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fastsync.go
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fastsync.go
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package blockchain
import (
"encoding/binary"
"errors"
"fmt"
"github.com/btcsuite/go-socks/socks"
"github.com/gcash/bchd/bchec"
"github.com/gcash/bchd/chaincfg"
"github.com/gcash/bchd/chaincfg/chainhash"
"github.com/gcash/bchd/wire"
"io"
"math"
"net"
"net/http"
"os"
"path"
"time"
)
const numWorkers = 8
// fastSyncUtxoSet will download the UTXO set from the sources provided in the checkpoint. Each
// UTXO will be saved to the database and the ECMH hash of the UTXO set will be validated against
// the checkpoint. If a proxyAddr is provided it will use that proxy for the HTTP connection.
func (b *BlockChain) fastSyncUtxoSet(checkpoint *chaincfg.Checkpoint, proxyAddr string) error {
// If the UTXO set is already caught up with the last checkpoint then
// we can just close the done chan and exit.
if b.utxoCache.lastFlushHash.IsEqual(checkpoint.Hash) {
close(b.fastSyncDone)
return nil
}
if checkpoint.UtxoSetHash == nil {
return AssertError("cannot perform fast sync with nil UTXO set hash")
}
if len(checkpoint.UtxoSetSources) == 0 {
return AssertError("no UTXO download sources provided")
}
if checkpoint.UtxoSetSize == 0 {
return AssertError("expected UTXO set size is zero")
}
var proxy *socks.Proxy
if proxyAddr != "" {
proxy = &socks.Proxy{Addr: proxyAddr}
}
tmpPath := path.Join(os.TempDir(), "bchd-utxo.dat")
err := downloadUtxoSet(checkpoint.UtxoSetSources, proxy, tmpPath)
if err != nil {
log.Errorf("Error downloading UTXO set: %s", err.Error())
return err
}
file, err := os.Open(tmpPath)
if err != nil {
log.Errorf("Error opening temp UTXO file: %s", err.Error())
return err
}
defer func() {
file.Close()
os.Remove(tmpPath)
}()
var (
maxScriptLen = uint32(1000000)
buf52 = make([]byte, 52)
pkScript []byte
serializedUtxo []byte
n int
totalRead int
scriptLen uint32
progress float64
progressStr string
)
ticker := time.NewTicker(time.Minute * 5)
defer ticker.Stop()
go func() {
for range ticker.C {
progress = math.Min(float64(totalRead)/float64(checkpoint.UtxoSetSize), 1.0) * 100
progressStr = fmt.Sprintf("%d/%d MiB (%.2f%%)", totalRead/(1024*1024)+1, checkpoint.UtxoSetSize/(1024*1024)+1, progress)
log.Infof("UTXO verification progress: processed %s", progressStr)
}
}()
resultsChan := make(chan *result)
jobsChan := make(chan []byte)
for i := 0; i < numWorkers; i++ {
go worker(b.utxoCache, jobsChan, resultsChan)
}
// In this loop we're going read each serialized UTXO off the reader and then
// pass it off to a worker to deserialize, calculate the ECMH hash, and save
// to the UTXO cache.
for {
// Read the first 52 bytes of the utxo
n, err = file.Read(buf52)
if err == io.EOF { // We've hit the end
break
} else if err != nil {
log.Errorf("Error reading UTXO set: %s", err.Error())
return err
}
totalRead += n
// The last four bytes that we read is the length of the script
scriptLen = binary.LittleEndian.Uint32(buf52[48:])
if scriptLen > maxScriptLen {
log.Error("Read invalid UTXO script length", totalRead)
return errors.New("invalid script length")
}
// Read the script
pkScript = make([]byte, scriptLen)
n, err = file.Read(pkScript)
if err != nil {
log.Errorf("Error reading UTXO set: %s", err.Error())
return err
}
totalRead += n
serializedUtxo = make([]byte, 52+scriptLen)
serializedUtxo = append(buf52, pkScript...)
jobsChan <- serializedUtxo
}
close(jobsChan)
// Read each result and add the returned hash to the
// existing multiset.
m := bchec.NewMultiset(bchec.S256())
for i := 0; i < numWorkers; i++ {
result := <-resultsChan
if result.err != nil {
log.Errorf("Error processing UTXO set: %s", err.Error())
return err
}
m.Merge(result.m)
}
close(resultsChan)
if err = b.utxoCache.Flush(FlushRequired, &BestState{Hash: *checkpoint.Hash}); err != nil {
log.Errorf("Error processing UTXO set: %s", err.Error())
return err
}
if err = b.index.flushToDB(); err != nil {
log.Errorf("Error processing UTXO set: %s", err.Error())
return err
}
utxoHash := m.Hash()
// Make sure the hash of the UTXO set we downloaded matches the expected hash.
if !checkpoint.UtxoSetHash.IsEqual(&utxoHash) {
log.Errorf("Downloaded UTXO set hash does not match checkpoint."+
" Expected %s, got %s.", checkpoint.UtxoSetHash.String(), m.Hash().String())
return AssertError("downloaded invalid UTXO set")
}
log.Infof("Verification complete. UTXO hash %s.", m.Hash().String())
// Signal fastsync complete
close(b.fastSyncDone)
return nil
}
// result holds a multiset with a hash of all the UTXOs read by
// this worker and a possible error.
type result struct {
m *bchec.Multiset
err error
}
// worker handles the work of deserializing the UTXO, calculating the ECMH hash of
// each serialized UTXO as well as saving it into the utxoCache. The resulting
// multiset or an error will be returned over the results chan when the jobs
// chan is closed.
func worker(cache *utxoCache, jobs <-chan []byte, results chan<- *result) {
var (
err error
m = bchec.NewMultiset(bchec.S256())
entry *UtxoEntry
outpoint *wire.OutPoint
state = &BestState{Hash: chainhash.Hash{}}
)
for serializedUtxo := range jobs {
m.Add(serializedUtxo)
outpoint, entry, err = deserializeUtxoCommitmentFormat(serializedUtxo)
if err != nil {
log.Errorf("Error deserializing UTXO: %s", err.Error())
results <- &result{err: err}
return
}
if err = cache.AddEntry(*outpoint, entry, true); err != nil {
results <- &result{err: err}
return
}
if err = cache.Flush(FlushIfNeeded, state); err != nil {
results <- &result{err: err}
return
}
}
results <- &result{m: m}
}
// downloadUtxoSet will attempt to connect to make an HTTP GET request to the
// provided sources one at a time and download the UTXO set to the provided path.
// If a proxy is provided it will use it for the HTTP connection.
func downloadUtxoSet(sources []string, proxy *socks.Proxy, pth string) error {
dialFunc := net.Dial
if proxy != nil {
dialFunc = proxy.Dial
}
tr := &http.Transport{
Dial: dialFunc,
}
client := &http.Client{Transport: tr}
for _, src := range sources {
resp, err := client.Get(src)
if err != nil {
continue
}
if resp.StatusCode != http.StatusOK {
continue
}
file, err := os.Create(pth)
if err != nil {
return err
}
log.Infof("Downloading UTXO set from %s", src)
_, err = io.Copy(file, resp.Body)
if err != nil {
return err
}
log.Info("UTXO download complete. Verifying integrity...")
return file.Close()
}
return AssertError("all UTXO sources are unavailable")
}