// Copyright 2018 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/>.
package stream
import (
"context"
"strconv"
"time"
"github.com/ethereum/go-ethereum/swarm/chunk"
"github.com/ethereum/go-ethereum/swarm/storage"
)
const (
BatchSize = 128
)
// SwarmSyncerServer implements an Server for history syncing on bins
// offered streams:
// * live request delivery with or without checkback
// * (live/non-live historical) chunk syncing per proximity bin
type SwarmSyncerServer struct {
po uint8
netStore *storage.NetStore
quit chan struct{}
}
// NewSwarmSyncerServer is constructor for SwarmSyncerServer
func NewSwarmSyncerServer(po uint8, netStore *storage.NetStore) (*SwarmSyncerServer, error) {
return &SwarmSyncerServer{
po: po,
netStore: netStore,
quit: make(chan struct{}),
}, nil
}
func RegisterSwarmSyncerServer(streamer *Registry, netStore *storage.NetStore) {
streamer.RegisterServerFunc("SYNC", func(_ *Peer, t string, _ bool) (Server, error) {
po, err := ParseSyncBinKey(t)
if err != nil {
return nil, err
}
return NewSwarmSyncerServer(po, netStore)
})
// streamer.RegisterServerFunc(stream, func(p *Peer) (Server, error) {
// return NewOutgoingProvableSwarmSyncer(po, db)
// })
}
// Close needs to be called on a stream server
func (s *SwarmSyncerServer) Close() {
close(s.quit)
}
// GetData retrieves the actual chunk from netstore
func (s *SwarmSyncerServer) GetData(ctx context.Context, key []byte) ([]byte, error) {
ch, err := s.netStore.Get(ctx, chunk.ModeGetSync, storage.Address(key))
if err != nil {
return nil, err
}
return ch.Data(), nil
}
// SessionIndex returns current storage bin (po) index.
func (s *SwarmSyncerServer) SessionIndex() (uint64, error) {
return s.netStore.LastPullSubscriptionBinID(s.po)
}
// SetNextBatch retrieves the next batch of hashes from the localstore.
// It expects a range of bin IDs, both ends inclusive in syncing, and returns
// concatenated byte slice of chunk addresses and bin IDs of the first and
// the last one in that slice. The batch may have up to BatchSize number of
// chunk addresses. If at least one chunk is added to the batch and no new chunks
// are added in batchTimeout period, the batch will be returned. This function
// will block until new chunks are received from localstore pull subscription.
func (s *SwarmSyncerServer) SetNextBatch(from, to uint64) ([]byte, uint64, uint64, *HandoverProof, error) {
//TODO: maybe add unit test for intervals usage in netstore/localstore together with SwarmSyncerServer?
if from > 0 {
from--
}
descriptors, stop := s.netStore.SubscribePull(context.Background(), s.po, from, to)
defer stop()
const batchTimeout = 2 * time.Second
var (
batch []byte
batchSize int
batchStartID *uint64
batchEndID uint64
timer *time.Timer
timerC <-chan time.Time
)
defer func() {
if timer != nil {
timer.Stop()
}
}()
for iterate := true; iterate; {
select {
case d, ok := <-descriptors:
if !ok {
iterate = false
break
}
batch = append(batch, d.Address[:]...)
// This is the most naive approach to label the chunk as synced
// allowing it to be garbage collected. A proper way requires
// validating that the chunk is successfully stored by the peer.
err := s.netStore.Set(context.Background(), chunk.ModeSetSync, d.Address)
if err != nil {
return nil, 0, 0, nil, err
}
batchSize++
if batchStartID == nil {
// set batch start id only if
// this is the first iteration
batchStartID = &d.BinID
}
batchEndID = d.BinID
if batchSize >= BatchSize {
iterate = false
}
if timer == nil {
timer = time.NewTimer(batchTimeout)
} else {
if !timer.Stop() {
<-timer.C
}
timer.Reset(batchTimeout)
}
timerC = timer.C
case <-timerC:
// return batch if new chunks are not
// received after some time
iterate = false
case <-s.quit:
iterate = false
}
}
if batchStartID == nil {
// if batch start id is not set, return 0
batchStartID = new(uint64)
}
return batch, *batchStartID, batchEndID, nil, nil
}
// SwarmSyncerClient
type SwarmSyncerClient struct {
netStore *storage.NetStore
peer *Peer
stream Stream
}
// NewSwarmSyncerClient is a contructor for provable data exchange syncer
func NewSwarmSyncerClient(p *Peer, netStore *storage.NetStore, stream Stream) (*SwarmSyncerClient, error) {
return &SwarmSyncerClient{
netStore: netStore,
peer: p,
stream: stream,
}, nil
}
// RegisterSwarmSyncerClient registers the client constructor function for
// to handle incoming sync streams
func RegisterSwarmSyncerClient(streamer *Registry, netStore *storage.NetStore) {
streamer.RegisterClientFunc("SYNC", func(p *Peer, t string, live bool) (Client, error) {
return NewSwarmSyncerClient(p, netStore, NewStream("SYNC", t, live))
})
}
// NeedData
func (s *SwarmSyncerClient) NeedData(ctx context.Context, key []byte) (wait func(context.Context) error) {
return s.netStore.FetchFunc(ctx, key)
}
// BatchDone
func (s *SwarmSyncerClient) BatchDone(stream Stream, from uint64, hashes []byte, root []byte) func() (*TakeoverProof, error) {
// TODO: reenable this with putter/getter refactored code
// if s.chunker != nil {
// return func() (*TakeoverProof, error) { return s.TakeoverProof(stream, from, hashes, root) }
// }
return nil
}
func (s *SwarmSyncerClient) Close() {}
// base for parsing and formating sync bin key
// it must be 2 <= base <= 36
const syncBinKeyBase = 36
// FormatSyncBinKey returns a string representation of
// Kademlia bin number to be used as key for SYNC stream.
func FormatSyncBinKey(bin uint8) string {
return strconv.FormatUint(uint64(bin), syncBinKeyBase)
}
// ParseSyncBinKey parses the string representation
// and returns the Kademlia bin number.
func ParseSyncBinKey(s string) (uint8, error) {
bin, err := strconv.ParseUint(s, syncBinKeyBase, 8)
if err != nil {
return 0, err
}
return uint8(bin), nil
}
