetcher loop, checking and processing various notification
|
||||
// events.
|
||||
func (f *Fetcher) loop() {
|
||||
announced := make(map[common.Hash][]*announce)
|
||||
fetching := make(map[common.Hash]*announce)
|
||||
fetch := time.NewTimer(0)
|
||||
done := make(chan common.Hash)
|
||||
|
||||
// Iterate the block fetching until a quit is requested
|
||||
for {
|
||||
// Clean up any expired block fetches
|
||||
for hash, announce := range fetching {
|
||||
if time.Since(announce.time) > fetchTimeout {
|
||||
delete(announced, hash)
|
||||
delete(fetching, hash)
|
||||
}
|
||||
}
|
||||
// Wait for an outside event to occur
|
||||
select {
|
||||
case <-f.quit:
|
||||
// Fetcher terminating, abort all operations
|
||||
return
|
||||
|
||||
case notification := <-f.notify:
|
||||
// A block was announced, schedule if it's not yet downloading
|
||||
glog.V(logger.Debug).Infof("Peer %s: scheduling %x", notification.origin, notification.hash[:4])
|
||||
if _, ok := fetching[notification.hash]; ok {
|
||||
break
|
||||
}
|
||||
if len(announced) == 0 {
|
||||
fetch.Reset(arriveTimeout)
|
||||
}
|
||||
announced[notification.hash] = append(announced[notification.hash], notification)
|
||||
|
||||
case hash := <-done:
|
||||
// A pending import finished, remove all traces of the notification
|
||||
delete(announced, hash)
|
||||
delete(fetching, hash)
|
||||
|
||||
case <-fetch.C:
|
||||
// At least one block's timer ran out, check for needing retrieval
|
||||
request := make(map[string][]common.Hash)
|
||||
|
||||
for hash, announces := range announced {
|
||||
if time.Since(announces[0].time) > arriveTimeout {
|
||||
announce := announces[rand.Intn(len(announces))]
|
||||
if !f.hasBlock(hash) {
|
||||
request[announce.origin] = append(request[announce.origin], hash)
|
||||
fetching[hash] = announce
|
||||
}
|
||||
delete(announced, hash)
|
||||
}
|
||||
}
|
||||
// Send out all block requests
|
||||
for peer, hashes := range request {
|
||||
glog.V(logger.Debug).Infof("Peer %s: explicitly fetching %d blocks", peer, len(hashes))
|
||||
go fetching[hashes[0]].fetch(hashes)
|
||||
}
|
||||
// Schedule the next fetch if blocks are still pending
|
||||
if len(announced) > 0 {
|
||||
nearest := time.Now()
|
||||
for _, announces := range announced {
|
||||
if nearest.Before(announces[0].time) {
|
||||
nearest = announces[0].time
|
||||
}
|
||||
}
|
||||
fetch.Reset(arriveTimeout + time.Since(nearest))
|
||||
}
|
||||
|
||||
case filter := <-f.filter:
|
||||
// Blocks arrived, extract any explicit fetches, return all else
|
||||
var blocks types.Blocks
|
||||
select {
|
||||
case blocks = <-filter:
|
||||
case <-f.quit:
|
||||
return
|
||||
}
|
||||
|
||||
explicit, download := []*types.Block{}, []*types.Block{}
|
||||
for _, block := range blocks {
|
||||
hash := block.Hash()
|
||||
|
||||
// Filter explicitly requested blocks from hash announcements
|
||||
if _, ok := fetching[hash]; ok {
|
||||
// Discard if already imported by other means
|
||||
if !f.hasBlock(hash) {
|
||||
explicit = append(explicit, block)
|
||||
} else {
|
||||
delete(fetching, hash)
|
||||
}
|
||||
} else {
|
||||
download = append(download, block)
|
||||
}
|
||||
}
|
||||
|
||||
select {
|
||||
case filter <- download:
|
||||
case <-f.quit:
|
||||
return
|
||||
}
|
||||
// Create a closure with the retrieved blocks and origin peers
|
||||
peers := make([]string, 0, len(explicit))
|
||||
blocks = make([]*types.Block, 0, len(explicit))
|
||||
for _, block := range explicit {
|
||||
hash := block.Hash()
|
||||
if announce := fetching[hash]; announce != nil {
|
||||
// Drop the block if it surely cannot fit
|
||||
if f.hasBlock(hash) || !f.hasBlock(block.ParentHash()) {
|
||||
// delete(fetching, hash) // if we drop, it will re-fetch it, wait for timeout?
|
||||
continue
|
||||
}
|
||||
// Otherwise accumulate for import
|
||||
peers = append(peers, announce.origin)
|
||||
blocks = append(blocks, block)
|
||||
}
|
||||
}
|
||||
// If any explicit fetches were replied to, import them
|
||||
if count := len(blocks); count > 0 {
|
||||
glog.V(logger.Debug).Infof("Importing %d explicitly fetched blocks", len(blocks))
|
||||
go func() {
|
||||
// Make sure all hashes are cleaned up
|
||||
for _, block := range blocks {
|
||||
hash := block.Hash()
|
||||
defer func() { done <- hash }()
|
||||
}
|
||||
// Try and actually import the blocks
|
||||
for i := 0; i < len(blocks); i++ {
|
||||
if err := f.importBlock(peers[i], blocks[i]); err != nil {
|
||||
glog.V(logger.Detail).Infof("Failed to import explicitly fetched block: %v", err)
|
||||
return
|
||||
}
|
||||
}
|
||||
}()
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user